Skip read-only check when output file specified

Only check if input files are read-only when overwriting them; skip
that check when the output goes to a different file.

* src/patch.c (main): Set read_only_behavior to RO_IGNORE when an output
file has been specified.
* tests/read-only-files: Add test case.

.gitattributes

@@ -0,0 +1,7 @@
+# Run this to make 'git diff' on texinfo files give nicer hunk context:
+#   git config diff.texinfo.funcname '^@node[	 ][	 ]*\\([^,][^,]*\\)'
+*.texi*	diff=texinfo
+
+# Run this to make 'git diff' on .m4 files give nicer hunk context:
+#   git config diff.m4.xfuncname '^((AC_DEFUN|m4_define)[^,)]*)'
+*.m4	diff=m4

.gitignore

@@ -1,5 +1,7 @@
+*.log
 *.o
--/lib/Makefile.am
+*.trs
+*~
 .deps/
 /.pc/
 /.version
@@ -8,24 +10,25 @@
 /ID
 /INSTALL
 /VERSION
+/[0-9]*.patch
 /aclocal.m4
 /autom4te.cache/
-/build-aux
+/build-aux/
 /config.cache
 /config.h
 /config.hin
 /config.log
 /config.status
 /configure
-/doc
-/lib
+/doc/
+/lib/
+!/lib/Makefile.am
+/m4/*.m4
+/m4/.gitignore
+!/m4/setmode.m4
+!/m4/xattr.m4
 /maint.mk
-/patch-*.tar.bz2
-/patch-*.tar.bz2.sig
-/patch-*.tar.gz
-/patch-*.tar.gz.sig
-/patch-*.tar.xz
-/patch-*.tar.xz.sig
+/patch-*.tar.*
 /src/patch
 /stamp-h1
 Makefile

ChangeLog-2011

@@ -1039,7 +1039,7 @@
 	* tests/asymmetric-hunks: New test case.
 	* Makefile.in (TESTS): Add test case.
 
-	* util.c (move_file): Create backup files of nonexisting files with
+	* util.c (move_file): Create backup files of nonexistent files with
 	the default mode instead of mode 0: files with mode 0 cause too many
 	problems with applications which do not expect unreadable files.
 	* tests/create-delete: Test for this.
@@ -2030,7 +2030,7 @@
 
 	* util.c (move_file): Don't assume that ENOENT is reported when both
 	ENOENT and EXDEV apply; this isn't true with DJGPP, and
-	Posix doesn't require it.
+	POSIX doesn't require it.
 
 	* pch.c (there_is_another_patch):
 	Suggest -p when we can't intuit a file.
@@ -2185,7 +2185,7 @@
 	verbosity.
 	(fetchname): Change argument head_says_nonexistent to pstamp, and
 	store header timestamp into *pstamp.
-	If -T or -Z option is given, match time stamps more precisely.
+	If -T or -Z option is given, match timestamps more precisely.
 	(ask): Remove unnecessary close of ttyfd.
 	When there is no terminal at all, output a newline to make the
 	output look nicer.  After reporting EOF, flush stdout;
@@ -3658,23 +3658,20 @@ Sun Dec 17 17:29:48 1989  Jim Kingdon  (kingdon at hobbes.ai.mit.edu)
 	* patch.c: Initial revision
 
 
-Copyright (C) 1984, 1985, 1986, 1987, 1988 Larry Wall.
-
-Copyright (C) 1989-1993, 1997-2002, 2009-2012 Free Software Foundation, Inc.
+Copyright 1989-2025 Free Software Foundation, Inc.
+Copyright 1984-1988 Larry Wall.
 
 This file is part of GNU Patch.
 
-This program is free software; you can redistribute it and/or modify
+This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 3, or (at your option)
-any later version.
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
 
-This program is distributed in the hope that they will be useful,
+This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
-along with this program; see the file COPYING.  If not, write to
-the Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
-MA 02110-1301, USA.
+along with this program.  If not, see <http://www.gnu.org/licenses/>.

Makefile.am

@@ -1,5 +1,4 @@
-# Copyright (C) 1989-1993, 1997-1999, 2002-2003, 2006, 2009-2012 Free Software
-# Foundation, Inc.
+# Copyright 1989-2025 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -23,17 +22,19 @@ dist_man1_MANS = patch.man
 EXTRA_DIST = \
 	ChangeLog-2011 \
 	cfg.mk \
+	m4/gnulib-cache.m4 \
 	m4/mkdir.m4 \
 	m4/setmode.m4 \
-	m4/utimbuf.m4 \
 	bootstrap \
 	pc
 
 if ALPHA_VERSION
   EXTRA_DIST += README-alpha
   GNU_SERVER = alpha.gnu.org
+  RELEASE_TYPE = alpha
 else
   GNU_SERVER = ftp.gnu.org
+  RELEASE_TYPE = stable
 endif
 
 EXTRA_DIST += $(top_srcdir)/.version
@@ -52,14 +53,3 @@ gen-ChangeLog:
 	  rm -f $(distdir)/ChangeLog;					\
 	  mv $(distdir)/cl-t $(distdir)/ChangeLog;			\
 	fi
-
-tell-upload:
-	echo; \
-	(echo "Upload with: "; \
-	 for archive in $(DIST_ARCHIVES); do \
-	   echo "gnupload --to $(GNU_SERVER):patch $$archive"; \
-	 done) | \
-	 sed -e 1h -e 1s/./=/g -e 1p -e 1x -e '$$p' -e '$$x'; \
-	echo
-upload: dist tell-upload
-uploadcheck: distcheck tell-upload

NEWS

@@ -1,3 +1,50 @@
+Unreleased changes:
+
+Changes in version 2.8:
+
+* The --follow-symlinks option now applies to output files as well as input.
+* 'patch' now supports file timestamps after 2038 even on traditional
+  GNU/Linux platforms where time_t defaults to 32 bits.
+* 'patch' no longer creates files with names containing newlines,
+  as encouraged by POSIX.1-2024.
+* Patches can no longer contain NUL ('\0') bytes in diff directive lines.
+  These bytes would otherwise cause unpredictable behavior.
+* Patches can now contain sequences of spaces and tabs around line numbers
+  and in other places where POSIX requires support for these sequences.
+* --enable-gcc-warnings no longer uses expensive static checking.
+  Use --enable-gcc-warnings=expensive if you still want it.
+* Fix undefined or ill-defined behavior in unusual cases, such as very
+  large sizes, possible stack overflow, I/O errors, memory exhaustion,
+  races with other processes, and signals arriving at inopportune moments.
+* Remove old "Plan B" code, designed for machines with 16-bit pointers.
+* Assume C99 or later; previously it assumed C89 or later.
+* Port to current GCC, Autoconf, Gnulib, etc.
+
+Changes in version 2.7.6:
+
+* Files specified on the command line are no longer verified to be inside the
+  current working directory, so commands like "patch -i foo.diff ../foo" will
+  work again.
+* Various fixes.
+
+Changes in version 2.7.5:
+
+* There are users which expect patch to follow symbolic links in the working
+  directory, so patch now again follows symbolic links as long as they do not
+  leave the working directory.
+
+Changes until version 2.7.4:
+
+* When a file isn't being deleted because the file contents don't match the
+  patch, the resulting message is now "Not deleting file ... as content
+  differs from patch" instead of "File ... is not empty after patch; not
+  deleting".
+* Function names in hunks (from diff -p) are now preserved in reject files.
+* Patch no longer follows symbolic links to input and output files.  This
+  ensures that symbolic links created by git-style patches cannot cause
+  patch to write outside the working directory (CVE-2015-1196).
+* Various fixes.
+
 Changes in version 2.7.1:
 
 * Two critical bug fixes in the "diff --git" format support.
@@ -84,7 +131,7 @@ Changes in version 2.6:
   line endings in patches.  This allows to preserve CRs even in mangled
   patches, or in patches generated on non-POSIX systems and without the
   --binary option.
-* Backup files for nonexisting files are now created with default
+* Backup files for nonexistent files are now created with default
   permissions rather than with mode 0: backup files with mode 0 were
   causing problems with applications which do not expect unreadable
   files.
@@ -110,7 +157,7 @@ Changes in version 2.5.6:
 
 * File names in context patches may now contain spaces, so long
   as the context patch headers use a tab to separate the file name
-  from the time stamp.
+  from the timestamp.
 * Perforce is now supported.
 * Patch lines beginning with "#" are comments and are ignored.
 
@@ -317,22 +364,19 @@ Changes in version 2.0.12g8:
 
 
 
-Copyright (C) 1992-1993, 1997-2003, 2006, 2009, 2011-2012 Free Software
-Foundation, Inc.
+Copyright 1992-2025 Free Software Foundation, Inc.
 
 This file is part of GNU Patch.
 
-This program is free software; you can redistribute it and/or modify
+This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2, or (at your option)
-any later version.
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
 
-This program is distributed in the hope that they will be useful,
+This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
-along with this program; see the file COPYING.  If not, write to
-the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
-Boston, MA 02110-1301, USA.
+along with this program.  If not, see <http://www.gnu.org/licenses/>.

README

@@ -16,7 +16,7 @@ README-hacking file.  If this file came to you as part of a tar archive,
 then see the file INSTALL for compilation and installation instructions.
 
 See the file NEWS for a list of major changes in the current release.
-A more detailed descripiton of all changes can be found in the file ChangeLog
+A more detailed description of all changes can be found in the file ChangeLog
 in tar archives, and with "git log" which shows the version control history.
 
 Tutorial-style documentation for patch is included in the GNU
@@ -41,12 +41,15 @@ too busy working on other things, like Perl.  He has graciously agreed
 to let GNU `patch' be distributed under the terms of the GNU General
 Public License.
 
+For any copyright year range specified as YYYY-ZZZZ in this package
+note that the range specifies every single year in that closed interval.
+
+Please see the file COPYING for copying conditions.
+
 ------
 
-Copyright (C) 1984, 1985, 1986, 1987, 1988 Larry Wall
-
-Copyright (C) 1989-1993, 1997, 1999, 2002, 2009, 2011-2012 Free Software
-Foundation, Inc.
+Copyright 1989-2025 Free Software Foundation, Inc.
+Copyright 1984-1988 Larry Wall
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by

README-hacking

@@ -1,40 +1,47 @@
--*- outline -*-
+Building from a Git repository				-*- outline -*-
 
 These notes intend to help people working on the checked-out sources.
 These requirements do not apply when building from a distribution tarball.
+If this package has a file HACKING, please also read that file for
+more detailed contribution guidelines.
 
 * Requirements
 
-We've opted to keep only the highest-level sources in the GIT repository.
-This eases our maintenance burden, (fewer merges etc.), but imposes more
+We've opted to keep only the highest-level sources in the Git repository.
+This eases our maintenance burden (fewer merges etc.), but imposes more
 requirements on anyone wishing to build from the just-checked-out sources.
-For example, you have to use the latest stable versions of the maintainer
-tools we depend upon, including:
-
-- Automake <http://www.gnu.org/software/automake/>
-- Autoconf <http://www.gnu.org/software/autoconf/>
-- Gettext <http://www.gnu.org/software/gettext/>
-- Gzip <http://www.gnu.org/software/gzip/>
-- M4 <http://www.gnu.org/software/m4/>
-- Tar <http://www.gnu.org/software/tar/>
-- Wget <http://www.gnu.org/software/wget/>
+(The requirements to build from a release are much less and are just
+the requirements of the standard './configure && make' procedure.)
+Specific development tools and versions will be checked for and listed by
+the bootstrap script.  See README-prereq for specific notes on obtaining
+these prerequisite tools.
 
 Valgrind <http://valgrind.org/> is also highly recommended, if
-Valgrind supports your architecture.
+Valgrind supports your architecture.  See also README-valgrind
+(if present).
 
 While building from a just-cloned source tree may require installing a
-few prerequisites, later, a plain `git pull && make' should be sufficient.
+few prerequisites, later, a plain 'git pull && make' typically suffices.
 
-* First GIT checkout
+* First Git checkout
 
 You can get a copy of the source repository like this:
 
-        $ git clone git://git.sv.gnu.org/patch
-        $ cd patch
+        $ git clone git://git.sv.gnu.org/<packagename>
+        $ cd <packagename>
 
-As an optional step, if you already have a copy of the gnulib git
-repository on your hard drive, then you can use it as a reference to
-reduce download time and disk space requirements:
+where '<packagename>' stands for 'coreutils' or whatever other package
+you are building.
+
+To use the most-recent Gnulib (as opposed to the Gnulib version that
+the package last synchronized to), do this next:
+
+        $ git submodule foreach git pull origin master
+        $ git commit -m 'build: update gnulib submodule to latest' gnulib
+
+As an optional step, if you already have a copy of the Gnulib Git
+repository, then you can use it as a reference to reduce download
+time and file system space requirements:
 
         $ export GNULIB_SRCDIR=/path/to/gnulib
 
@@ -43,20 +50,14 @@ which are extracted from other source packages:
 
         $ ./bootstrap
 
-To use the most-recent gnulib (as opposed to the gnulib version that
-the package last synchronized to), do this next:
-
-        $ git submodule foreach git pull origin master
-        $ git commit -m 'build: update gnulib submodule to latest' gnulib
-
 And there you are!  Just
 
-        $ ./configure --quiet
+        $ ./configure --quiet #[--disable-gcc-warnings] [*]
         $ make
         $ make check
 
 At this point, there should be no difference between your local copy,
-and the GIT master copy:
+and the Git master copy:
 
         $ git diff
 
@@ -64,22 +65,34 @@ should output no difference.
 
 Enjoy!
 
+[*] By default GCC warnings are enabled when building from Git.
+If you get warnings with recent GCC and Glibc with default
+configure-time options, please report the warnings to the bug
+reporting address of this package instead of to bug-gnulib,
+even if the problem seems to originate in a Gnulib-provided file.
+If you get warnings with other configurations, you can run
+'./configure --disable-gcc-warnings' or 'make WERROR_CFLAGS='
+to build quietly or verbosely, respectively.
+-----
+
 * Submitting patches
 
 If you develop a fix or a new feature, please send it to the
 appropriate bug-reporting address as reported by the --help option of
 each program.  One way to do this is to use vc-dwim
-<http://www.gnu.org/software/vc-dwim/>), as follows.
+<https://www.gnu.org/software/vc-dwim/>), as follows.
 
-  Run the command "vc-dwim --help", copy its definition of the
-  "git-changelog-symlink-init" function into your shell, and then run
-  this function at the top-level directory of the package.
+  Run the command "vc-dwim --initialize" from the top-level directory
+  of this package's git-cloned hierarchy.
 
-  Edit the ChangeLog file that this command creates, creating a
+  Edit the (empty) ChangeLog file that this command creates, creating a
   properly-formatted entry according to the GNU coding standards
-  <http://www.gnu.org/prep/standards/html_node/Change-Logs.html>.
+  <https://www.gnu.org/prep/standards/html_node/Change-Logs.html>.
 
-  Run the command "vc-dwim" and make sure its output looks good.
+  Make your changes.
+
+  Run the command "vc-dwim" and make sure its output (the diff of all
+  your changes) looks good.
 
   Run "vc-dwim --commit".
 
@@ -88,7 +101,7 @@ each program.  One way to do this is to use vc-dwim
 
 -----
 
-Copyright (C) 2002-2007, 2009-2012 Free Software Foundation, Inc.
+Copyright 2002-2025 Free Software Foundation, Inc.
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -101,4 +114,4 @@ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
-along with this program.  If not, see <http://www.gnu.org/licenses/>.
+along with this program.  If not, see <https://www.gnu.org/licenses/>.

README-prereq

@@ -0,0 +1,36 @@
+This gives some notes on obtaining the tools required for development.
+These tools can be used by the 'bootstrap' and 'configure' scripts,
+as well as by 'make'.  They include:
+
+- Autoconf   <https://www.gnu.org/software/autoconf/>
+- Automake   <https://www.gnu.org/software/automake/>
+- Git        <https://git-scm.com/>
+- Gzip       <https://www.gnu.org/software/gzip/>
+- M4         <https://www.gnu.org/software/m4/>
+- Make       <https://www.gnu.org/software/make/>
+- Tar        <https://www.gnu.org/software/tar/>
+- Texinfo    <https://www.gnu.org/software/texinfo/>
+- Wget       <http://www.gnu.org/software/wget/>
+- XZ Utils   <https://tukaani.org/xz/>
+
+It is generally better to use official packages for your system.
+If a package is not officially available you can build it from source
+and install it into a directory that you can then use to build this
+package.  If some packages are available but are too old, install the
+too-old versions first as they may be needed to build newer versions.
+
+Here is an example of how to build a program from source.  This
+example is for Autoconf; a similar approach should work for the other
+developer prerequisites.  This example assumes Autoconf 2.it; 72
+should be OK to use a later version of Autoconf, if available.
+
+  prefix=$HOME/prefix   # (or wherever else you choose)
+  export PATH=$prefix/bin:$PATH
+  wget https://ftp.gnu.org/pub/gnu/autoconf/autoconf-2.72.tar.gz
+  gzip -d <autoconf-2.72.tar.gz | tar xf -
+  cd autoconf-2.72
+  ./configure --prefix=$prefix
+  make install
+
+Once the prerequisites are installed, you can build this package as
+described in README-hacking.

bootstrap.conf

@@ -1,10 +1,10 @@
-# Bootstrap configuration.
+# Bootstrap configuration.                                          -*- sh -*-
 
-# Copyright (C) 2006-2007, 2009-2012 Free Software Foundation, Inc.
+# Copyright 2006-2025 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
-# the Free Software Foundation; either version 3 of the License, or
+# the Free Software Foundation, either version 3 of the License, or
 # (at your option) any later version.
 
 # This program is distributed in the hope that it will be useful,
@@ -13,103 +13,92 @@
 # GNU General Public License for more details.
 
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 
 # gnulib modules used by this package.
 gnulib_modules="
+announce-gen
 argmatch
+assert-h
+attribute
 backupfile
-clock-time
+basename-lgpl
+bool
+c-ctype
+closeout
 diffseq
-dirname
 dup2
-errno
+errno-h
 exitfail
 extensions
+faccessat
+fchownat
+fchmodat
 fcntl-h
-full-write
-getdate
+filename
+fseeko
+fstatat
+ftello
+futimens
 getopt-gnu
 gettime
 gitlog-to-changelog
 git-version-gen
+gnupload
 hash
+idx
 ignore-value
+intprops
+inttypes-h
 largefile
-lchmod
-linked-list
-lstat
 maintainer-makefile
-malloc
+malloc-gnu
 manywarnings
 memchr
+mempcpy
 minmax
-mkdir
+mkdirat
+nullptr
+openat
+parse-datetime
 progname
 quotearg
-readlink
-realloc
-rename
-rmdir
+raise
+readlinkat
+realloc-posix
+renameat
 setenv
-signal
+signal-h
 ssize_t
 stat-time
-stdbool
-stdlib
-symlink
-sys_stat
+stdckdint-h
+stdlib-h
+stpcpy
+symlinkat
+sys_stat-h
 tempname
-time
-unistd
-unlink
+test-xfail
+unistd-h
+unlinkat
 update-copyright
-utimens
+utimensat
 verror
 xalloc
-xlist
+xstdopen
+year2038-recommended
 "
 
-gnulib_tool_option_extras='--symlink --makefile-name=gnulib.mk'
+# Build prerequisites
+buildreq="\
+autoconf   2.59
+automake   1.9.6
+git        1.5.5
+tar        -
+"
 
-# # Additional xgettext options to use.  Use "\\\newline" to break lines.
-# XGETTEXT_OPTIONS=$XGETTEXT_OPTIONS'\\\
-#  --from-code=UTF-8\\\
-#  --flag=asprintf:2:c-format --flag=vasprintf:2:c-format\\\
-#  --flag=asnprintf:3:c-format --flag=vasnprintf:3:c-format\\\
-#  --flag=wrapf:1:c-format\\\
-# '
-#
-# # If "AM_GNU_GETTEXT(external" or "AM_GNU_GETTEXT([external]"
-# # appears in configure.ac, exclude some unnecessary files.
-# # Without grep's -E option (not portable enough, pre-configure),
-# # the following test is ugly.  Also, this depends on the existence
-# # of configure.ac, not the obsolescent-named configure.in.  But if
-# # you're using this infrastructure, you should care about such things.
-#
-# gettext_external=0
-# grep '^[	 ]*AM_GNU_GETTEXT(external\>' configure.ac > /dev/null &&
-#   gettext_external=1
-# grep '^[	 ]*AM_GNU_GETTEXT(\[external\]' configure.ac > /dev/null &&
-#   gettext_external=1
-#
-# if test $gettext_external = 1; then
-#   # Gettext supplies these files, but we don't need them since
-#   # we don't have an intl subdirectory.
-#   excluded_files='
-#       m4/glibc2.m4
-#       m4/intdiv0.m4
-#       m4/lcmessage.m4
-#       m4/lock.m4
-#       m4/printf-posix.m4
-#       m4/size_max.m4
-#       m4/uintmax_t.m4
-#       m4/ulonglong.m4
-#       m4/visibility.m4
-#       m4/xsize.m4
-#   '
-# fi
-
-# Automake requires that ChangeLog exist.
-touch ChangeLog || exit 1
+bootstrap_post_import_hook ()
+{
+  # Automake requires that ChangeLog exist.
+  touch ChangeLog || exit 1
+}

cfg.mk

@@ -1,5 +1,5 @@
 # Customize maint.mk                           -*- makefile -*-
-# Copyright (C) 2011-2012 Free Software Foundation, Inc.
+# Copyright 2011-2025 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -16,8 +16,17 @@
 
 config_h_header = <(common|config)\.h>
 
+ifeq ($(RELEASE_TYPE),alpha)
+  news-check-regexp = "Unreleased changes"
+else
+  news-check-regexp = '^Changes in version $(VERSION_REGEXP):'
+endif
+
+release-prep-hook =
+
 update-copyright-env = \
-  UPDATE_COPYRIGHT_USE_INTERVALS=1 \
+  UPDATE_COPYRIGHT_FORCE=1 \
+  UPDATE_COPYRIGHT_USE_INTERVALS=2 \
   UPDATE_COPYRIGHT_MAX_LINE_LENGTH=79
 
 local-checks-to-skip = \

configure.ac

@@ -1,10 +1,9 @@
-# Copyright (C) 1993, 1997-1999, 2002-2003, 2006, 2009, 2011-2012 Free Software
-# Foundation, Inc.
+# Copyright 1993-2025 Free Software Foundation, Inc.
 
-# This program is free software; you can redistribute it and/or modify
+# This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
-# the Free Software Foundation; either version 2, or (at your option)
-# any later version.
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
 
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -12,9 +11,7 @@
 # GNU General Public License for more details.
 
