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/*
* $Id$
*
* This function provides a thread safer version of getgrnam() for use
* with PAM modules that care about this sort of thing.
*
* XXX - or at least it should provide a thread-safe alternative.
*/
#include "pammodutil.h"
#include <limits.h>
#include <grp.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
static pthread_mutex_t _pammodutil_mutex = PTHREAD_MUTEX_INITIALIZER;
static void _pammodutil_lock(void)
{
pthread_mutex_lock(&_pammodutil_mutex);
}
static void _pammodutil_unlock(void)
{
pthread_mutex_unlock(&_pammodutil_mutex);
}
static int intlen(int number)
{
int len = 2;
while (number != 0) {
number /= 10;
len++;
}
return len;
}
struct group *_pammodutil_getgrnam(pam_handle_t *pamh, const char *group)
{
#ifdef HAVE_GETGRNAM_R
void *buffer=NULL;
size_t length = PWD_INITIAL_LENGTH;
do {
int status;
void *new_buffer;
struct group *result = NULL;
new_buffer = realloc(buffer, sizeof(struct passwd) + length);
if (new_buffer == NULL) {
D(("out of memory"));
/* no memory for the group - so delete the memory */
if (buffer) {
free(buffer);
}
return NULL;
}
buffer = new_buffer;
/* make the re-entrant call to get the grp structure */
status = getgrnam_r(group, buffer,
sizeof(struct group) + (char *) buffer,
length, &result);
if (!status && (result == buffer)) {
char *data_name;
const void *ignore;
int i;
data_name = malloc(strlen("_pammodutil_getgrnam") + 1 +
strlen(group) + 1 + intlen(INT_MAX) + 1);
if ((pamh != NULL) && (data_name == NULL)) {
D(("was unable to register the data item [%s]",
pam_strerror(pamh, status)));
free(buffer);
return NULL;
}
if (pamh != NULL) {
for (i = 0; i < INT_MAX; i++) {
sprintf(data_name, "_pammodutil_getgrnam_%s_%d", group, i);
_pammodutil_lock();
status = PAM_NO_MODULE_DATA;
if (pam_get_data(pamh, data_name, &ignore) != PAM_SUCCESS) {
status = pam_set_data(pamh, data_name,
result, _pammodutil_cleanup);
}
_pammodutil_unlock();
if (status == PAM_SUCCESS) {
break;
}
}
} else {
status = PAM_SUCCESS;
}
free(data_name);
if (status == PAM_SUCCESS) {
D(("success"));
return result;
}
D(("was unable to register the data item [%s]",
pam_strerror(pamh, status)));
free(buffer);
return NULL;
}
length <<= 1;
} while (length < PWD_ABSURD_PWD_LENGTH);
D(("grp structure took %u bytes or so of memory",
length+sizeof(struct group)));
free(buffer);
return NULL;
#else /* ie. ifndef HAVE_GETGRNAM_R */
/*
* Sorry, there does not appear to be a reentrant version of
* getgrnam(). So, we use the standard libc function.
*/
return getgrnam(group);
#endif /* def HAVE_GETGRNAM_R */
}
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