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/* Initgroups handling in nss_files module.
Copyright (C) 2011-2017 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library 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.
The GNU C Library 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 the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <alloca.h>
#include <errno.h>
#include <grp.h>
#include <nss.h>
#include <stdio_ext.h>
#include <string.h>
#include <sys/param.h>
#include <stdbool.h>
#include <stdlib.h>
enum nss_status
_nss_files_initgroups_dyn (const char *user, gid_t group, long int *start,
long int *size, gid_t **groupsp, long int limit,
int *errnop)
{
FILE *stream = fopen ("/etc/group", "rce");
if (stream == NULL)
{
*errnop = errno;
return *errnop == ENOMEM ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;
}
/* No other thread using this stream. */
__fsetlocking (stream, FSETLOCKING_BYCALLER);
char *line = NULL;
size_t linelen = 0;
enum nss_status status = NSS_STATUS_SUCCESS;
bool any = false;
size_t buflen = 1024;
void *buffer = alloca (buflen);
bool buffer_use_malloc = false;
gid_t *groups = *groupsp;
/* We have to iterate over the entire file. */
while (1)
{
fpos_t pos;
fgetpos (stream, &pos);
ssize_t n = getline (&line, &linelen, stream);
if (n < 0)
{
if (! feof_unlocked (stream))
status = ((*errnop = errno) == ENOMEM
? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL);
break;
}
struct group grp;
int res = _nss_files_parse_grent (line, &grp, buffer, buflen, errnop);
if (res == -1)
{
size_t newbuflen = 2 * buflen;
if (buffer_use_malloc || ! __libc_use_alloca (buflen + newbuflen))
{
void *newbuf = realloc (buffer_use_malloc ? buffer : NULL,
newbuflen);
if (newbuf == NULL)
{
*errnop = ENOMEM;
status = NSS_STATUS_TRYAGAIN;
goto out;
}
buffer = newbuf;
buflen = newbuflen;
buffer_use_malloc = true;
}
else
buffer = extend_alloca (buffer, buflen, newbuflen);
/* Reread current line, the parser has clobbered it. */
fsetpos (stream, &pos);
continue;
}
if (res > 0 && grp.gr_gid != group)
for (char **m = grp.gr_mem; *m != NULL; ++m)
if (strcmp (*m, user) == 0)
{
/* Matches user. Insert this group. */
if (*start == *size)
{
/* Need a bigger buffer. */
if (limit > 0 && *size == limit)
/* We reached the maximum. */
goto out;
long int newsize;
if (limit <= 0)
newsize = 2 * *size;
else
newsize = MIN (limit, 2 * *size);
gid_t *newgroups = realloc (groups,
newsize * sizeof (*groups));
if (newgroups == NULL)
{
*errnop = ENOMEM;
status = NSS_STATUS_TRYAGAIN;
goto out;
}
*groupsp = groups = newgroups;
*size = newsize;
}
groups[*start] = grp.gr_gid;
*start += 1;
any = true;
break;
}
}
out:
/* Free memory. */
if (buffer_use_malloc)
free (buffer);
free (line);
fclose (stream);
return status == NSS_STATUS_SUCCESS && !any ? NSS_STATUS_NOTFOUND : status;
}
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