 # You should have received a copy of the GNU General Public License
-# along with this program; if not, write to the Free Software
-# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
-# 02110-1301, USA.
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 AC_PREREQ([2.65])
 
@@ -33,116 +30,87 @@ AM_CONDITIONAL([ENABLE_MERGE], [test "$enableval" != no])
 AM_CONDITIONAL([ALPHA_VERSION],
   [[echo "$PACKAGE_VERSION" | grep -- "-[0-9a-f][0-9a-f]*\\(-dirty\\)\\?$" >/dev/null]])
 
-AM_INIT_AUTOMAKE([1.11.2 -Wall -Werror gnu dist-bzip2 dist-xz color-tests parallel-tests])
+AM_INIT_AUTOMAKE([1.11.2 -Wall gnu dist-bzip2 dist-xz color-tests parallel-tests subdir-objects])
 AM_SILENT_RULES([yes])
 
-AC_CONFIG_HEADER([config.h:config.hin])
+AC_CONFIG_HEADERS([config.h:config.hin])
 
 AC_PROG_CC
-AC_PROG_CC_STDC
 gl_EARLY
-gl_USE_SYSTEM_EXTENSIONS
-AC_HEADER_STDC
 gl_INIT
 AM_PROG_AR
 
 AC_ARG_ENABLE([gcc-warnings],
-  [AS_HELP_STRING([--enable-gcc-warnings],
-                  [turn on lots of GCC warnings (for developers)])],
+  [AS_HELP_STRING([--enable-gcc-warnings@<:@=TYPE@:>@],
+    [control generation of GCC warnings.  The TYPE 'no' disables
+     warnings (default for non-developer builds); 'yes' generates
+     cheap warnings if available;
+     'expensive' in addition generates expensive-to-compute warnings
+     if available.])],
   [case $enableval in
-     yes|no) ;;
+     no|yes|expensive) ;;
      *)      AC_MSG_ERROR([bad value $enableval for gcc-warnings option]) ;;
    esac
    gl_gcc_warnings=$enableval],
   [gl_gcc_warnings=no]
 )
 
-if test "$gl_gcc_warnings" = yes; then
+if test $gl_gcc_warnings != no; then
   gl_WARN_ADD([-Werror], [WERROR_CFLAGS])
   AC_SUBST([WERROR_CFLAGS])
 
-  nw=
+  ew=
+  AS_IF([test $gl_gcc_warnings != expensive],
+    [# -fanalyzer and related options slow GCC considerably.
+     ew="$ew -fanalyzer -Wno-analyzer-malloc-leak"])
+
   # This, $nw, is the list of warnings we disable.
-  nw="$nw -Wdeclaration-after-statement" # too useful to forbid
-  nw="$nw -Waggregate-return"       # anachronistic
-  nw="$nw -Wlong-long"              # C90 is anachronistic (lib/gethrxtime.h)
-  nw="$nw -Wc++-compat"             # We don't care about C++ compilers
-  nw="$nw -Wundef"                  # Warns on '#if GNULIB_FOO' etc in gnulib
-  nw="$nw -Wtraditional"            # Warns on #elif which we use often
-  nw="$nw -Wcast-qual"              # Too many warnings for now
-  nw="$nw -Wconversion"             # Too many warnings for now
-  nw="$nw -Wsystem-headers"         # Don't let system headers trigger warnings
-  nw="$nw -Wsign-conversion"        # Too many warnings for now
-  nw="$nw -Wtraditional-conversion" # Too many warnings for now
-  nw="$nw -Wunreachable-code"       # Too many warnings for now
-  nw="$nw -Wpadded"                 # Our structs are not padded
-  nw="$nw -Wredundant-decls"        # openat.h declares e.g., mkdirat
-  nw="$nw -Wlogical-op"             # any use of fwrite provokes this
-  nw="$nw -Wformat-nonliteral"      # who.c and pinky.c strftime uses
-  nw="$nw -Wvla"                    # warnings in gettext.h
-  nw="$nw -Wnested-externs"         # use of XARGMATCH/verify_function__
-  nw="$nw -Wswitch-enum"            # Too many warnings for now
-  nw="$nw -Wswitch-default"         # Too many warnings for now
-  nw="$nw -Wstack-protector"        # not worth working around
-  nw="$nw -Wmissing-format-attribute" # not worth working around in patch
-  nw="$nw -Wsuggest-attribute=format" # warns about util.c
-  # things to fix soon:
-  nw="$nw -Wshadow"
-  nw="$nw -Wstrict-overflow"
-  nw="$nw -Wunsafe-loop-optimizations"
-#  nw="$nw -Wfloat-equal"            # sort.c, seq.c
-#  nw="$nw -Wmissing-format-attribute" # copy.c
-#  nw="$nw -Winline"                 # system.h's readdir_ignoring_dot_and_dotdot
-  # ?? -Wstrict-overflow
+  nw=$ew
+  nw="$nw -Winline"                  # It's OK for a compiler to not inline.
+
+  # Using -Wstrict-overflow is a pain, but the alternative is worse.
+  # For an example, see the code that provoked this report:
+  # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=33498
+  # Code like that still infloops with gcc-4.6.0 and -O2.  Scary indeed.
 
   gl_MANYWARN_ALL_GCC([ws])
   gl_MANYWARN_COMPLEMENT([ws], [$ws], [$nw])
   for w in $ws; do
     gl_WARN_ADD([$w])
   done
-  gl_WARN_ADD([-Wno-missing-field-initializers]) # We need this one
   gl_WARN_ADD([-Wno-sign-compare])     # Too many warnings for now
-  gl_WARN_ADD([-Wno-unused-parameter]) # Too many warnings for now
-
-  # In spite of excluding -Wlogical-op above, it is enabled, as of
-  # gcc 4.5.0 20090517, and it provokes warnings in cat.c, dd.c, truncate.c
-  gl_WARN_ADD([-Wno-logical-op])
 
   gl_WARN_ADD([-fdiagnostics-show-option])
-  gl_WARN_ADD([-funit-at-a-time])
-  gl_WARN_ADD([-Wno-format-nonliteral])
 
   AC_SUBST([WARN_CFLAGS])
 
   AC_DEFINE([lint], [1], [Define to 1 if the compiler is checking for lint.])
-  AC_DEFINE([_FORTIFY_SOURCE], [2],
-    [enable compile-time and run-time bounds-checking, and some warnings])
+  AH_VERBATIM([FORTIFY_SOURCE],
+  [/* Enable compile-time and run-time bounds-checking, and some warnings,
+      without upsetting glibc 2.15+. */
+   #if !defined _FORTIFY_SOURCE && defined __OPTIMIZE__ && __OPTIMIZE__
+   # define _FORTIFY_SOURCE 2
+   #endif
+  ])
   AC_DEFINE([GNULIB_PORTCHECK], [1], [enable some gnulib portability checks])
 
-  # We use a slightly smaller set of warning options for lib/.
+  # We also use a smaller set of warning options for lib/.
   # Remove the following and save the result in GNULIB_WARN_CFLAGS.
-  nw=
-  nw="$nw -Wuninitialized"
-  nw="$nw -Wunused-macros"
-  nw="$nw -Wmissing-prototypes"
-  nw="$nw -Wold-style-definition"
+  nw=$ew
   gl_MANYWARN_COMPLEMENT([GNULIB_WARN_CFLAGS], [$WARN_CFLAGS], [$nw])
   AC_SUBST([GNULIB_WARN_CFLAGS])
-
-  # For gnulib-tests, the set is slightly smaller still.
-  nw=
-  nw="$nw -Wstrict-prototypes"
-  gl_MANYWARN_COMPLEMENT([GNULIB_TEST_WARN_CFLAGS],
-                         [$GNULIB_WARN_CFLAGS], [$nw])
-  AC_SUBST([GNULIB_TEST_WARN_CFLAGS])
 fi
 
+# Ensure VLAs are not used.
+# Note -Wvla is implicitly added by gl_MANYWARN_ALL_GCC
+AC_DEFINE([GNULIB_NO_VLA], [1], [Define to 1 to disable use of VLAs])
+
 AC_TYPE_MODE_T
 AC_TYPE_OFF_T
 
 gl_FUNC_XATTR
 
-AC_CHECK_FUNCS(geteuid getuid raise sigaction sigprocmask sigsetmask)
+AC_CHECK_FUNCS_ONCE([geteuid getuid sigaction sigfillset])
 AC_FUNC_SETMODE_DOS
 
 AC_PATH_PROG([ED], [ed], [ed])

gnulib

@@ -1 +1 @@
-Subproject commit 77b054428b11be9cd76d1e3b0a7cd7cf86053173
+Subproject commit 9829f0a93c40492875f67ee738e000611bdcf0e7

lib/Makefile.am

@@ -1,14 +0,0 @@
-## Process this file with automake to produce Makefile.in.
-
-AM_CFLAGS =
-AM_CPPFLAGS =
-BUILT_SOURCES =
-CLEANFILES =
-EXTRA_DIST =
-MAINTAINERCLEANFILES =
-MOSTLYCLEANDIRS =
-MOSTLYCLEANFILES =
-SUFFIXES =
-noinst_LIBRARIES =
-
-include gnulib.mk

m4/.gitignore

@@ -1,250 +0,0 @@
-/00gnulib.m4
-/alloca.m4
-/argmatch.m4
-/backupfile.m4
-/bison.m4
-/canonicalize.m4
-/clock_time.m4
-/closedir.m4
-/codeset.m4
-/configmake.m4
-/d-ino.m4
-/dirent-safer.m4
-/dirent_h.m4
-/dirfd.m4
-/dirname.m4
-/double-slash-root.m4
-/dup2.m4
-/eealloc.m4
-/environ.m4
-/errno_h.m4
-/error.m4
-/exponentd.m4
-/extensions.m4
-/fcntl-o.m4
-/fcntl.m4
-/fcntl_h.m4
-/float_h.m4
-/fstat.m4
-/getdtablesize.m4
-/getopt.m4
-/gettime.m4
-/gettimeofday.m4
-/glibc21.m4
-/gnulib-cache.m4
-/gnulib-common.m4
-/gnulib-comp.m4
-/gnulib-tool.m4
-/hash.m4
-/include_next.m4
-/inline.m4
-/intmax_t.m4
-/inttypes_h.m4
-/largefile.m4
-/lchmod.m4
-/localcharset.m4
-/locale-fr.m4
-/locale-ja.m4
-/locale-zh.m4
-/longlong.m4
-/lstat.m4
-/malloc.m4
-/malloca.m4
-/manywarnings.m4
-/math_h.m4
-/mbrtowc.m4
-/mbsinit.m4
-/mbstate_t.m4
-/memchr.m4
-/minmax.m4
-/mkdir.m4
-/mktime.m4
-/mmap-anon.m4
-/msvc-inval.m4
-/msvc-nothrow.m4
-/multiarch.m4
-/nocrash.m4
-/opendir.m4
-/parse-datetime.m4
-/pathmax.m4
-/printf.m4
-/quote.m4
-/quotearg.m4
-/raise.m4
-/readdir.m4
-/readlink.m4
-/realloc.m4
-/rename.m4
-/rmdir.m4
-/safe-read.m4
-/safe-write.m4
-/setenv.m4
-/signal_h.m4
-/size_max.m4
-/ssize_t.m4
-/stat-time.m4
-/stat.m4
-/stdarg.m4
-/stdbool.m4
-/stddef_h.m4
-/stdint.m4
-/stdint_h.m4
-/stdio_h.m4
-/stdlib_h.m4
-/strerror.m4
-/string_h.m4
-/strndup.m4
-/strnlen.m4
-/symlink.m4
-/sys_socket_h.m4
-/sys_stat_h.m4
-/sys_time_h.m4
-/tempname.m4
-/time_h.m4
-/time_r.m4
-/timespec.m4
-/tm_gmtoff.m4
-/unistd-safer.m4
-/unistd_h.m4
-/unlink.m4
-/utimbuf.m4
-/utimens.m4
-/utimes.m4
-/vasnprintf.m4
-/vasprintf.m4
-/warn-on-use.m4
-/warnings.m4
-/wchar_h.m4
-/wchar_t.m4
-/wctype_h.m4
-/wint_t.m4
-/write.m4
-/xalloc.m4
-/xsize.m4
-/xstrndup.m4
-/xvasprintf.m4
-00gnulib.m4
-alloca.m4
-argmatch.m4
-backupfile.m4
-bison.m4
-canonicalize.m4
-clock_time.m4
-codeset.m4
-configmake.m4
-d-ino.m4
-dirent-safer.m4
-dirent_h.m4
-dirfd.m4
-dirname.m4
-dos.m4
-double-slash-root.m4
-dup2.m4
-eealloc.m4
-environ.m4
-errno_h.m4
-error.m4
-extensions.m4
-fcntl-o.m4
-fcntl.m4
-fcntl_h.m4
-float_h.m4
-fseek.m4
-fseeko.m4
-ftell.m4
-ftello.m4
-getdate.m4
-getdtablesize.m4
-getopt.m4
-gettime.m4
-gettimeofday.m4
-glibc21.m4
-gnulib-cache.m4
-gnulib-common.m4
-gnulib-comp.m4
-gnulib-tool.m4
-hash.m4
-include_next.m4
-inline.m4
-intmax_t.m4
-inttypes_h.m4
-lchmod.m4
-localcharset.m4
-locale-fr.m4
-locale-ja.m4
-locale-zh.m4
-longlong.m4
-lseek.m4
-lstat.m4
-malloc.m4
-malloca.m4
-manywarnings.m4
-mbrtowc.m4
-mbsinit.m4
-mbstate_t.m4
-memchr.m4
-minmax.m4
-mkdir.m4
-mktime.m4
-mmap-anon.m4
-multiarch.m4
-onceonly.m4
-parse-datetime.m4
-pathmax.m4
-printf.m4
-quote.m4
-quotearg.m4
-readlink.m4
-realloc.m4
-rename.m4
-rmdir.m4
-safe-read.m4
-safe-write.m4
-setenv.m4
-size_max.m4
-ssize_t.m4
-stat-time.m4
-stat.m4
-stdarg.m4
-stdbool.m4
-stddef_h.m4
-stdint.m4
-stdint_h.m4
-stdio_h.m4
-stdlib_h.m4
-strerror.m4
-string_h.m4
-strndup.m4
-strnlen.m4
-symlink.m4
-sys_stat_h.m4
-sys_time_h.m4
-tempname.m4
-time_h.m4
-time_r.m4
-timespec.m4
-tm_gmtoff.m4
-unistd-safer.m4
-unistd_h.m4
-unlink.m4
-utimbuf.m4
-utimens.m4
-utimes.m4
-vasnprintf.m4
-vasprintf.m4
-warn-on-use.m4
-warnings.m4
-wchar_h.m4
-wchar_t.m4
-wctype_h.m4
-wint_t.m4
-write.m4
-xalloc.m4
-xsize.m4
-xstrndup.m4
-xvasprintf.m4
-/close.m4
-/gl_list.m4
-/off_t.m4
-/sys_types_h.m4
-/extern-inline.m4

m4/setmode.m4

@@ -1,35 +1,33 @@
 # Check for setmode, DOS style.
 
-# Copyright (C) 2001-2002, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2001-2025 Free Software Foundation, Inc.
 
-# This program is free software; you can redistribute it and/or modify
+# This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
-# the Free Software Foundation; either version 2, or (at your option)
-# any later version.
-
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
-
+#
 # You should have received a copy of the GNU General Public License
-# along with this program; if not, write to the Free Software
-# Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
-# USA.
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 AC_DEFUN([AC_FUNC_SETMODE_DOS],
-  [AC_CHECK_HEADERS([fcntl.h unistd.h])
+  [AC_CHECK_HEADERS_ONCE([fcntl.h unistd.h])
    AC_CACHE_CHECK([for DOS-style setmode],
      [ac_cv_func_setmode_dos],
-     [AC_TRY_LINK(
-	[#include <io.h>
+     [AC_LINK_IFELSE([AC_LANG_PROGRAM(
+	[[#include <io.h>
 	 #if HAVE_FCNTL_H
 	 # include <fcntl.h>
 	 #endif
 	 #if HAVE_UNISTD_H
 	 # include <unistd.h>
-	 #endif],
-	[int ret = setmode && setmode (1, O_BINARY);],
+	 #endif]],
+	[int ret = setmode && setmode (1, O_BINARY);])],
 	[ac_cv_func_setmode_dos=yes],
 	[ac_cv_func_setmode_dos=no])])
    if test $ac_cv_func_setmode_dos = yes; then

m4/xattr.m4

@@ -1,7 +1,7 @@
 # xattr.m4 - check for Extended Attributes (Linux)
-# serial 3
+# serial 4
 
-# Copyright (C) 2003, 2008-2012 Free Software Foundation, Inc.
+# Copyright 2003-2025 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
@@ -12,7 +12,7 @@
 AC_DEFUN([gl_FUNC_XATTR],
 [
   AC_ARG_ENABLE([xattr],
-        AC_HELP_STRING([--disable-xattr],
+        AS_HELP_STRING([--disable-xattr],
                        [do not support extended attributes]),
         [use_xattr=$enableval], [use_xattr=yes])
 

