1 /* 2 * Copyright 2009 Sun Microsystems, Inc. All rights reserved. 3 * Use is subject to license terms. 4 */ 5 6 7 #include <port_before.h> 8 #ifdef DO_PTHREADS 9 #include <pthread.h> 10 #endif 11 #include <errno.h> 12 #include <netdb.h> 13 #include <stdlib.h> 14 #include <string.h> 15 #include <resolv_mt.h> 16 #include <irs.h> 17 #include <port_after.h> 18 19 #ifdef DO_PTHREADS 20 static pthread_key_t key; 21 static int mt_key_initialized = 0; 22 23 static int __res_init_ctx(void); 24 static void __res_destroy_ctx(void *); 25 26 #if defined(sun) && !defined(__GNUC__) 27 #pragma init (_mtctxres_init) 28 #endif 29 #endif 30 31 static mtctxres_t sharedctx; 32 33 #ifdef DO_PTHREADS 34 /* 35 * Initialize the TSD key. By doing this at library load time, we're 36 * implicitly running without interference from other threads, so there's 37 * no need for locking. 38 */ 39 static void 40 _mtctxres_init(void) { 41 int pthread_keycreate_ret; 42 43 pthread_keycreate_ret = pthread_key_create(&key, __res_destroy_ctx); 44 if (pthread_keycreate_ret == 0) 45 mt_key_initialized = 1; 46 } 47 #endif 48 49 /* 50 * To support binaries that used the private MT-safe interface in 51 * Solaris 8, we still need to provide the __res_enable_mt() 52 * and __res_disable_mt() entry points. They're do-nothing routines. 53 */ 54 int 55 __res_enable_mt(void) { 56 return (-1); 57 } 58 59 int 60 __res_disable_mt(void) { 61 return (0); 62 } 63 64 #ifdef DO_PTHREADS 65 static int 66 __res_init_ctx(void) { 67 68 mtctxres_t *mt; 69 int ret; 70 71 72 if (pthread_getspecific(key) != 0) { 73 /* Already exists */ 74 return (0); 75 } 76 77 if ((mt = malloc(sizeof (mtctxres_t))) == 0) { 78 errno = ENOMEM; 79 return (-1); 80 } 81 82 memset(mt, 0, sizeof (mtctxres_t)); 83 84 if ((ret = pthread_setspecific(key, mt)) != 0) { 85 free(mt); 86 errno = ret; 87 return (-1); 88 } 89 90 return (0); 91 } 92 93 static void 94 __res_destroy_ctx(void *value) { 95 96 mtctxres_t *mt = (mtctxres_t *)value; 97 98 if (mt != 0) 99 free(mt); 100 } 101 #endif 102 103 mtctxres_t * 104 ___mtctxres(void) { 105 #ifdef DO_PTHREADS 106 mtctxres_t *mt; 107 108 /* 109 * This if clause should only be executed if we are linking 110 * statically. When linked dynamically _mtctxres_init() should 111 * be called at binding time due the #pragma above. 112 */ 113 if (!mt_key_initialized) { 114 static pthread_mutex_t keylock = PTHREAD_MUTEX_INITIALIZER; 115 if (pthread_mutex_lock(&keylock) == 0) { 116 _mtctxres_init(); 117 (void) pthread_mutex_unlock(&keylock); 118 } 119 } 120 121 /* 122 * If we have already been called in this thread return the existing 123 * context. Otherwise recreat a new context and return it. If 124 * that fails return a global context. 125 */ 126 if (mt_key_initialized) { 127 if (((mt = pthread_getspecific(key)) != 0) || 128 (__res_init_ctx() == 0 && 129 (mt = pthread_getspecific(key)) != 0)) { 130 return (mt); 131 } 132 } 133 #endif 134 return (&sharedctx); 135 } 136