lib/libc/include/reentrant.h

   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(__minix) || !defined(_LIBC_REENTRANT_H)
  88 #ifdef __minix
  89 /*
  90  * If _REENTRANT is not defined, the header may not be included more than once.
  91  * This is probably a NetBSD libc bug, but for now we solve it for MINIX3 only.
  92  */
  93 #define _LIBC_REENTRANT_H
  94 #endif /* __minix */
  95
  96 /*
  97  * Abstract thread interface for thread-safe libraries.  These routines
  98  * will use stubs in libc if the application is not linked against the
  99  * pthread library, and the real function in the pthread library if it
 100  * is.
 101  */
 102
 103 #ifndef __minix
 104
 105 #include <pthread.h>
 106 #include <signal.h>
 107
 108 #define mutex_t                 pthread_mutex_t
 109 #define MUTEX_INITIALIZER       PTHREAD_MUTEX_INITIALIZER
 110
 111 #define mutexattr_t             pthread_mutexattr_t
 112
 113 #define MUTEX_TYPE_NORMAL       PTHREAD_MUTEX_NORMAL
 114 #define MUTEX_TYPE_ERRORCHECK   PTHREAD_MUTEX_ERRORCHECK
 115 #define MUTEX_TYPE_RECURSIVE    PTHREAD_MUTEX_RECURSIVE
 116
 117 #define cond_t                  pthread_cond_t
 118 #define COND_INITIALIZER        PTHREAD_COND_INITIALIZER
 119
 120 #define condattr_t              pthread_condattr_t
 121
 122 #define rwlock_t                pthread_rwlock_t
 123 #define RWLOCK_INITIALIZER      PTHREAD_RWLOCK_INITIALIZER
 124
 125 #define rwlockattr_t            pthread_rwlockattr_t
 126
 127 #define thread_key_t            pthread_key_t
 128
 129 #define thr_t                   pthread_t
 130
 131 #define thrattr_t               pthread_attr_t
 132
 133 #define once_t                  pthread_once_t
 134 #define ONCE_INITIALIZER        PTHREAD_ONCE_INIT
 135
 136 #else /* __minix */
 137
 138 typedef struct {
 139         int pto_done;
 140 } once_t;
 141 #define ONCE_INITIALIZER        { .pto_done = 0 }
 142
 143 #endif /* __minix */
 144
 145 #ifdef _REENTRANT
 146
 147 #ifndef __LIBC_THREAD_STUBS
 148
 149 __BEGIN_DECLS
 150 int     __libc_mutex_init(mutex_t *, const mutexattr_t *);
 151 int     __libc_mutex_lock(mutex_t *);
 152 int     __libc_mutex_trylock(mutex_t *);
 153 int     __libc_mutex_unlock(mutex_t *);
 154 int     __libc_mutex_destroy(mutex_t *);
 155
 156 int     __libc_mutexattr_init(mutexattr_t *);
 157 int     __libc_mutexattr_settype(mutexattr_t *, int);
 158 int     __libc_mutexattr_destroy(mutexattr_t *);
 159 __END_DECLS
 160
 161 #define mutex_init(m, a)        __libc_mutex_init((m), (a))
 162 #define mutex_lock(m)           __libc_mutex_lock((m))
 163 #define mutex_trylock(m)        __libc_mutex_trylock((m))
 164 #define mutex_unlock(m)         __libc_mutex_unlock((m))
 165 #define mutex_destroy(m)        __libc_mutex_destroy((m))
 166
 167 #define mutexattr_init(ma)      __libc_mutexattr_init((ma))
 168 #define mutexattr_settype(ma, t) __libc_mutexattr_settype((ma), (t))
 169 #define mutexattr_destroy(ma)   __libc_mutexattr_destroy((ma))
 170
 171 __BEGIN_DECLS
 172 int     __libc_cond_init(cond_t *, const condattr_t *);
 173 int     __libc_cond_signal(cond_t *);
 174 int     __libc_cond_broadcast(cond_t *);
 175 int     __libc_cond_wait(cond_t *, mutex_t *);
 176 #ifndef __LIBC12_SOURCE__
 177 int     __libc_cond_timedwait(cond_t *, mutex_t *, const struct timespec *);
 178 #endif
 179 int     __libc_cond_destroy(cond_t *);
 180 __END_DECLS
 181
 182 #define cond_init(c, t, a)      __libc_cond_init((c), (a))
 183 #define cond_signal(c)          __libc_cond_signal((c))