patch.man

@@ -1,14 +1,13 @@
 .\" patch man page
-.de Id
-.ds Dt \\$4
-..
 .ds = \-\^\-
 .de Sp
 .if t .sp .3
 .if n .sp
 ..
-.TH PATCH 1 \*(Dt GNU
-.ta 3n
+.ds Cw CW
+.if \n(.g .if f CR .ds Cw CR
+.ds fC \f(\*(Cw
+.TH PATCH 1 "" GNU
 .SH NAME
 patch \- apply a diff file to an original
 .SH SYNOPSIS
@@ -60,7 +59,7 @@ editor via a pipe.
 .B patch
 tries to skip any leading garbage, apply the diff,
 and then skip any trailing garbage.
-Thus you could feed an article or message containing a
+Thus you could feed an email message containing a
 diff listing to
 .BR patch ,
 and it should work.
@@ -149,8 +148,8 @@ to edit is, using the following rules.
 First,
 .B patch
 takes an ordered list of candidate file names as follows:
-.TP 3
-.B " \(bu"
+.RS "\w'  'u"
+.IP \(bu "\w'\(bu  'u"
 If the header is that of a context diff,
 .B patch
 takes the old and new file names in the header.
@@ -162,8 +161,7 @@ option.
 The name
 .B /dev/null
 is also ignored.
-.TP
-.B " \(bu"
+.IP \(bu
 If there is an
 .B Index:\&
 line in the leading garbage
@@ -174,23 +172,22 @@ is conforming to \s-1POSIX\s0,
 takes the name in the
 .B Index:\&
 line.
-.TP
-.B " \(bu"
+.IP \(bu
 For the purpose of the following rules,
 the candidate file names are considered to be in the order (old, new, index),
 regardless of the order that they appear in the header.
+.RE
 .LP
 Then
 .B patch
 selects a file name from the candidate list as follows:
-.TP 3
-.B " \(bu"
+.RS "\w'  'u"
+.IP \(bu "\w'\(bu  'u"
 If some of the named files exist,
 .B patch
 selects the first name if conforming to \s-1POSIX\s0,
 and the best name otherwise.
-.TP
-.B " \(bu"
+.IP \(bu
 If
 .B patch
 is not ignoring \s-1RCS\s0, ClearCase, Perforce, and \s-1SCCS\s0 (see the
@@ -202,8 +199,7 @@ but an \s-1RCS\s0, ClearCase, Perforce, or \s-1SCCS\s0 master is found,
 .B patch
 selects the first named file
 with an \s-1RCS\s0, ClearCase, Perforce, or \s-1SCCS\s0 master.
-.TP
-.B " \(bu"
+.IP \(bu
 If no named files exist,
 no \s-1RCS\s0, ClearCase, Perforce, or \s-1SCCS\s0 master was found,
 some names are given,
@@ -212,12 +208,12 @@ is not conforming to \s-1POSIX\s0,
 and the patch appears to create a file,
 .B patch
 selects the best name requiring the creation of the fewest directories.
-.TP
-.B " \(bu"
+.IP \(bu
 If no file name results from the above heuristics, you are asked
 for the name of the file to patch, and
 .B patch
 selects that name.
+.RE
 .LP
 To determine the
 .I best
@@ -238,15 +234,16 @@ If not,
 .B patch
 asks for confirmation before proceeding.
 .PP
-The upshot of all this is that you should be able to say, while in a news
-interface, something like the following:
+The upshot of all this is that you should be able to run
+something like the following shell command:
 .Sp
-	\fB| patch \-d /usr/src/local/blurfl\fP
+.RS
+\fBpatch \-d /usr/src/local/blurfl\fP
+.RE
 .Sp
 and patch a file in the
 .B blurfl
-directory directly from the article containing
-the patch.
+directory directly from a patch that is read from standard input.
 .PP
 If the patch file contains more than one patch,
 .B patch
@@ -262,9 +259,6 @@ mentioned previously.
 Make backup files.
 That is, when patching a file,
 rename or copy the original instead of removing it.
-When backing up a file that does not exist,
-an empty, unreadable backup file is created
-as a placeholder to represent the nonexistent file.
 See the
 .B \-V
 or
@@ -342,7 +336,7 @@ script.
 Remove output files that are empty after the patches have been applied.
 Normally this option is unnecessary, since
 .B patch
-can examine the time stamps on the header to determine whether a file
+can examine the timestamps on the header to determine whether a file
 should exist after patching.
 However, if the input is not a context diff or if
 .B patch
@@ -423,21 +417,22 @@ A typical conflict will look like this:
 .LP
 .RS
 .nf
-.B <<<<<<<
-.I lines from the original file
-.B |||||||
-.I original lines from the patch
-.B =======
-.I new lines from the patch
-.B >>>>>>>
+.ne 7
+\*(fC<<<<<<<\fP
+\fIlines from the original file\fP
+\*(fC|||||||\fP
+\fIoriginal lines from the patch\fP
+\*(fC=======\fP
+\fInew lines from the patch\fP
+\*(fC>>>>>>>\fP
 .RE
 .fi
 .IP "" 3
 The optional argument of \fB\*=merge\fP determines the output format for
-conflicts: the diff3 format shows the \fB|||||||\fP section with the original
+conflicts: the diff3 format shows the \*(fC|||||||\fP section with the original
 lines from the patch; in the merge format, this section is missing.  The merge
 format is the default.
-
+.Sp
 This option implies \fB\*=forward\fP and does not take the
 \fB--fuzz\fR=\fInum\fP option into account.
 .TP
@@ -445,9 +440,9 @@ This option implies \fB\*=forward\fP and does not take the
 Interpret the patch file as a normal diff.
 .TP
 \fB\-N\fP  or  \fB\*=forward\fP
-Ignore patches that seem to be reversed or already applied. It is only checked if
-the first hunk of a patch can be reversed.
-See also
+When a patch does not apply, patch usually checks if the patch looks like it
+has been applied already by trying to reverse-apply the first hunk.  The
+\fB\*=forward\fP option prevents that.  See also
 .BR \-R .
 .TP
 \fB\-o\fP \fIoutfile\fP  or  \fB\*=output=\fP\fIoutfile\fP
@@ -470,7 +465,9 @@ you keep your files in a different directory than the person who sent
 out the patch.
 For example, supposing the file name in the patch file was
 .Sp
-	\fB/u/howard/src/blurfl/blurfl.c\fP
+.RS
+\fB/u/howard/src/blurfl/blurfl.c\fP
+.RE
 .Sp
 setting
 .B \-p0
@@ -478,13 +475,17 @@ gives the entire file name unmodified,
 .B \-p1
 gives
 .Sp
-	\fBu/howard/src/blurfl/blurfl.c\fP
+.RS
+\fBu/howard/src/blurfl/blurfl.c\fP
+.RE
 .Sp
 without the leading slash,
 .B \-p4
 gives
 .Sp
-	\fBblurfl/blurfl.c\fP
+.RS
+\fBblurfl/blurfl.c\fP
+.RE
 .Sp
 and not specifying
 .B \-p
@@ -496,23 +497,18 @@ option.
 .TP
 .B \*=posix
 Conform more strictly to the \s-1POSIX\s0 standard, as follows.
-.RS
-.TP 3
-.B " \(bu"
+.RS "\w'  'u"
+.IP \(bu "\w'\(bu  'u"
 Take the first existing file from the list (old, new, index)
 when intuiting file names from diff headers.
-.TP
-.B " \(bu"
+.IP \(bu
 Do not remove files that are empty after patching.
-.TP
-.B " \(bu"
+.IP \(bu
 Do not ask whether to get files from \s-1RCS\s0, ClearCase, Perforce,
 or \s-1SCCS\s0.
-.TP
-.B " \(bu"
+.IP \(bu
 Require that all options precede the files in the command line.
-.TP
-.B " \(bu"
+.IP \(bu
 Do not backup files when there is a mismatch.
 .RE
 .TP
@@ -619,15 +615,15 @@ in the patch; and assume that patches are reversed if they look like
 they are.
 .TP
 \fB\-T\fP  or  \fB\*=set\-time\fP
-Set the modification and access times of patched files from time stamps
-given in context diff headers.  Unless specified in the time stamps,
+Set the modification and access times of patched files from timestamps
+given in context diff headers.  Unless specified in the timestamps,
 assume that the context diff headers use local time.
 .Sp
-Use of this option with time stamps that do not include time zones is
+Use of this option with timestamps that do not include time zones is
 not recommended, because patches using local time cannot easily be used
-by people in other time zones, and because local time stamps are
+by people in other time zones, and because local timestamps are
 ambiguous when local clocks move backwards during daylight-saving time
-adjustments.  Make sure that time stamps include time zones, or generate
+adjustments.  Make sure that timestamps include time zones, or generate
 patches with \s-1UTC\s0 and use the
 .B \-Z
 or
@@ -657,7 +653,7 @@ it affects only the names of any backup files that are made.
 The value of
 .I method
 is like the \s-1GNU\s0
-Emacs `version-control' variable;
+Emacs version-control variable;
 .B patch
 also recognizes synonyms that
 are more descriptive.  The valid values for
@@ -754,8 +750,8 @@ is
 .BR src/patch/util.c- .
 .TP
 \fB\-Z\fP  or  \fB\*=set\-utc\fP
-Set the modification and access times of patched files from time stamps
-given in context diff headers. Unless specified in the time stamps,
+Set the modification and access times of patched files from timestamps
+given in context diff headers. Unless specified in the timestamps,
 assume that the context diff headers use Coordinated Universal Time
 (\s-1UTC\s0, often known as \s-1GMT\s0).  Also see the
 .B \-T
@@ -847,13 +843,16 @@ controlling terminal; used to get answers to questions asked of the user
 .Sp
 Marshall T. Rose and Einar A. Stefferud,
 Proposed Standard for Message Encapsulation,
-Internet RFC 934 <URL:ftp://ftp.isi.edu/in-notes/rfc934.txt> (1985-01).
+Internet RFC 934 <https://datatracker.ietf.org/doc/html/rfc934> (1985-01).
 .SH "NOTES FOR PATCH SENDERS"
 There are several things you should bear in mind if you are going to
 be sending out patches.
 .PP
 Create your patch systematically.
-A good method is the command
+When using a version control system this should be easy;
+for example, with Git you can use
+.BR "git diff" .
+Otherwise, a good method is the command
 .BI "diff\ \-Naur\ " "old\ new"
 where
 .I old
@@ -865,18 +864,21 @@ The names
 and
 .I new
 should not contain any slashes.
-The
+.PP
+If the patch should communicate file timestamps as well as file contents, its
 .B diff
-command's headers should have dates
+commands' headers should have dates
 and times in Universal Time using traditional Unix format,
 so that patch recipients can use the
 .B \-Z
 or
 .B \*=set\-utc
 option.
-Here is an example command, using Bourne shell syntax:
+Here is an example command to generate such headers, using Bourne shell syntax:
 .Sp
-	\fBLC_ALL=C TZ=UTC0 diff \-Naur gcc\-2.7 gcc\-2.8\fP
+.RS
+\fBLC_ALL=C TZ=UTC0 diff \-Naur myprog\-2.7 myprog\-2.8\fP
+.RE
 .PP
 Tell your recipients how to apply the patch
 by telling them which directory to
@@ -925,14 +927,16 @@ If the recipient is supposed to use the
 .BI \-p N
 option, do not send output that looks like this:
 .Sp
-.ft B
+.RS
+.ft \*(Cw
 .ne 3
-	diff \-Naur v2.0.29/prog/README prog/README
+diff \-Naur v2.0.29/prog/README prog/README
 .br
-	\-\^\-\^\- v2.0.29/prog/README   Mon Mar 10 15:13:12 1997
+\-\^\-\^\- v2.0.29/prog/README   Mon Mar 10 15:13:12 2024
 .br
-	+\^+\^+ prog/README   Mon Mar 17 14:58:22 1997
++\^+\^+ prog/README   Mon Mar 17 14:58:22 2024
 .ft
+.RE
 .Sp
 because the two file names have different numbers of slashes,
 and different versions of
@@ -940,14 +944,16 @@ and different versions of
 interpret the file names differently.
 To avoid confusion, send output that looks like this instead:
 .Sp
-.ft B
+.RS
+.ft \*(Cw
 .ne 3
-	diff \-Naur v2.0.29/prog/README v2.0.30/prog/README
+diff \-Naur v2.0.29/prog/README v2.0.30/prog/README
 .br
-	\-\^\-\^\- v2.0.29/prog/README   Mon Mar 10 15:13:12 1997
+\-\^\-\^\- v2.0.29/prog/README   Mon Mar 10 15:13:12 2024
 .br
-	+\^+\^+ v2.0.30/prog/README   Mon Mar 17 14:58:22 1997
++\^+\^+ v2.0.30/prog/README   Mon Mar 17 14:58:22 2024
 .ft
+.RE
 .Sp
 .PP
 Avoid sending patches that compare backup file names like
@@ -968,7 +974,7 @@ Try not to have your patch modify derived files
 (e.g. the file
 .B configure
 where there is a line
-.B "configure: configure.in"
+.B "configure: configure.ac"
 in your makefile), since the recipient should be
 able to regenerate the derived files anyway.
 If you must send diffs of derived files,
@@ -1033,57 +1039,15 @@ applied to exactly the same version of the file that the patch was
 generated from.
 .SH "COMPATIBILITY ISSUES"
 The \s-1POSIX\s0 standard specifies behavior that differs from
-.BR patch 's
-traditional behavior.
-You should be aware of these differences if you must interoperate with
+GNU
+.BR patch .
+.RS "\w'  'u"
+.IP \(bu "\w'\(bu  'u"
+In \s-1POSIX\s0
 .B patch
-versions 2.1 and earlier, which do not conform to \s-1POSIX\s0.
-.TP 3
-.B " \(bu"
-In traditional
-.BR patch ,
-the
-.B \-p
-option's operand was optional, and a bare
-.B \-p
-was equivalent to
-.BR \-p0.
-The
-.B \-p
-option now requires an operand, and
-.B "\-p\ 0"
-is now equivalent to
-.BR \-p0 .
-For maximum compatibility, use options like
-.B \-p0
-and
-.BR \-p1 .
-.Sp
-Also,
-traditional
-.B patch
-simply counted slashes when stripping path prefixes;
-.B patch
-now counts pathname components.
-That is, a sequence of one or more adjacent slashes
-now counts as a single slash.
-For maximum portability, avoid sending patches containing
-.B //
-in file names.
-.TP
-.B " \(bu"
-In traditional
-.BR patch ,
-backups were enabled by default.
-This behavior is now enabled with the
+when
 .B \-b
-or
-.B \*=backup
-option.
-.Sp
-Conversely, in \s-1POSIX\s0
-.BR patch ,
-backups are never made, even when there is a mismatch.
+is not used, backups are not made even when there is a mismatch.
 In \s-1GNU\s0
 .BR patch ,
 this behavior is enabled with the
@@ -1093,88 +1057,46 @@ option, or by conforming to \s-1POSIX\s0 with the
 option or by setting the
 .B POSIXLY_CORRECT
 environment variable.
-.Sp
-The
-.BI \-b "\ suffix"
-option
-of traditional
+.IP \(bu
+When intuiting the name of the file to be patched from the patch header,
 .B patch
-is equivalent to the
-.BI "\-b\ \-z" "\ suffix"
-options of \s-1GNU\s0
-.BR patch .
-.TP
-.B " \(bu"
-Traditional
-.B patch
-used a complicated (and incompletely documented) method
-to intuit the name of the file to be patched from the patch header.
-This method did not conform to \s-1POSIX\s0, and had a few gotchas.
-Now
-.B patch
-uses a different, equally complicated (but better documented) method
-that is optionally \s-1POSIX\s0-conforming; we hope it has
-fewer gotchas.  The two methods are compatible if the
+uses a complicated method
+that is optionally \s-1POSIX\s0-conforming.
+The method is equivalent to \s-1POSIX\s0 if the
 file names in the context diff header and the
 .B Index:\&
 line are all identical after prefix-stripping.
 Your patch is normally compatible if each header's file names
 all contain the same number of slashes.
-.TP
-.B " \(bu"
-When traditional
-.B patch
-asked the user a question, it sent the question to standard error
-and looked for an answer from
-the first file in the following list that was a terminal:
-standard error, standard output,
-.BR /dev/tty ,
-and standard input.
-Now
-.B patch
-sends questions to standard output and gets answers from
-.BR /dev/tty .
-Defaults for some answers have been changed so that
-.B patch
-never goes into an infinite loop when using default answers.
-.TP
-.B " \(bu"
-Traditional
-.B patch
-exited with a status value that counted the number of bad hunks,
-or with status 1 if there was real trouble.
-Now
-.B patch
-exits with status 1 if some hunks failed,
-or with 2 if there was real trouble.
-.TP
-.B " \(bu"
+.IP \(bu
 Limit yourself to the following options when sending instructions
 meant to be executed by anyone running \s-1GNU\s0
-.BR patch ,
-traditional
-.BR patch ,
+.B patch
 or a
 .B patch
 that conforms to \s-1POSIX\s0.
-Spaces are significant in the following list, and operands are required.
+Spaces are optional in the following list.
 .Sp
 .nf
 .in +3
 .ne 11
+.B \-b
 .B \-c
 .BI \-d " dir"
 .BI \-D " define"
 .B \-e
+.BI \-i " patchfile"
 .B \-l
 .B \-n
 .B \-N
 .BI \-o " outfile"
-.BI \-p num
+.BI \-p " num"
 .B \-R
 .BI \-r " rejectfile"
+.BI \-u
 .in
 .fi
+.RE
 .SH BUGS
 Please report bugs via email to
 .BR <bug-patch@gnu.org> .
@@ -1194,16 +1116,9 @@ Computing how to merge a hunk is significantly harder than using the standard
 fuzzy algorithm.  Bigger hunks, more context, a bigger offset from the
 original location, and a worse match all slow the algorithm down.
 .SH COPYING
-Copyright
-.ie t \(co
-.el (C)
-1984, 1985, 1986, 1988 Larry Wall.
+Copyright \(co 1989\(en2025 Free Software Foundation, Inc.
 .br
-Copyright
-.ie t \(co
-.el (C)
-1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
-2000, 2001, 2002, 2009 Free Software Foundation, Inc.
+Copyright \(co 1984\(en1986, 1988 Larry Wall.
 .PP
 Permission is granted to make and distribute verbatim copies of
 this manual provided the copyright notice and this permission notice
@@ -1229,4 +1144,4 @@ setting file times, and deleting files;
 and made it conform better to \s-1POSIX\s0.
 Other contributors include Wayne Davison, who added unidiff support,
 and David MacKenzie, who added configuration and backup support.
-Andreas Gr\[:u]nbacher added support for merging.
+Andreas Gruenbacher added support for merging.

src/Makefile.am

@@ -1,5 +1,4 @@
-# Copyright (C) 1989-1993, 1997-1999, 2002-2003, 2006, 2009-2012 Free Software
-# Foundation, Inc.
+# Copyright 1989-2025 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -27,14 +26,19 @@ patch_SOURCES = \
 	patch.c \
 	pch.c \
 	pch.h \
+	safe.c \
+	safe.h \
 	util.c \
 	util.h \
 	version.c \
-	version.h
+	version.h \
+	list.h
 
 AM_CPPFLAGS = -I$(top_builddir)/lib -I$(top_srcdir)/lib
-patch_LDADD = $(LDADD) $(top_builddir)/lib/libpatch.a $(LIB_CLOCK_GETTIME) \
-	      $(LIB_XATTR)
+patch_LDADD = $(LDADD) $(top_builddir)/lib/libpatch.a \
+ $(CLOCK_TIME_LIB) $(EUIDACCESS_LIBGEN) $(GETRANDOM_LIB) \
+ $(HARD_LOCALE_LIB) $(LIBINTL) $(MBRTOWC_LIB) $(SETLOCALE_NULL_LIB) \
+ $(LIB_XATTR)
 
 if ENABLE_MERGE
   patch_SOURCES += merge.c

src/bestmatch.h

@@ -1,6 +1,6 @@
 /* Find a best match between two vectors.
 
-   Copyright (C) 2009-2012 Free Software Foundation, Inc.
+   Copyright 2009-2025 Free Software Foundation, Inc.
    Written by Andreas Gruenbacher <agruen@gnu.org>, 2009.
 
    This program is free software: you can redistribute it and/or modify
@@ -64,7 +64,7 @@ bestmatch(OFFSET xoff, OFFSET xlim, OFFSET yoff, OFFSET ylim,
     OFFSET fmid_plus_2_min, ymax = -1;
     OFFSET c;
 
-    V = malloc ((2 * max + 3) * sizeof (OFFSET));
+    V = xmalloc ((2 * max + 3) * sizeof (OFFSET));
     fd = V + max + 1 - fmid;
 
     /*

src/common.h

@@ -1,9 +1,7 @@
 /* common definitions for 'patch' */
 
-/* Copyright (C) 1986, 1988 Larry Wall
-
-   Copyright (C) 1990-1993, 1997-1999, 2002-2003, 2006, 2009-2012 Free Software
-   Foundation, Inc.
+/* Copyright 1990-2025 Free Software Foundation, Inc.
+   Copyright 1986, 1988 Larry Wall
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -24,39 +22,26 @@
 
 #include <config.h>
 
+#include <attribute.h>
+#include <c-ctype.h>
+#include <idx.h>
+#include <intprops.h>
+#include <progname.h>
+#include <minmax.h>
+
 #include <assert.h>
-#include <stdbool.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <stdckdint.h>
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
 #include <sys/types.h>
 #include <time.h>
-
-#include <sys/stat.h>
-
-#include <limits.h>
-
-#if HAVE_INTTYPES_H
-# include <inttypes.h>
-#elif HAVE_STDINT_H
-# include <stdint.h>
-#endif
-
-#include <ctype.h>
-/* CTYPE_DOMAIN (C) is nonzero if the unsigned char C can safely be given
-   as an argument to <ctype.h> macros like 'isspace'.  */
-#if STDC_HEADERS
-#define CTYPE_DOMAIN(c) 1
-#else
-#define CTYPE_DOMAIN(c) ((unsigned) (c) <= 0177)
-#endif
-#ifndef ISSPACE
-#define ISSPACE(c) (CTYPE_DOMAIN (c) && isspace (c))
-#endif
-
-#ifndef ISDIGIT
-#define ISDIGIT(c) ((unsigned) (c) - '0' <= 9)
-#endif
-
-#include <progname.h>
+#include <unistd.h>
 
 /* handy definitions */
 
@@ -66,52 +51,60 @@
 
 /* typedefs */
 
-typedef off_t lin;			/* must be signed */
+/* A description of an output file.  It may be temporary.  */
+struct outfile
+{
+  /* Name of the file.  */
+  char *name;
+
+  /* Equal to NAME if the file exists; otherwise a null pointer.
+     When non-null, the storage it points to is safe to access in
+     a signal handler.  */
+  char volatile *volatile exists;
+
+  /* Equal to NAME if NAME should be freed when this structure is
+     freed or reused; otherwise, a null pointer.  */
+  char *alloc;
+
+  /* Whether the file is intended to be temporary, and therefore
+     should be cleaned up before exit, if it exists.  */
+  bool temporary;
+};
 
 /* globals */
 
-XTERN char *buf;			/* general purpose buffer */
-XTERN size_t bufsize;			/* allocated size of buf */
+extern char *inname;
+extern char *outfile;
+extern int inerrno;
+extern signed char invc;
+extern struct stat instat;
+extern bool dry_run;
+extern bool posixly_correct;
 
-XTERN bool using_plan_a;		/* try to keep everything in memory */
+extern char const *origprae;
+extern char const *origbase;
+extern char const *origsuff;
 
-XTERN char *inname;
-XTERN char *outfile;
-XTERN int inerrno;
-XTERN int invc;
-XTERN struct stat instat;
-XTERN bool dry_run;
-XTERN bool posixly_correct;
+extern struct outfile tmped;
+extern struct outfile tmppat;
 
-XTERN char const *origprae;
-XTERN char const *origbase;
-XTERN char const *origsuff;
-
-XTERN char const * TMPINNAME;
-XTERN char const * TMPOUTNAME;
-XTERN char const * TMPPATNAME;
-
-XTERN bool TMPINNAME_needs_removal;
-XTERN bool TMPOUTNAME_needs_removal;
-XTERN bool TMPPATNAME_needs_removal;
-
-#ifdef DEBUGGING
-XTERN int debug;
+#if DEBUGGING
+extern unsigned short int debug;
 #else
 # define debug 0
 #endif
-XTERN bool force;
-XTERN bool batch;
-XTERN bool noreverse;
-XTERN bool reverse;
-XTERN enum { DEFAULT_VERBOSITY, SILENT, VERBOSE } verbosity;
-XTERN bool skip_rest_of_patch;
-XTERN int strippath;
-XTERN bool canonicalize;
-XTERN int patch_get;
-XTERN bool set_time;
-XTERN bool set_utc;
-XTERN bool follow_symlinks;
+extern bool force;
+extern bool batch;
+extern bool noreverse_flag;
+extern bool reverse_flag;
+extern enum verbosity { DEFAULT_VERBOSITY, SILENT, VERBOSE } verbosity;
+extern bool skip_rest_of_patch;
+extern intmax_t strippath;
+extern bool canonicalize_ws;
+extern intmax_t patch_get;
+extern bool set_time;
+extern bool set_utc;
+extern bool follow_symlinks;
 
 enum diff
   {
@@ -124,42 +117,12 @@ enum diff
     GIT_BINARY_DIFF
   };
 
-XTERN enum diff diff_type;
+extern enum diff diff_type;
 
-XTERN char *revision;			/* prerequisite revision, if any */
+extern char *revision;			/* prerequisite revision, if any */
 
-#ifndef __attribute__
-/* The __attribute__ feature is available in gcc versions 2.5 and later.
-   The __-protected variants of the attributes 'format' and 'printf' are
-   accepted by gcc versions 2.6.4 (effectively 2.7) and later.
-   We enable __attribute__ only if these are supported too, because
-   gnulib and libintl do '#define printf __printf__' when they override
-   the 'printf' function.  */
-# if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 7)
-#  define __attribute__(Spec)   /* empty */
-# endif
-#endif
-
-void fatal_exit (int) __attribute__ ((noreturn));
-
-#include <errno.h>
-#if !STDC_HEADERS && !defined errno
-extern int errno;
-#endif
-
-#include <string.h>
-#include <stdlib.h>
-#include <unistd.h>
-
-#if HAVE_FSEEKO
-  typedef off_t file_offset;
-# define file_seek fseeko
-# define file_tell ftello
-#else
-  typedef long file_offset;
-# define file_seek fseek
-# define file_tell ftell
-#endif
+void fatal_cleanup (void);
+_Noreturn void fatal_exit (void);
 
 #if ! (HAVE_GETEUID || defined geteuid)
 # if ! (HAVE_GETUID || defined getuid)
@@ -169,16 +132,14 @@ extern int errno;
 # endif
 #endif
 
-#include <fcntl.h>
-
 #ifdef HAVE_SETMODE_DOS
-  XTERN int binary_transput;	/* O_BINARY if binary i/o is desired */
+  extern int binary_transput;	/* O_BINARY if binary i/o is desired */
 #else
 # define binary_transput 0
 #endif
 
 /* Disable the CR stripping heuristic?  */
-XTERN bool no_strip_trailing_cr;
+extern bool no_strip_trailing_cr;
 
 #ifndef NULL_DEVICE
 #define NULL_DEVICE "/dev/null"
@@ -197,20 +158,20 @@ struct outstate
 };
 
 /* offset in the input and output at which the previous hunk matched */
-XTERN lin in_offset;
-XTERN lin out_offset;
+extern ptrdiff_t in_offset;
+extern ptrdiff_t out_offset;
 
 /* how many input lines have been irretractably output */
-XTERN lin last_frozen_line;
+extern idx_t last_frozen_line;
 
-bool copy_till (struct outstate *, lin);
-bool similar (char const *, size_t, char const *, size_t) _GL_ATTRIBUTE_PURE;
+bool copy_till (struct outstate *, idx_t);
+bool similar (char const *, idx_t, char const *, idx_t) ATTRIBUTE_PURE;
 
 #ifdef ENABLE_MERGE
 enum conflict_style { MERGE_MERGE, MERGE_DIFF3 };
-XTERN enum conflict_style conflict_style;
+extern enum conflict_style conflict_style;
 
-bool merge_hunk (int hunk, struct outstate *, lin where, bool *);
+bool merge_hunk (intmax_t hunk, struct outstate *, idx_t where, bool *);
 #else
 # define merge_hunk(hunk, outstate, where, somefailed) false
 #endif

src/inp.c

@@ -1,8 +1,7 @@
 /* inputting files to be patched */
 
-/* Copyright (C) 1986, 1988 Larry Wall
-   Copyright (C) 1991-1993, 1997-1999, 2002-2003, 2006, 2009-2012 Free Software
-   Foundation, Inc.
+/* Copyright 1991-2025 Free Software Foundation, Inc.
+   Copyright 1986, 1988 Larry Wall
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -17,78 +16,34 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-#define XTERN extern
 #include <common.h>
+
 #include <quotearg.h>
 #include <util.h>
 #include <xalloc.h>
-#undef XTERN
-#define XTERN
+
 #include <inp.h>
+#include <safe.h>
 
 /* Input-file-with-indexable-lines abstract type */
 
-static char *i_buffer;			/* plan A buffer */
-static char const **i_ptr;		/* pointers to lines in plan A buffer */
+static char *i_buffer;			/* buffer of input file lines */
+static char const **i_ptr;		/* pointers to lines in buffer */
+idx_t input_lines;			/* how long is input file in lines */
 
-static size_t tibufsize;		/* size of plan b buffers */
-#ifndef TIBUFSIZE_MINIMUM
-#define TIBUFSIZE_MINIMUM (8 * 1024)	/* minimum value for tibufsize */
-#endif
-static int tifd = -1;			/* plan b virtual string array */
-static char *tibuf[2];			/* plan b buffers */
-static lin tiline[2] = {-1, -1};	/* 1st line in each buffer */
-static lin lines_per_buf;		/* how many lines per buffer */
-static size_t tireclen;			/* length of records in tmp file */
-static size_t last_line_size;		/* size of last input line */
-
-static bool plan_a (char const *);	/* yield false if memory runs out */
-static void plan_b (char const *);
 static void report_revision (bool);
-static void too_many_lines (char const *) __attribute__((noreturn));
 
 /* New patch--prepare to edit another file. */
 
 void
 re_input (void)
 {
-    if (using_plan_a) {
       if (i_buffer)
 	{
 	  free (i_buffer);
 	  i_buffer = 0;
 	  free (i_ptr);
 	}
-    }
-    else {
-	if (tifd >= 0)
-	  close (tifd);
-	tifd = -1;
-	if (tibuf[0])
-	  {
-	    free (tibuf[0]);
-	    tibuf[0] = 0;
-	  }
-	tiline[0] = tiline[1] = -1;
-	tireclen = 0;
-    }
-}
-
-/* Construct the line index, somehow or other. */
-
-void
-scan_input (char *filename, mode_t file_type)
-{
-    using_plan_a = ! (debug & 16) && plan_a (filename);
-    if (!using_plan_a)
-      {
-	if (! S_ISREG (file_type))
-	  {
-	    assert (S_ISLNK (file_type));
-	    fatal ("Can't handle %s %s", "symbolic link", quotearg (filename));
-	  }
-	plan_b(filename);
-      }
 }
 
