Replace groups.sh with groups.c.

* src/groups.c (main): New file, replacing groups.sh.
* src/group-list.c, src/group-list.h: New files, factored out of id.c,
implementing the functionality that "id" and "groups" have in common.
* src/id.c (print_full_info): Avoid a segfault when trying to print
an error message if getgroups fails.
(print_group_list): Move to group-list.c.
(print_group): Likewise.
* man/Makefile.am: When building groups.1, obtain the help text
from src/groups.c, not src/groups.sh.
(noinst_HEADERS): Add group-list.h.
(group): Remove rule.
(dist_man_MANS): Remove groups.1.
* doc/coreutils.texi (groups: Print group names a user is in):
Explain why "groups" and "groups $(id -un)" give different results
in existing login sessions after you change the group database.
(id: Print user identity): Likewise for "id".
* po/POTFILES.in: Add src/group-list.c and src/groups.c.
* NEWS: mention this.
* AUTHORS: Update.

1 files changed, 153 insertions, 0 deletions

diff --git a/src/groups.c b/src/groups.c
new file mode 100644
index 000000000..8a4673ced
--- /dev/null
+++ b/src/groups.c
@@ -0,0 +1,153 @@
+/* groups -- print the groups a user is in
+   Copyright (C) 1989-2008 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 <http://www.gnu.org/licenses/>.  */
+
+/* Written by James Youngman based on id.c and groups.sh,
+   which were written by Arnold Robbins and David MacKenzie. */
+
+#include <config.h>
+#include <stdio.h>
+#include <getopt.h>
+#include <sys/types.h>
+#include <pwd.h>
+#include <grp.h>
+#include <getopt.h>
+
+#include "system.h"
+#include "error.h"
+#include "group-list.h"
+
+/* The name this program was run with. */
+char *program_name;
+
+/* The official name of this program (e.g., no `g' prefix).  */
+#define PROGRAM_NAME "groups"
+
+#define AUTHORS "David MacKenzie", "James Youngman"
+
+
+static struct option const longopts[] =
+{
+  {GETOPT_HELP_OPTION_DECL},
+  {GETOPT_VERSION_OPTION_DECL},
+  {NULL, 0, NULL, 0}
+};
+
+void
+usage (int status)
+{
+  if (status != EXIT_SUCCESS)
+    fprintf (stderr, _("Try `%s --help' for more information.\n"),
+             program_name);
+  else
+    {
+      printf (_("Usage: %s [OPTION]... [USERNAME]\n"), program_name);
+      fputs (_("\
+Print information for USERNAME or, if no USERNAME is specified,\n\
+the current process (which is different if the groups database has changed).\n"),
+             stdout);
+      fputs (HELP_OPTION_DESCRIPTION, stdout);
+      fputs (VERSION_OPTION_DESCRIPTION, stdout);
+      emit_bug_reporting_address ();
+    }
+  exit (status);
+}
+
+static void
+write_error (void)
+{
+  error (0, errno, _("write error"));
+}
+
+
+int
+main (int argc, char **argv)
+{
+  int optc;
+  bool ok = true;
+  gid_t rgid, egid;
+  uid_t ruid;
+
+  initialize_main (&argc, &argv);
+  program_name = argv[0];
+  setlocale (LC_ALL, "");
+  bindtextdomain (PACKAGE, LOCALEDIR);
+  textdomain (PACKAGE);
+
+  atexit (close_stdout);
+
+  /* Processing the arguments this way makes groups.c behave differently to
+   * groups.sh if one of the arguments is "--".
+   */
+  while ((optc = getopt_long (argc, argv, "", longopts, NULL)) != -1)
+    {
+      switch (optc)
+        {
+        case_GETOPT_HELP_CHAR;
+        case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
+        default:
+          usage (EXIT_FAILURE);
+        }
+    }
+
+  if (optind == argc)
+    {
+      /* No arguments.  Divulge the details of the current process. */
+      ruid = getuid ();
+      egid = getegid ();
+      rgid = getgid ();
+
+      if (!print_group_list (NULL, ruid, rgid, egid, true))
+        ok = false;
+      if (EOF == putchar ('\n'))
+        {
+          write_error ();
+          ok = false;
+        }
+    }
+  else
+    {
+      /* At least one argument.  Divulge the details of the specified users. */
+      while (optind < argc)
+        {
+          struct passwd *pwd = getpwnam (argv[optind]);
+          if (pwd == NULL)
+            error (EXIT_FAILURE, 0, _("%s: No such user"), argv[optind]);
+          ruid = pwd->pw_uid;
+          rgid = egid = pwd->pw_gid;
+
+          if (printf ("%s : ", argv[optind]) < 0)
+            {
+              write_error ();
+              ok = false;
+            }
+          if (!print_group_list (argv[optind++], ruid, rgid, egid, true))
+            ok = false;
+          if (EOF == putchar ('\n'))
+            {
+              write_error ();
+              ok = false;
+            }
+        }
+    }
+
+  exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);
+}
+
+/*
+ * Local variables:
+ *  indent-tabs-mode: nil
+ * End:
+ */