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/* getugroups.c -- return a list of the groups a user is in
Copyright (C) 1990-1991, 1998-2000, 2003-2023 Free Software Foundation, Inc.
This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
This file 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by David MacKenzie. */
#include <config.h>
#include "getugroups.h"
#include <errno.h>
#include <limits.h>
#include <stdio.h> /* grp.h on alpha OSF1 V2.0 uses "FILE *". */
#include <string.h>
#include <unistd.h>
#if !HAVE_GRP_H || defined __ANDROID__
/* Mingw lacks all things related to group management. The best we
can do is fail with ENOSYS.
Bionic declares e.g. getgrent() in <grp.h> but it isn't actually
defined in the library. */
int
getugroups (_GL_UNUSED int maxcount,
_GL_UNUSED gid_t *grouplist,
_GL_UNUSED char const *username,
_GL_UNUSED gid_t gid)
{
errno = ENOSYS;
return -1;
}
#else /* HAVE_GRP_H */
# include <grp.h>
# define STREQ(a, b) (strcmp (a, b) == 0)
/* Like 'getgroups', but for user USERNAME instead of for the current
process. Store at most MAXCOUNT group IDs in the GROUPLIST array.
If GID is not -1, store it first (if possible). GID should be the
group ID (pw_gid) obtained from getpwuid, in case USERNAME is not
listed in /etc/groups. Upon failure, set errno and return -1.
Otherwise, return the number of IDs we've written into GROUPLIST. */
int
getugroups (int maxcount, gid_t *grouplist, char const *username,
gid_t gid)
{
int count = 0;
if (gid != (gid_t) -1)
{
if (maxcount != 0)
grouplist[count] = gid;
++count;
}
setgrent ();
while (1)
{
char **cp;
struct group *grp;
errno = 0;
grp = getgrent ();
if (grp == NULL)
break;
for (cp = grp->gr_mem; *cp; ++cp)
{
int n;
if ( ! STREQ (username, *cp))
continue;
/* See if this group number is already on the list. */
for (n = 0; n < count; ++n)
if (grouplist && grouplist[n] == grp->gr_gid)
break;
/* If it's a new group number, then try to add it to the list. */
if (n == count)
{
if (maxcount != 0)
{
if (count >= maxcount)
goto done;
grouplist[count] = grp->gr_gid;
}
if (count == INT_MAX)
{
errno = EOVERFLOW;
goto done;
}
count++;
}
}
}
if (errno != 0)
count = -1;
done:
{
int saved_errno = errno;
endgrent ();
errno = saved_errno;
}
return count;
}
#endif /* HAVE_GRP_H */
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