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/* |
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* Copyright (C) 2010 David Xu <davidxu@freebsd.org>. |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* 1. Redistributions of source code must retain the above copyright |
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* notice(s), this list of conditions and the following disclaimer as |
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* the first lines of this file unmodified other than the possible |
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* addition of one or more copyright notices. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice(s), this list of conditions and the following disclaimer in |
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* the documentation and/or other materials provided with the |
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* distribution. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY |
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE |
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR |
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* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE |
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* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, |
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* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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* |
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* $FreeBSD$ |
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*/ |
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|
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#include "namespace.h" |
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#include <sys/types.h> |
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#include <sys/queue.h> |
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#include <sys/mman.h> |
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#include <sys/stat.h> |
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#include <errno.h> |
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#include <machine/atomic.h> |
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#include <sys/umtx.h> |
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#include <limits.h> |
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#include <fcntl.h> |
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#include <pthread.h> |
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#include <stdarg.h> |
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#include <stdlib.h> |
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#include <string.h> |
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#include <time.h> |
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#include <semaphore.h> |
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#include <unistd.h> |
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#include "un-namespace.h" |
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#include "libc_private.h" |
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|
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__weak_reference(_sem_close, sem_close); |
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__weak_reference(_sem_destroy, sem_destroy); |
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__weak_reference(_sem_getvalue, sem_getvalue); |
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__weak_reference(_sem_init, sem_init); |
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__weak_reference(_sem_open, sem_open); |
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__weak_reference(_sem_post, sem_post); |
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__weak_reference(_sem_timedwait, sem_timedwait); |
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__weak_reference(_sem_trywait, sem_trywait); |
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__weak_reference(_sem_unlink, sem_unlink); |
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__weak_reference(_sem_wait, sem_wait); |
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|
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#define SEM_PREFIX "/tmp/SEMD" |
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#define SEM_MAGIC ((u_int32_t)0x73656d31) |
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|
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struct sem_nameinfo { |
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int open_count; |
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char *name; |
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sem_t *sem; |
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LIST_ENTRY(sem_nameinfo) next; |
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}; |
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|
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static pthread_once_t once = PTHREAD_ONCE_INIT; |
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static pthread_mutex_t sem_llock; |
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static LIST_HEAD(,sem_nameinfo) sem_list = LIST_HEAD_INITIALIZER(sem_list); |
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|
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static void |
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sem_prefork() |
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{ |
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|
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_pthread_mutex_lock(&sem_llock); |
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} |
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|
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static void |
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sem_postfork() |
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{ |
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_pthread_mutex_unlock(&sem_llock); |
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} |
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|
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static void |
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sem_child_postfork() |
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{ |
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_pthread_mutex_unlock(&sem_llock); |
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} |
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|
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static void |
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sem_module_init(void) |
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{ |
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pthread_mutexattr_t ma; |
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|
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_pthread_mutexattr_init(&ma); |
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_pthread_mutexattr_settype(&ma, PTHREAD_MUTEX_RECURSIVE); |
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_pthread_mutex_init(&sem_llock, &ma); |
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_pthread_mutexattr_destroy(&ma); |
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_pthread_atfork(sem_prefork, sem_postfork, sem_child_postfork); |
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} |
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|
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static inline int |
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sem_check_validity(sem_t *sem) |
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{ |
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|
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if (sem->_magic == SEM_MAGIC) |
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return (0); |
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else { |
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errno = EINVAL; |
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return (-1); |
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} |
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} |
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|
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int |
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_sem_init(sem_t *sem, int pshared, unsigned int value) |
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{ |
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|
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if (value > SEM_VALUE_MAX) { |
