2 * Copyright (C) 2010 David Xu <davidxu@freebsd.org>.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice(s), this list of conditions and the following disclaimer as
10 * the first lines of this file unmodified other than the possible
11 * addition of one or more copyright notices.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice(s), this list of conditions and the following disclaimer in
14 * the documentation and/or other materials provided with the
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
20 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
21 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
22 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
23 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
24 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
25 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
26 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
27 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 #include "namespace.h"
33 #include <sys/types.h>
34 #include <sys/queue.h>
38 #include <machine/atomic.h>
47 #include <semaphore.h>
49 #include "un-namespace.h"
50 #include "libc_private.h"
52 __weak_reference(_sem_close, sem_close);
53 __weak_reference(_sem_destroy, sem_destroy);
54 __weak_reference(_sem_getvalue, sem_getvalue);
55 __weak_reference(_sem_init, sem_init);
56 __weak_reference(_sem_open, sem_open);
57 __weak_reference(_sem_post, sem_post);
58 __weak_reference(_sem_timedwait, sem_timedwait);
59 __weak_reference(_sem_clockwait_np, sem_clockwait_np);
60 __weak_reference(_sem_trywait, sem_trywait);
61 __weak_reference(_sem_unlink, sem_unlink);
62 __weak_reference(_sem_wait, sem_wait);
64 #define SEM_PREFIX "/tmp/SEMD"
65 #define SEM_MAGIC ((u_int32_t)0x73656d32)
67 _Static_assert(SEM_VALUE_MAX <= USEM_MAX_COUNT, "SEM_VALUE_MAX too large");
75 LIST_ENTRY(sem_nameinfo) next;
78 static pthread_once_t once = PTHREAD_ONCE_INIT;
79 static pthread_mutex_t sem_llock;
80 static LIST_HEAD(, sem_nameinfo) sem_list = LIST_HEAD_INITIALIZER(sem_list);
86 _pthread_mutex_lock(&sem_llock);
93 _pthread_mutex_unlock(&sem_llock);
97 sem_child_postfork(void)
100 _pthread_mutex_unlock(&sem_llock);
104 sem_module_init(void)
106 pthread_mutexattr_t ma;
108 _pthread_mutexattr_init(&ma);
109 _pthread_mutexattr_settype(&ma, PTHREAD_MUTEX_RECURSIVE);
110 _pthread_mutex_init(&sem_llock, &ma);
111 _pthread_mutexattr_destroy(&ma);
112 _pthread_atfork(sem_prefork, sem_postfork, sem_child_postfork);
116 sem_check_validity(sem_t *sem)
119 if (sem->_magic == SEM_MAGIC)
126 _sem_init(sem_t *sem, int pshared, unsigned int value)
129 if (value > SEM_VALUE_MAX) {
134 bzero(sem, sizeof(sem_t));
135 sem->_magic = SEM_MAGIC;
136 sem->_kern._count = (u_int32_t)value;
137 sem->_kern._flags = pshared ? USYNC_PROCESS_SHARED : 0;
142 _sem_open(const char *name, int flags, ...)
147 struct sem_nameinfo *ni;
149 int errsave, fd, len, mode, value;
156 if (name[0] != '/') {
161 strcpy(path, SEM_PREFIX);
162 if (strlcat(path, name, sizeof(path)) >= sizeof(path)) {
163 errno = ENAMETOOLONG;
166 if (flags & ~(O_CREAT|O_EXCL)) {
170 if ((flags & O_CREAT) != 0) {
172 mode = va_arg(ap, int);
173 value = va_arg(ap, int);
177 _pthread_once(&once, sem_module_init);
179 _pthread_mutex_lock(&sem_llock);
180 LIST_FOREACH(ni, &sem_list, next) {
181 if (ni->name != NULL && strcmp(name, ni->name) == 0) {
182 fd = _open(path, flags | O_RDWR | O_CLOEXEC |
184 if (fd == -1 || _fstat(fd, &sb) == -1) {
188 if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT |
189 O_EXCL) || ni->dev != sb.st_dev ||
190 ni->ino != sb.st_ino) {
197 _pthread_mutex_unlock(&sem_llock);
203 len = sizeof(*ni) + strlen(name) + 1;
204 ni = (struct sem_nameinfo *)malloc(len);
210 ni->name = (char *)(ni+1);
