--- diffutils-2.8.7/src/diff.c.orig	2004-04-12 07:44:35 +0000
+++ diffutils-2.8.7/src/diff.c	2005-05-17 11:54:30 +0000
@@ -62,6 +62,9 @@ static void try_help (char const *, char
 static void check_stdout (void);
 static void usage (void);
 
+/* Backup suffix, if any.  */
+static char *backup_suffix;
+
 /* If comparing directories, compare their common subdirectories
    recursively.  */
 static bool recursive;
@@ -137,7 +140,7 @@ exclude_options (void)
 }
 
 static char const shortopts[] =
-"0123456789abBcC:dD:eEfF:hHiI:lL:nNpPqrsS:tTuU:vwW:x:X:y";
+"0123456789abBcC:dD:eEfF:hHiI:k:lL:nNpPqrsS:tTuU:vwW:x:X:y";
 
 /* Values for long options that do not have single-letter equivalents.  */
 enum
@@ -187,6 +190,7 @@ static char const line_format_option[][s
 
 static struct option const longopts[] =
 {
+  {"backup", 2, 0, 'k'},
   {"binary", 0, 0, BINARY_OPTION},
   {"brief", 0, 0, 'q'},
   {"changed-group-format", 1, 0, CHANGED_GROUP_FORMAT_OPTION},
@@ -400,6 +404,14 @@ main (int argc, char **argv)
 	  add_regexp (&ignore_regexp_list, optarg);
 	  break;
 
+	case 'k':
+	  /* Backup mode: if backup suffix specified, compare files
+	     against backups with that suffix.  */
+	  backup_suffix = optarg ?: ".orig";
+	  recursive = true;
+	  new_file = true;
+	  break;
+
 	case 'l':
 	  if (!pr_program[0])
 	    try_help ("pagination not supported on this host", 0);
@@ -751,16 +763,25 @@ main (int argc, char **argv)
 	  }
       else
 	{
-	  if (argc - optind != 2)
+	  if (argc - optind != 1 + !backup_suffix)
 	    {
-	      if (argc - optind < 2)
+	      if (argc - optind < 1 + !backup_suffix)
 		try_help ("missing operand after `%s'", argv[argc - 1]);
 	      else
-		try_help ("extra operand `%s'", argv[optind + 2]);
+		try_help ("extra operand `%s'", argv[optind + 1 + !backup_suffix]);
 	    }
 
-	  exit_status = compare_files ((struct comparison *) 0,
-				       argv[optind], argv[optind + 1]);
+	  if (backup_suffix)
+	    {
+	      char bak[strlen (argv[optind]) + strlen (backup_suffix) + 1];
+	      strcpy (bak, argv[optind]);
+	      strcat (bak, backup_suffix);
+	      exit_status = compare_files ((struct comparison *) 0,
+					   bak, argv[optind]);
+	    }
+	  else
+	    exit_status = compare_files ((struct comparison *) 0,
+					 argv[optind], argv[optind + 1]);
 	}
     }
 
@@ -915,6 +936,7 @@ static char const * const option_help_ms
   N_("-N  --new-file  Treat absent files as empty."),
   N_("--unidirectional-new-file  Treat absent first files as empty."),
   N_("-s  --report-identical-files  Report when two files are the same."),
+  N_("-k SUF  --backup[=SUF]  Compare file(s) against backup(s) ending in SUF."),
   N_("-x PAT  --exclude=PAT  Exclude files that match PAT."),
   N_("-X FILE  --exclude-from=FILE  Exclude files that match any pattern in FILE."),
   N_("-S FILE  --starting-file=FILE  Start with FILE when comparing directories."),