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errno = EINVAL; |
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return (-1); |
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} |
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|
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bzero(sem, sizeof(sem_t)); |
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sem->_magic = SEM_MAGIC; |
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sem->_kern._count = (u_int32_t)value; |
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sem->_kern._has_waiters = 0; |
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sem->_kern._flags = pshared ? USYNC_PROCESS_SHARED : 0; |
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return (0); |
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} |
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|
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sem_t * |
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_sem_open(const char *name, int flags, ...) |
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{ |
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char path[PATH_MAX]; |
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|
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struct stat sb; |
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va_list ap; |
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struct sem_nameinfo *ni = NULL; |
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sem_t *sem = NULL; |
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int fd = -1, mode, len, errsave; |
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int value = 0; |
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|
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if (name[0] != '/') { |
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errno = EINVAL; |
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return (SEM_FAILED); |
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} |
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name++; |
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|
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if (flags & ~(O_CREAT|O_EXCL)) { |
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errno = EINVAL; |
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return (SEM_FAILED); |
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} |
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|
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_pthread_once(&once, sem_module_init); |
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|
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_pthread_mutex_lock(&sem_llock); |
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LIST_FOREACH(ni, &sem_list, next) { |
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if (strcmp(name, ni->name) == 0) { |
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if ((flags & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL)) { |
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_pthread_mutex_unlock(&sem_llock); |
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errno = EEXIST; |
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return (SEM_FAILED); |
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} else { |
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ni->open_count++; |
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sem = ni->sem; |
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_pthread_mutex_unlock(&sem_llock); |
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return (sem); |
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} |
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} |
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} |
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|
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if (flags & O_CREAT) { |
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va_start(ap, flags); |
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mode = va_arg(ap, int); |
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value = va_arg(ap, int); |
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va_end(ap); |
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} |
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|
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len = sizeof(*ni) + strlen(name) + 1; |
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ni = (struct sem_nameinfo *)malloc(len); |
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if (ni == NULL) { |
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errno = ENOSPC; |
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goto error; |
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} |
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|
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ni->name = (char *)(ni+1); |
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strcpy(ni->name, name); |
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|
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strcpy(path, SEM_PREFIX); |
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if (strlcat(path, name, sizeof(path)) >= sizeof(path)) { |
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errno = ENAMETOOLONG; |
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goto error; |
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} |
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|
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fd = _open(path, flags|O_RDWR, mode); |
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if (fd == -1) |
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goto error; |
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if (flock(fd, LOCK_EX) == -1) |
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goto error; |
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if (_fstat(fd, &sb)) { |
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flock(fd, LOCK_UN); |
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goto error; |
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} |
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if (sb.st_size < sizeof(sem_t)) { |
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sem_t tmp; |
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|
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tmp._magic = SEM_MAGIC; |
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tmp._kern._has_waiters = 0; |
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tmp._kern._count = value; |
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tmp._kern._flags = USYNC_PROCESS_SHARED | SEM_NAMED; |
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if (_write(fd, &tmp, sizeof(tmp)) != sizeof(tmp)) { |
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flock(fd, LOCK_UN); |
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goto error; |
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} |
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} |
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flock(fd, LOCK_UN); |
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sem = (sem_t *)mmap(NULL, sizeof(sem_t), PROT_READ|PROT_WRITE, |
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MAP_SHARED|MAP_NOSYNC, fd, 0); |
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if (sem == MAP_FAILED) { |
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sem = NULL; |
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if (errno == ENOMEM) |
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errno = ENOSPC; |
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goto error; |
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} |
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if (sem->_magic != SEM_MAGIC) { |
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errno = EINVAL; |
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goto error; |
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} |
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ni->open_count = 1; |
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ni->sem = sem; |
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LIST_INSERT_HEAD(&sem_list, ni, next); |
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_pthread_mutex_unlock(&sem_llock); |
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_close(fd); |
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return (sem); |
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|
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error: |
