* Copyright (c) 2004 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Christos Zoulas.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
-------------------------
This file contains the thread-safe versions of res functions, taken from
NetBSD's libpthread directory. Do *not* replace it with the legacy
single-threaded version from NetBSD's netresolv directory.
*/
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: res_state.c,v 1.6 2008/04/28 20:23:02 martin Exp $");
#endif
#include <sys/types.h>
#include <sys/queue.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <stdlib.h>
#include <unistd.h>
#include <resolv.h>
#include <netdb.h>
#include <pthread.h>
struct __res_state _nres
# if defined(__BIND_RES_TEXT)
= { .retrans = RES_TIMEOUT, }
# endif
;
static SLIST_HEAD(, _res_st) res_list = LIST_HEAD_INITIALIZER(&res_list);
struct _res_st {
struct __res_state st_res;
SLIST_ENTRY(_res_st) st_list;
};
static pthread_mutex_t res_mtx = PTHREAD_MUTEX_INITIALIZER;
res_state __res_state(void);
res_state __res_get_state(void);
void __res_put_state(res_state);
#ifdef RES_STATE_DEBUG
static void
res_state_debug(const char *msg, void *p)
{
char buf[512];
pthread_t self = pthread__self();
int len = snprintf(buf, sizeof(buf), "%p: %s %p\n", self, msg, p);
(void)write(STDOUT_FILENO, buf, (size_t)len);
}
#else
#define res_state_debug(a, b)
#endif
res_state
__res_get_state(void)
{
res_state res;
struct _res_st *st;
pthread_mutex_lock(&res_mtx);
st = SLIST_FIRST(&res_list);
if (st != NULL) {
SLIST_REMOVE_HEAD(&res_list, st_list);
pthread_mutex_unlock(&res_mtx);
res = &st->st_res;
res_state_debug("checkout from list", st);
} else {
pthread_mutex_unlock(&res_mtx);
st = calloc(1, sizeof(*st));
if (st == NULL) {
h_errno = NETDB_INTERNAL;
return NULL;
}
res = &st->st_res;
res->options = 0;
res_state_debug("alloc new", res);
}
if ((res->options & RES_INIT) == 0) {
if (res_ninit(res) == -1) {
h_errno = NETDB_INTERNAL;
free(st);
return NULL;
}
}
return res;
}
void
__res_put_state(res_state res)
{
struct _res_st *st = (struct _res_st *)(void *)res;
res_state_debug("free", res);
pthread_mutex_lock(&res_mtx);
SLIST_INSERT_HEAD(&res_list, st, st_list);
pthread_mutex_unlock(&res_mtx);
}
* This is aliased via a macro to _res.
* This function is not thread safe.
*/
res_state
__res_state(void)
{
if ((_nres.options & RES_INIT) == 0 && res_ninit(&_nres) == -1) {
h_errno = NETDB_INTERNAL;
return NULL;
}
return &_nres;
}
