1 /* $NetBSD: reentrant.h,v 1.18 2015/01/20 18:31:25 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 1997, 1998, 2003 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by J.T. Conklin, by Nathan J. Williams, and by Jason R. Thorpe. 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 * 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. 30 */ 31 32 /* 33 * Requirements: 34 * 35 * 1. The thread safe mechanism should be lightweight so the library can 36 * be used by non-threaded applications without unreasonable overhead. 37 * 38 * 2. There should be no dependency on a thread engine for non-threaded 39 * applications. 40 * 41 * 3. There should be no dependency on any particular thread engine. 42 * 43 * 4. The library should be able to be compiled without support for thread 44 * safety. 45 * 46 * 47 * Rationale: 48 * 49 * One approach for thread safety is to provide discrete versions of the 50 * library: one thread safe, the other not. The disadvantage of this is 51 * that libc is rather large, and two copies of a library which are 99%+ 52 * identical is not an efficent use of resources. 53 * 54 * Another approach is to provide a single thread safe library. However, 55 * it should not add significant run time or code size overhead to non- 56 * threaded applications. 57 * 58 * Since the NetBSD C library is used in other projects, it should be 59 * easy to replace the mutual exclusion primitives with ones provided by 60 * another system. Similarly, it should also be easy to remove all 61 * support for thread safety completely if the target environment does 62 * not support threads. 63 * 64 * 65 * Implementation Details: 66 * 67 * The thread primitives used by the library (mutex_t, mutex_lock, etc.) 68 * are macros which expand to the cooresponding primitives provided by 69 * the thread engine or to nothing. The latter is used so that code is 70 * not unreasonably cluttered with #ifdefs when all thread safe support 71 * is removed. 72 * 73 * The thread macros can be directly mapped to the mutex primitives from 74 * pthreads, however it should be reasonably easy to wrap another mutex 75 * implementation so it presents a similar interface. 76 * 77 * The thread functions operate by dispatching to symbols which are, by 78 * default, weak-aliased to no-op functions in thread-stub/thread-stub.c 79 * (some uses of thread operations are conditional on __isthreaded, but 80 * not all of them are). 81 * 82 * When the thread library is linked in, it provides strong-alias versions 83 * of those symbols which dispatch to its own real thread operations. 84 * 85 */ 86 87 #if defined(_REENTRANT) && defined(__minix) 88 89 /* 90 * Abstract thread interface for thread-safe libraries. These routines 91 * will use stubs in libc if the application is not linked against the 92 * pthread library, and the real function in the pthread library if it 93 * is. 94 */ 95 96 #include <pthread.h> 97 #include <signal.h> 98 99 #define mutex_t pthread_mutex_t 100 #define MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER 101 102 #define mutexattr_t pthread_mutexattr_t 103 104 #define MUTEX_TYPE_NORMAL PTHREAD_MUTEX_NORMAL 105 #define MUTEX_TYPE_ERRORCHECK PTHREAD_MUTEX_ERRORCHECK 106 #define MUTEX_TYPE_RECURSIVE PTHREAD_MUTEX_RECURSIVE 107 108 #define cond_t pthread_cond_t 109 #define COND_INITIALIZER PTHREAD_COND_INITIALIZER 110 111 #define condattr_t pthread_condattr_t 112 113 #define rwlock_t pthread_rwlock_t 114 #define RWLOCK_INITIALIZER PTHREAD_RWLOCK_INITIALIZER 115 116 #define rwlockattr_t pthread_rwlockattr_t 117 118 #define thread_key_t pthread_key_t 119 120 #define thr_t pthread_t 121 122 #define thrattr_t pthread_attr_t 123 124 #define once_t pthread_once_t 125 #define ONCE_INITIALIZER PTHREAD_ONCE_INIT 126 127 #ifndef __LIBC_THREAD_STUBS 128 129 __BEGIN_DECLS 130 int __libc_mutex_init(mutex_t *, const mutexattr_t *); 131 int __libc_mutex_lock(mutex_t *); 132 int __libc_mutex_trylock(mutex_t *); 133 int __libc_mutex_unlock(mutex_t *); 134 int __libc_mutex_destroy(mutex_t *); 135 136 int __libc_mutexattr_init(mutexattr_t *); 137 int __libc_mutexattr_settype(mutexattr_t *, int); 138 int __libc_mutexattr_destroy(mutexattr_t *); 139 __END_DECLS 140 141 #define mutex_init(m, a) __libc_mutex_init((m), (a)) 142 #define mutex_lock(m) __libc_mutex_lock((m)) 143 #define mutex_trylock(m) __libc_mutex_trylock((m)) 144 #define mutex_unlock(m) __libc_mutex_unlock((m)) 145 #define mutex_destroy(m) __libc_mutex_destroy((m)) 146 147 #define mutexattr_init(ma) __libc_mutexattr_init((ma)) 148 #define mutexattr_settype(ma, t) __libc_mutexattr_settype((ma), (t)) 149 #define mutexattr_destroy(ma) __libc_mutexattr_destroy((ma)) 150 151 __BEGIN_DECLS 152 int __libc_cond_init(cond_t *, const condattr_t *); 153 int __libc_cond_signal(cond_t *); 154 int __libc_cond_broadcast(cond_t *); 155 int __libc_cond_wait(cond_t *, mutex_t *); 156 #ifndef __LIBC12_SOURCE__ 157 int __libc_cond_timedwait(cond_t *, mutex_t *, const struct timespec *); 158 #endif 159 int __libc_cond_destroy(cond_t *); 160 __END_DECLS 161 162 #define cond_init(c, t, a) __libc_cond_init((c), (a)) 163 #define cond_signal(c) __libc_cond_signal((c)) 164 #define cond_broadcast(c) __libc_cond_broadcast((c)) 165 #define cond_wait(c, m) __libc_cond_wait((c), (m)) 166 #define cond_timedwait(c, m, t) __libc_cond_timedwait((c), (m), (t)) 167 #define cond_destroy(c) __libc_cond_destroy((c)) 168 169 __BEGIN_DECLS 170 int __libc_rwlock_init(rwlock_t *, const rwlockattr_t *); 171 int __libc_rwlock_rdlock(rwlock_t *); 172 int __libc_rwlock_wrlock(rwlock_t *); 173 int __libc_rwlock_tryrdlock(rwlock_t *); 174 int __libc_rwlock_trywrlock(rwlock_t *); 175 int __libc_rwlock_unlock(rwlock_t *); 176 int __libc_rwlock_destroy(rwlock_t *); 177 __END_DECLS 178 179 #define rwlock_init(l, a) __libc_rwlock_init((l), (a)) 180 #define rwlock_rdlock(l) __libc_rwlock_rdlock((l)) 181 #define rwlock_wrlock(l) __libc_rwlock_wrlock((l)) 182 #define rwlock_tryrdlock(l) __libc_rwlock_tryrdlock((l)) 183 #define rwlock_trywrlock(l) __libc_rwlock_trywrlock((l)) 184 #define rwlock_unlock(l) __libc_rwlock_unlock((l)) 185 #define rwlock_destroy(l) __libc_rwlock_destroy((l)) 186 187 __BEGIN_DECLS 188 int __libc_thr_keycreate(thread_key_t *, void (*)(void *)); 189 int __libc_thr_setspecific(thread_key_t, const void *); 190 void *__libc_thr_getspecific(thread_key_t); 191 int __libc_thr_keydelete(thread_key_t); 192 __END_DECLS 193 194 #define thr_keycreate(k, d) __libc_thr_keycreate((k), (d)) 195 #define thr_setspecific(k, p) __libc_thr_setspecific((k), (p)) 196 #define thr_getspecific(k) __libc_thr_getspecific((k)) 197 #define thr_keydelete(k) __libc_thr_keydelete((k)) 198 199 __BEGIN_DECLS 200 int __libc_thr_once(once_t *, void (*)(void)); 201 int __libc_thr_sigsetmask(int, const sigset_t *, sigset_t *); 202 thr_t __libc_thr_self(void); 203 int __libc_thr_yield(void); 204 void __libc_thr_create(thr_t *, const thrattr_t *, 205 void *(*)(void *), void *); 206 void __libc_thr_exit(void *) __attribute__((__noreturn__)); 207 int *__libc_thr_errno(void); 208 int __libc_thr_setcancelstate(int, int *); 209 unsigned int __libc_thr_curcpu(void); 210 211 extern int __isthreaded; 212 __END_DECLS 213 214 #define thr_once(o, f) __libc_thr_once((o), (f)) 215 #define thr_sigsetmask(f, n, o) __libc_thr_sigsetmask((f), (n), (o)) 216 #define thr_self() __libc_thr_self() 217 #define thr_yield() __libc_thr_yield() 218 #define thr_create(tp, ta, f, a) __libc_thr_create((tp), (ta), (f), (a)) 219 #define thr_exit(v) __libc_thr_exit((v)) 220 #define thr_errno() __libc_thr_errno() 221 #define thr_enabled() (__isthreaded) 222 #define thr_setcancelstate(n, o) __libc_thr_setcancelstate((n),(o)) 