Add --follow-symlinks option for backwards compatibility

* src/common.h (follow_symlinks): New variable.
* src/patch.c (longopts): Add new --follow-symlinks option.
(get_some_switches): Recognize the new option.
* src/util.c (stat_file): Follow symlinks if requested.
* patch.man: Document the new option.
* tests/symlinks: Add test case.

patch.man

@@ -600,6 +600,13 @@ diff form.
 \fB\-s\fP  or  \fB\*=silent\fP  or  \fB\*=quiet\fP
 Work silently, unless an error occurs.
 .TP
+\fB\*=follow\-symlinks\fP
+When looking for input files, follow symbolic links.  Replaces the symbolic
+links, instead of modifying the files the symbolic links point to.  Git-style
+patches to symbolic links will no longer apply.  This option exists for
+backwards compatibility with previous versions of patch; its use is
+discouraged.
+.TP
 \fB\-t\fP  or  \fB\*=batch\fP
 Suppress questions like
 .BR \-f ,

src/common.h

@@ -111,6 +111,7 @@ XTERN bool canonicalize;
 XTERN int patch_get;
 XTERN bool set_time;
 XTERN bool set_utc;
+XTERN bool follow_symlinks;
 
 enum diff
   {

src/patch.c

@@ -726,6 +726,7 @@ static struct option const longopts[] =
   {"quoting-style", required_argument, NULL, CHAR_MAX + 8},
   {"reject-format", required_argument, NULL, CHAR_MAX + 9},
   {"read-only", required_argument, NULL, CHAR_MAX + 10},
+  {"follow-symlinks", no_argument, NULL, CHAR_MAX + 11},
   {NULL, no_argument, NULL, 0}
 };
 
@@ -1017,6 +1018,9 @@ get_some_switches (void)
 		else
 		  usage (stderr, 2);
 		break;
+	    case CHAR_MAX + 11:
+		follow_symlinks = true;
+		break;
 	    default:
 		usage (stderr, 2);
 	}

src/util.c

@@ -1652,5 +1652,8 @@ make_tempfile (char const **name, char letter, char const *real_name,
 
 int stat_file (char const *filename, struct stat *st)
 {
-  return lstat (filename, st) == 0 ? 0 : errno;
+  int (*xstat)(char const *, struct stat *) =
+    follow_symlinks ? stat : lstat;
+
+  return xstat (filename, st) == 0 ? 0 : errno;
 }

tests/symlinks

@@ -54,6 +54,11 @@ File l is not a regular file -- refusing to patch
 1 out of 1 hunk ignored -- saving rejects to file l.rej
 Status: 1
 EOF
+
+check 'patch --follow-symlinks < modify.diff || echo "Status: $?"' <<EOF
+patching file l
+EOF
+
 # --------------------------------------------------------------
 
 rm -f f l