211 strcpy(ni->name, name);
214 fd = _open(path, flags | O_RDWR | O_CLOEXEC | O_EXLOCK, mode);
215 if (fd == -1 || _fstat(fd, &sb) == -1)
218 if (sb.st_size < sizeof(sem_t)) {
219 tmp._magic = SEM_MAGIC;
220 tmp._kern._count = value;
221 tmp._kern._flags = USYNC_PROCESS_SHARED | SEM_NAMED;
222 if (_write(fd, &tmp, sizeof(tmp)) != sizeof(tmp))
226 sem = mmap(NULL, sizeof(sem_t), PROT_READ | PROT_WRITE,
227 MAP_SHARED | MAP_NOSYNC, fd, 0);
228 if (sem == MAP_FAILED) {
234 if (sem->_magic != SEM_MAGIC) {
242 LIST_INSERT_HEAD(&sem_list, ni, next);
244 _pthread_mutex_unlock(&sem_llock);
252 munmap(sem, sizeof(sem_t));
254 _pthread_mutex_unlock(&sem_llock);
260 _sem_close(sem_t *sem)
262 struct sem_nameinfo *ni;
264 if (sem_check_validity(sem) != 0)
267 if (!(sem->_kern._flags & SEM_NAMED)) {
272 _pthread_once(&once, sem_module_init);
274 _pthread_mutex_lock(&sem_llock);
275 LIST_FOREACH(ni, &sem_list, next) {
276 if (sem == ni->sem) {
277 if (--ni->open_count > 0) {
278 _pthread_mutex_unlock(&sem_llock);
286 LIST_REMOVE(ni, next);
287 _pthread_mutex_unlock(&sem_llock);
288 munmap(sem, sizeof(*sem));
292 _pthread_mutex_unlock(&sem_llock);
298 _sem_unlink(const char *name)
302 if (name[0] != '/') {
307 strcpy(path, SEM_PREFIX);
308 if (strlcat(path, name, sizeof(path)) >= sizeof(path)) {
309 errno = ENAMETOOLONG;
313 return (unlink(path));
317 _sem_destroy(sem_t *sem)
320 if (sem_check_validity(sem) != 0)
323 if (sem->_kern._flags & SEM_NAMED) {
332 _sem_getvalue(sem_t * __restrict sem, int * __restrict sval)
335 if (sem_check_validity(sem) != 0)
338 *sval = (int)USEM_COUNT(sem->_kern._count);
343 usem_wake(struct _usem2 *sem)
346 return (_umtx_op(sem, UMTX_OP_SEM2_WAKE, 0, NULL, NULL));
350 usem_wait(struct _usem2 *sem, clockid_t clock_id, int flags,
351 const struct timespec *rqtp, struct timespec *rmtp)
354 struct _umtx_time timeout;
355 struct timespec remain;
365 tms.timeout._clockid = clock_id;
366 tms.timeout._flags = (flags & TIMER_ABSTIME) ? UMTX_ABSTIME : 0;
367 tms.timeout._timeout = *rqtp;
369 tm_size = sizeof(tms);
371 retval = _umtx_op(sem, UMTX_OP_SEM2_WAIT, 0, (void *)tm_size, tm_p);
372 if (retval == -1 && errno == EINTR && (flags & TIMER_ABSTIME) == 0 &&
373 rqtp != NULL && rmtp != NULL) {
381 _sem_trywait(sem_t *sem)
385 if (sem_check_validity(sem) != 0)
388 while (USEM_COUNT(val = sem->_kern._count) > 0) {
389 if (atomic_cmpset_acq_int(&sem->_kern._count, val, val - 1))
397 _sem_clockwait_np(sem_t * __restrict sem, clockid_t clock_id, int flags,
398 const struct timespec *rqtp, struct timespec *rmtp)
402 if (sem_check_validity(sem) != 0)
406 _pthread_testcancel();
408 while (USEM_COUNT(val = sem->_kern._count) > 0) {
409 if (atomic_cmpset_acq_int(&sem->_kern._count, val,
415 _pthread_testcancel();
420 * The timeout argument is only supposed to
421 * be checked if the thread would have blocked.
424 if (rqtp->tv_nsec >= 1000000000 || rqtp->tv_nsec < 0) {
429 _pthread_cancel_enter(1);
430 retval = usem_wait(&sem->_kern, clock_id, flags, rqtp, rmtp);
431 _pthread_cancel_leave(0);
437 _sem_timedwait(sem_t * __restrict sem,
438 const struct timespec * __restrict abstime)
441 return (_sem_clockwait_np(sem, CLOCK_REALTIME, TIMER_ABSTIME, abstime,
446 _sem_wait(sem_t *sem)
449 return (_sem_timedwait(sem, NULL));
454 * The sem_post() interface is reentrant with respect to signals and may be
455 * invoked from a signal-catching function.
456 * The implementation does not use lock, so it should be safe.
459 _sem_post(sem_t *sem)
463 if (sem_check_validity(sem) != 0)
467 count = sem->_kern._count;
468 if (USEM_COUNT(count) + 1 > SEM_VALUE_MAX) {
472 } while (!atomic_cmpset_rel_int(&sem->_kern._count, count, count + 1));
473 if (count & USEM_HAS_WAITERS)
474 usem_wake(&sem->_kern);