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/*
* Copyright (C) 2012-2013 Red Hat, Inc. All rights reserved.
*
* This 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.
*
* This 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 this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Author: Robin Hack <rhack@redhat.com>
*/
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <error.h>
#include <limits.h>
#include <glib.h>
#include "lock.h"
static lock_pools_t pools;
/* Critical sections lock */
static inline void LOCK_CSEC_POOLS (void) { pthread_mutex_lock (&pools.csec); }
static inline void UNLOCK_CSEC_POOLS (void) { pthread_mutex_unlock (&pools.csec); }
static inline void LOCK_CSEC_USER (void) { pthread_mutex_lock (&pools.user_pool.csec); }
static inline void UNLOCK_CSEC_USER (void) { pthread_mutex_unlock (&pools.user_pool.csec); }
static inline void LOCK_CSEC_GROUP (void) { pthread_mutex_lock (&pools.group_pool.csec); }
static inline void UNLOCK_CSEC_GROUP (void) { pthread_mutex_unlock (&pools.group_pool.csec); }
static pthread_once_t pools_are_initialized = PTHREAD_ONCE_INIT;
static unsigned int ref_count = 0;
/* Callbacks */
static void new_pools (void);
static void free_lock (gpointer lock) __attribute__((nonnull));
/* Internal functions */
static int search_key (lock_pool_t *const pool, const char *const key, lock_t **lck) __attribute__((nonnull));
static int add_key (lock_pool_t *const pool, const char *const key) __attribute__((nonnull));
static int release_lock (lock_pool_t *const pool, const char *const key) __attribute__((nonnull));
static int get_lock (lock_pool_t *const pool, const char *const key) __attribute__((nonnull));
int init_lock_pools (void)
{
pthread_once (&pools_are_initialized, new_pools);
if ( pools.initialized == 0 ) { return 0; }
LOCK_CSEC_POOLS ();
++ref_count;
if (ref_count >= UINT_MAX) { UNLOCK_CSEC_POOLS(); return 0; }
UNLOCK_CSEC_POOLS ();
return 1;
}
static void new_pools (void)
{
memset (&pools, 0, sizeof (lock_pools_t));
pools.user_pool.hash_table = g_hash_table_new_full (&g_str_hash, &g_str_equal, NULL, &free_lock);
if ( pools.user_pool.hash_table == NULL ) {
/* paranoia? */
memset (&pools, 0, sizeof (lock_pools_t));
return;
}
pools.group_pool.hash_table = g_hash_table_new_full (&g_str_hash, &g_str_equal, NULL, &free_lock);
if ( pools.group_pool.hash_table == NULL ) {
g_hash_table_destroy (pools.user_pool.hash_table);
memset (&pools, 0, sizeof (lock_pools_t));
return;
}
pthread_mutex_init (&pools.user_pool.csec, NULL);
pthread_mutex_init (&pools.group_pool.csec, NULL);
pthread_mutex_init (&pools.csec, NULL);
pools.initialized = 1;
}
static void free_lock (gpointer lock)
{
lock_t *const lck = (lock_t *) lock;
pthread_mutex_unlock (&lck->mutex);
pthread_mutex_destroy (&lck->mutex);
free (lock);
}
void destroy_lock_pools (void)
{
assert (pools.initialized == 1);
LOCK_CSEC_POOLS ();
--ref_count;
if ( ref_count > 0 ) { UNLOCK_CSEC_POOLS(); return; }
assert (pools.user_pool.hash_table != NULL);
assert (pools.group_pool.hash_table != NULL);
/* Remove all pairs. Memory is deallocated by free_lock callback. */
g_hash_table_destroy (pools.user_pool.hash_table);
g_hash_table_destroy (pools.group_pool.hash_table);
/* What if mutex is locked? */
pthread_mutex_destroy (&pools.user_pool.csec);
pthread_mutex_destroy (&pools.group_pool.csec);
UNLOCK_CSEC_POOLS ();
pthread_mutex_destroy (&pools.csec);
memset (&pools, 0, sizeof (lock_pools_t));
pools_are_initialized = PTHREAD_ONCE_INIT;
}
/* search for keys */
static int search_key (lock_pool_t *const pool, const char *const username, lock_t **lck)
{
assert (pool != NULL);
*lck = (lock_t *) g_hash_table_lookup (pool->hash_table, username);
if ( *lck != NULL ) { return 1; }
return 0;
}
static int add_key (lock_pool_t *const pool, const char *const key)
{
assert (pool != NULL);
lock_t *const new_lock = calloc (1, sizeof (lock_t));
if ( new_lock == NULL ) { return 0; }
pthread_mutex_init (&new_lock->mutex, NULL);
pthread_mutex_lock (&new_lock->mutex);
new_lock->instances = 1;
/* -1 for null char */
strncpy (new_lock->id, key, sizeof (new_lock->id) - 1);
g_hash_table_insert (pool->hash_table, (gpointer) new_lock->id, new_lock);
return 1;
}
int get_user_lock (const char *const username)
{
assert (pools.initialized == 1);
LOCK_CSEC_USER ();
lock_pool_t *const pool = &pools.user_pool;
const int ret = get_lock (pool, username);
UNLOCK_CSEC_USER ();
return ret;
}
int get_group_lock (const char *const groupname)
{
assert (pools.initialized == 1);
LOCK_CSEC_GROUP ();
lock_pool_t *const pool = &pools.group_pool;
const int ret = get_lock (pool, groupname);
UNLOCK_CSEC_GROUP ();
return ret;
}
static int get_lock (lock_pool_t *const pool, const char *const key)
{
assert (pool != NULL);
lock_t *lck = NULL;
int ret = search_key (pool, key, &lck);
if ( ret == 1 ) {
assert (lck != NULL);
pthread_mutex_t *const mutex = &lck->mutex;
if ( lck->instances >= UINT_MAX ) { return 0; }
++lck->instances;
/* This will raise warning in covscan.
But I just want return locked mutex. */
pthread_mutex_lock (mutex);
return 1;
}
/* no keys found - add new key to list */
return (add_key (pool, key));
}
int release_user_lock (const char *const username)
{
assert (pools.initialized == 1);
LOCK_CSEC_USER ();
lock_pool_t *const pool = &pools.user_pool;
const int ret = release_lock (pool, username);
UNLOCK_CSEC_USER ();
return ret;
}
int release_group_lock (const char *const groupname)
{
assert (pools.initialized == 1);
LOCK_CSEC_GROUP ();
lock_pool_t *const pool = &pools.group_pool;
const int ret = release_lock (pool, groupname);
UNLOCK_CSEC_GROUP ();
return ret;
}
static int release_lock (lock_pool_t *const pool, const char *const key)
{
assert (pool != NULL);
lock_t *lck = NULL;
int ret = search_key (pool, key, &lck);
if ( ret == 0 ) { return ret; }
assert (lck != NULL);
--lck->instances;
if ( lck->instances > 0 ) {
pthread_mutex_unlock (&lck->mutex);
return ret;
}
g_hash_table_remove (pool->hash_table, (gpointer) key);
return ret;
}
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