lib/libc/include/reentrant.h

   1 /*      $NetBSD: reentrant.h,v 1.15 2012/06/03 21:27:30 joerg 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 #ifdef _REENTRANT
  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 #endif /* __LIBC_THREAD_STUBS */
 225
 226 #define FLOCKFILE(fp)           __flockfile_internal(fp, 1)
 227 #define FUNLOCKFILE(fp)         __funlockfile_internal(fp, 1)
 228
 229 #else /* _REENTRANT */
 230
 231 #define mutex_init(m, a)
 232 #define mutex_lock(m)
 233 #define mutex_trylock(m)
 234 #define mutex_unlock(m)
 235 #define mutex_destroy(m)
 236
 237 #define cond_init(c, t, a)
 238 #define cond_signal(c)
 239 #define cond_broadcast(c)
 240 #define cond_wait(c, m)
 241 #define cond_timedwait(c, m, t)
 242 #define cond_destroy(c)
 243
 244 #define rwlock_init(l, a)
 245 #define rwlock_rdlock(l)
 246 #define rwlock_wrlock(l)
 247 #define rwlock_tryrdlock(l)
 248 #define rwlock_trywrlock(l)
 249 #define rwlock_unlock(l)
 250 #define rwlock_destroy(l)
 251
 252 #define thr_keycreate(k, d)
 253 #define thr_setspecific(k, p)
 254 #define thr_getspecific(k)
 255 #define thr_keydelete(k)
 256
 257 #if !defined(__minix)
 258 static inline int
 259 thr_once(once_t *once_control, void (*routine)(void))
 260 {
 261         if (__predict_false(once_control->pto_done == 0)) {
 262                 (*routine)();
 263                 once_control->pto_done = 1;
 264         }
 265         return 0;
 266 }
 267 #endif /* defined(__minix) */
 268 #define thr_sigsetmask(f, n, o)
 269 #define thr_self()
 270 #define thr_errno()
 271 #define thr_curcpu()            ((unsigned int)0)
 272
 273 #define FLOCKFILE(fp)
 274 #define FUNLOCKFILE(fp)
 275
 276 #endif /* _REENTRANT */