/* group-member.c -- determine whether group id is in calling user's group list
- Copyright (C) 1994, 1997-1998, 2003, 2005-2006, 2009-2010 Free Software
+ Copyright (C) 1994, 1997-1998, 2003, 2005-2006, 2009-2013 Free Software
Foundation, Inc.
This program is free software: you can redistribute it and/or modify
#include <config.h>
-#include "group-member.h"
+/* Specification. */
+#include <unistd.h>
-#include <stdbool.h>
#include <stdio.h>
#include <sys/types.h>
#include <stdlib.h>
-#include <unistd.h>
+#include "xalloc-oversized.h"
-#include "xalloc.h"
+/* Most processes have no more than this many groups, and for these
+ processes we can avoid using malloc. */
+enum { GROUPBUF_SIZE = 100 };
struct group_info
{
- int n_groups;
gid_t *group;
+ gid_t groupbuf[GROUPBUF_SIZE];
};
static void
free_group_info (struct group_info const *g)
{
- free (g->group);
+ if (g->group != g->groupbuf)
+ free (g->group);
}
-static bool
+static int
get_group_info (struct group_info *gi)
{
- int n_groups;
- int n_group_slots = getgroups (0, NULL);
- gid_t *group;
-
- if (n_group_slots < 0)
- return false;
-
- /* Avoid xnmalloc, as it goes awry when SIZE_MAX < n_group_slots. */
- if (xalloc_oversized (n_group_slots, sizeof *group))
- xalloc_die ();
- group = xmalloc (n_group_slots * sizeof *group);
- n_groups = getgroups (n_group_slots, group);
+ int n_groups = getgroups (GROUPBUF_SIZE, gi->groupbuf);
+ gi->group = gi->groupbuf;
- /* In case of error, the user loses. */
if (n_groups < 0)
{
- free (group);
- return false;
+ int n_group_slots = getgroups (0, NULL);
+ if (0 <= n_group_slots
+ && ! xalloc_oversized (n_group_slots, sizeof *gi->group))
+ {
+ gi->group = malloc (n_group_slots * sizeof *gi->group);
+ if (gi->group)
+ n_groups = getgroups (n_group_slots, gi->group);
+ }
}
- gi->n_groups = n_groups;
- gi->group = group;
-
- return true;
+ /* In case of error, the user loses. */
+ return n_groups;
}
/* Return non-zero if GID is one that we have in our groups list.
int i;
int found;
struct group_info gi;
-
- if (! get_group_info (&gi))
- return 0;
+ int n_groups = get_group_info (&gi);
/* Search through the list looking for GID. */
found = 0;
- for (i = 0; i < gi.n_groups; i++)
+ for (i = 0; i < n_groups; i++)
{
if (gid == gi.group[i])
{