>From 08d0505683cebed0fc10cff082255fd79da2d989 Mon Sep 17 00:00:00 2001
From: Bernhard Voelker <address@hidden>
Date: Thu, 29 Nov 2018 09:06:26 +0100
Subject: [PATCH] long-options: add parse_gnu_standard_options_only

Discussed in https://bugs.gnu.org/33468 .

* lib/long-options.c (parse_long_options): Use EXIT_SUCCESS instead
of 0.
(parse_gnu_standard_options_only): Add function to
process the GNU default options --help and --version and fail for any other
unknown long or short option. See
https://gnu.org/prep/standards/html_node/Command_002dLine-Interfaces.html .
* lib/long-options.h (parse_gnu_standard_options_only): Declare it.
* modules/long-options (depends-on): Add stdbool, exitfail.
* top/maint.mk (sc_prohibit_long_options_without_use): Update
syntax-check rule, add new function name.
---
 lib/long-options.c   | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 lib/long-options.h   | 17 +++++++++++++
 modules/long-options |  2 ++
 top/maint.mk         |  2 +-
 4 files changed, 87 insertions(+), 2 deletions(-)

diff --git a/lib/long-options.c b/lib/long-options.c
index 037f74b3a..b7acdb040 100644
--- a/lib/long-options.c
+++ b/lib/long-options.c
@@ -29,6 +29,7 @@
 #include <getopt.h>
 
 #include "version-etc.h"
+#include "exitfail.h"
 
 static struct option const long_options[] =
 {
@@ -71,7 +72,7 @@ parse_long_options (int argc,
             va_list authors;
             va_start (authors, usage_func);
             version_etc_va (stdout, command_name, package, version, authors);
-            exit (0);
+            exit (EXIT_SUCCESS);
           }
 
         default:
@@ -87,3 +88,68 @@ parse_long_options (int argc,
      the probably-new parameters when/if getopt is called later.  */
   optind = 0;
 }
+
+/* Process the GNU default long options --help and --version (see also
+   https://gnu.org/prep/standards/html_node/Command_002dLine-Interfaces.html),
+   and fail for any other unknown long or short option.
+   Use with SCAN_ALL=true to scan until "--", or with SCAN_ALL=false to stop
+   at the first non-option argument (or "--", whichever comes first).
+
+   if RESET_OPTIND=true, the global optind variable will be reset to zero,
+   preparing (and requiring) a follow-up gnu-compatible getopt() call
+   (non-gnu getopt functions use optreset=optind=1 instead of 0 for reset).
+
+   if RESET_OPTIND=false, optind is left as-is (suitable for programs
+   which do not process further option parameters (but could still
+   process parameters directly by examining argv[optind]).  */
+void
+parse_gnu_standard_options_only (int argc,
+                                 char **argv,
+                                 const char *command_name,
+                                 const char *package,
+                                 const char *version,
+                                 bool scan_all,
+                                 bool reset_optind,
+                                 void (*usage_func) (int),
+                                 /* const char *author1, ...*/ ...)
+{
+  int c;
+  int saved_opterr;
+
+  saved_opterr = opterr;
+
+  /* Print an error message for unrecognized options.  */
+  opterr = 1;
+
+  const char *optstring = scan_all ? "" : "+";
+
+  if ((c = getopt_long (argc, argv, optstring, long_options, NULL)) != -1)
+    {
+      switch (c)
+        {
+        case 'h':
+          (*usage_func) (EXIT_SUCCESS);
+          break;
+
+        case 'v':
+          {
+            va_list authors;
+            va_start (authors, usage_func);
+            version_etc_va (stdout, command_name, package, version, authors);
+            exit (EXIT_SUCCESS);
+          }
+
+        default:
+          (*usage_func) (exit_failure);
+          break;
+        }
+    }
+
+  /* Restore previous value.  */
+  opterr = saved_opterr;
+
+  /* Reset this to zero so that getopt internals get initialized from
+     the probably-new parameters when/if getopt is called later.  */
+  if (reset_optind)
+    optind = 0;
+}
diff --git a/lib/long-options.h b/lib/long-options.h
index f4d6a83d5..01bea4c27 100644
--- a/lib/long-options.h
+++ b/lib/long-options.h
@@ -17,6 +17,11 @@
 
 /* Written by Jim Meyering.  */
 
+#ifndef LONG_OPTIONS_H_
+# define LONG_OPTIONS_H_ 1
+
+# include <stdbool.h>
+
 void parse_long_options (int _argc,
                          char **_argv,
                          const char *_command_name,
@@ -24,3 +29,15 @@ void parse_long_options (int _argc,
                          const char *_version,
                          void (*_usage) (int),
                          /* const char *author1, ...*/ ...);
+
+void parse_gnu_standard_options_only (int argc,
+                                      char **argv,
+                                      const char *command_name,
+                                      const char *package,
+                                      const char *version,
+                                      bool scan_all,
+                                      bool reset_optind,
+                                      void (*usage_func) (int),
+                                      /* const char *author1, ...*/ ...);
+
+#endif /* LONG_OPTIONS_H_ */
diff --git a/modules/long-options b/modules/long-options
index f1106c3cc..b845d4293 100644
--- a/modules/long-options
+++ b/modules/long-options
@@ -6,7 +6,9 @@ lib/long-options.h
 lib/long-options.c
 
 Depends-on:
+exitfail
 getopt-gnu
+stdbool
 stdlib
 version-etc
 
diff --git a/top/maint.mk b/top/maint.mk
index 4e37efeb5..e9d5ee7d4 100644
--- a/top/maint.mk
+++ b/top/maint.mk
@@ -537,7 +537,7 @@ sc_prohibit_quote_without_use:
 
 # Don't include this header unless you use one of its functions.
 sc_prohibit_long_options_without_use:
-	@h='long-options.h' re='\<parse_long_options *\(' \
+	@h='long-options.h' re='\<parse_(long_options|gnu_standard_options_only) *\(' \
 	  $(_sc_header_without_use)
 
 # Don't include this header unless you use one of its functions.
-- 
2.11.0