setuidgid: set all groups, not just the primary one; mgetgroups: new module

I wanted to use the xgetgroups function from id.c, so factored it out
and made it into a non-exiting function (hence the "m" prefix rather than "x").
* src/setuidgid.c (main): Use mgetgroups. Include "mgetgroups.h".

* src/id.c (xgetgroups): Remove function.
Include "mgetgroups.h".
(print_group_list): Use mgetgroups, not xgetgroups.

* gl/modules/mgetgroups: New module.
* gl/lib/mgetgroups.c: New file.  mgetgroups is derived from
id.c's xgetgroups function.
* bootstrap.conf (gnulib_modules): Add mgetgroups.
* gl/m4/mgetgroups.m4: New file.
* gl/lib/mgetgroups.h: New file.

4 files changed, 136 insertions, 0 deletions

diff --git a/gl/lib/mgetgroups.c b/gl/lib/mgetgroups.c
new file mode 100644
index 000000000..8552f2639
--- /dev/null
+++ b/gl/lib/mgetgroups.c
@@ -0,0 +1,80 @@
+/* getugroups.c -- return a list of the groups a user is in
+
+   Copyright (C) 2007 Free Software Foundation.
+
+   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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* Extracted from coreutils' src/id.c. */
+
+#include <config.h>
+
+#include "mgetgroups.h"
+
+#include <unistd.h>
+#include <stdint.h>
+#include <errno.h>
+
+#include "getugroups.h"
+#include "xalloc.h"
+
+/* Like getugroups, but store the result in malloc'd storage.
+   Set *GROUPS to the malloc'd list of all group IDs of which USERNAME
+   is a member.  If GID is not -1, store it first.  GID should be the
+   group ID (pw_gid) obtained from getpwuid, in case USERNAME is not
+   listed in the groups database (e.g., /etc/groups).  Upon failure,
+   don't modify *GROUPS, set errno, and return -1.  Otherwise, return
+   the number of groups.  */
+
+int
+mgetgroups (const char *username, gid_t gid, GETGROUPS_T **groups)
+{
+  int max_n_groups;
+  int ng;
+  GETGROUPS_T *g;
+
+  max_n_groups = (username
+		  ? getugroups (0, NULL, username, gid)
+		  : getgroups (0, NULL));
+
+  /* If we failed to count groups with NULL for a buffer,
+     try again with a non-NULL one, just in case.  */
+  if (max_n_groups < 0)
+      max_n_groups = 5;
+
+  if (xalloc_oversized (max_n_groups, sizeof *g))
+    {
+      errno = ENOMEM;
+      return -1;
+    }
+
+  g = malloc (max_n_groups * sizeof *g);
+  if (g == NULL)
+    return -1;
+
+  ng = (username
+	? getugroups (max_n_groups, g, username, gid)
+	: getgroups (max_n_groups, g));
+
+  if (ng < 0)
+    {
+      int saved_errno = errno;
+      free (g);
+      errno = saved_errno;
+      return -1;
+    }
+
+  *groups = g;
+  return ng;
+}
diff --git a/gl/lib/mgetgroups.h b/gl/lib/mgetgroups.h
new file mode 100644
index 000000000..23f04e189
--- /dev/null
+++ b/gl/lib/mgetgroups.h
@@ -0,0 +1,21 @@
+/* Get a list of all group IDs associated with a specified user ID.
+   Copyright (C) 2007 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; see the file COPYING.
+   If not, write to the Free Software Foundation,
+   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+#include <sys/types.h>
+
+int mgetgroups (const char *username, gid_t gid, GETGROUPS_T **groups);
diff --git a/gl/m4/mgetgroups.m4 b/gl/m4/mgetgroups.m4
new file mode 100644
index 000000000..81835415f
--- /dev/null
+++ b/gl/m4/mgetgroups.m4
@@ -0,0 +1,10 @@
+#serial 1
+dnl Copyright (C) 2007 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_MGETGROUPS],
+[
+  AC_LIBOBJ([mgetgroups])
+])
diff --git a/gl/modules/mgetgroups b/gl/modules/mgetgroups
new file mode 100644
index 000000000..3e2ead100
--- /dev/null
+++ b/gl/modules/mgetgroups
@@ -0,0 +1,25 @@
+Description:
+Return the group IDs of a user in malloc'd storage.
+
+Files:
+lib/mgetgroups.c
+lib/mgetgroups.h
+m4/mgetgroups.m4
+
+Depends-on:
+free
+getugroups
+xalloc
+
+configure.ac:
+gl_MGETGROUPS
+
+Makefile.am:
+
+Include:
+
+License:
+LGPL
+
+Maintainer:
+Jim Meyering