 /* Report whether a desired revision was found.  */
@@ -114,23 +69,16 @@ report_revision (bool found_revision)
 	   rev);
   else
     {
-      ask ("This file doesn't appear to be the %s version -- patch anyway? [n] ",
-	   rev);
-      if (*buf != 'y')
+      if (*ask (("This file doesn't appear to be the %s version"
+		 " -- patch anyway? [n] "),
+		rev)
+	  != 'y')
 	fatal ("aborted");
     }
 }
 
-
-static void
-too_many_lines (char const *filename)
-{
-  fatal ("File %s has too many lines", quotearg (filename));
-}
-
-
 bool
-get_input_file (char const *filename, char const *outname, mode_t file_type)
+get_input_file (char *filename, char const *outname, mode_t file_type)
 {
     bool elsewhere = strcmp (filename, outname) != 0;
     char const *cs;
@@ -207,38 +155,29 @@ get_input_file (char const *filename, char const *outname, mode_t file_type)
 }
 
 
-/* Try keeping everything in memory. */
+/* Read input and build its line index.  */
 
-static bool
-plan_a (char const *filename)
+void
+scan_input (char *filename, mode_t file_type, int ifd)
 {
-  char const *s;
-  char const *lim;
-  char const **ptr;
-  char *buffer;
-  lin iline;
-  size_t size = instat.st_size;
-
-  /* Fail if the file size doesn't fit in a size_t,
+  /* Fail if the file size doesn't fit,
      or if storage isn't available.  */
-  if (! (size == instat.st_size
-	 && (buffer = malloc (size ? size : (size_t) 1))))
-    return false;
+  idx_t size;
+  if (ckd_add (&size, instat.st_size, 0))
+    xalloc_die ();
+  char *buffer = ximalloc (size);
 
   /* Read the input file, but don't bother reading it if it's empty.
      When creating files, the files do not actually exist.  */
   if (size)
     {
-      if (S_ISREG (instat.st_mode))
+      if (S_ISREG (file_type))
         {
-	  int ifd = open (filename, O_RDONLY|binary_transput);
-	  size_t buffered = 0, n;
-	  if (ifd < 0)
-	    pfatal ("can't open file %s", quotearg (filename));
+	  idx_t buffered = 0;
 
 	  while (size - buffered != 0)
 	    {
-	      n = read (ifd, buffer + buffered, size - buffered);
+	      ssize_t n = Read (ifd, buffer + buffered, size - buffered);
 	      if (n == 0)
 		{
 		  /* Some non-POSIX hosts exaggerate st_size in text mode;
@@ -246,52 +185,30 @@ plan_a (char const *filename)
 		  size = buffered;
 		  break;
 		}
-	      if (n == (size_t) -1)
-		{
-		  /* Perhaps size is too large for this host.  */
-		  close (ifd);
-		  free (buffer);
-		  return false;
-		}
 	      buffered += n;
 	    }
-
-	  if (close (ifd) != 0)
-	    read_fatal ();
 	}
-      else if (S_ISLNK (instat.st_mode))
+      else
 	{
-	  ssize_t n;
-	  n = readlink (filename, buffer, size);
+	  ssize_t n = safe_readlink (filename, buffer, size);
 	  if (n < 0)
 	    pfatal ("can't read %s %s", "symbolic link", quotearg (filename));
 	  size = n;
 	}
-      else
-	{
-	  free (buffer);
-	  return false;
-	}
   }
 
   /* Scan the buffer and build array of pointers to lines.  */
-  lim = buffer + size;
-  iline = 3; /* 1 unused, 1 for SOF, 1 for EOF if last line is incomplete */
-  for (s = buffer;  (s = (char *) memchr (s, '\n', lim - s));  s++)
-    if (++iline < 0)
-      too_many_lines (filename);
-  if (! (iline == (size_t) iline
-	 && (size_t) iline * sizeof *ptr / sizeof *ptr == (size_t) iline
-	 && (ptr = (char const **) malloc ((size_t) iline * sizeof *ptr))))
-    {
-      free (buffer);
-      return false;
-    }
+  char const *lim = buffer + size;
+  idx_t iline = 3; /* 1 unused, 1 for SOF,
+		      1 for EOF if last line is incomplete.  */
+  for (char const *s = buffer;  (s = memchr (s, '\n', lim - s));  s++)
+    iline++;
+  char const **ptr = xireallocarray (nullptr, iline, sizeof *ptr);
   iline = 0;
-  for (s = buffer;  ;  s++)
+  for (char const *s = buffer; ; s++)
     {
       ptr[++iline] = s;
-      if (! (s = (char *) memchr (s, '\n', lim - s)))
+      if (! (s = memchr (s, '\n', lim - s)))
 	break;
     }
   if (size && lim[-1] != '\n')
@@ -301,18 +218,18 @@ plan_a (char const *filename)
   if (revision)
     {
       char const *rev = revision;
-      int rev0 = rev[0];
+      char rev0 = rev[0];
       bool found_revision = false;
-      size_t revlen = strlen (rev);
+      idx_t revlen = strlen (rev);
 
       if (revlen <= size)
 	{
 	  char const *limrev = lim - revlen;
 
-	  for (s = buffer;  (s = (char *) memchr (s, rev0, limrev - s));  s++)
+	  for (char const *s = buffer; (s = memchr (s, rev0, limrev - s)); s++)
 	    if (memcmp (s, rev, revlen) == 0
-		&& (s == buffer || ISSPACE ((unsigned char) s[-1]))
-		&& (s + 1 == limrev || ISSPACE ((unsigned char) s[revlen])))
+		&& (s == buffer || c_isspace (s[-1]))
+		&& (s + 1 == limrev || c_isspace (s[revlen])))
 	      {
 		found_revision = true;
 		break;
@@ -322,164 +239,18 @@ plan_a (char const *filename)
       report_revision (found_revision);
     }
 
-  /* Plan A will work.  */
   i_buffer = buffer;
   i_ptr = ptr;
-  return true;
 }
 
-/* Keep (virtually) nothing in memory. */
+/* Fetch a line from the input file.  */
 
-static void
-plan_b (char const *filename)
+struct iline
+ifetch (idx_t line)
 {
-  FILE *ifp;
-  int c;
-  size_t len;
-  size_t maxlen;
-  bool found_revision;
-  size_t i;
-  char const *rev;
-  size_t revlen;
-  lin line = 1;
+  if (! (1 <= line && line <= input_lines))
+    return (struct iline) { .ptr = "", .size = 0 };
 
-  if (instat.st_size == 0)
-    filename = NULL_DEVICE;
-  if (! (ifp = fopen (filename, binary_transput ? "rb" : "r")))
-    pfatal ("Can't open file %s", quotearg (filename));
-  if (TMPINNAME_needs_removal)
-    {
-      /* Reopen the existing temporary file. */
-      tifd = create_file (TMPINNAME, O_RDWR | O_BINARY, 0, true);
-    }
-  else
-    {
-      tifd = make_tempfile (&TMPINNAME, 'i', NULL, O_RDWR | O_BINARY,
-			    S_IRUSR | S_IWUSR);
-      TMPINNAME_needs_removal = true;
-    }
-  i = 0;
-  len = 0;
-  maxlen = 1;
-  rev = revision;
-  found_revision = !rev;
-  revlen = rev ? strlen (rev) : 0;
-
-  while ((c = getc (ifp)) != EOF)
-    {
-      len++;
-
-      if (c == '\n')
-	{
-	  if (++line < 0)
-	    too_many_lines (filename);
-	  if (maxlen < len)
-	      maxlen = len;
-	  len = 0;
-	}
-
-      if (!found_revision)
-	{
-	  if (i == revlen)
-	    {
-	      found_revision = ISSPACE ((unsigned char) c);
-	      i = (size_t) -1;
-	    }
-	  else if (i != (size_t) -1)
-	    i = rev[i]==c ? i + 1 : (size_t) -1;
-
-	  if (i == (size_t) -1  &&  ISSPACE ((unsigned char) c))
-	    i = 0;
-	}
-    }
-
-  if (revision)
-    report_revision (found_revision);
-  Fseek (ifp, 0, SEEK_SET);		/* rewind file */
-  for (tibufsize = TIBUFSIZE_MINIMUM;  tibufsize < maxlen;  tibufsize <<= 1)
-    /* do nothing */ ;
-  lines_per_buf = tibufsize / maxlen;
-  tireclen = maxlen;
-  tibuf[0] = xmalloc (2 * tibufsize);
-  tibuf[1] = tibuf[0] + tibufsize;
-
-  for (line = 1; ; line++)
-    {
-      char *p = tibuf[0] + maxlen * (line % lines_per_buf);
-      char const *p0 = p;
-      if (! (line % lines_per_buf))	/* new block */
-	if (write (tifd, tibuf[0], tibufsize) != tibufsize)
-	  write_fatal ();
-      if ((c = getc (ifp)) == EOF)
-	break;
-
-      for (;;)
-	{
-	  *p++ = c;
-	  if (c == '\n')
-	    {
-	      last_line_size = p - p0;
-	      break;
-	    }
-
-	  if ((c = getc (ifp)) == EOF)
-	    {
-	      last_line_size = p - p0;
-	      line++;
-	      goto EOF_reached;
-	    }
-	}
-    }
- EOF_reached:
-  if (ferror (ifp)  ||  fclose (ifp) != 0)
-    read_fatal ();
-
-  if (line % lines_per_buf  !=  0)
-    if (write (tifd, tibuf[0], tibufsize) != tibufsize)
-      write_fatal ();
-  input_lines = line - 1;
-}
-
-/* Fetch a line from the input file.
-   WHICHBUF is ignored when the file is in memory.  */
-
-char const *
-ifetch (lin line, bool whichbuf, size_t *psize)
-{
-    char const *q;
-    char const *p;
-
-    if (line < 1 || line > input_lines) {
-	*psize = 0;
-	return "";
-    }
-    if (using_plan_a) {
-	p = i_ptr[line];
-	*psize = i_ptr[line + 1] - p;
-	return p;
-    } else {
-	lin offline = line % lines_per_buf;
-	lin baseline = line - offline;
-
-	if (tiline[0] == baseline)
-	    whichbuf = false;
-	else if (tiline[1] == baseline)
-	    whichbuf = true;
-	else {
-	    tiline[whichbuf] = baseline;
-	    if ((lseek (tifd, baseline/lines_per_buf * tibufsize, SEEK_SET)
-		 == -1)
-		|| read (tifd, tibuf[whichbuf], tibufsize) < 0)
-	      read_fatal ();
-	}
-	p = tibuf[whichbuf] + (tireclen*offline);
-	if (line == input_lines)
-	    *psize = last_line_size;
-	else {
-	    for (q = p;  *q++ != '\n';  )
-		/* do nothing */ ;
-	    *psize = q - p;
-	}
-	return p;
-    }
+  char const *ptr = i_ptr[line];
+  return (struct iline) { .ptr = ptr, .size = i_ptr[line + 1] - ptr };
 }

src/inp.h

@@ -1,8 +1,7 @@
 /* inputting files to be patched */
 
-/* Copyright (C) 1986, 1988 Larry Wall
-   Copyright (C) 1991-1993, 1997-1999, 2002-2003, 2009-2012 Free Software
-   Foundation, Inc.
+/* Copyright 1991-2025 Free Software Foundation, Inc.
+   Copyright 1986, 1988 Larry Wall
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -17,9 +16,14 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-XTERN lin input_lines;		/* how long is input file in lines */
+/* Number of lines in input file.  */
+extern idx_t input_lines;
 
-char const *ifetch (lin, bool, size_t *);
-bool get_input_file (char const *, char const *, mode_t);
+/* Description of an input line: a pointer to its start, and the
+   number of bytes in it (including any trailing newline).  */
+struct iline { char const *ptr; idx_t size; };
+
+struct iline ifetch (idx_t) ATTRIBUTE_PURE;
+bool get_input_file (char *, char const *, mode_t);
 void re_input (void);
-void scan_input (char *, mode_t);
+void scan_input (char *, mode_t, int);

src/list.h

@@ -0,0 +1,67 @@
+#ifndef __LIST_H
+#define __LIST_H
+
+struct list_head {
+  struct list_head *next, *prev;
+};
+
+#define LIST_HEAD_INIT(name) { &(name), &(name) }
+
+#define LIST_HEAD(name) \
+  struct list_head name = LIST_HEAD_INIT(name)
+
+_GL_INLINE_HEADER_BEGIN
+#ifndef LIST_INLINE
+# define LIST_INLINE _GL_INLINE
+#endif
+
+LIST_INLINE void
+INIT_LIST_HEAD (struct list_head *list)
+{
+  list->next = list;
+  list->prev = list;
+}
+
+LIST_INLINE void
+list_add (struct list_head *entry, struct list_head *head)
+{
+  struct list_head *next = head->next;
+  entry->prev = head;
+  entry->next = next;
+  next->prev = head->next = entry;
+}
+
+LIST_INLINE void
+list_del (struct list_head *entry)
+{
+  struct list_head *next = entry->next;
+  struct list_head *prev = entry->prev;
+  next->prev = prev;
+  prev->next = next;
+}
+
+LIST_INLINE void
+list_del_init (struct list_head *entry)
+{
+  list_del (entry);
+  INIT_LIST_HEAD (entry);
+}
+
+LIST_INLINE bool
+list_empty (const struct list_head *head)
+{
+  return head->next == head;
+}
+
+/* Return PTR - OFFSET, ignoring the type of PTR and treating OFFSET
+   as a byte offset.  */
+LIST_INLINE void *
+list_entry (void *ptr, idx_t offset)
+{
+  char *p = ptr;
+  return p - offset;
+}
+
+_GL_INLINE_HEADER_END
+
+#endif  /* __LIST_H */

src/merge.c

@@ -1,6 +1,6 @@
 /*  Merge a patch
 
-    Copyright (C) 2009-2012 Free Software Foundation, Inc.
+    Copyright 2009-2025 Free Software Foundation, Inc.
     Written by Andreas Gruenbacher <agruen@gnu.org>, 2009.
 
    This program is free software: you can redistribute it and/or modify
@@ -16,24 +16,22 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-#define XTERN extern
 #include <common.h>
-#include <minmax.h>
 #include <xalloc.h>
 #include <inp.h>
 #include <pch.h>
 #include <util.h>
 
-static lin count_context_lines (void);
-static bool context_matches_file (lin, lin);
-static void compute_changes (lin, lin, lin, lin, char *, char *);
+static idx_t count_context_lines (void);
+static bool context_matches_file (idx_t, idx_t);
+static void compute_changes (idx_t, idx_t, idx_t, idx_t, char *, char *);
 
-#define OFFSET lin
+#define OFFSET ptrdiff_t
 #define EQUAL_IDX(x, y) (context_matches_file (x, y))
 #include "bestmatch.h"
 
 #define XVECREF_YVECREF_EQUAL(ctxt, x, y) (context_matches_file (x, y))
-#define OFFSET lin
+#define OFFSET ptrdiff_t
 #define EXTRA_CONTEXT_FIELDS \
 	char *xchar; \
 	char *ychar;
@@ -42,21 +40,19 @@ static void compute_changes (lin, lin, lin, lin, char *, char *);
 #define USE_HEURISTIC 1
 #include "diffseq.h"
 
-static lin
-locate_merge (lin *matched)
+static idx_t
+locate_merge (idx_t *matched)
 {
-    lin first_guess = pch_first () + in_offset;
-    lin pat_lines = pch_ptrn_lines ();
-    lin context_lines = count_context_lines ();
-    lin max_where = input_lines - pat_lines + context_lines + 1;
-    lin min_where = last_frozen_line + 1;
-    lin max_pos_offset = max_where - first_guess;
-    lin max_neg_offset = first_guess - min_where;
-    lin max_offset = (max_pos_offset < max_neg_offset
-		      ? max_neg_offset : max_pos_offset);
-    lin where = first_guess, max_matched = 0;
-    lin min, max;
-    lin offset;
+    idx_t first_guess = pch_first () + in_offset;
+    idx_t pat_lines = pch_ptrn_lines ();
+    idx_t context_lines = count_context_lines ();
+    idx_t max_where = input_lines - pat_lines + context_lines + 1;
+    idx_t min_where = last_frozen_line + 1;
+    ptrdiff_t max_pos_offset = max_where - first_guess;
+    ptrdiff_t max_neg_offset = first_guess - min_where;
+    ptrdiff_t max_offset = MAX (max_pos_offset, max_neg_offset);
+    idx_t where = first_guess;
+    idx_t max_matched = 0;
     bool match_until_eof;
 
     /* Note: we need to preserve patch's property that it applies hunks at the
@@ -70,21 +66,15 @@ locate_merge (lin *matched)
 
     /* Allow at most CONTEXT_LINES lines to be replaced (replacing counts
        as insert + delete), and require the remaining MIN lines to match.  */
-    max = 2 * context_lines;
-    min = pat_lines - context_lines;
+    idx_t max = 2 * context_lines;
+    idx_t min = pat_lines - context_lines;
 
     if (debug & 1)
-      {
-	char numbuf0[LINENUM_LENGTH_BOUND + 1];
-	char numbuf1[LINENUM_LENGTH_BOUND + 1];
-	say ("locating merge: min=%s max=%s ",
-	     format_linenum (numbuf0, min),
-	     format_linenum (numbuf1, max));
-      }
+      say ("locating merge: min=%td max=%td ", min, max);
 
     /* Hunks from the start or end of the file have less context. Anchor them
        to the start or end, trying to make up for this disadvantage.  */
-    offset = pch_suffix_context () - pch_prefix_context ();
+    ptrdiff_t offset = pch_suffix_context () - pch_prefix_context ();
     if (offset > 0 && pch_first () <= 1)
       max_pos_offset = 0;
     match_until_eof = offset < 0;
@@ -97,9 +87,7 @@ locate_merge (lin *matched)
       {
 	if (offset <= max_pos_offset)
 	  {
-	    lin guess = first_guess + offset;
-	    lin last;
-	    lin changes;
+	    idx_t guess = first_guess + offset, last, changes;
 
 	    changes = bestmatch (1, pat_lines + 1, guess, input_lines + 1,
 				 match_until_eof ? input_lines - guess + 1 : min,
@@ -116,9 +104,7 @@ locate_merge (lin *matched)
 	  }
 	if (0 < offset && offset <= max_neg_offset)
 	  {
-	    lin guess = first_guess - offset;
-	    lin last;
-	    lin changes;
+	    idx_t guess = first_guess - offset, last, changes;
 
 	    changes = bestmatch (1, pat_lines + 1, guess, input_lines + 1,
 				 match_until_eof ? input_lines - guess + 1 : min,
@@ -135,15 +121,7 @@ locate_merge (lin *matched)
 	  }
       }
     if (debug & 1)
-      {
-	char numbuf0[LINENUM_LENGTH_BOUND + 1];
-	char numbuf1[LINENUM_LENGTH_BOUND + 1];
-	char numbuf2[LINENUM_LENGTH_BOUND + 1];
-	say ("where=%s matched=%s changes=%s\n",
-	     format_linenum (numbuf0, where),
-	     format_linenum (numbuf1, max_matched),
-	     format_linenum (numbuf2, max + 1));
-      }
+      say ("where=%td matched=%td changes=%td\n", where, max_matched, max + 1);
 
   out:
     *matched = max_matched;
@@ -153,72 +131,66 @@ locate_merge (lin *matched)
 }
 
 static void
-print_linerange (lin from, lin to)
+print_linerange (idx_t from, idx_t to)
 {
-  char numbuf0[LINENUM_LENGTH_BOUND + 1];
-  char numbuf1[LINENUM_LENGTH_BOUND + 1];
-
   if (to <= from)
-    printf ("%s",
-	    format_linenum (numbuf0, from));
+    Fprintf (stdout, "%td", from);
   else
-    printf ("%s-%s",
-	    format_linenum (numbuf0, from),
-	    format_linenum (numbuf1, to));
+    Fprintf (stdout, "%td-%td", from, to);
 }
 
 static void
-merge_result (bool *first_result, int hunk, char const *what, lin from, lin to)
+merge_result (bool *first_result, intmax_t hunk, char const *what,
+	      idx_t from, idx_t to)
 {
   static char const *last_what;
 
   if (*first_result && what)
     {
-      printf ("Hunk #%d %s at ", hunk, what);
+      Fprintf (stdout, "Hunk #%jd %s at ", hunk, what);
       last_what = what;
     }
   else if (! what)
     {
       if (! *first_result)
 	{
-	  fputs (".\n", stdout);
-	  fflush (stdout);
+	  Fputs (".\n", stdout);
+	  Fflush (stdout);
 	  last_what = 0;
 	}
       return;
     }
   else if (last_what == what)
-    fputs (",", stdout);
+    Fputc (',', stdout);
   else
-    printf (", %s at ", what);
+    Fprintf (stdout, ", %s at ", what);
+
   print_linerange (from + out_offset, to + out_offset);
   *first_result = false;
 }
 
 bool
-merge_hunk (int hunk, struct outstate *outstate, lin where, bool *somefailed)
+merge_hunk (intmax_t hunk, struct outstate *outstate,
+	    idx_t where, bool *somefailed)
 {
   bool applies_cleanly;
   bool first_result = true;
   bool already_applied;
   FILE *fp = outstate->ofp;
-  lin old = 1;
-  lin firstold = pch_ptrn_lines ();
-  lin new = firstold + 1;
-  lin firstnew = pch_end ();
-  lin in;
-  lin firstin;
+  idx_t old = 1;
+  idx_t firstold = pch_ptrn_lines ();
+  idx_t new = firstold + 1;
   char *oldin;
-  lin matched;
-  lin lastwhere;
+  idx_t lastwhere;
 
   /* Convert '!' markers into '-' and '+' to simplify things here.  */
   pch_normalize (UNI_DIFF);
 
-  assert (pch_char (firstnew + 1) == '^');
+  assert (pch_char (pch_end () + 1) == '^');
   while (pch_char (new) == '=' || pch_char (new) == '\n')
     new++;
 
+  idx_t matched;
   if (where)
     {
       applies_cleanly = true;
@@ -230,7 +202,7 @@ merge_hunk (int hunk, struct outstate *outstate, lin where, bool *somefailed)
       applies_cleanly = false;
     }
 