 184 #define cond_broadcast(c)       __libc_cond_broadcast((c))
 185 #define cond_wait(c, m)         __libc_cond_wait((c), (m))
 186 #define cond_timedwait(c, m, t) __libc_cond_timedwait((c), (m), (t))
 187 #define cond_destroy(c)         __libc_cond_destroy((c))
 188
 189 __BEGIN_DECLS
 190 int     __libc_rwlock_init(rwlock_t *, const rwlockattr_t *);
 191 int     __libc_rwlock_rdlock(rwlock_t *);
 192 int     __libc_rwlock_wrlock(rwlock_t *);
 193 int     __libc_rwlock_tryrdlock(rwlock_t *);
 194 int     __libc_rwlock_trywrlock(rwlock_t *);
 195 int     __libc_rwlock_unlock(rwlock_t *);
 196 int     __libc_rwlock_destroy(rwlock_t *);
 197 __END_DECLS
 198
 199 #define rwlock_init(l, a)       __libc_rwlock_init((l), (a))
 200 #define rwlock_rdlock(l)        __libc_rwlock_rdlock((l))
 201 #define rwlock_wrlock(l)        __libc_rwlock_wrlock((l))
 202 #define rwlock_tryrdlock(l)     __libc_rwlock_tryrdlock((l))
 203 #define rwlock_trywrlock(l)     __libc_rwlock_trywrlock((l))
 204 #define rwlock_unlock(l)        __libc_rwlock_unlock((l))
 205 #define rwlock_destroy(l)       __libc_rwlock_destroy((l))
 206
 207 __BEGIN_DECLS
 208 int     __libc_thr_keycreate(thread_key_t *, void (*)(void *));
 209 int     __libc_thr_setspecific(thread_key_t, const void *);
 210 void    *__libc_thr_getspecific(thread_key_t);
 211 int     __libc_thr_keydelete(thread_key_t);
 212 __END_DECLS
 213
 214 #define thr_keycreate(k, d)     __libc_thr_keycreate((k), (d))
 215 #define thr_setspecific(k, p)   __libc_thr_setspecific((k), (p))
 216 #define thr_getspecific(k)      __libc_thr_getspecific((k))
 217 #define thr_keydelete(k)        __libc_thr_keydelete((k))
 218
 219 __BEGIN_DECLS
 220 int     __libc_thr_once(once_t *, void (*)(void));
 221 int     __libc_thr_sigsetmask(int, const sigset_t *, sigset_t *);
 222 thr_t   __libc_thr_self(void);
 223 int     __libc_thr_yield(void);
 224 void    __libc_thr_create(thr_t *, const thrattr_t *,
 225             void *(*)(void *), void *);
 226 void    __libc_thr_exit(void *) __attribute__((__noreturn__));
 227 int     *__libc_thr_errno(void);
 228 int     __libc_thr_setcancelstate(int, int *);
 229 unsigned int    __libc_thr_curcpu(void);
 230
 231 extern int __isthreaded;
 232 __END_DECLS
 233
 234 #define thr_once(o, f)          __libc_thr_once((o), (f))
 235 #define thr_sigsetmask(f, n, o) __libc_thr_sigsetmask((f), (n), (o))
 236 #define thr_self()              __libc_thr_self()
 237 #define thr_yield()             __libc_thr_yield()
 238 #define thr_create(tp, ta, f, a) __libc_thr_create((tp), (ta), (f), (a))
 239 #define thr_exit(v)             __libc_thr_exit((v))
 240 #define thr_errno()             __libc_thr_errno()
 241 #define thr_enabled()           (__isthreaded)
 242 #define thr_setcancelstate(n, o) __libc_thr_setcancelstate((n),(o))
 243 #define thr_curcpu()            __libc_thr_curcpu()
 244
 245 #else /* __LIBC_THREAD_STUBS */
 246
 247 __BEGIN_DECLS
 248 void    __libc_thr_init_stub(void);
 249
 250 int     __libc_mutex_init_stub(mutex_t *, const mutexattr_t *);
 251 int     __libc_mutex_lock_stub(mutex_t *);
 252 int     __libc_mutex_trylock_stub(mutex_t *);
 253 int     __libc_mutex_unlock_stub(mutex_t *);
 254 int     __libc_mutex_destroy_stub(mutex_t *);
 255
 256 int     __libc_mutexattr_init_stub(mutexattr_t *);
 257 int     __libc_mutexattr_destroy_stub(mutexattr_t *);
 258 int     __libc_mutexattr_settype_stub(mutexattr_t *, int);
 259
 260 int     __libc_cond_init_stub(cond_t *, const condattr_t *);
