1 #include <sys/cdefs.h> 2 __FBSDID("$FreeBSD$"); 3 4 #include <port_before.h> 5 #ifdef DO_PTHREADS 6 #include <pthread.h> 7 #ifdef _LIBC 8 #include <pthread_np.h> 9 #endif 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 <port_after.h> 17 18 #ifdef DO_PTHREADS 19 static pthread_key_t key; 20 static int mt_key_initialized = 0; 21 22 static int __res_init_ctx(void); 23 static void __res_destroy_ctx(void *); 24 25 #if defined(sun) && !defined(__GNUC__) 26 #pragma init (_mtctxres_init) 27 #endif 28 #endif 29 30 static mtctxres_t sharedctx; 31 32 #ifdef DO_PTHREADS 33 /* 34 * Initialize the TSD key. By doing this at library load time, we're 35 * implicitly running without interference from other threads, so there's 36 * no need for locking. 37 */ 38 static void 39 _mtctxres_init(void) { 40 int pthread_keycreate_ret; 41 42 pthread_keycreate_ret = pthread_key_create(&key, __res_destroy_ctx); 43 if (pthread_keycreate_ret == 0) 44 mt_key_initialized = 1; 45 } 46 #endif 47 48 #ifndef _LIBC 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 #endif 64 65 #ifdef DO_PTHREADS 66 static int 67 __res_init_ctx(void) { 68 69 mtctxres_t *mt; 70 int ret; 71 72 73 if (pthread_getspecific(key) != 0) { 74 /* Already exists */ 75 return (0); 76 } 77 78 if ((mt = malloc(sizeof(mtctxres_t))) == NULL) { 79 errno = ENOMEM; 80 return (-1); 81 } 82 83 memset(mt, 0, sizeof (mtctxres_t)); 84 85 if ((ret = pthread_setspecific(key, mt)) != 0) { 86 free(mt); 87 errno = ret; 88 return (-1); 89 } 90 91 return (0); 92 } 93 94 static void 95 __res_destroy_ctx(void *value) { 96 97 free(value); 98 } 99 #endif 100 101 mtctxres_t * 102 ___mtctxres(void) { 103 #ifdef DO_PTHREADS 104 mtctxres_t *mt; 105 106 #ifdef _LIBC 107 if (pthread_main_np() != 0) 108 return (&sharedctx); 109 #endif 110 111 /* 112 * This if clause should only be executed if we are linking 113 * statically. When linked dynamically _mtctxres_init() should 114 * be called at binding time due the #pragma above. 115 */ 116 if (!mt_key_initialized) { 117 static pthread_mutex_t keylock = PTHREAD_MUTEX_INITIALIZER; 118 if (pthread_mutex_lock(&keylock) == 0) { 119 _mtctxres_init(); 120 (void) pthread_mutex_unlock(&keylock); 121 } 122 } 123 124 /* 125 * If we have already been called in this thread return the existing 126 * context. Otherwise recreat a new context and return it. If 127 * that fails return a global context. 128 */ 129 if (mt_key_initialized) { 130 if (((mt = pthread_getspecific(key)) != NULL) || 131 (__res_init_ctx() == 0 && 132 (mt = pthread_getspecific(key)) != NULL)) { 133 return (mt); 134 } 135 } 136 #endif 137 return (&sharedctx); 138 } 139