Refuse to patch symlinks

* src/inp.c (get_input_file), src/pch.c (there_is_another_patch,
intuit_diff_type): Use lstat instead of stat.  This causes patch to
refuse patching symlinks (get_input_file() will refuse to read them).
* src/util.c (create_backup): Refuse to create backups of symlinks.
* tests/symlinks: New test case.
* tests/Makefile.am (TESTS): Add test case.
* bootstrap.conf: Use the gnulib lstat module.

ChangeLog

@@ -1,5 +1,13 @@
 2009-04-26  Andreas Gruenbacher  <agruen@suse.de>
 
+	* src/inp.c (get_input_file), src/pch.c (there_is_another_patch,
+	intuit_diff_type): Use lstat instead of stat.  This causes patch to
+	refuse patching symlinks (get_input_file() will refuse to read them).
+	* src/util.c (create_backup): Refuse to create backups of symlinks.
+	* tests/symlinks: New test case.
+	* tests/Makefile.am (TESTS): Add test case.
+	* bootstrap.conf: Use the gnulib lstat module.
+
 	* src/pch.c (intuit_diff_type): Only check for reversed patches when
 	the input file is patchable in the first place.
 

bootstrap.conf

@@ -33,6 +33,7 @@ getopt-gnu
 gettime
 git-version-gen
 hash
+lstat
 malloc
 memchr
 minmax

src/inp.c

@@ -143,7 +143,7 @@ get_input_file (char const *filename, char const *outname)
     char *getbuf;
 
     if (inerrno == -1)
-      inerrno = stat (filename, &instat) == 0 ? 0 : errno;
+      inerrno = lstat (filename, &instat) == 0 ? 0 : errno;
 
     /* Perhaps look for RCS or SCCS versions.  */
     if (patch_get

src/patch.c

@@ -479,7 +479,7 @@ main (int argc, char **argv)
 			struct stat oldst;
 			int olderrno;
 
-			olderrno = stat (rej, &oldst) ? errno : 0;
+			olderrno = lstat (rej, &oldst) ? errno : 0;
 			if (olderrno && olderrno != ENOENT)
 			  write_fatal ();
 		        if (! olderrno && file_already_seen (&oldst))

src/pch.c

@@ -283,7 +283,7 @@ there_is_another_patch (bool need_header)
 	  {
 	    inname = savebuf (buf, t - buf);
 	    inname[t - buf - 1] = 0;
-	    if (stat (inname, &instat) == 0)
+	    if (lstat (inname, &instat) == 0)
 	      {
 		inerrno = 0;
 		invc = -1;
@@ -656,7 +656,7 @@ intuit_diff_type (bool need_header)
 		  if (! stat_errno[i])
 		    st[i] = st[i0];
 		}
-	      else if (stat (p_name[i], &st[i]) != 0)
+	      else if (lstat (p_name[i], &st[i]) != 0)
 		stat_errno[i] = errno;
 	      else
 		{
@@ -747,7 +747,7 @@ intuit_diff_type (bool need_header)
       {
 	if (inname)
 	  {
-	    inerrno = stat (inname, &instat) == 0 ? 0 : errno;
+	    inerrno = lstat (inname, &instat) == 0 ? 0 : errno;
 	    if (inerrno || S_ISREG (instat.st_mode))
 	      maybe_reverse (inname, inerrno, inerrno || instat.st_size == 0);
 	  }

src/util.c

@@ -157,7 +157,10 @@ create_backup (char *to, struct stat *to_st, int *to_errno,
       to_st = &tmp_st;
       to_errno = &tmp_errno;
     }
-  *to_errno = stat (to, to_st) == 0 ? 0 : errno;
+  *to_errno = lstat (to, to_st) == 0 ? 0 : errno;
+
+  if (! to_errno && ! S_ISREG (to_st->st_mode))
+    fatal ("File %s is not a regular file -- can't create backup", to);
 
   if (! *to_errno && file_already_seen (to_st))
     {

tests/Makefile.am

@@ -38,6 +38,7 @@ TESTS = \
 	reject-format \
 	remember-backup-files \
 	remember-reject-files \
+	symlinks \
 	unmodified-files
 
 XFAIL_TESTS = \

tests/symlinks

@@ -0,0 +1,76 @@
+# Copyright (C) 2010 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.
+
+# Symlink related tests
+
+. $srcdir/test-lib.sh
+
+require_cat
+use_local_patch
+use_tmpdir
+
+# ==============================================================
+
+cat > create.diff <<EOF
+--- /dev/null
++++ l
+@@ -0,0 +1 @@
++one
+EOF
+
+rm -f f l
+echo f > f
+ncheck 'ln -s f l'
+
+check 'patch < create.diff || echo "Status: $?"' <<EOF
+File l is not a regular file -- can't patch
+1 out of 1 hunk ignored -- saving rejects to file l.rej
+Status: 1
+EOF
+
+check 'cat f' <<EOF
+f
+EOF
+
+# --------------------------------------------------------------
+
+rm -f f l
+echo f > f
+ncheck 'ln -s f l'
+
+cat > modify.diff <<EOF
+--- l
++++ l
+@@ -1 +1 @@
+-one
++two
+EOF
+
+check 'patch < modify.diff || echo "Status: $?"' <<EOF
+File l is not a regular file -- can't patch
+1 out of 1 hunk ignored -- saving rejects to file l.rej
+Status: 1
+EOF
+# --------------------------------------------------------------
+
+rm -f f l
+echo f > f
+ncheck 'ln -s f l'
+
+cat > delete.diff <<EOF
+--- l
++++ /dev/null
+@@ -1 +0,0 @@
+-one
+EOF
+
+check 'patch < delete.diff || echo "Status: $?"' <<EOF
+File l is not a regular file -- can't patch
+1 out of 1 hunk ignored -- saving rejects to file l.rej
+Status: 1
+EOF
+
+# FIXME: Add tests for backup / reject file clashes with symlinks