 261 int     __libc_cond_signal_stub(cond_t *);
 262 int     __libc_cond_broadcast_stub(cond_t *);
 263 int     __libc_cond_wait_stub(cond_t *, mutex_t *);
 264 int     __libc_cond_timedwait_stub(cond_t *, mutex_t *,
 265                                    const struct timespec *);
 266 int     __libc_cond_destroy_stub(cond_t *);
 267
 268 int     __libc_rwlock_init_stub(rwlock_t *, const rwlockattr_t *);
 269 int     __libc_rwlock_rdlock_stub(rwlock_t *);
 270 int     __libc_rwlock_wrlock_stub(rwlock_t *);
 271 int     __libc_rwlock_tryrdlock_stub(rwlock_t *);
 272 int     __libc_rwlock_trywrlock_stub(rwlock_t *);
 273 int     __libc_rwlock_unlock_stub(rwlock_t *);
 274 int     __libc_rwlock_destroy_stub(rwlock_t *);
 275
 276 int     __libc_thr_keycreate_stub(thread_key_t *, void (*)(void *));
 277 int     __libc_thr_setspecific_stub(thread_key_t, const void *);
 278 void    *__libc_thr_getspecific_stub(thread_key_t);
 279 int     __libc_thr_keydelete_stub(thread_key_t);
 280
 281 int     __libc_thr_once_stub(once_t *, void (*)(void));
 282 int     __libc_thr_sigsetmask_stub(int, const sigset_t *, sigset_t *);
 283 thr_t   __libc_thr_self_stub(void);
 284 int     __libc_thr_yield_stub(void);
 285 int     __libc_thr_create_stub(thr_t *, const thrattr_t *,
 286             void *(*)(void *), void *);
 287 void    __libc_thr_exit_stub(void *) __dead;
 288 int     *__libc_thr_errno_stub(void);
 289 int     __libc_thr_setcancelstate_stub(int, int *);
 290 int     __libc_thr_equal_stub(pthread_t, pthread_t);
 291 unsigned int    __libc_thr_curcpu_stub(void);
 292 __END_DECLS
 293
 294 #endif /* __LIBC_THREAD_STUBS */
 295
 296 #define FLOCKFILE(fp)           __flockfile_internal(fp, 1)
 297 #define FUNLOCKFILE(fp)         __funlockfile_internal(fp, 1)
 298
 299 #else /* _REENTRANT */
 300
 301 #ifndef __empty
 302 #define __empty do {} while (/*CONSTCOND*/0)
 303 #endif
 304 #define mutex_init(m, a) __empty
 305 #define mutex_lock(m) __empty
 306 #define mutex_trylock(m) __empty
 307 #define mutex_unlock(m) __empty
 308 #define mutex_destroy(m) __empty
 309
 310 #define cond_init(c, t, a) __empty
 311 #define cond_signal(c) __empty
 312 #define cond_broadcast(c) __empty
 313 #define cond_wait(c, m) __empty
 314 #define cond_timedwait(c, m, t) __empty
 315 #define cond_destroy(c) __empty
 316
 317 #define rwlock_init(l, a) __empty
 318 #define rwlock_rdlock(l) __empty
 319 #define rwlock_wrlock(l) __empty
 320 #define rwlock_tryrdlock(l) __empty
 321 #define rwlock_trywrlock(l) __empty
 322 #define rwlock_unlock(l) __empty
 323 #define rwlock_destroy(l) __empty
 324
 325 #define thr_keycreate(k, d) /*LINTED*/0
 326 #define thr_setspecific(k, p) __empty
 327 #define thr_getspecific(k) /*LINTED*/0
 328 #define thr_keydelete(k) __empty
 329
 330 #define mutexattr_init(ma) __empty
 331 #define mutexattr_settype(ma, t) __empty
 332 #define mutexattr_destroy(ma) __empty
 333
 334 static inline int
 335 thr_once(once_t *once_control, void (*routine)(void))
 336 {
 337         if (__predict_false(once_control->pto_done == 0)) {
 338                 (*routine)();
 339                 once_control->pto_done = 1;
 340         }
 341         return 0;
 342 }
 343 #define thr_sigsetmask(f, n, o) __empty
 344 #define thr_self() __empty
 345 #define thr_errno() __empty
 346 #define thr_curcpu()            ((unsigned int)0)
 347
 348 #define FLOCKFILE(fp) __empty
 349 #define FUNLOCKFILE(fp) __empty
 350
 351 #endif /* _REENTRANT */
 352
 353 #endif /* !defined(__minix) || !defined(_LIBC_REENTRANT_H) */