* Support the environtmental var "DIFF_OPTIONS". Which can hold a set of

default options for diff.  These options are interpreted first and can be
overwritten by explicit command line parameters.
* Add the "-o" option to specify old-traditional output style.
* Add utility functions for env vars obtained from GNU Grep 2.3h.

contrib/diff/diff.c

@@ -20,6 +20,8 @@ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
 /* GNU DIFF was written by Mike Haertel, David Hayes,
    Richard Stallman, Len Tower, and Paul Eggert.  */
 
+/* $FreeBSD$ */
+
 #define GDIFF_MAIN
 #include "diff.h"
 #include <signal.h>
@@ -30,6 +32,7 @@ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
 #else
 #include "fnmatch.h"
 #endif
+#include "prepend_args.h"
 
 #ifndef DEFAULT_WIDTH
 #define DEFAULT_WIDTH 130
@@ -249,10 +252,12 @@ main (argc, argv)
   output_style = OUTPUT_NORMAL;
   context = -1;
 
+  prepend_default_options (getenv ("DIFF_OPTIONS"), &argc, &argv);
+
   /* Decode the options.  */
 
   while ((c = getopt_long (argc, argv,
-			   "0123456789abBcC:dD:efF:hHiI:lL:nNpPqrsS:tTuU:vwW:x:X:y",
+			   "0123456789abBcC:dD:efF:hHiI:lL:nNopPqrsS:tTuU:vwW:x:X:y",
 			   longopts, 0)) != EOF)
     {
       switch (c)
@@ -424,6 +429,11 @@ main (argc, argv)
 	  entire_new_file_flag = 1;
 	  break;
 
+	case 'o':
+	  /* Output in the old tradition style.  */
+	  specify_style (OUTPUT_NORMAL);
+	  break;
+
 	case 'p':
 	  /* Make context-style output and show name of last C function.  */
 	  show_c_function = 1;

contrib/diff/prepend_args.c

@@ -0,0 +1,86 @@
+/* prepend_args.c - utilility programs for manpiulating argv[]
+   Copyright (C) 1999 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 2, 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, Inc., 59 Temple Place - Suite 330, Boston, MA
+   02111-1307, USA.  */
+
+/* $FreeBSD$ */
+
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+#include "system.h"
+#include "prepend_args.h"
+
+
+/* Find the white-space-separated options specified by OPTIONS, and
+   using BUF to store copies of these options, set ARGV[0], ARGV[1],
+   etc. to the option copies.  Return the number N of options found.
+   Do not set ARGV[N] to NULL.  If ARGV is NULL, do not store ARGV[0]
+   etc.  Backslash can be used to escape whitespace (and backslashes).  */
+static int
+prepend_args (options, buf, argv)
+     char const *options;
+     char *buf;
+     char **argv;
+{
+  char const *o = options;
+  char *b = buf;
+  int n = 0;
+
+  for (;;)
+    {
+      while (ISSPACE ((unsigned char) *o))
+	o++;
+      if (!*o)
+	return n;
+      if (argv)
+	argv[n] = b;
+      n++;
+
+      do
+	if ((*b++ = *o++) == '\\' && *o)
+	  b[-1] = *o++;
+      while (*o && ! ISSPACE ((unsigned char) *o));
+
+      *b++ = '\0';
+    }
+}
+
+/* Prepend the whitespace-separated options in OPTIONS to the argument
+   vector of a main program with argument count *PARGC and argument
+   vector *PARGV.  */
+void
+prepend_default_options (options, pargc, pargv)
+     char const *options;
+     int *pargc;
+     char ***pargv;
+{
+  if (options)
+    {
+      char *buf = xmalloc (strlen (options) + 1);
+      int prepended = prepend_args (options, buf, (char **) NULL);
+      int argc = *pargc;
+      char * const *argv = *pargv;
+      char **pp = (char **) xmalloc ((prepended + argc + 1) * sizeof *pp);
+      *pargc = prepended + argc;
+      *pargv = pp;
+      *pp++ = *argv++;
+      pp += prepend_args (options, buf, pp);
+      while ((*pp++ = *argv++))
+	continue;
+    }
+}

contrib/diff/prepend_args.h

@@ -0,0 +1,21 @@
+/* prepend_args.h - utilility programs for manpiulating argv[]
+   Copyright (C) 1999 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 2, 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, Inc., 59 Temple Place - Suite 330, Boston, MA
+   02111-1307, USA.  */
+
+/* $FreeBSD$ */
+
+void prepend_default_options PARAMS ((char const *, int *, char ***));

gnu/usr.bin/diff/Makefile

@@ -4,7 +4,7 @@
 
 PROG=	diff
 SRCS=	diff.c analyze.c io.c context.c ed.c normal.c ifdef.c util.c dir.c \
-	version.c getopt.c getopt1.c side.c cmpbuf.c
+	version.c getopt.c getopt1.c side.c cmpbuf.c prepend_args.c
 
 # Important for ctype macros!
 CFLAGS+=-funsigned-char

gnu/usr.bin/diff/diff.1

@@ -1,3 +1,4 @@
+.\" $FreeBSD$
 .TH DIFF 1 "22sep1993" "GNU Tools" "GNU Tools"
 .SH NAME
 diff \- find differences between two files
@@ -297,6 +298,9 @@ Use
 to output a line taken from just the second file in
 if-then-else format.
 .TP
+.B \-o
+Use the old traditional output format.
+.TP
 .BI \-\-old\-group\-format= format
 Use
 .I format
@@ -463,6 +467,14 @@ match any pattern contained in
 .TP
 .B \-y
 Use the side by side output format.
+.SH ENVIRONMENT
+The environment variable
+.B DIFF_OPTIONS
+can hold a set of default
+options for
+.I diff.
+These options are interpreted first and can be overwritten by explicit command
+line parameters.
 .SH EXAMPLES
 To save to a file some changes that you have made to your local source
 tree (possibly including new files), which you would like to show to others