Patrick Welche <prlw1@cam.ac.uk>
[netbsd-mini2440.git] / lib / libpthread / res_state.c
blob566083531dd9341edec59e0b14ef652e59ed0a15
1 /* $NetBSD: res_state.c,v 1.5 2007/11/13 15:57:14 ad Exp $ */
3 /*-
4 * Copyright (c) 2004 The NetBSD Foundation, Inc.
5 * All rights reserved.
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Christos Zoulas.
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
32 #include <sys/cdefs.h>
33 #if defined(LIBC_SCCS) && !defined(lint)
34 __RCSID("$NetBSD: res_state.c,v 1.5 2007/11/13 15:57:14 ad Exp $");
35 #endif
37 #include <sys/types.h>
38 #include <sys/queue.h>
39 #include <arpa/inet.h>
40 #include <arpa/nameser.h>
41 #include <stdlib.h>
42 #include <unistd.h>
43 #include <resolv.h>
44 #include <netdb.h>
46 #include "pthread.h"
47 #include "pthread_int.h"
49 static SLIST_HEAD(, _res_st) res_list = LIST_HEAD_INITIALIZER(&res_list);
51 struct _res_st {
52 /* __res_put_state() assumes st_res is the first member. */
53 struct __res_state st_res;
55 SLIST_ENTRY(_res_st) st_list;
58 static pthread_mutex_t res_mtx = PTHREAD_MUTEX_INITIALIZER;
60 res_state __res_state(void);
61 res_state __res_get_state(void);
62 void __res_put_state(res_state);
64 #ifdef RES_STATE_DEBUG
65 static void
66 res_state_debug(const char *msg, void *p)
68 char buf[512];
69 pthread_t self = pthread__self();
70 int len = snprintf(buf, sizeof(buf), "%p: %s %p\n", self, msg, p);
72 (void)write(STDOUT_FILENO, buf, (size_t)len);
74 #else
75 #define res_state_debug(a, b)
76 #endif
79 res_state
80 __res_get_state(void)
82 res_state res;
83 struct _res_st *st;
84 pthread_mutex_lock(&res_mtx);
85 st = SLIST_FIRST(&res_list);
86 if (st != NULL) {
87 SLIST_REMOVE_HEAD(&res_list, st_list);
88 pthread_mutex_unlock(&res_mtx);
89 res = &st->st_res;
90 res_state_debug("checkout from list", st);
91 } else {
92 pthread_mutex_unlock(&res_mtx);
93 st = malloc(sizeof(*st));
94 if (st == NULL) {
95 h_errno = NETDB_INTERNAL;
96 return NULL;
98 res = &st->st_res;
99 res->options = 0;
100 res_state_debug("alloc new", res);
102 if ((res->options & RES_INIT) == 0) {
103 if (res_ninit(res) == -1) {
104 h_errno = NETDB_INTERNAL;
105 free(st);
106 return NULL;
109 return res;
112 void
113 /*ARGSUSED*/
114 __res_put_state(res_state res)
116 struct _res_st *st = (struct _res_st *)(void *)res;
118 res_state_debug("free", res);
119 pthread_mutex_lock(&res_mtx);
120 SLIST_INSERT_HEAD(&res_list, st, st_list);
121 pthread_mutex_unlock(&res_mtx);
125 * This is aliased via a macro to _res; don't allow multi-threaded programs
126 * to use it.
128 res_state
129 __res_state(void)
131 static const char res[] = "_res is not supported for multi-threaded"
132 " programs.\n";
133 (void)write(STDERR_FILENO, res, sizeof(res) - 1);
134 abort();
135 return NULL;