-  in = firstold + 2;
+  idx_t in = firstold + 2;
   oldin = xmalloc (in + matched + 1);
   memset (oldin, ' ', in + matched);
   oldin[0] = '*';
@@ -241,40 +213,29 @@ merge_hunk (int hunk, struct outstate *outstate, lin where, bool *somefailed)
 
   if (debug & 2)
     {
-      char numbuf0[LINENUM_LENGTH_BOUND + 1];
-      char numbuf1[LINENUM_LENGTH_BOUND + 1];
-      lin n;
-
-      fputc ('\n', stderr);
-      for (n = 0; n <= in + matched; n++)
+      Fputc ('\n', stderr);
+      for (idx_t n = 0; n <= in + matched; n++)
 	{
-	  fprintf (stderr, "%s %c",
-		  format_linenum (numbuf0, n),
-		  oldin[n]);
+	  Fprintf (stderr, "%td %c", n, oldin[n]);
 	  if (n == 0)
-	    fprintf(stderr, " %s,%s\n",
-		    format_linenum (numbuf0, pch_first()),
-		    format_linenum (numbuf1, pch_ptrn_lines()));
+	    Fprintf (stderr, " %td,%td\n", pch_first (), pch_ptrn_lines ());
 	  else if (n <= firstold)
-	    fprintf (stderr, " |%.*s",
-		     (int) pch_line_len (n), pfetch (n));
+	    {
+	      Fputs (" |", stderr);
+	      Fwrite (pfetch (n), 1, pch_line_len (n), stderr);
+	    }
 	  else if (n == in - 1)
-	    fprintf(stderr, " %s,%s\n",
-		    format_linenum (numbuf0, where),
-		    format_linenum (numbuf1, matched));
+	    Fprintf (stderr, " %td,%td\n", where, matched);
 	  else if (n >= in && n < in + matched)
 	    {
-	      size_t size;
-	      const char *line;
-
-	      line = ifetch (where + n - in, false, &size);
-	      fprintf (stderr, " |%.*s",
-		       (int) size, line);
+	      struct iline line = ifetch (where + n - in);
+	      Fputs (" |", stderr);
+	      Fwrite (line.ptr, 1, line.size, stderr);
 	    }
 	  else
-	    fputc('\n', stderr);
+	    Fputc ('\n', stderr);
 	}
-      fflush (stderr);
+      Fflush (stderr);
     }
 
   if (last_frozen_line < where - 1)
@@ -284,13 +245,11 @@ merge_hunk (int hunk, struct outstate *outstate, lin where, bool *somefailed)
   for (;;)
     {
       firstold = old;
-      firstnew = new;
-      firstin = in;
+      idx_t firstnew = new;
+      idx_t firstin = in;
 
       if (pch_char (old) == '-' || pch_char (new) == '+')
 	{
-	  lin lines;
-
 	  while (pch_char (old) == '-')
 	    {
 	      if (oldin[old] == '-' || oldin[in] == '+')
@@ -307,7 +266,7 @@ merge_hunk (int hunk, struct outstate *outstate, lin where, bool *somefailed)
 	  while (pch_char (new) == '+')
 	    new++;
 
-	  lines = new - firstnew;
+	  idx_t lines = new - firstnew;
 	  if (verbosity == VERBOSE
 	      || ((verbosity != SILENT) && ! applies_cleanly))
 	    merge_result (&first_result, hunk, "merged",
@@ -432,7 +391,7 @@ merge_hunk (int hunk, struct outstate *outstate, lin where, bool *somefailed)
 		      where, lastwhere - 1);
       if (conflict_style == MERGE_DIFF3)
 	{
-	  lin common_prefix = lastwhere - where;
+	  idx_t common_prefix = lastwhere - where;
 
 	  /* Forget about common prefix lines.  */
 	  firstin -= common_prefix;
@@ -448,8 +407,7 @@ merge_hunk (int hunk, struct outstate *outstate, lin where, bool *somefailed)
 
       if (! already_applied)
 	{
-	  lin common_suffix = 0;
-	  lin lines;
+	  idx_t common_suffix = 0;
 
 	  if (conflict_style == MERGE_MERGE)
 	    {
@@ -461,14 +419,14 @@ merge_hunk (int hunk, struct outstate *outstate, lin where, bool *somefailed)
 		/* do nothing */ ;
 	    }
 
-	  lines = 3 + (in - firstin) + (new - firstnew);
+	  idx_t lines = 3 + (in - firstin) + (new - firstnew);
 	  if (conflict_style == MERGE_DIFF3)
 	    lines += 1 + (old - firstold);
 	  merge_result (&first_result, hunk, "NOT MERGED",
 			where, where + lines - 1);
 	  out_offset += lines - (in - firstin);
 
-	  fputs (outstate->after_newline + "\n<<<<<<<\n", fp);
+	  Fputs (&"\n<<<<<<<\n"[outstate->after_newline], fp);
 	  outstate->after_newline = true;
 	  if (firstin < in)
 	    {
@@ -479,7 +437,7 @@ merge_hunk (int hunk, struct outstate *outstate, lin where, bool *somefailed)
 
 	  if (conflict_style == MERGE_DIFF3)
 	    {
-	      fputs (outstate->after_newline + "\n|||||||\n", fp);
+	      Fputs (&"\n|||||||\n"[outstate->after_newline], fp);
 	      outstate->after_newline = true;
 	      while (firstold < old)
 		{
@@ -488,14 +446,14 @@ merge_hunk (int hunk, struct outstate *outstate, lin where, bool *somefailed)
 		}
 	    }
 
-	  fputs (outstate->after_newline + "\n=======\n", fp);
+	  Fputs (&"\n=======\n"[outstate->after_newline], fp);
 	  outstate->after_newline = true;
 	  while (firstnew < new)
 	    {
 	      outstate->after_newline = pch_write_line (firstnew, fp);
 	      firstnew++;
 	    }
-	  fputs (outstate->after_newline + "\n>>>>>>>\n", fp);
+	  Fputs (&"\n>>>>>>>\n"[outstate->after_newline], fp);
 	  outstate->after_newline = true;
 	  outstate->zero_output = false;
 	  if (ferror (fp))
@@ -520,53 +478,48 @@ merge_hunk (int hunk, struct outstate *outstate, lin where, bool *somefailed)
   return true;
 }
 
-static lin
+static idx_t
 count_context_lines (void)
 {
-  lin old;
-  lin lastold = pch_ptrn_lines ();
-  lin context;
+  idx_t lastold = pch_ptrn_lines ();
+  idx_t context = 0;
 
-  for (context = 0, old = 1; old <= lastold; old++)
+  for (idx_t old = 1; old <= lastold; old++)
     if (pch_char (old) == ' ')
       context++;
   return context;
 }
 
 static bool
-context_matches_file (lin old, lin where)
+context_matches_file (idx_t old, idx_t where)
 {
-  size_t size;
-  const char *line;
-
-  line = ifetch (where, false, &size);
-  return size &&
-	 (canonicalize ?
-	  similar (pfetch (old), pch_line_len (old), line, size) :
-	  (size == pch_line_len (old) &&
-	   memcmp (line, pfetch (old), size) == 0));
+  struct iline line = ifetch (where);
+  return line.size &&
+	 (canonicalize_ws ?
+	  similar (pfetch (old), pch_line_len (old), line.ptr, line.size) :
+	  (line.size == pch_line_len (old) &&
+	   memcmp (line.ptr, pfetch (old), line.size) == 0));
 }
 
 static void
-compute_changes (lin xmin, lin xmax, lin ymin, lin ymax,
+compute_changes (idx_t xmin, idx_t xmax, idx_t ymin, idx_t ymax,
 		 char *xchar, char *ychar)
 {
   struct context ctxt;
-  lin diags;
-
   ctxt.xchar = xchar - xmin;
   ctxt.ychar = ychar - ymin;
 
-  diags = xmax + ymax + 3;
-  ctxt.fdiag = xmalloc (2 * diags * sizeof (*ctxt.fdiag));
+  idx_t diags;
+  if (ckd_add (&diags, xmax, ymax) || ckd_add (&diags, diags, 3))
+    xalloc_die ();
+  ctxt.fdiag = xinmalloc (diags, 2 * sizeof *ctxt.fdiag);
   ctxt.bdiag = ctxt.fdiag + diags;
   ctxt.fdiag += ymax + 1;
   ctxt.bdiag += ymax + 1;
 
   ctxt.heuristic = true;
-  ctxt.too_expensive = xmax + ymax;
 
-  compareseq (xmin, xmax, ymin, ymax, true, &ctxt);
+  compareseq (xmin, xmax, ymin, ymax, false, &ctxt);
 
   ctxt.fdiag -= ymax + 1;
   free (ctxt.fdiag);

src/pch.h

@@ -1,8 +1,7 @@
 /* reading patches */
 
-/* Copyright (C) 1986, 1987, 1988 Larry Wall
-
-   Copyright (C) 1990-1993, 1997-2003, 2009-2012 Free Software Foundation, Inc.
+/* Copyright 1990-2025 Free Software Foundation, Inc.
+   Copyright 1986-1988 Larry Wall
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -19,43 +18,39 @@
 
 enum nametype { OLD, NEW, INDEX, NONE };
 
-lin pch_end (void) _GL_ATTRIBUTE_PURE;
-lin pch_first (void) _GL_ATTRIBUTE_PURE;
-lin pch_hunk_beg (void) _GL_ATTRIBUTE_PURE;
-char const *pch_c_function (void) _GL_ATTRIBUTE_PURE;
-bool pch_git_diff (void) _GL_ATTRIBUTE_PURE;
-char const * pch_timestr (bool which) _GL_ATTRIBUTE_PURE;
-char const *pch_sha1 (bool which) _GL_ATTRIBUTE_PURE;
-mode_t pch_mode (bool which) _GL_ATTRIBUTE_PURE;
-lin pch_newfirst (void) _GL_ATTRIBUTE_PURE;
-lin pch_prefix_context (void) _GL_ATTRIBUTE_PURE;
-lin pch_ptrn_lines (void) _GL_ATTRIBUTE_PURE;
-lin pch_repl_lines (void) _GL_ATTRIBUTE_PURE;
-lin pch_suffix_context (void) _GL_ATTRIBUTE_PURE;
-bool pch_swap (void);
-bool pch_write_line (lin, FILE *);
+/* General purpose buffer.  */
+extern char *patchbuf;
+
+/* Allocated size of buf.  It is at least IO_BUFSIZE.  */
+extern idx_t patchbufsize;
+
+void grow_patchbuf (void);
+idx_t pch_end (void) ATTRIBUTE_PURE;
+idx_t pch_first (void) ATTRIBUTE_PURE;
+idx_t pch_hunk_beg (void) ATTRIBUTE_PURE;
+char const *pch_c_function (void) ATTRIBUTE_PURE;
+bool pch_git_diff (void) ATTRIBUTE_PURE;
+char const * pch_timestr (bool which) ATTRIBUTE_PURE;
+mode_t pch_mode (bool which) ATTRIBUTE_PURE;
+idx_t pch_newfirst (void) ATTRIBUTE_PURE;
+idx_t pch_prefix_context (void) ATTRIBUTE_PURE;
+idx_t pch_ptrn_lines (void) ATTRIBUTE_PURE;
+idx_t pch_repl_lines (void) ATTRIBUTE_PURE;
+idx_t pch_suffix_context (void) ATTRIBUTE_PURE;
+void pch_swap (void);
+bool pch_write_line (idx_t, FILE *);
 bool there_is_another_patch (bool, mode_t *);
-char *pfetch (lin) _GL_ATTRIBUTE_PURE;
-char pch_char (lin) _GL_ATTRIBUTE_PURE;
-int another_hunk (enum diff, bool);
-int pch_says_nonexistent (bool) _GL_ATTRIBUTE_PURE;
-size_t pch_line_len (lin) _GL_ATTRIBUTE_PURE;
-const char *pch_name(enum nametype) _GL_ATTRIBUTE_PURE;
-bool pch_copy (void) _GL_ATTRIBUTE_PURE;
-bool pch_rename (void) _GL_ATTRIBUTE_PURE;
-void do_ed_script (char const *, char const *, bool *, FILE *);
+char *pfetch (idx_t) ATTRIBUTE_PURE;
+char pch_char (idx_t) ATTRIBUTE_PURE;
+bool another_hunk (enum diff, bool);
+char pch_says_nonexistent (bool) ATTRIBUTE_PURE;
+idx_t pch_line_len (idx_t) ATTRIBUTE_PURE;
+char *pch_name (enum nametype) ATTRIBUTE_PURE;
+bool pch_copy (void) ATTRIBUTE_PURE;
+bool pch_rename (void) ATTRIBUTE_PURE;
+void do_ed_script (char *, struct outfile *, FILE *);
 void open_patch_file (char const *);
 void re_patch (void);
-void set_hunkmax (void);
 void pch_normalize (enum diff);
 
-XTERN struct timespec p_timestamp[2];  /* timestamps in patch headers */
-
-/* Return timestamp of patch header for file WHICH (false = old, true = new),
-   or a timestamp with tv_sec == -1 if there was no timestamp or an error in
-   the timestamp.  */
-
-static inline struct timespec pch_timestamp (bool which)
-{
-  return p_timestamp[which];
-}
+extern struct timespec p_timestamp[2];  /* timestamps in patch headers */

src/safe.c

@@ -0,0 +1,729 @@
+/* safe path traversal functions for 'patch' */
+
+/* Copyright 2015-2025 Free Software Foundation, Inc.
+
+   Written by Tim Waugh <twaugh@redhat.com> and
+   Andreas Gruenbacher <agruenba@redhat.com>.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/resource.h>
+#include <sys/time.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <safe.h>
+
+#include <basename-lgpl.h>
+#include <hash.h>
+#include <filename.h>
+#include <xalloc.h>
+
+#include "common.h"
+
+#include "util.h"
+
+#define LIST_INLINE _GL_EXTERN_INLINE
+#include "list.h"
+
+#ifndef EFTYPE
+# define EFTYPE 0
+#endif
+
+#ifdef O_PATH
+enum { O_PATHSEARCH = O_PATH };
+#else
+enum { O_PATHSEARCH = O_SEARCH };
+#endif
+
+enum { MAX_PATH_COMPONENTS = 1024 };
+
+/* Flag to turn the safe_* functions into their unsafe variants; files may then
+   lie outside the current working directory. */
+bool unsafe;
+
+/* Path lookup results are cached in a hash table + LRU list. When the
+   cache is full, the oldest entries are removed.  */
+
+static intmax_t dirfd_cache_misses;
+
+struct cached_dirfd {
+  struct list_head lru_link;
+  struct list_head children_link, children;
+  struct cached_dirfd *parent;
+
+  char *name;
+  int fd;
+};
+
+static Hash_table *cached_dirfds;
+static rlim_t min_cached_fds = 8;
+static rlim_t max_cached_fds;
+static LIST_HEAD (lru_list);
+
+static size_t hash_cached_dirfd (const void *entry, size_t table_size)
+{
+  const struct cached_dirfd *d = entry;
+  size_t strhash = hash_string (d->name, table_size);
+  return (strhash * 31 + d->parent->fd) % table_size;
+}
+
+static bool compare_cached_dirfds (const void *_a,
+				   const void *_b)
+{
+  const struct cached_dirfd *a = _a;
+  const struct cached_dirfd *b = _b;
+
+  return (a->parent->fd == b->parent->fd &&
+	  !strcmp (a->name, b->name));
+}
+
+static void free_cached_dirfd (struct cached_dirfd *entry)
+{
+  list_del (&entry->children_link);
+  free (entry->name);
+  free (entry);
+}
+
+static void init_dirfd_cache (void)
+{
+  struct rlimit nofile;
+
+  if (getrlimit (RLIMIT_NOFILE, &nofile) == 0)
+    {
+      if (nofile.rlim_cur == RLIM_INFINITY)
+        max_cached_fds = RLIM_INFINITY;
+      else
+	max_cached_fds = MAX (nofile.rlim_cur / 4, min_cached_fds);
+    }
+  else
+    max_cached_fds = min_cached_fds;
+
+  cached_dirfds = hash_initialize (min_cached_fds, nullptr,
+				   hash_cached_dirfd,
+				   compare_cached_dirfds, nullptr);
+
+  if (!cached_dirfds)
+    xalloc_die ();
+}
+
+static struct cached_dirfd *lookup_cached_dirfd (struct cached_dirfd *dir, const char *name)
+{
+  struct cached_dirfd *entry = nullptr;
+
+  if (cached_dirfds)
+    {
+      struct cached_dirfd key;
+      key.parent = dir;
+      key.name = (char *) name;
+      entry = hash_lookup (cached_dirfds, &key);
+    }
+
+  return entry;
+}
+
+static void remove_cached_dirfd (struct cached_dirfd *entry)
+{
+  while (! list_empty (&entry->children))
+    {
+      struct cached_dirfd *child =
+	list_entry (entry->children.next,
+		    offsetof (struct cached_dirfd, children_link));
+      list_del_init (&child->children_link);
+      /* assert (list_empty (&child->children_link)); */
+      hash_remove (cached_dirfds, child);  /* noop when not hashed */
+    }
+  list_del (&entry->lru_link);
+  hash_remove (cached_dirfds, entry);  /* noop when not hashed */
+  close (entry->fd);
+  free_cached_dirfd (entry);
+}
+
+static void insert_cached_dirfd (struct cached_dirfd *entry, int keepfd)
+{
+  if (!cached_dirfds)
+    init_dirfd_cache ();
+
+  if (max_cached_fds != RLIM_INFINITY)
+    {
+      /* Trim off the least recently used entries */
+      while (hash_get_n_entries (cached_dirfds) >= max_cached_fds)
+	{
+	  struct cached_dirfd *last =
+	    list_entry (lru_list.prev,
+			offsetof (struct cached_dirfd, lru_link));
+	  if (&last->lru_link == &lru_list)
+	    break;
+	  if (last->fd == keepfd)
+	    {
+	      last = list_entry (last->lru_link.prev,
+				 offsetof (struct cached_dirfd, lru_link));
+	      if (&last->lru_link == &lru_list)
+		break;
+	    }
+	  remove_cached_dirfd (last);
+	}
+    }
+
+  /* Only insert if the parent still exists. */
+  if (! list_empty (&entry->children_link))
+    if (hash_insert (cached_dirfds, entry) != entry)
+      xalloc_die ();
+}
+
+static void invalidate_cached_dirfd (int dirfd, const char *name)
+{
+  struct cached_dirfd dir, key, *entry;
+  if (!cached_dirfds)
+    return;
+
+  dir.fd = dirfd;
+  key.parent = &dir;
+  key.name = (char *) name;
+  entry = hash_lookup (cached_dirfds, &key);
+  if (entry)
+    remove_cached_dirfd (entry);
+}
+
+/* Put the looked up path back onto the lru list.  Return the file descriptor
+   of the top entry.  */
+static int put_path (struct cached_dirfd *entry)
+{
+  int fd = entry->fd;
+
+  while (entry)
+    {
+      struct cached_dirfd *parent = entry->parent;
+      if (! parent)
+	break;
+      list_add (&entry->lru_link, &lru_list);
+      entry = parent;
+    }
+
+  return fd;
+}
+
+static struct cached_dirfd *
+new_cached_dirfd (struct cached_dirfd *dir, char *name, int fd)
+{
+  struct cached_dirfd *entry = xmalloc (sizeof (struct cached_dirfd));
+
+  INIT_LIST_HEAD (&entry->lru_link);
+  list_add (&entry->children_link, &dir->children);
+  INIT_LIST_HEAD (&entry->children);
+  entry->parent = dir;
+  entry->name = name;
+  entry->fd = fd;
+  return entry;
+}
+
+/* In DIR, look up NAME as a subdirectory.
+   Return the corresponding cache entry if found, a null pointer otherwise.
+   If KEEPFD is nonnegative, make sure that any cache entry for it is not
+   removed from the cache (and KEEPFD remains open).  */
+static struct cached_dirfd *
+openat_cached (struct cached_dirfd *dir, char const *name, int keepfd)
+{
+  int fd;
+  struct cached_dirfd *entry = lookup_cached_dirfd (dir, name);
+
+  if (entry)
+    {
+      list_del_init (&entry->lru_link);
+      /* assert (list_empty (&entry->lru_link)); */
+      return entry;
+    }
+  dirfd_cache_misses++;
+
+  /* Actually get the new directory file descriptor. Don't follow
+     symbolic links. */
+  fd = openat (dir->fd, name, O_PATHSEARCH | O_DIRECTORY | O_NOFOLLOW);
+
+  /* Don't cache errors. */
+  if (fd < 0)
+    return nullptr;
+
+  /* Store new cache entry */
+  entry = new_cached_dirfd (dir, xstrdup (name), fd);
+  insert_cached_dirfd (entry, keepfd);
+  return entry;
+}
+
+static idx_t ATTRIBUTE_PURE
+count_path_components (const char *path)
+{
+  while (ISSLASH (*path))
+    path++;
+  if (! *path)
+    return 1;
+  for (idx_t components = 0; ; components++)
+    {
+      if (!*path)
+	return components;
+      while (*path && ! ISSLASH (*path))
+	path++;
+      while (ISSLASH (*path))
+	path++;
+    }
+}
+
+/* A symlink to resolve. */
+struct symlink {
+  struct symlink *prev;
+  char *path;
+};
+
+static void push_symlink (struct symlink **stack, struct symlink *symlink)
+{
+  symlink->prev = *stack;
+  *stack = symlink;
+}
+
+static void pop_symlink (struct symlink **stack)
+{
+  struct symlink *top = *stack;
+  *stack = top->prev;
+  free (top);
+}
+
+static int cwd_stat_errno = -1;
+static struct stat cwd_stat;
+
+static struct symlink *read_symlink(int dirfd, const char *name)
+{
+  int saved_errno = errno;
+  struct stat st;
+  struct symlink *symlink;
+  char *buffer;
+  ssize_t ret;
+
+  if (fstatat (dirfd, name, &st, AT_SYMLINK_NOFOLLOW)
+      || ! S_ISLNK (st.st_mode))
+    {
+      errno = saved_errno;
+      return nullptr;
+    }
+  idx_t symlinksize;
+  if (ckd_add (&symlinksize, st.st_size, 1 + sizeof *symlink))
+    xalloc_die ();
+  symlink = ximalloc (symlinksize);
+  buffer = (char *)(symlink + 1);
+  ret = readlinkat (dirfd, name, buffer, st.st_size);
+  if (ret <= 0)
+    goto fail;
+  buffer[ret] = 0;
+  symlink->path = buffer;
+  if (ISSLASH (*buffer))
+    {
+      char *end;
+
+      if (cwd_stat_errno == -1)
+	{
+	  cwd_stat_errno = stat (".", &cwd_stat) == 0 ? 0 : errno;
+	  if (cwd_stat_errno)
+	    goto fail_exdev;
+	}
+      end = buffer + ret;
+      for (;;)
+	{
+	  char slash;
+	  int rv;
+
+	  slash = *end; *end = 0;
+	  rv = stat (symlink->path, &st);
+	  *end = slash;
+
+	  if (rv == 0
+	      && st.st_dev == cwd_stat.st_dev
+	      && st.st_ino == cwd_stat.st_ino)
+	    {
+	      while (ISSLASH (*end))
+		end++;
+	      symlink->path = end;
+	      return symlink;
+	    }
+	  end--;
+	  if (end == symlink->path)
+	    break;
+	  while (end != symlink->path + 1 && ! ISSLASH (*end))
+	    end--;
+	  while (end != symlink->path + 1 && ISSLASH (*(end - 1)))
+	    end--;
+	}
+      goto fail_exdev;
+    }
+  return symlink;
+
+fail_exdev:
+  errno = EXDEV;
+fail:
+  free (symlink);
+  return nullptr;
+}
+
+/* Resolve the next path component in PATH inside DIR.  If it is a symlink,
+   read it and returned it in TOP. */
+static struct cached_dirfd *
+traverse_next (struct cached_dirfd *dir, char **path, int keepfd,
+	       struct symlink **symlink)
+{
+  char *p = *path;
+  struct cached_dirfd *entry = dir;
+
+  while (*p && ! ISSLASH (*p))
+    p++;
+  if (**path == '.' && *path + 1 == p)
+    ;
+  else if (**path == '.' && *(*path + 1) == '.' && *path + 2 == p)
+    {
+      entry = dir->parent;
+      if (! entry)
+	{
+	  /* Must not leave the working tree. */
+	  errno = EXDEV;
+	}
+      else
+	{
+	  assert (list_empty (&dir->lru_link));
+	  list_add (&dir->lru_link, &lru_list);
+	}
+    }
+  else
+    {
+      char slash_or_nul = *p;
+      *p = '\0';
+      entry = openat_cached (dir, *path, keepfd);
+      if (! entry)
+	{
+	  if (errno == ELOOP
+	      || errno == EMLINK  /* FreeBSD 10.1: Too many links */
+	      || (errno == EFTYPE
+		  /* NetBSD 6.1: Inappropriate file type or format.  */)
+	      || errno == ENOTDIR)
+	    {
+	      *symlink = read_symlink (dir->fd, *path);
+	      if (*symlink)
+		entry = dir;
+	      errno = ELOOP;
+	    }
+	}
+      *p = slash_or_nul;
+    }
+  if (entry)
+    while (ISSLASH (*p))
+      p++;
+  *path = p;
+  return entry;
+}
+
+/* Traverse PATHNAME.
+
+   If REJECT_NL, fail if the PATHNAME's last component contains a newline.
+   Otherwise, if unsafe or PATHNAME is absolute, just return AT_FDCWD.
+   Otherwise, update PATHNAME to point to the last path component and
+   return a file descriptor to its parent directory (which can be AT_FDCWD).
+   If KEEPFD is nonnegative, make sure that any cache entry for it is not
+   removed from the cache (and KEEPFD remains open).
+
+   When this function is not running, all cache entries are on the lru list,
+   and all cache entries which still have a parent are also in the hash table.
+   While this function is running, all cache entries on the path being looked
+   up are off the lru list but in the hash table.
+    */
+static int
+traverse_another_path (char **pathname, bool reject_nl, int keepfd)
+{
+  char *path = *pathname;
+  char *last = last_component (path);
+  if (reject_nl && strchr (last, '\n'))
+    {
+      errno = EILSEQ;
+      return DIRFD_INVALID;
+    }
+  if (unsafe || last == path || IS_ABSOLUTE_FILE_NAME (path))
+    return AT_FDCWD;
+
+  static struct cached_dirfd cwd = {
+    .fd = AT_FDCWD,
+  };
+
+  intmax_t misses = dirfd_cache_misses;
+  struct cached_dirfd *dir = &cwd;
+  struct symlink *stack = nullptr;
+  idx_t steps = count_path_components (path);
+  struct cached_dirfd *traversed_symlink = nullptr;
+
+  INIT_LIST_HEAD (&cwd.children);
+
+  if (steps > MAX_PATH_COMPONENTS)
+    {
+      errno = ELOOP;
+      return DIRFD_INVALID;
+    }
+
+  if (debug & 32)
+    {
+      idx_t full_pathlen = last - path;
+      int pathlen = ckd_sub (&pathlen, full_pathlen, 0) ? -1 : pathlen;
+      Fprintf (stdout, "Resolving path \"%.*s\"", pathlen, path);
+    }
+
+  while (stack || path != last)
+    {
+      struct cached_dirfd *entry;
+      struct symlink *symlink = nullptr;
+      char *prev = path;
+
+      entry = traverse_next (dir, stack ? &stack->path : &path, keepfd, &symlink);
+      if (! entry)
+	{
+	  if (debug & 32)
+	    {
+	      Fputs (" (failed)\n", stdout);
+	      Fflush (stdout);
+	    }
+	  goto fail;
+	}
+      dir = entry;
+      if (! stack && symlink)
+	{
+	  const char *p = prev;
+	  while (*p && ! ISSLASH (*p))
+	    p++;
+	  char *name = ximemdup0 (prev, p - prev);
+	  traversed_symlink = new_cached_dirfd (dir, name, DIRFD_INVALID);
+	}
+      if (stack && ! *stack->path)
+	pop_symlink (&stack);
+      if (symlink && *symlink->path)
+	{
+	  push_symlink (&stack, symlink);
+	  steps += count_path_components (symlink->path);
+	  if (steps > MAX_PATH_COMPONENTS)
+	    {
+	      errno = ELOOP;
+	      goto fail;
+	    }
+	}
+      else if (symlink)
+	pop_symlink (&symlink);
+      if (traversed_symlink && ! stack)
+	{
+	  traversed_symlink->fd =
+	    entry->fd == AT_FDCWD ? AT_FDCWD : dup (entry->fd);
+	  if (traversed_symlink->fd < 0)
+	    free_cached_dirfd (traversed_symlink);
+	  else
+	    {
+	      insert_cached_dirfd (traversed_symlink, keepfd);
+	      list_add (&traversed_symlink->lru_link, &lru_list);
+	    }
+	  traversed_symlink = nullptr;
+	}
+    }
+  *pathname = last;
+  if (debug & 32)
+    {
+      misses = dirfd_cache_misses - misses;
+      if (! misses)
+	Fprintf (stdout, " (cached)\n");
+      else
+	Fprintf (stdout, " (%jd miss%s)\n", misses, misses == 1 ? "" : "es");
+      Fflush (stdout);
+    }
+  return put_path (dir);
+
+fail:
+  if (traversed_symlink)
+    free_cached_dirfd (traversed_symlink);
+  put_path (dir);
+  while (stack)
+    pop_symlink (&stack);
+  return DIRFD_INVALID;
+}
+
+/* Just traverse PATHNAME; see traverse_another_path(). */
+static int
+traverse_path (char **pathname, bool reject_nl)
+{
+  return traverse_another_path (pathname, reject_nl, DIRFD_INVALID);
+}
+
+static int
+safe_xstat (char *pathname, struct stat *buf, int flags)
+{
+  int dirfd = traverse_path (&pathname, false);
+  if (dirfd == DIRFD_INVALID)
+    return -1;
+  if (! strcmp (pathname, ""))
+    return EINVAL;
+  return fstatat (dirfd, pathname, buf, flags);
+}
+
+/* Replacement for stat() */
+int
+safe_stat (char *pathname, struct stat *buf)
+{
+  return safe_xstat (pathname, buf, 0);
+}
+
+/* Replacement for lstat() */
+int
+safe_lstat (char *pathname, struct stat *buf)
+{
+  return safe_xstat (pathname, buf, AT_SYMLINK_NOFOLLOW);
+}
+
+/* Replacement for open() */
+int
+safe_open (char *pathname, int flags, mode_t mode)
+{
+  int creat_excl = flags & (O_CREAT | O_EXCL);
+  int dirfd = traverse_path (&pathname, creat_excl == (O_CREAT | O_EXCL));
+  if (dirfd == DIRFD_INVALID)
+    return -1;
+
+  /* If O_CREAT is set but O_EXCL is not, traverse_path does not
+     suffice for checking file names with '\n', so check by hand.  */
+  if (creat_excl == O_CREAT
+      && strchr (last_component (pathname), '\n')
+      && faccessat (dirfd, pathname, F_OK, AT_EACCESS) < 0
+      && errno == ENOENT)
+    {
+      errno = EILSEQ;
+      return -1;
+    }
+
+  return openat (dirfd, pathname, flags, mode);
+}
+
+/* Replacement for rename() */
+int
+safe_rename (char *oldpath, char *newpath)
+{
+  int olddirfd = traverse_path (&oldpath, false);
+  if (olddirfd == DIRFD_INVALID)
+    return -1;
+
+  int newdirfd = traverse_another_path (&newpath, true, olddirfd);
+  if (newdirfd == DIRFD_INVALID)
+    return -1;
+
+  int ret = renameat (olddirfd, oldpath, newdirfd, newpath);
+  if (! ret)
+    {
+      invalidate_cached_dirfd (olddirfd, oldpath);
+      invalidate_cached_dirfd (newdirfd, newpath);
+    }
+  return ret;
+}
+
+/* Replacement for mkdir() */
+int
+safe_mkdir (char *pathname, mode_t mode)
+{
+  int dirfd = traverse_path (&pathname, true);
+  if (dirfd == DIRFD_INVALID)
+    return -1;
+  return mkdirat (dirfd, pathname, mode);
+}
+
+/* Replacement for rmdir() */
+int
+safe_rmdir (char *pathname)
+{
+  int dirfd = traverse_path (&pathname, false);
+  if (dirfd == DIRFD_INVALID)
+    return -1;
+
+  int ret = unlinkat (dirfd, pathname, AT_REMOVEDIR);
+  if (! ret)
+    invalidate_cached_dirfd (dirfd, pathname);
+  return ret;
+}
+
+/* Replacement for unlink() */
+int
+safe_unlink (char *pathname)
+{
+  int dirfd = traverse_path (&pathname, false);
+  if (dirfd == DIRFD_INVALID)
+    return -1;
+  return unlinkat (dirfd, pathname, 0);
+}
+
+/* Replacement for symlink() */
+int
+safe_symlink (char const *target, char *linkpath)
+{
+  int dirfd = traverse_path (&linkpath, true);
+  if (dirfd == DIRFD_INVALID)
+    return -1;
+  return symlinkat (target, dirfd, linkpath);
+}
+
+/* Replacement for chmod() */
+int
+safe_chmod (char *pathname, mode_t mode)
+{
+  int dirfd = traverse_path (&pathname, false);
+  if (dirfd == DIRFD_INVALID)
+    return -1;
+  return fchmodat (dirfd, pathname, mode, 0);
+}
+
+/* Replacement for lchown() */
+int
+safe_lchown (char *pathname, uid_t owner, gid_t group)
+{
+  int dirfd = traverse_path (&pathname, false);
+  if (dirfd == DIRFD_INVALID)
+    return -1;
+  return fchownat (dirfd, pathname, owner, group, AT_SYMLINK_NOFOLLOW);
+}
+
+/* Replacement for lutimens() */
+int
+safe_lutimens (char *pathname, struct timespec const times[2])
+{
+  int dirfd = traverse_path (&pathname, false);
+  if (dirfd == DIRFD_INVALID)
+    return -1;
+  return utimensat (dirfd, pathname, times, AT_SYMLINK_NOFOLLOW);
+}
+
+/* Replacement for readlink() */
+ssize_t
+safe_readlink (char *pathname, char *buf, size_t bufsiz)
+{
+  int dirfd = traverse_path (&pathname, false);
+  if (dirfd == DIRFD_INVALID)
+    return -1;
+  return readlinkat (dirfd, pathname, buf, bufsiz);
+}
+
+/* Replacement for access() */
+int
+safe_access (char *pathname, int mode)
+{
+  int dirfd = traverse_path (&pathname, false);
+  if (dirfd == DIRFD_INVALID)
+    return -1;
+  return faccessat (dirfd, pathname, mode, AT_EACCESS);
+}

