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, 134 insertions, 0 deletions

diff --git a/src/group-list.c b/src/group-list.c
new file mode 100644
index 000000000..e788f8e87
--- /dev/null
+++ b/src/group-list.c
@@ -0,0 +1,134 @@
+/* group-list.c --Print a list of group IDs or names.
+   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 Arnold Robbins.
+   Major rewrite by David MacKenzie, djm@gnu.ai.mit.edu.
+   Extracted from id.c by James Youngman. */
+
+#include <config.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <getopt.h>
+#include <pwd.h>
+#include <grp.h>
+
+#include "system.h"
+#include "error.h"
+#include "mgetgroups.h"
+#include "quote.h"
+#include "group-list.h"
+
+
+/* Print all of the distinct groups the user is in. */
+extern bool
+print_group_list (const char *username,
+                  uid_t ruid, gid_t rgid, gid_t egid,
+                  bool use_names)
+{
+  bool ok = true;
+  struct passwd *pwd;
+
+  pwd = getpwuid (ruid);
+  if (pwd == NULL)
+    ok = false;
+
+  if (!print_group (rgid, use_names))
+    ok = false;
+
+  if (egid != rgid)
+    {
+      putchar (' ');
+      if (!print_group (egid, use_names))
+        ok = false;
+    }
+
+#if HAVE_GETGROUPS
+  {
+    GETGROUPS_T *groups;
+    size_t i;
+
+    int n_groups = mgetgroups (username, (pwd ? pwd->pw_gid : (gid_t) -1),
+                               &groups);
+    if (n_groups < 0)
+      {
+        if (username)
+          {
+            error (0, errno, _("failed to get groups for user %s"),
+                   quote (username));
+          }
+        else
+          {
+            error (0, errno, _("failed to get groups for the current process"));
+          }
+        return false;
+      }
+
+    for (i = 0; i < n_groups; i++)
+      if (groups[i] != rgid && groups[i] != egid)
+        {
+          putchar (' ');
+          if (!print_group (groups[i], use_names))
+            ok = false;
+        }
+    free (groups);
+    return ok;
+  }
+#endif /* HAVE_GETGROUPS */
+}
+
+
+/* Print the name or value of group ID GID. */
+extern bool
+print_group (gid_t gid, bool use_name)
+{
+  struct group *grp = NULL;
+  bool ok = true;
+
+  if (use_name)
+    {
+      grp = getgrgid (gid);
+      if (grp == NULL)
+        {
+          error (0, 0, _("cannot find name for group ID %lu"),
+                 (unsigned long int) gid);
+          ok = false;
+        }
+    }
+
+  if (grp == NULL)
+    {
+      if (printf ("%lu", (unsigned long int) gid) < 0)
+        {
+          error (0, errno, _("write error"));
+          ok = false;
+        }
+    }
+  else
+    {
+      if (printf ("%s", grp->gr_name) < 0)
+        {
+          error (0, errno, _("write error"));
+          ok = false;
+        }
+    }
+  return ok;
+}
+
+/*
+ * Local variables:
+ *  indent-tabs-mode: nil
+ * End:
+ */