223 #define thr_curcpu() __libc_thr_curcpu() 224 225 #else /* __LIBC_THREAD_STUBS */ 226 227 __BEGIN_DECLS 228 void __libc_thr_init_stub(void); 229 230 int __libc_mutex_init_stub(mutex_t *, const mutexattr_t *); 231 int __libc_mutex_lock_stub(mutex_t *); 232 int __libc_mutex_trylock_stub(mutex_t *); 233 int __libc_mutex_unlock_stub(mutex_t *); 234 int __libc_mutex_destroy_stub(mutex_t *); 235 236 int __libc_mutexattr_init_stub(mutexattr_t *); 237 int __libc_mutexattr_destroy_stub(mutexattr_t *); 238 int __libc_mutexattr_settype_stub(mutexattr_t *, int); 239 240 int __libc_cond_init_stub(cond_t *, const condattr_t *); 241 int __libc_cond_signal_stub(cond_t *); 242 int __libc_cond_broadcast_stub(cond_t *); 243 int __libc_cond_wait_stub(cond_t *, mutex_t *); 244 int __libc_cond_timedwait_stub(cond_t *, mutex_t *, 245 const struct timespec *); 246 int __libc_cond_destroy_stub(cond_t *); 247 248 int __libc_rwlock_init_stub(rwlock_t *, const rwlockattr_t *); 249 int __libc_rwlock_rdlock_stub(rwlock_t *); 250 int __libc_rwlock_wrlock_stub(rwlock_t *); 251 int __libc_rwlock_tryrdlock_stub(rwlock_t *); 252 int __libc_rwlock_trywrlock_stub(rwlock_t *); 253 int __libc_rwlock_unlock_stub(rwlock_t *); 254 int __libc_rwlock_destroy_stub(rwlock_t *); 255 256 int __libc_thr_keycreate_stub(thread_key_t *, void (*)(void *)); 257 int __libc_thr_setspecific_stub(thread_key_t, const void *); 258 void *__libc_thr_getspecific_stub(thread_key_t); 259 int __libc_thr_keydelete_stub(thread_key_t); 260 261 int __libc_thr_once_stub(once_t *, void (*)(void)); 262 int __libc_thr_sigsetmask_stub(int, const sigset_t *, sigset_t *); 263 thr_t __libc_thr_self_stub(void); 264 int __libc_thr_yield_stub(void); 265 int __libc_thr_create_stub(thr_t *, const thrattr_t *, 266 void *(*)(void *), void *); 267 void __libc_thr_exit_stub(void *) __dead; 268 int *__libc_thr_errno_stub(void); 269 int __libc_thr_setcancelstate_stub(int, int *); 270 int __libc_thr_equal_stub(pthread_t, pthread_t); 271 unsigned int __libc_thr_curcpu_stub(void); 272 __END_DECLS 273 274 #endif /* __LIBC_THREAD_STUBS */ 275 276 #define FLOCKFILE(fp) __flockfile_internal(fp, 1) 277 #define FUNLOCKFILE(fp) __funlockfile_internal(fp, 1) 278 279 #else /* _REENTRANT */ 280 281 #ifndef __empty 282 #define __empty do {} while (/*CONSTCOND*/0) 283 #endif 284 #define mutex_init(m, a) __empty 285 #define mutex_lock(m) __empty 286 #define mutex_trylock(m) __empty 287 #define mutex_unlock(m) __empty 288 #define mutex_destroy(m) __empty 289 290 #define cond_init(c, t, a) __empty 291 #define cond_signal(c) __empty 292 #define cond_broadcast(c) __empty 293 #define cond_wait(c, m) __empty 294 #define cond_timedwait(c, m, t) __empty 295 #define cond_destroy(c) __empty 296 297 #define rwlock_init(l, a) __empty 298 #define rwlock_rdlock(l) __empty 299 #define rwlock_wrlock(l) __empty 300 #define rwlock_tryrdlock(l) __empty 301 #define rwlock_trywrlock(l) __empty 302 #define rwlock_unlock(l) __empty 303 #define rwlock_destroy(l) __empty 304 305 #define thr_keycreate(k, d) /*LINTED*/0 306 #define thr_setspecific(k, p) __empty 307 #define thr_getspecific(k) /*LINTED*/0 308 #define thr_keydelete(k) __empty 309 310 #define mutexattr_init(ma) __empty 311 #define mutexattr_settype(ma, t) __empty 312 #define mutexattr_destroy(ma) __empty 313 314 #if !defined(__minix) 315 static inline int 316 thr_once(once_t *once_control, void (*routine)(void)) 317 { 318 if (__predict_false(once_control->pto_done == 0)) { 319 (*routine)(); 320 once_control->pto_done = 1; 321 } 322 return 0; 323 } 324 #endif /* defined(__minix) */ 325 #define thr_sigsetmask(f, n, o) __empty 326 #define thr_self() __empty 327 #define thr_errno() __empty 328 #define thr_curcpu() ((unsigned int)0) 329 330 #define FLOCKFILE(fp) __empty 331 #define FUNLOCKFILE(fp) __empty 332 333 #endif /* _REENTRANT */ 334