1 files changed, 139 insertions, 0 deletions
diff --git a/lib/long-options.c b/lib/long-options.c
new file mode 100644
index 0000000..212863d
--- /dev/null
+++ b/lib/long-options.c
@@ -0,0 +1,139 @@
+/* Utility to accept --help and --version options as unobtrusively as possible.
+
+   Copyright (C) 1993-1994, 1998-2000, 2002-2006, 2009-2023 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 3 of the License, 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, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by Jim Meyering.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include "long-options.h"
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <getopt.h>
+
+#include "version-etc.h"
+#include "exitfail.h"
+
+static struct option const long_options[] =
+{
+  {"help", no_argument, NULL, 'h'},
+  {"version", no_argument, NULL, 'v'},
+  {NULL, 0, NULL, 0}
+};
+
+/* Process long options --help and --version, but only if argc == 2.
+   Be careful not to gobble up "--".  */
+
+void
+parse_long_options (int argc,
+                    char **argv,
+                    const char *command_name,
+                    const char *package,
+                    const char *version,
+                    void (*usage_func) (int),
+                    /* const char *author1, ...*/ ...)
+{
+  int c;
+  int saved_opterr;
+
+  saved_opterr = opterr;
+
+  /* Don't print an error message for unrecognized options.  */
+  opterr = 0;
+
+  if (argc == 2
+      && (c = getopt_long (argc, argv, "+", 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:
+          /* Don't process any other long-named options.  */
+          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.  */
+  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).  */
+void
+parse_gnu_standard_options_only (int argc,
+                                 char **argv,
+                                 const char *command_name,
+                                 const char *package,
+                                 const char *version,
+                                 bool scan_all,
+                                 void (*usage_func) (int),
+                                 /* const char *author1, ...*/ ...)
+{
+  int c;
+  int 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;
+}