src/safe.h

@@ -0,0 +1,42 @@
+/* safe path traversal functions for 'patch' */
+
+/* Copyright 2015-2025 Free Software Foundation, Inc.
+
+   Written by Tim Waugh <twaugh@redhat.com> and
+   Andreas Gruenbacher <agruenba@redhat.com>.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* A constant that cannot be successfully passed as a directory file
+   descriptor to openat etc.  Its value is negative but does not equal
+   AT_FDCWD.  Normally the value is -1, but it is -2 on perverse
+   platforms where AT_FDCWD == -1.  */
+
+enum { DIRFD_INVALID = -1 - (AT_FDCWD == -1) };
+
+extern bool unsafe;
+
+int safe_stat (char *pathname, struct stat *buf);
+int safe_lstat (char *pathname, struct stat *buf);
+int safe_open (char *pathname, int flags, mode_t mode);
+int safe_rename (char *oldpath, char *newpath);
+int safe_mkdir (char *pathname, mode_t mode);
+int safe_rmdir (char *pathname);
+int safe_unlink (char *pathname);
+int safe_symlink (const char *target, char *linkpath);
+int safe_chmod (char *pathname, mode_t mode);
+int safe_lchown (char *pathname, uid_t owner, gid_t group);
+int safe_lutimens (char *pathname, struct timespec const times[2]);
+ssize_t safe_readlink(char *pathname, char *buf, size_t bufsiz);
+int safe_access(char *pathname, int mode);

src/util.h

@@ -1,9 +1,7 @@
 /* utility functions for 'patch' */
 
-/* Copyright (C) 1986 Larry Wall
-
-   Copyright (C) 1992-1993, 1997-1999, 2001-2003, 2009-2012 Free Software
-   Foundation, Inc.
+/* Copyright 1992-2025 Free Software Foundation, Inc.
+   Copyright 1986 Larry Wall
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -18,58 +16,12 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-#include <utimens.h>
 #include <timespec.h>
 #include <stat-time.h>
 #include <backupfile.h>
 
-/* An upper bound on the print length of a signed decimal line number.
-   Add one for the sign.  */
-#define LINENUM_LENGTH_BOUND (sizeof (lin) * CHAR_BIT / 3 + 1)
-
 enum file_id_type { UNKNOWN, CREATED, DELETE_LATER, OVERWRITTEN };
 
-XTERN enum backup_type backup_type;
-
-bool ok_to_reverse (char const *, ...) __attribute__ ((format (printf, 1, 2)));
-void ask (char const *, ...) __attribute__ ((format (printf, 1, 2)));
-void say (char const *, ...) __attribute__ ((format (printf, 1, 2)));
-
-void fatal (char const *, ...)
-	__attribute__ ((noreturn, format (printf, 1, 2)));
-void pfatal (char const *, ...)
-	__attribute__ ((noreturn, format (printf, 1, 2)));
-
-void fetchname (char const *, int, char **, char **, struct timespec *);
-char *parse_name (char const *, int, char const **);
-char *savebuf (char const *, size_t);
-char *savestr (char const *);
-char const *version_controller (char const *, bool, struct stat const *, char **, char **);
-bool version_get (char const *, char const *, bool, bool, char const *, struct stat *);
-int create_file (char const *, int, mode_t, bool);
-int systemic (char const *);
-char *format_linenum (char[LINENUM_LENGTH_BOUND + 1], lin);
-void Fseek (FILE *, file_offset, int);
-void copy_file (char const *, char const *, struct stat *, int, mode_t, bool);
-void append_to_file (char const *, char const *);
-void exit_with_signal (int) __attribute__ ((noreturn));
-void ignore_signals (void);
-void init_backup_hash_table (void);
-void init_time (void);
-void xalloc_die (void) __attribute__ ((noreturn));
-void create_backup (char const *, const struct stat *, bool);
-void move_file (char const *, bool *, struct stat const *, char const *, mode_t, bool);
-void read_fatal (void) __attribute__ ((noreturn));
-void remove_prefix (char *, size_t);
-void removedirs (char const *);
-void set_signals (bool);
-void write_fatal (void) __attribute__ ((noreturn));
-void insert_file_id (struct stat const *, enum file_id_type);
-enum file_id_type lookup_file_id (struct stat const *);
-void set_queued_output (struct stat const *, bool);
-bool has_queued_output (struct stat const *);
-int stat_file (char const *, struct stat *);
-
 enum file_attributes {
   FA_TIMES = 1,
   FA_IDS = 2,
@@ -77,15 +29,89 @@ enum file_attributes {
   FA_XATTRS = 8
 };
 
-void set_file_attributes (char const *, enum file_attributes, char const *,
-			  const struct stat *, mode_t, struct timespec *);
+/* Exit status for trouble, such as write failure.  */
+enum { EXIT_TROUBLE = 2 };
 
-static inline char const * _GL_ATTRIBUTE_PURE
-skip_spaces (char const *str)
+/* Read or write at most IO_BUFSIZE bytes at a time.
+   In 2024 256 KiB was determined to be the best blocksize
+   to minimize system call overhead across most systems
+   when copying files.  See coreutils/src/ioblksize.h.  */
+enum { IO_BUFSIZE = 256 * 1024 };
+
+/* POSIX says behavior is implementation-defined for I/O requests
+   larger than SSIZE_MAX.  IO_BUFSIZE is OK on all known platforms.
+   Check it to be sure.  */
+static_assert (IO_BUFSIZE <= SSIZE_MAX);
+
+extern enum backup_type backup_type;
+
+_GL_INLINE_HEADER_BEGIN
+#ifndef UTIL_INLINE
+# define UTIL_INLINE _GL_INLINE
+#endif
+
+char volatile *volatilize (char *);
+
+/* Convert S to a pointer to non-volatile.  This is the inverse of volatilize.
+   S’s contents must not be updated by a signal handler.  */
+UTIL_INLINE char *
+devolatilize (char volatile *s)
 {
-  while (ISSPACE ((unsigned char) *str))
-    str++;
-  return str;
+  return (char *) s;
 }
 
-int make_tempfile(char const **, char, char const *, int, mode_t);
+bool ok_to_reverse (char const *, ...) ATTRIBUTE_FORMAT ((printf, 1, 2));
+char *ask (char const *, ...) ATTRIBUTE_FORMAT ((printf, 1, 2));
+void say (char const *, ...) ATTRIBUTE_FORMAT ((printf, 1, 2));
+
+_Noreturn void fatal (char const *, ...) ATTRIBUTE_FORMAT ((printf, 1, 2));
+_Noreturn void pfatal (char const *, ...) ATTRIBUTE_FORMAT ((printf, 1, 2));
+
+void fetchname (char const *, intmax_t, char **, char **, struct timespec *);
+char *parse_name (char const *, intmax_t, char const **);
+char *savebuf (char const *, idx_t)
+  ATTRIBUTE_MALLOC ATTRIBUTE_DEALLOC_FREE ATTRIBUTE_ALLOC_SIZE ((2));
+char const *version_controller (char const *, bool, struct stat const *, char **, char **);
+bool version_get (char *, char const *, bool, bool, char const *, struct stat *);
+int create_file (struct outfile *, int, mode_t, bool);
+int systemic (char const *);
+void Fclose (FILE *);
+void Fflush (FILE *);
+void Fprintf (FILE *, char const *, ...) ATTRIBUTE_FORMAT ((printf, 2, 3));
+void Fputc (int, FILE *);
+void Fputs (char const *restrict, FILE *restrict);
+void Fseeko (FILE *, off_t, int);
+off_t Ftello (FILE *);
+void Fwrite (void const *restrict, size_t, size_t, FILE *restrict);
+idx_t Read (int, void *, idx_t);
+void copy_file (char *, struct stat const *, struct outfile *, struct stat *,
+		int, mode_t, enum file_attributes, bool);
+void append_to_file (char *, char *);
+idx_t quote_system_arg (char *, char const *);
+void init_signals (void);
+void defer_signals (void);
+void undefer_signals (void);
+void init_backup_hash_table (void);
+void init_time (void);
+_Noreturn void xalloc_die (void);
+void create_backup (char *, const struct stat *, bool);
+void move_file (struct outfile *, struct stat const *,
+		char *, mode_t, bool);
+_Noreturn void read_fatal (void);
+void removedirs (char const *);
+_Noreturn void write_fatal (void);
+void putline (FILE *, ...);
+void insert_file_id (struct stat const *, enum file_id_type);
+enum file_id_type lookup_file_id (struct stat const *);
+void set_queued_output (struct stat const *, bool);
+bool has_queued_output (struct stat const *);
+int stat_file (char *, struct stat *);
+bool filename_is_safe (char const *) ATTRIBUTE_PURE;
+bool cwd_is_root (char const *);
+
+void set_file_attributes (char *, int, enum file_attributes, char const *, int,
+			  const struct stat *, mode_t, struct timespec *);
+
+int make_tempfile (struct outfile *, char, char const *, int, mode_t);
+
+_GL_INLINE_HEADER_END

src/version.c

@@ -1,12 +1,12 @@
 /* Print the version number.  */
 
-#define XTERN extern
 #include <common.h>
 #include <version.h>
+#include <util.h>
 
 static char const copyright_string[] = "\
-Copyright (C) 2003, 2009-2012 Free Software Foundation, Inc.\n\
-Copyright (C) 1988 Larry Wall";
+Copyright 1989-2025 Free Software Foundation, Inc.\n\
+Copyright 1984-1988 Larry Wall";
 
 static char const free_software_msgid[] = "\
 License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.\n\
@@ -19,6 +19,6 @@ Written by Larry Wall and Paul Eggert";
 void
 version (void)
 {
-  printf ("%s %s\n%s\n\n%s\n\n%s\n", PACKAGE_NAME, PACKAGE_VERSION,
-	  copyright_string, free_software_msgid, authorship_msgid);
+  Fprintf (stdout, "%s %s\n%s\n\n%s\n\n%s\n", PACKAGE_NAME, PACKAGE_VERSION,
+	   copyright_string, free_software_msgid, authorship_msgid);
 }

tests/.gitignore

@@ -1,2 +0,0 @@
-*.log
-*.trs

tests/Makefile.am

@@ -1,5 +1,4 @@
-# Copyright (C) 1989-1993, 1997-1999, 2002-2003, 2006, 2009-2012 Free Software
-# Foundation, Inc.
+# Copyright 1989-2025 Free Software Foundation, Inc.
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -20,20 +19,30 @@ TESTS = \
 	asymmetric-hunks \
 	backup-prefix-suffix \
 	bad-filenames \
+	bad-usage \
 	concat-git-diff \
+	context-format \
 	copy-rename \
+	corrupt-patch \
 	corrupt-reject-files \
 	create-delete \
 	create-directory \
 	criss-cross \
 	crlf-handling \
 	dash-o-append \
+	deep-directories \
+	ed-style \
 	empty-files \
+	false-match \
 	fifo \
+	file-create-modes \
 	file-modes \
 	filename-choice \
 	git-binary-diff \
+	git-cleanup \
+	garbage \
 	global-reject-files \
+	hardlinks \
 	inname \
 	line-numbers \
 	merge \
@@ -41,19 +50,29 @@ TESTS = \
 	mixed-patch-types \
 	munged-context-format \
 	need-filename \
+	no-backup \
+	no-mode-change-git-diff \
 	no-newline-triggers-assert \
 	preserve-c-function-names \
 	preserve-mode-and-timestamp \
 	quoted-filenames \
 	read-only-files \
+	regression-abe92e8010ab \
 	reject-format \
 	remember-backup-files \
 	remember-reject-files \
+	remove-directories \
 	symlinks \
-	unmodified-files
+	unmodified-files \
+	unusual-blanks
 
 XFAIL_TESTS = \
-	dash-o-append
+	dash-o-append \
+	context-format
+if OS_IS_HAIKU
+XFAIL_TESTS += \
+	preserve-mode-and-timestamp
+endif
 
 EXTRA_DIST = \
 	$(TESTS) \

tests/asymmetric-hunks

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -6,7 +6,7 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
 use_local_patch
 use_tmpdir
 

tests/backup-prefix-suffix

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -6,7 +6,7 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
 use_local_patch
 use_tmpdir
 

tests/bad-filenames

@@ -1,4 +1,4 @@
-# Copyright (C) 2011-2012 Free Software Foundation, Inc.
+# Copyright 2011-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -126,6 +126,57 @@ check 'patch -f -p1 --dry-run < d.diff || echo status: $?' <<EOF
 checking file g
 EOF
 
