NetBSD/lib/libpthread/res_state.c

144 lines
4.1 KiB
C

/* $NetBSD: res_state.c,v 1.4 2004/06/03 19:32:27 christos Exp $ */
/*-
* 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* 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.
*/
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: res_state.c,v 1.4 2004/06/03 19:32:27 christos 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"
#include "pthread_int.h"
static SLIST_HEAD(, _res_st) res_list = LIST_HEAD_INITIALIZER(&res_list);
struct _res_st {
/* __res_put_state() assumes st_res is the first member. */
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 = malloc(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
/*ARGSUSED*/
__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; don't allow multi-threaded programs
* to use it.
*/
res_state
__res_state(void)
{
static const char res[] = "_res is not supported for multi-threaded"
" programs.\n";
(void)write(STDERR_FILENO, res, sizeof(res) - 1);
abort();
return NULL;
}