1 /* $NetBSD: res_state.c,v 1.5 2007/11/13 15:57:14 ad Exp $ */ 2 3 /*- 4 * Copyright (c) 2004 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Christos Zoulas. 9 * 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. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 __RCSID("$NetBSD: res_state.c,v 1.5 2007/11/13 15:57:14 ad Exp $"); 42 #endif 43 44 #include <sys/types.h> 45 #include <sys/queue.h> 46 #include <arpa/inet.h> 47 #include <arpa/nameser.h> 48 #include <stdlib.h> 49 #include <unistd.h> 50 #include <resolv.h> 51 #include <netdb.h> 52 53 #include "pthread.h" 54 #include "pthread_int.h" 55 56 static SLIST_HEAD(, _res_st) res_list = LIST_HEAD_INITIALIZER(&res_list); 57 58 struct _res_st { 59 /* __res_put_state() assumes st_res is the first member. */ 60 struct __res_state st_res; 61 62 SLIST_ENTRY(_res_st) st_list; 63 }; 64 65 static pthread_mutex_t res_mtx = PTHREAD_MUTEX_INITIALIZER; 66 67 res_state __res_state(void); 68 res_state __res_get_state(void); 69 void __res_put_state(res_state); 70 71 #ifdef RES_STATE_DEBUG 72 static void 73 res_state_debug(const char *msg, void *p) 74 { 75 char buf[512]; 76 pthread_t self = pthread__self(); 77 int len = snprintf(buf, sizeof(buf), "%p: %s %p\n", self, msg, p); 78 79 (void)write(STDOUT_FILENO, buf, (size_t)len); 80 } 81 #else 82 #define res_state_debug(a, b) 83 #endif 84 85 86 res_state 87 __res_get_state(void) 88 { 89 res_state res; 90 struct _res_st *st; 91 pthread_mutex_lock(&res_mtx); 92 st = SLIST_FIRST(&res_list); 93 if (st != NULL) { 94 SLIST_REMOVE_HEAD(&res_list, st_list); 95 pthread_mutex_unlock(&res_mtx); 96 res = &st->st_res; 97 res_state_debug("checkout from list", st); 98 } else { 99 pthread_mutex_unlock(&res_mtx); 100 st = malloc(sizeof(*st)); 101 if (st == NULL) { 102 h_errno = NETDB_INTERNAL; 103 return NULL; 104 } 105 res = &st->st_res; 106 res->options = 0; 107 res_state_debug("alloc new", res); 108 } 109 if ((res->options & RES_INIT) == 0) { 110 if (res_ninit(res) == -1) { 111 h_errno = NETDB_INTERNAL; 112 free(st); 113 return NULL; 114 } 115 } 116 return res; 117 } 118 119 void 120 /*ARGSUSED*/ 121 __res_put_state(res_state res) 122 { 123 struct _res_st *st = (struct _res_st *)(void *)res; 124 125 res_state_debug("free", res); 126 pthread_mutex_lock(&res_mtx); 127 SLIST_INSERT_HEAD(&res_list, st, st_list); 128 pthread_mutex_unlock(&res_mtx); 129 } 130 131 /* 132 * This is aliased via a macro to _res; don't allow multi-threaded programs 133 * to use it. 134 */ 135 res_state 136 __res_state(void) 137 { 138 static const char res[] = "_res is not supported for multi-threaded" 139 " programs.\n"; 140 (void)write(STDERR_FILENO, res, sizeof(res) - 1); 141 abort(); 142 return NULL; 143 } 144