+fixup='s/ file ab\.[^ ]*/ file ab.*/'
+check_ignoring_temp_file_name() {
+  pat=\'$1\'
+  unset arg1; eval ${2+"arg1=\\''$2'\\'"}
+  unset arg2; eval ${3+"arg2=\\''$3'\\'"}
+  check '
+    emit_patch '"$pat"' | patch '"$arg1"' '"$arg2"' >patch.out 2>&1
+    status=$?
+    sed "$fixup" patch.out
+    echo status: $status
+  '
+}
+
+nl='
+'
+nlname="a${nl}b"
+quoted_nlname='"a\nb"'
+
+check_ignoring_temp_file_name "$quoted_nlname" <<EOF
+patching file 'a
+b'
+$PATCH: **** Can't rename file ab.* to 'a
+b' : Invalid byte sequence
+status: 2
+EOF
+
+check_ignoring_temp_file_name foo "$nlname" <<EOF
+patching file 'a
+b'
+$PATCH: **** Can't rename file ab.* to 'a
+b' : Invalid byte sequence
+status: 2
+EOF
+
+check_ignoring_temp_file_name foo -o "$nlname" <<EOF
+$PATCH: **** Can't create file 'a
+b' : Invalid byte sequence
+status: 2
+EOF
+
+emit_patch_with_NUL()
+{
+  printf '%s\n' '--- /dev/null'
+  printf '+++ a\0b\n'
+  printf '%s\n' '@@ -0,0 +1 @@' '+x'
+}
+check 'emit_patch_with_NUL | patch; echo status: $?' <<EOF
+$PATCH: **** patch line 2 contains NUL byte
+status: 2
+EOF
+
 mkdir d
 cd d
 cat > d.diff <<EOF
@@ -149,3 +200,11 @@ No file to patch.  Skipping patch.
 1 out of 1 hunk ignored
 status: 1
 EOF
+
+# Empty filenames are not allowed:
+
+check 'emit_patch f | patch -r- "" || echo status: $?' <<EOF
+File '' is not a regular file -- refusing to patch
+1 out of 1 hunk ignored
+status: 1
+EOF

tests/bad-usage

@@ -0,0 +1,18 @@
+# Copyright 2009-2025 Free Software Foundation, Inc.
+#
+# Copying and distribution of this file, with or without modification,
+# in any medium, are permitted without royalty provided the copyright
+# notice and this notice are preserved.
+
+. $srcdir/test-lib.sh
+
+require cat
+use_local_patch
+use_tmpdir
+
+# ==============================================================
+
+check 'patch -px || echo "status: $?"' <<EOF
+$PATCH: **** strip count x is not a number
+status: 2
+EOF

tests/concat-git-diff

@@ -1,4 +1,4 @@
-# Copyright (C) 2010-2012 Free Software Foundation, Inc.
+# Copyright 2010-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -6,7 +6,7 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
 use_local_patch
 use_tmpdir
 

tests/context-format

@@ -0,0 +1,122 @@
+# Copyright 2016-2025 Free Software Foundation, Inc.
+#
+# Copying and distribution of this file, with or without modification,
+# in any medium, are permitted without royalty provided the copyright
+# notice and this notice are preserved.
+
+. $srcdir/test-lib.sh
+
+use_local_patch
+use_tmpdir
+
+# ==============================================================
+
+printf "%s\n" 1 2 4 5 > a
+cat > ab.diff <<EOF
+*** a
+--- b
+***************
+*** 1,4 ****
+--- 1,5 ----
+  1
+  2
++ 3
+  4
+  5
+EOF
+
+check 'patch < ab.diff' <<EOF
+patching file a
+EOF
+
+printf "%s\n" 1 2 3 4 5 > a
+cat > ab.diff <<EOF
+*** a
+--- b
+***************
+*** 1,5 ****
+  1
+  2
+- 3
+  4
+  5
+--- 1,4 ----
+EOF
+
+check 'patch < ab.diff' <<EOF
+patching file a
+EOF
+
+# --------------------------------------------------------------
+
+printf "%s\n" a a a a a b a a a a a > a
+
+cat > ab.diff <<EOF
+*** a
+--- b
+***************
+*** 6 ****
+- b
+--- 5 ----
+EOF
+
+check 'patch < ab.diff' <<EOF
+patching file a
+EOF
+
+check 'echo `cat a`' <<EOF
+a a a a a a a a a a
+EOF
+
+cat > ba.diff <<EOF
+*** b
+--- a
+***************
+*** 5 ****
+--- 6 ----
++ b
+EOF
+
+check 'patch < ba.diff' <<EOF
+patching file a
+EOF
+
+check 'echo `cat a`' <<EOF
+a a a a a b a a a a a
+EOF
+
+printf "%s\n" a a a a a a a a a a b > a
+
+cat > ab.diff <<EOF
+*** a
+--- b
+***************
+*** 11 ****
+- b
+--- 10 ----
+EOF
+
+check 'patch < ab.diff' <<EOF
+patching file a
+EOF
+
+check 'echo `cat a`' <<EOF
+a a a a a a a a a a
+EOF
+
+cat > ba.diff <<EOF
+*** b
+--- a
+***************
+*** 10 ****
+--- 11 ----
++ b
+EOF
+
+check 'patch < ba.diff' <<EOF
+patching file a
+EOF
+
+check 'echo `cat a`' <<EOF
+a a a a a a a a a a b
+EOF

tests/copy-rename

@@ -1,4 +1,4 @@
-# Copyright (C) 2010-2012 Free Software Foundation, Inc.
+# Copyright 2010-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -8,7 +8,7 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
 use_local_patch
 use_tmpdir
 
@@ -63,6 +63,30 @@ check 'cat h' <<EOF
 new
 EOF
 
+echo old > h
+
+check 'patch -p1 < rename.diff || echo "Status: $?"' <<EOF
+patching file h (already renamed from f)
+EOF
+
+ncheck 'test ! -e f'
+
+check 'cat h' <<EOF
+new
+EOF
+
+mv h f
+
+check 'patch -p1 -R < rename.diff || echo "Status: $?"' <<EOF
+patching file f (already renamed from h)
+EOF
+
+ncheck 'test ! -e h'
+
+check 'cat f' <<EOF
+old
+EOF
+
 # --------------------------------------------------------------
 # Patches with no hunks
 

tests/corrupt-patch

@@ -0,0 +1,33 @@
+# Copyright 2015-2025 Free Software Foundation, Inc.
+#
+# Copying and distribution of this file, with or without modification,
+# in any medium, are permitted without royalty provided the copyright
+# notice and this notice are preserved.
+
+. $srcdir/test-lib.sh
+
+require cat
+use_local_patch
+use_tmpdir
+
+# ==============================================================
+
+# Patch missing the traditional "--- old\n+++ new\n" header
+
+cat > test.diff <<EOF
+diff --git a/test b/test
+index 8e139fc..4c03766 100644
+@@ -1 +1 @@
+-a
++b
+EOF
+
+echo a > test
+
+check 'patch -p1 -i test.diff' <<EOF
+patching file test
+EOF
+
+check 'cat test' <<EOF
+b
+EOF

tests/corrupt-reject-files

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -6,7 +6,7 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
 use_local_patch
 use_tmpdir
 

tests/create-delete

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -6,8 +6,8 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
-require_sed
+require cat
+require sed
 use_local_patch
 use_tmpdir
 
@@ -182,7 +182,7 @@ EOF
 
 check 'patch -p0 < p.diff || echo status: $?' <<EOF
 patching file target
-File target is not empty after patch; not deleting
+Not deleting file target as content differs from patch
 status: 1
 EOF
 
@@ -202,7 +202,7 @@ EOF
 
 check 'patch -p0 < p.diff || echo status: $?' <<EOF
 patching file target
-File target is not empty after patch; not deleting
+Not deleting file target as content differs from patch
 status: 1
 EOF
 
@@ -212,23 +212,27 @@ EOF
 
 # --------------------------------------------------------------
 printf '\0' > target
-cat > p.diff <<EOF
+if ! test -s target; then
+    echo "Failed to printf a null character; skipping this test"
+else
+    cat > p.diff <<EOF
 diff --git a/target b/target
 deleted file mode 100644
 index f76dd23..0000000
 Binary files a/target and /dev/null differ
 EOF
 
-check 'patch -p1 -b < p.diff || echo status: $?' <<EOF
+    check 'patch -p1 -b < p.diff || echo status: $?' <<EOF
 patching file target
-File target is not empty after patch; not deleting
+Not deleting file target as content differs from patch
 status: 1
 EOF
 
-ncheck 'test -e target'
+    ncheck 'test -e target'
 
 # Patch creates a backup file even when the original file remains unchanged:
-ncheck 'test -e target.orig'
+    ncheck 'test -e target.orig'
+fi
 
 # ================================================================
 # File not expected to become empty does become empty

tests/create-directory

@@ -1,18 +1,17 @@
-# Copyright (C) 2010-2012 Free Software Foundation, Inc.
+# Copyright 2010-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
 # notice and this notice are preserved.
 
-# Check whether patch correctly creates directories before creating
-# new files.
-
 . $srcdir/test-lib.sh
 
 use_local_patch
 use_tmpdir
 
 # ==============================================================
+# Check whether patch correctly creates directories before creating
+# new files.
 
 cat > f.diff <<EOF
 --- /dev/null
@@ -25,3 +24,20 @@ EOF
 check 'patch -p0 < f.diff' <<EOF
 patching file b/newfile
 EOF
+
+# ==============================================================
+# Make sure it doesn't create files or directories in the target
+#  location in --dry-run mode
+mkdir d
+cat > f.diff <<EOF
+--- /dev/null
++++ d/e/f
+@@ -0,0 +1 @@
++f
+EOF
+
+chmod u-w d
+check 'patch -p0 --dry-run < f.diff' <<EOF
+checking file d/e/f
+EOF
+chmod u+w d

tests/criss-cross

@@ -1,4 +1,4 @@
-# Copyright (C) 2010-2012 Free Software Foundation, Inc.
+# Copyright 2010-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -8,7 +8,7 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
 use_local_patch
 use_tmpdir
 

tests/crlf-handling

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -8,13 +8,13 @@
 
 . $srcdir/test-lib.sh
 
-require_gnu_diff
-require_sed
+require gnu_diff
+require sed
 use_local_patch
 use_tmpdir
 
 lf2crlf() {
-    while read l; do echo -e "$l\r"; done
+    while read l; do printf "%s\r\n" "$l"; done
 }
 
 echo 1 > a

tests/dash-o-append

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -6,7 +6,7 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
 use_local_patch
 use_tmpdir
 

tests/deep-directories

@@ -0,0 +1,28 @@
+# Copyright 2015-2025 Free Software Foundation, Inc.
+#
+# Copying and distribution of this file, with or without modification,
+# in any medium, are permitted without royalty provided the copyright
+# notice and this notice are preserved.
+
+. $srcdir/test-lib.sh
+
+require cat
+use_local_patch
+use_tmpdir
+
+# ==============================================================
+# Exercise the directory file descriptor cache
+
+# Artificially limit to 8 cache entries
+ulimit -n 32 > /dev/null 2>&1 || exit 77
+
+cat > ab.diff <<EOF
+--- /dev/null
++++ b/1/2/3/4/5/6/7/8/9/foo
+@@ -0,0 +1 @@
++foo
+EOF
+
+check 'patch -p1 < ab.diff || echo Status: $?' <<EOF
+patching file 1/2/3/4/5/6/7/8/9/foo
+EOF

tests/ed-style

@@ -0,0 +1,72 @@
+# Copyright 2018-2025 Free Software Foundation, Inc.
+#
+# Copying and distribution of this file, with or without modification,
+# in any medium, are permitted without royalty provided the copyright
+# notice and this notice are preserved.
+
+. $srcdir/test-lib.sh
+
+require cat
+require ed
+use_local_patch
+use_tmpdir
+
+# ==============================================================
+
+cat > ed1.diff <<EOF
+0a
+foo
+.
+EOF
+
+check 'patch -e foo -i ed1.diff' <<EOF
+EOF
+
+check 'cat foo' <<EOF
+foo
+EOF
+
+cat > ed2.diff <<EOF
+1337a
+r !echo bar
+,p
+EOF
+
+check 'patch -e foo -i ed2.diff > /dev/null 2> /dev/null || echo "Status: $?"' <<EOF
+Status: 2
+EOF
+
+check 'cat foo' <<EOF
+foo
+EOF
+
+# Test the case where one ed-style patch modifies several files
+
+cat > ed3.diff <<EOF
+--- foo
++++ foo
+1c
+bar
+.
+--- baz
++++ baz
+0a
+baz
+.
+EOF
+
+# Apparently we can't create a file with such a patch, while it works fine
+# when the file name is provided on the command line
+cat > baz <<EOF
+EOF
+
+check 'patch -e -i ed3.diff' <<EOF
+EOF
+
+check 'cat foo' <<EOF
+bar
+EOF
+
+check 'cat baz' <<EOF
+baz
+EOF

tests/empty-files

@@ -1,4 +1,4 @@
-# Copyright (C) 2010-2012 Free Software Foundation, Inc.
+# Copyright 2010-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -8,7 +8,7 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
 use_local_patch
 use_tmpdir
 umask 022

tests/false-match

@@ -0,0 +1,55 @@
+# Copyright 2017-2025 Free Software Foundation, Inc.
+#
+# Copying and distribution of this file, with or without modification,
+# in any medium, are permitted without royalty provided the copyright
+# notice and this notice are preserved.
+
+. $srcdir/test-lib.sh
+
+require cat
+use_local_patch
+use_tmpdir
+
+# ==============================================================
+
+# Check if patch incorrectly applies overlapping hunks: after the
+# first hunk is applied, the second hunk should not apply
+# anymore.  Older versions of patch didn't recognize that and did
+# apply the second hunk on top of the first one, leading to the
+# following incorrect result, with no information about hunk 2:
+#
+# Hunk #1 succeeded at 7 (offset 6 lines).
+#
+# printf '%s\n' x x x x x x 1 2 3 a a 4 5 6
+
+cat > a.diff <<EOF
+--- a
++++ a
+@@ -1,6 +1,7 @@
+ 1
+ 2
+ 3
++a
+ 4
+ 5
+ 6
+@@ -7,6 +8,7 @@
+ 1
+ 2
+ 3
++a
+ 4
+ 5
+ 6
+EOF
+
+printf "%s\n" x x x x x x > a
+seq 1 6 >> a
+
+check 'patch < a.diff || echo status: $?' <<EOF
+patching file a
+Hunk #1 succeeded at 7 (offset 6 lines).
+Hunk #2 FAILED at 8.
+1 out of 2 hunks FAILED -- saving rejects to file a.rej
+status: 1
+EOF

tests/fifo

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -8,7 +8,7 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
 use_local_patch
 use_tmpdir
 

tests/file-create-modes

@@ -0,0 +1,52 @@
+# Copyright 2010-2025 Free Software Foundation, Inc.
+#
+# Copying and distribution of this file, with or without modification,
+# in any medium, are permitted without royalty provided the copyright
+# notice and this notice are preserved.
+
+# Test if git diffs can create files with proper modes
+
+. $srcdir/test-lib.sh
+
+require cat
+require sed
+require chmod
+use_local_patch
+use_tmpdir
+
+# ==============================================================
+
+cat > f.diff <<EOF
+diff --git a/f b/f
+new file mode 100710
+index 0000000..3e75765
+--- /dev/null
++++ b/f
+@@ -0,0 +1 @@
++new
+
+diff --git a/g b/g
+new file mode 100654
+index 0000000..3e75765
+--- /dev/null
++++ b/g
+@@ -0,0 +1 @@
++new
+EOF
+
+check 'patch -p1 < f.diff' <<EOF
+patching file f
+patching file g
+EOF
+
+check 'ls -l f g | sed "s,\(..........\).*,\1,"' <<EOF
+-rwx--x---
+-rw-r-xr--
+EOF
+
+check 'patch -p1 -R < f.diff' <<EOF
+patching file f
+patching file g
+EOF
+
+ncheck '! test -e f -o -e g || echo fail'

tests/file-modes

@@ -1,4 +1,4 @@
-# Copyright (C) 2010-2012 Free Software Foundation, Inc.
+# Copyright 2010-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -8,8 +8,9 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
-require_sed
+require cat
+require sed
+require chmod
 use_local_patch
 use_tmpdir
 

tests/filename-choice

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -8,7 +8,7 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
 use_local_patch
 use_tmpdir
 

tests/garbage

@@ -0,0 +1,25 @@
+# Copyright 2015-2025 Free Software Foundation, Inc.
+#
+# Copying and distribution of this file, with or without modification,
+# in any medium, are permitted without royalty provided the copyright
+# notice and this notice are preserved.
+
+. $srcdir/test-lib.sh
+
+require cat
+use_local_patch
+use_tmpdir
+
+# ==============================================================
+
+cat > bad.diff <<EOF
+ ***************
+*** 0 ****
+--- 1 ----
++ foo
+EOF
+
+check 'patch foo -i bad.diff || echo "Status: $?"' <<EOF
+$PATCH: **** Only garbage was found in the patch input.
+Status: 2
+EOF

tests/git-binary-diff

@@ -1,4 +1,4 @@
-# Copyright (C) 2010-2012 Free Software Foundation, Inc.
+# Copyright 2010-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -6,7 +6,7 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
 use_local_patch
 use_tmpdir
 

tests/git-cleanup

@@ -0,0 +1,75 @@
+# Copyright 2009-2025 Free Software Foundation, Inc.
+#
+# Copying and distribution of this file, with or without modification,
+# in any medium, are permitted without royalty provided the copyright
+# notice and this notice are preserved.
+
+. $srcdir/test-lib.sh
+
+require cat
+use_local_patch
+use_tmpdir
+
+# ==============================================================
+
+cat > 1.diff <<EOF
+diff --git a/f b/f
+--- f
++++ f
+@@ -1 +1 @@
+-1
++1a
+@@ -5 +5 @@
+-out
++in
+diff --git a/g b/g
+--- g
++++ g
+@@ -1 +1 @@
+-out
++in
+diff --git a/h b/h
+--- h
++++ h
+@@ -1 +1 @@
+BAD PATCH
+EOF
+
+echo 1 > f
+printf '' > g
+printf '' > h
+
+check 'patch -f -i 1.diff || echo status: $?' <<EOF
+patching file f
+Hunk #2 FAILED at 5.
+1 out of 2 hunks FAILED -- saving rejects to file f.rej
+patching file g
+Hunk #1 FAILED at 1.
+1 out of 1 hunk FAILED -- saving rejects to file g.rej
+patching file h
+$PATCH: **** malformed patch at line 20: BAD PATCH
+
+status: 2
+EOF
+
+check 'cat f' <<EOF
+1a
+EOF
+
+check 'cat f.rej' <<EOF
+--- f
++++ f
+@@ -5 +5 @@
+-out
++in
+EOF
+
+ncheck 'cat g'
+
+check 'cat g.rej' <<EOF
+--- g
++++ g
+@@ -1 +1 @@
+-out
++in
+EOF

tests/global-reject-files

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -8,7 +8,7 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
 use_local_patch
 use_tmpdir
 

tests/hardlinks

@@ -0,0 +1,50 @@
+# Copyright 2009-2025 Free Software Foundation, Inc.
+#
+# Copying and distribution of this file, with or without modification,
+# in any medium, are permitted without royalty provided the copyright
+# notice and this notice are preserved.
+
+# Patch must not overwrite backup files it has created itself.
+# (Backup file tests for symlinks are in tests/symlinks.)
+
+. $srcdir/test-lib.sh
+
+require cat
+require hardlinks
+use_local_patch
+use_tmpdir
+
+# ==============================================================
+
+# Hardlinks between source files
+
+echo one > f
+ln f g
+
+cat > fg.diff <<EOF
+--- f.orig
++++ f
+@@ -2 +2 @@
+-one
++two
+--- g.orig
++++ g
+@@ -2 +2 @@
+-one
++two
+EOF
+
+check 'patch -p0 < fg.diff' <<EOF
+patching file f
+Hunk #1 succeeded at 1 (offset -1 lines).
+patching file g
+Hunk #1 succeeded at 1 (offset -1 lines).
+EOF
+
+check 'cat f.orig' <<EOF
+one
+EOF
+
+check 'cat g.orig' <<EOF
+one
+EOF

tests/inname

@@ -1,14 +1,12 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
 # notice and this notice are preserved.
 
-# Don't recognize hunks before a filename has been specified/seen
-
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
 use_local_patch
 use_tmpdir
 
@@ -37,3 +35,21 @@ EOF
 check 'cat x' <<EOF
 three
 EOF
+
+# --------------------------------------------------------------
+
+echo aa > file1
+
+mkdir 1
+cd 1
+cat > g.diff <<EOF
+--- file1
++++ file2
+@@ -1 +1 @@
+-aa
++bb
+EOF
+
+check 'patch ../file1 < g.diff' <<EOF
+patching file ../file1
+EOF

tests/line-numbers

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -6,8 +6,8 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
-require_sed
+require cat
+require sed
 use_local_patch
 use_tmpdir
 

tests/mangled-numbers-abort

@@ -1,4 +1,4 @@
-# Copyright (C) 2011-2012 Free Software Foundation, Inc.
+# Copyright 2011-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -6,7 +6,7 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
 use_local_patch
 use_tmpdir
 

tests/merge

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -8,9 +8,9 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
-require_gnu_diff
-require_sed
+require cat
+require gnu_diff
+require sed
 use_local_patch
 use_tmpdir
 
@@ -30,30 +30,28 @@ x2() {
     while test $# -gt 0 && test "$1" != -- ; do
 	echo "$1"
 	shift
-    done > a.sed
-    echo "$body" | sed -f a.sed > b
-    shift
+    done > b.sed
+    echo "$body" | sed -f b.sed > b
+    test $# -eq 0 || shift
     while test $# -gt 0 ; do
 	echo "$1"
 	shift
-    done > b.sed
-    echo "$body" | sed -f b.sed > c
-    rm -f a.sed b.sed
+    done > c.sed
+    echo "$body" | sed -f c.sed > c
+    rm -f b.sed c.sed
     output=`diff -u a b | patch $ARGS -f c`
     status=$?
     echo "$output" | sed -e '/^$/d' -e '/^patching file c$/d'
     cat c
-    test $status == 0 || echo "Status: $status"
+    test $status = 0 || echo "Status: $status"
 }
 
 x() {
-    ARGS="$ARGS --merge" x2 "$@"
+    ARGS="--merge" x2 "$@"
     echo
-    ARGS="$ARGS --merge=diff3" x2 "$@"
+    ARGS="--merge=diff3" x2 "$@"
 }
 
-unset ARGS
-
 # ==============================================================
 
 check 'x 3' <<EOF

tests/mixed-patch-types

@@ -1,4 +1,4 @@
-# Copyright (C) 2010-2012 Free Software Foundation, Inc.
+# Copyright 2010-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -6,7 +6,7 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
 use_local_patch
 use_tmpdir
 umask 022

tests/munged-context-format

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -8,8 +8,8 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
-require_sed
+require cat
+require sed
 use_local_patch
 use_tmpdir
 

tests/need-filename

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -8,8 +8,8 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
-require_sed
+require cat
+require sed
 use_local_patch
 use_tmpdir
 

tests/no-backup

@@ -0,0 +1,56 @@
+# Copyright 2025 Free Software Foundation, Inc.
+#
+# Copying and distribution of this file, with or without modification,
+# in any medium, are permitted without royalty provided the copyright
+# notice and this notice are preserved.
+
+# Test the --no-backup-if-mismatch option
+
+. $srcdir/test-lib.sh
+
+require cat
+use_local_patch
+use_tmpdir
+
+# ==============================================================
+
+cat >my_file <<'EOF'
+/* ... */
+void baz();
+
+
+void baz() {
+	/* ... */
+}
+
+int main() {
+	int foo;
+	int bar;
+
+	/* ... */
+	baz();
+}
+EOF
+
+cat >my_file.patch <<'EOF'
+--- my_file	2025-02-16 11:22:12.881765792 +0000
++++ my_file_new	2025-02-16 11:22:12.881796732 +0000
+@@ -2,7 +2,7 @@
+ void baz();
+
+ void baz() {
+-	/* ... */
++	// ...
+ }
+
+ int main() {
+EOF
+
+unset POSIXLY_CORRECT
+
+check 'patch -N --no-backup-if-mismatch <my_file.patch || echo "Status: $?"' <<'EOF'
+patching file my_file
+Hunk #1 succeeded at 3 with fuzz 1 (offset 1 line).
+EOF
+
+ncheck 'test ! -f my_file.orig'

tests/no-mode-change-git-diff

@@ -0,0 +1,35 @@
+# Copyright 2010-2025 Free Software Foundation, Inc.
+#
+# Copying and distribution of this file, with or without modification,
+# in any medium, are permitted without royalty provided the copyright
+# notice and this notice are preserved.
+
+. $srcdir/test-lib.sh
+
+require cat
+require chmod
+require stat
+require chmod
+use_local_patch
+use_tmpdir
+
+echo 'ksplice' > f
+chmod 755 f
+
+cat > simple.diff <<EOF
+diff --git a/f b/f
+index 422a422a..736b6c7063690a 100644
+--- a/f
++++ b/f
+@@ -1 +1 @@
+-ksplice
++ksplice rocks!
+EOF
+
+check 'patch -p1 < simple.diff || echo "Status:  $?"' <<EOF
+patching file f
+EOF
+
+check 'ls -l f | sed "s,\(..........\).*,\1,"' <<EOF
+-rwxr-xr-x
+EOF

tests/no-newline-triggers-assert

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -8,7 +8,7 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
 use_local_patch
 use_tmpdir
 

tests/preserve-c-function-names

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -8,8 +8,7 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
-require_gnu_diff
+require cat
 use_local_patch
 use_tmpdir
 
