Add missing feature tests to the test suite

Check for chmod, hardlink, symlink, and special character support to
prevent test suite failures in feature constrained environments.

Thanks to Bruno Haible and Nelson H. F. Beebe for their testing and
analysis.

* tests/test-lib.sh: Add new feature tests.
* tests/hardlinks: Split this hardlinks related test off from
tests/remember-backup-files.
* tests/Makefile.am (TESTS): Add new hardlinks test here.
* tests/file-create-modes, tests/file-modes, tests/read-only-files,
tests/preserve-mode-and-timestamp, tests/no-mode-change-git-diff: These
tests require chmod support.
* tests/hardlinks, tests/unmodified-files: These tests require hardlink
support.
* tests/symlinks: This test requires symlink support.
* tests/quoted-filenames: This test requires special character support
in filenames.

tests/Makefile.am

@@ -42,6 +42,7 @@ TESTS = \
 	git-cleanup \
 	garbage \
 	global-reject-files \
+	hardlinks \
 	inname \
 	line-numbers \
 	merge \

tests/file-create-modes

@@ -10,6 +10,7 @@
 
 require cat
 require sed
+require chmod
 use_local_patch
 use_tmpdir
 

tests/file-modes

@@ -10,6 +10,7 @@
 
 require cat
 require sed
+require chmod
 use_local_patch
 use_tmpdir
 

tests/hardlinks

@@ -0,0 +1,50 @@
+# Copyright 2009-2024 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/no-mode-change-git-diff

@@ -9,6 +9,7 @@
 require cat
 require chmod
 require stat
+require chmod
 use_local_patch
 use_tmpdir
 

tests/preserve-mode-and-timestamp

@@ -8,6 +8,7 @@
 
 require cat
 require sed
+require chmod
 use_local_patch
 use_tmpdir
 

tests/quoted-filenames

@@ -9,13 +9,15 @@
 . $srcdir/test-lib.sh
 
 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"

tests/read-only-files

@@ -9,6 +9,7 @@
 . $srcdir/test-lib.sh
 
 require cat
+require chmod
 use_local_patch
 use_tmpdir
 

tests/remember-backup-files

@@ -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/symlinks

@@ -9,6 +9,7 @@
 . $srcdir/test-lib.sh
 
 require cat
+require symlinks
 use_local_patch
 use_tmpdir
 

tests/test-lib.sh

@@ -7,7 +7,7 @@
 
 # FIXME: Requires a version of diff that understands "-u".
 
-require_gnu_diff() {
+_require_gnu_diff() {
     case "`diff --version 2> /dev/null`" in
     *GNU*)
 	;;
@@ -17,10 +17,55 @@ require_gnu_diff() {
     esac
 }
 
+_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_${utility}
+    if type _require_${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

tests/unmodified-files

@@ -7,6 +7,7 @@
 . $srcdir/test-lib.sh
 
 require cat
+require hardlinks
 use_local_patch
 use_tmpdir