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/* mgetgroups.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 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/>. */
/* 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;
}
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