@@ -33,7 +32,23 @@ EOF
 
 preserve_trailing_blank=
 
-diff -p -c -L a -L b a b > ab.diff
+cat > ab.diff <<EOF
+*** a
+--- b
+*************** int foo()
+*** 2,6 ****
+    {
+      /* waste a line */
+  $preserve_trailing_blank
+!     return 1;
+    }
+--- 2,6 ----
+    {
+      /* waste a line */
+  $preserve_trailing_blank
+!     return 2;
+    }
+EOF
 touch c
 check 'patch c < ab.diff || cat c.rej' <<EOF
 patching file c

tests/preserve-mode-and-timestamp

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -6,8 +6,12 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
-require_sed
+# Note: This test fails on Haiku. This is normal; it is caused by
+# Haiku bug <https://dev.haiku-os.org/ticket/19213>.
+
+require cat
+require sed
+require chmod
 use_local_patch
 use_tmpdir
 
@@ -52,7 +56,7 @@ EOF
 # Some non-GNU versions of date can't show a file's timestamp
 timestamp2_touch=`echo "$timestamp2" | sed -e "$sed_expr"`
 TZ=UTC touch -t $timestamp2_touch f.compare
-ncheck 'test ! \( f -ot f.compare -o f -nt f.compare \) || echo "timstamp differs"'
+ncheck 'test ! \( f -ot f.compare -o f -nt f.compare \) || echo "timestamp differs"'
 
 # POSIX allows a byte like '+' or '.' in position 11 to indicate the
 # presence of extended permissions like ACLs.
@@ -118,4 +122,4 @@ check 'patch -p1 --backup --set-utc < f.diff' <<EOF
 patching file f
 EOF
 
-ncheck 'test ! \( f -ot f.compare -o f -nt f.compare \) || echo "timstamp differs"'
+ncheck 'test ! \( f -ot f.compare -o f -nt f.compare \) || echo "timestamp differs"'

tests/quoted-filenames

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -8,14 +8,16 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
+require special_characters
 use_local_patch
 use_tmpdir
 
 # ==============================================================
 
 # Forbidden characters in Windows filenames:
-#   \ / : * ? " < > |
+#   \ / : * ? " < > | TAB
+# Filenames with trailing space characters
 
 cat > d.diff <<EOF
 --- "\\t \\040"
@@ -31,3 +33,25 @@ ncheck 'patch -s -p0 < d.diff'
 check 'cat "	  "' <<EOF
 two
 EOF
+
+cat > e.diff <<\EOF
+*** /dev/null	Sat Sep 14 08:47:53 2024
+--- "f\000g"	Tue Sep 17 10:21:17 2024
+***************
+*** 0 ****
+--- 1 ----
++
+EOF
+
+check 'patch -f < e.diff; echo status: $?' <<EOF
+can't find file to patch at input line 3
+Perhaps you should have used the -p or --strip option?
+The text leading up to this was:
+--------------------------
+|*** /dev/null	Sat Sep 14 08:47:53 2024
+|--- "f\000g"	Tue Sep 17 10:21:17 2024
+--------------------------
+No file to patch.  Skipping patch.
+1 out of 1 hunk ignored
+status: 1
+EOF

tests/read-only-files

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -8,7 +8,8 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
+require chmod
 use_local_patch
 use_tmpdir
 
@@ -16,7 +17,7 @@ use_tmpdir
 
 : > read-only
 chmod a-w read-only
-if : 2> /dev/null > read-only; then
+if ( : 2> /dev/null > read-only ); then
     echo "Files with read-only permissions are writable" \
 	 "(probably running as superuser)" >&2
     exit 77
@@ -66,3 +67,8 @@ check 'patch -f -p0 --read-only=ignore < f.diff || echo "Status: $?"' <<EOF
 patching file f
 patching file f
 EOF
+
+check 'patch -o - f /dev/null || echo "Status: $?"' <<EOF
+patching file - (read from f)
+three
+EOF

tests/regression-abe92e8010ab

@@ -0,0 +1,33 @@
+. $srcdir/test-lib.sh
+
+require cat
+use_local_patch
+use_tmpdir
+
+cat > f <<EOF
+1
+2
+test:
+a
+4
+EOF
+
+cat > f.diff <<EOF
+2,3c2
+< test:
+< a
+---
+> 3
+EOF
+
+check 'patch f < f.diff' <<EOF
+patching file f
+Hunk #1 succeeded at 3 (offset 1 line).
+EOF
+
+check 'cat f' <<EOF
+1
+2
+3
+4
+EOF

tests/reject-format

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -8,12 +8,13 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
-require_sed
-require_gnu_diff
+require cat
+require sed
 use_local_patch
 use_tmpdir
 
+preserve_trailing_blank=
+
 # ==============================================================
 
 cat > f.orig <<EOF
@@ -27,7 +28,26 @@ a() {
 EOF
 
 sed -e 's/5/5a/' f.orig > f
-diff -p -c -L f.orig -L f f.orig f > f.diff
+
+cat > f.diff <<EOF
+*** f.orig
+--- f
+*************** a() {
+*** 2,7 ****
+  2
+  3
+  $preserve_trailing_blank
+! 5
+  6
+  }
+--- 2,7 ----
+  2
+  3
+  $preserve_trailing_blank
+! 5a
+  6
+  }
+EOF
 
 check 'patch -f -F0 --no-backup-if-mismatch --dry-run f < f.diff || echo "Status: $?"' <<EOF
 checking file f
@@ -43,8 +63,6 @@ Hunk #1 FAILED at 2.
 Status: 1
 EOF
 
-preserve_trailing_blank=
-
 check 'cat f.rej' <<EOF
 *** f.orig
 --- f
@@ -67,8 +85,20 @@ EOF
 
 # --------------------------------------------------------------
 
-( echo "Index: f"; diff -p -u -L f.orig -L f f.orig f ) > f.diff
-check 'patch -f -F0 --no-backup-if-mismatch f < f.diff || echo "Status: $?"' <<EOF
+cat > f1.diff <<EOF
+Index: f
+--- f.orig
++++ f
+@@ -2,6 +2,6 @@ a() {
+ 2
+ 3
+ $preserve_trailing_blank
+-5
++5a
+ 6
+ }
+EOF
+check 'patch -f -F0 --no-backup-if-mismatch f < f1.diff || echo "Status: $?"' <<EOF
 patching file f
 Hunk #1 FAILED at 2.
 1 out of 1 hunk FAILED -- saving rejects to file f.rej
@@ -79,7 +109,7 @@ check 'cat f.rej' <<EOF
 Index: f
 --- f.orig
 +++ f
-@@ -2,6 +2,6 @@
+@@ -2,6 +2,6 @@ a() {
  2
  3
  $preserve_trailing_blank
@@ -91,7 +121,6 @@ EOF
 
 # --------------------------------------------------------------
 
-diff -p -c -L f.orig -L f f.orig f > f.diff
 check 'patch -f -F0 --no-backup-if-mismatch --reject-format=unified f < f.diff || echo "Status: $?"' <<EOF
 patching file f
 Hunk #1 FAILED at 2.
@@ -102,7 +131,7 @@ EOF
 check 'cat f.rej' <<EOF
 --- f.orig
 +++ f
-@@ -2,6 +2,6 @@
+@@ -2,6 +2,6 @@ a() {
  2
  3
  $preserve_trailing_blank
@@ -114,8 +143,7 @@ EOF
 
 # --------------------------------------------------------------
 
-( echo "Index: f"; diff -p -u -L f.orig -L f f.orig f ) > f.diff
-check 'patch -f -F0 --no-backup-if-mismatch --reject-format=context f < f.diff || echo "Status: $?"' <<EOF
+check 'patch -f -F0 --no-backup-if-mismatch --reject-format=context f < f1.diff || echo "Status: $?"' <<EOF
 patching file f
 Hunk #1 FAILED at 2.
 1 out of 1 hunk FAILED -- saving rejects to file f.rej
@@ -147,7 +175,13 @@ EOF
 
 echo one > a
 echo two > b
-diff -u -L "a	label of a" -L "b	label of b" a b > ab.diff
+cat > ab.diff <<EOF
+--- a	label of a
++++ b	label of b
+@@ -1 +1 @@
+-one
++two
+EOF
 mv b a
 
 check 'patch -f < ab.diff || echo "Status: $?"' <<EOF

tests/remember-backup-files

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -9,7 +9,7 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
 use_local_patch
 use_tmpdir
 
@@ -50,41 +50,6 @@ EOF
 
 # ==============================================================
 
-# Hardlinks between source files
-
-echo one > f
-ln f g
-
-cat > fg.diff <<EOF
---- f.orig
-+++ f
-@@ -2 +2 @@
--one
-+two
---- g.orig
-+++ g
-@@ -2 +2 @@
--one
-+two
-EOF
-
-check 'patch -p0 < fg.diff' <<EOF
-patching file f
-Hunk #1 succeeded at 1 (offset -1 lines).
-patching file g
-Hunk #1 succeeded at 1 (offset -1 lines).
-EOF
-
-check 'cat f.orig' <<EOF
-one
-EOF
-
-check 'cat g.orig' <<EOF
-one
-EOF
-
-# ==============================================================
-
 echo one > f
 
 cat > f.diff <<EOF

tests/remember-reject-files

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -6,7 +6,7 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
 use_local_patch
 use_tmpdir
 

tests/remove-directories

@@ -0,0 +1,29 @@
+# Copyright 2013-2025 Free Software Foundation, Inc.
+#
+# Copying and distribution of this file, with or without modification,
+# in any medium, are permitted without royalty provided the copyright
+# notice and this notice are preserved.
+
+. $srcdir/test-lib.sh
+
+require cat
+use_local_patch
+use_tmpdir
+
+# ==============================================================
+# Remove empty parent directories when removing a file.
+
+mkdir dir
+echo foobar > dir/file
+cat > apatch <<EOF
+--- dir/file
++++ /dev/null
+@@ -1 +0,0 @@
+-foobar
+EOF
+
+check 'patch -p0 -E < apatch' <<EOF
+patching file dir/file
+EOF
+
+ncheck '! test -e dir'

tests/symlinks

@@ -1,4 +1,4 @@
-# Copyright (C) 2010-2012 Free Software Foundation, Inc.
+# Copyright 2010-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -8,7 +8,8 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
+require symlinks
 use_local_patch
 use_tmpdir
 
@@ -59,6 +60,14 @@ check 'patch --follow-symlinks < modify.diff || echo "Status: $?"' <<EOF
 patching file l
 EOF
 
+check 'cat f' <<EOF
+one
+EOF
+
+check 'cat l' <<EOF
+two
+EOF
+
 # --------------------------------------------------------------
 
 rm -f f l
@@ -146,6 +155,234 @@ ncheck 'test ! -L symlink'
 
 # --------------------------------------------------------------
 
+# Recursive symlinks
+
+ln -s l1 l2
+ln -s l2 l1
+
+cat > f.diff <<EOF
+--- l1/f
++++ l1/f
+@@ -0,0 +1 @@
++new
+EOF
+
+check 'patch -p0 < f.diff || echo "Status: $?"' <<EOF
+Invalid file name l1/f -- skipping patch
+Status: 1
+EOF
+
+rm -f l1 l2
+
+# --------------------------------------------------------------
+
+cat > retraverse.diff <<EOF
+--- abc/def/ghi/jkl
++++ abc/def/ghi/jkl
+@@ -0,0 +1 @@
++Parent directory traversal
+EOF
+
+ncheck 'mkdir abc'
+ncheck 'mkdir abc/def'
+ln -sf ../../abc/def abc/def/ghi
+check 'patch -p0 < retraverse.diff || echo "Status: $?"' << EOF
+patching file abc/def/ghi/jkl
+EOF
+
+# --------------------------------------------------------------
+
+# Patch should not create symlinks which point outside the working directory.
+
+mkdir d
+echo one > d/f
+ln -s d ld
+
+cat > ld.diff <<EOF
+--- ld/f
++++ ld/f
+@@ -1 +1 @@
+-one
++two
+EOF
+
+check 'patch -p0 < ld.diff' <<EOF
+patching file ld/f
+EOF
+
+mkdir e
+ln -s ../d e/ld
+
+cat > eld.diff <<EOF
+--- e/ld/f
++++ e/ld/f
+@@ -1 +1 @@
+-two
++three
+EOF
+
+check 'patch -p0 < eld.diff' <<EOF
+patching file e/ld/f
+EOF
+
+rm -f e/ld
+ln -sf ../ld e/ld
+
+check 'patch -p0 -R < eld.diff' <<EOF
+patching file e/ld/f
+EOF
+
+mkdir g
+ln -sf ../../z g/bad-rel
+ln -sf .. bad-rel-step2
+ln -sf ../bad-rel-step2/z g/bad-rel-step1
+ln -sf /z g/bad-abs
+
+cat > follow-bad-symlink.diff <<EOF
+--- g/bad-rel/x
++++ g/bad-rel/x
+@@ -0,0 +1 @@
++relative
+--- g/bad-rel-step1/x
++++ g/bad-rel-step1/x
+@@ -0,0 +1 @@
++relative, 2 steps
+--- g/bad-abs/x
++++ g/bad-abs/x
+@@ -0,0 +1 @@
++absolute
+EOF
+
+check 'patch -p0 < follow-bad-symlink.diff || echo "Status: $?"' <<EOF
+Invalid file name g/bad-rel/x -- skipping patch
+Invalid file name g/bad-rel-step1/x -- skipping patch
+Invalid file name g/bad-abs/x -- skipping patch
+Status: 1
+EOF
+
+rm -rf ld d e g
+
+cat > symlink-target.diff <<EOF
+diff --git a/dir/foo b/dir/foo
+new file mode 120000
+index 0000000..cad2309
+--- /dev/null
++++ b/dir/foo
+@@ -0,0 +1 @@
++../foo
+\ No newline at end of file
+EOF
+
+check 'patch -p1 < symlink-target.diff || echo "Status: $?"' <<EOF
+patching symbolic link dir/foo
+EOF
+
+rm -f dir/foo
+cat > follow-symlink.diff <<EOF
+diff --git a/dir/foo b/dir/foo
+new file mode 120000
+index 0000000..cad2309
+--- /dev/null
++++ b/dir/foo
+@@ -0,0 +1 @@
++..
+\ No newline at end of file
+diff --git a/dir/foo/bar b/dir/foo/bar
+new file mode 100644
+index 0000000..2ab772d
+--- /dev/null
++++ b/dir/foo/bar
+@@ -0,0 +1 @@
++created in ..
+diff --git a/dir/bad b/dir/bad
+new file mode 120000
+index 0000000..cad2309
+--- /dev/null
++++ b/dir/bad
+@@ -0,0 +1 @@
++../..
+\ No newline at end of file
+diff --git a/dir/bad/baz b/dir/bad/baz
+new file mode 100644
+index 0000000..2ab772d
+--- /dev/null
++++ b/dir/bad/baz
+@@ -0,0 +1 @@
++created in ../..
+EOF
+
+check 'patch -f -p1 < follow-symlink.diff || echo "Status: $?"' <<EOF
+patching symbolic link dir/foo
+patching file dir/foo/bar
+patching symbolic link dir/bad
+Invalid file name dir/bad/baz -- skipping patch
+Status: 1
+EOF
+
+check 'cat bar' <<EOF
+created in ..
+EOF
+
+rm -f bar
+
+cat > bad-symlink-target1.diff <<EOF
+diff --git a/bar b/bar
+new file mode 120000
+index 0000000..cad2309
+--- /dev/null
++++ b/bar
+@@ -0,0 +1 @@
++/bar
+\ No newline at end of file
+EOF
+
+check 'patch -p1 < bad-symlink-target1.diff || echo "Status: $?"' <<EOF
+patching symbolic link bar
+EOF
+
+cat > bad-symlink-target2.diff <<EOF
+diff --git a/baz b/baz
+new file mode 120000
+index 0000000..cad2309
+--- /dev/null
++++ b/baz
+@@ -0,0 +1 @@
++../baz
+\ No newline at end of file
+EOF
+
+check 'patch -p1 < bad-symlink-target2.diff || echo "Status: $?"' <<EOF
+patching symbolic link baz
+EOF
+
+# --------------------------------------------------------------
+
+# Absolute symlinks that point back into the working directory
+
+mkdir d
+ln -s $PWD here
+ln -s $PWD/here/d here_d
+
+cat > good-absolute.diff <<EOF
+--- /dev/null
++++ here/d/foo
+@@ -0,0 +1 @@
++foo
+--- /dev/null
++++ here_d/bar
+@@ -0,0 +1 @@
++bar
+EOF
+
+check 'patch -p0 < good-absolute.diff' <<EOF
+patching file here/d/foo
+patching file here_d/bar
+EOF
+
+rm -rf d
+
+# --------------------------------------------------------------
+
 # The backup file of a new symlink is an empty regular file.
 
 check 'patch -p1 --backup < create-symlink.diff || echo "Status: $?"' <<EOF
@@ -181,3 +418,20 @@ check 'echo b > symlink.orig && cat target2' <<EOF
 b
 EOF
 rm -f target2
+
+# --------------------------------------------------------------
+# Make sure we do follow symlinks to patch files.
+
+ncheck 'mkdir d'
+cat > d/ab.diff <<EOF
+--- /dev/null
++++ b/foo
+@@ -0,0 +1 @@
++foo
+EOF
+
+ncheck 'ln -sf d l'
+
+check 'patch -p1 -i l/ab.diff' <<EOF
+patching file foo
+EOF

tests/test-lib.sh

@@ -1,5 +1,5 @@
 # Library for simple test scripts
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -7,14 +7,7 @@
 
 # FIXME: Requires a version of diff that understands "-u".
 
-require_cat() {
-    if ! type cat > /dev/null 2> /dev/null; then
-	echo "This test requires the cat utility" >&2
-	exit 77
-    fi
-}
-
-require_gnu_diff() {
+_require_gnu_diff() {
     case "`diff --version 2> /dev/null`" in
     *GNU*)
 	;;
@@ -24,9 +17,57 @@ require_gnu_diff() {
     esac
 }
 
-require_sed() {
-    if ! type sed > /dev/null 2> /dev/null; then
-	echo "This test requires the sed utility" >&2
+_try_chmod() {
+    chmod "$1" "$2" && test "`ls -l "$2" | cut -b2-10`" = "$3"
+}
+
+_require_chmod() {
+    tmp=`mktemp working-chmod.XXXXXXXX`
+    if ! _try_chmod 644 "$tmp" "rw-r--r--" || \
+       ! _try_chmod 600 "$tmp" "rw-------"; then
+	rm -f "$tmp"
+	echo "This test requires chmod support" >&2
+	exit 77
+    fi
+    rm -f "$tmp"
+}
+
+_require_hardlinks() {
+    tmpdir=`mktemp -d hardlinks.XXXXXXXX`
+    if ! touch "$tmpdir/f" ||
+       ! ln "$tmpdir/f" "$tmpdir/g"; then
+	rm -rf "$tmpdir"
+	echo "This test requires hardlink support" >&2
+	exit 77
+    fi
+    rm -rf "$tmpdir"
+}
+
+_require_symlinks() {
+    tmpdir=`mktemp -d hardlinks.XXXXXXXX`
+    if ! touch "$tmpdir/f" ||
+       ! ln -s "f" "$tmpdir/g"; then
+	rm -rf "$tmpdir"
+	echo "This test requires symlink support" >&2
+	exit 77
+    fi
+    rm -rf "$tmpdir"
+}
+
+_require_special_characters() {
+    if ! tmp=`mktemp '	 '.XXXXXXXX`; then
+	echo "This test requires special character support in filenames" >&2
+	exit 77
+    fi
+    rm -f "$tmp"
+}
+
+require() {
+    utility="$1"
+    if type _require_${utility} > /dev/null 2> /dev/null; then
+	_require_${utility}
+    elif ! type "${utility}" > /dev/null 2> /dev/null; then
+	echo "This test requires the ${utility} utility" >&2
 	exit 77
     fi
 }
@@ -45,7 +86,7 @@ use_local_patch() {
 
     eval 'patch() {
 	if test -n "$GDB" ; then
-	  echo -e "\n" >&3
+	  printf "\n\n" >&3
 	  gdbserver localhost:53153 $PATCH "$@" 2>&3
 	else
           $PATCH "$@"
@@ -117,22 +158,15 @@ cleanup() {
     exit $status
 }
 
-if test -z "`echo -n`"; then
-    if eval 'test -n "${BASH_LINENO[0]}" 2>/dev/null'; then
-	eval '
-	    _start_test() {
-		echo -n "[${BASH_LINENO[2]}] $* -- "
-	    }'
-    else
-	eval '
-	    _start_test() {
-		echo -n "* $* -- "
-	    }'
-    fi
+if ( eval 'test -n "${BASH_LINENO[0]}"' 2>/dev/null ); then
+    eval '
+	_start_test() {
+	    printf "[${BASH_LINENO[2]}] %s -- " "$*"
+	}'
 else
     eval '
 	_start_test() {
-	    echo "* $*"
+	    printf "* %s -- " "$*"
 	}'
 fi
 
@@ -163,7 +197,7 @@ if ! type seq > /dev/null 2> /dev/null; then
     )}
 fi
 
-require_cat
+require cat
 clean_env
 
 checks_succeeded=0

tests/unmodified-files

@@ -1,4 +1,4 @@
-# Copyright (C) 2009, 2011-2012 Free Software Foundation, Inc.
+# Copyright 2009-2025 Free Software Foundation, Inc.
 #
 # Copying and distribution of this file, with or without modification,
 # in any medium, are permitted without royalty provided the copyright
@@ -6,7 +6,8 @@
 
 . $srcdir/test-lib.sh
 
-require_cat
+require cat
+require hardlinks
 use_local_patch
 use_tmpdir
 

tests/unusual-blanks

@@ -0,0 +1,45 @@
+# Copyright 2024-2025 Free Software Foundation, Inc.
+#
+# Copying and distribution of this file, with or without modification,
+# in any medium, are permitted without royalty provided the copyright
+# notice and this notice are preserved.
+
+. $srcdir/test-lib.sh
+
+require cat
+use_local_patch
+use_tmpdir
+
+# ==============================================================
+
+# Patch missing the traditional "--- old\n+++ new\n" header
+
+cat > test <<\EOF
+m
+n
+o
+EOF
+
+cat > test.diff <<\EOF
+*** a/test	Tue Sep  3 17:39:19 2024
+--- b/test	Tue Sep  3 17:39:26 2024
+***************
+***  1 ,	 3  ****
+  m
+! n
+  o
+--- 1	,	3 ----
+  m
+! o
+  o
+EOF
+
+check 'patch -p1 -i test.diff' <<\EOF
+patching file test
+EOF
+
+check 'cat test' <<\EOF
+m
+o
+o
+EOF