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errsave = errno; |
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_pthread_mutex_unlock(&sem_llock); |
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if (fd != -1) |
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_close(fd); |
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if (sem != NULL) |
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munmap(sem, sizeof(sem_t)); |
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free(ni); |
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errno = errsave; |
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return (SEM_FAILED); |
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} |
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|
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int |
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_sem_close(sem_t *sem) |
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{ |
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struct sem_nameinfo *ni; |
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|
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if (sem_check_validity(sem) != 0) |
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return (-1); |
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|
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if (!(sem->_kern._flags & SEM_NAMED)) { |
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errno = EINVAL; |
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return (-1); |
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} |
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|
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_pthread_once(&once, sem_module_init); |
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|
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_pthread_mutex_lock(&sem_llock); |
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LIST_FOREACH(ni, &sem_list, next) { |
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if (sem == ni->sem) { |
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if (--ni->open_count > 0) { |
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_pthread_mutex_unlock(&sem_llock); |
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return (0); |
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} |
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else |
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break; |
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} |
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} |
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|
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if (ni) { |
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LIST_REMOVE(ni, next); |
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_pthread_mutex_unlock(&sem_llock); |
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munmap(sem, sizeof(*sem)); |
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free(ni); |
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return (0); |
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} |
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_pthread_mutex_unlock(&sem_llock); |
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errno = EINVAL; |
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return (-1); |
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} |
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|
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int |
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_sem_unlink(const char *name) |
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{ |
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char path[PATH_MAX]; |
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|
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if (name[0] != '/') { |
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errno = ENOENT; |
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return -1; |
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} |
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name++; |
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|
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strcpy(path, SEM_PREFIX); |
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if (strlcat(path, name, sizeof(path)) >= sizeof(path)) { |
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errno = ENAMETOOLONG; |
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return (-1); |
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} |
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return unlink(path); |
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} |
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|
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int |
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_sem_destroy(sem_t *sem) |
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{ |
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|
| 316 |
if (sem_check_validity(sem) != 0) |
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return (-1); |
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|
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if (sem->_kern._flags & SEM_NAMED) { |
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errno = EINVAL; |
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return (-1); |
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} |
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sem->_magic = 0; |
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return (0); |
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} |
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|
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int |
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_sem_getvalue(sem_t * __restrict sem, int * __restrict sval) |
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{ |
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|
| 331 |
if (sem_check_validity(sem) != 0) |
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return (-1); |
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|
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*sval = (int)sem->_kern._count; |
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return (0); |
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} |
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|
| 338 |
static __inline int |
| 339 |
usem_wake(struct _usem *sem) |
| 340 |
{ |
| 341 |
if (!sem->_has_waiters) |
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return (0); |
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return _umtx_op(sem, UMTX_OP_SEM_WAKE, 0, NULL, NULL); |
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} |
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|
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static __inline int |
| 347 |
usem_wait(struct _usem *sem, const struct timespec *timeout) |
| 348 |
{ |
| 349 |
if (timeout && (timeout->tv_sec < 0 || (timeout->tv_sec == 0 && |
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timeout->tv_nsec <= 0))) { |
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errno = ETIMEDOUT; |
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return (-1); |
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} |
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return _umtx_op(sem, UMTX_OP_SEM_WAIT, 0, NULL, |
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__DECONST(void*, timeout)); |
| 356 |
} |
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|
| 358 |
int |
| 359 |
_sem_trywait(sem_t *sem) |
| 360 |
{ |
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int val; |
| 362 |
|
| 363 |
if (sem_check_validity(sem) != 0) |
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return (-1); |
| 365 |
|
| 366 |
while ((val = sem->_kern._count) > 0) { |
| 367 |
if (atomic_cmpset_acq_int(&sem->_kern._count, val, val - 1)) |
| 368 |
return (0); |
| 369 |
} |
| 370 |
errno = EAGAIN; |
| 371 |
return (-1); |
| 372 |
} |
| 373 |
|
| 374 |
#define TIMESPEC_SUB(dst, src, val) \ |
| 375 |
do { \ |
| 376 |
(dst)->tv_sec = (src)->tv_sec - (val)->tv_sec; \ |
| 377 |
(dst)->tv_nsec = (src)->tv_nsec - (val)->tv_nsec; \ |
| 378 |
if ((dst)->tv_nsec < 0) { \ |
| 379 |
(dst)->tv_sec--; \ |
| 380 |
(dst)->tv_nsec += 1000000000; \ |
| 381 |
} \ |
| 382 |
} while (0) |
| 383 |
|
| 384 |
|
| 385 |
int |
| 386 |
_sem_timedwait(sem_t * __restrict sem, |
| 387 |
const struct timespec * __restrict abstime) |
| 388 |
{ |
| 389 |
struct timespec ts, ts2; |
| 390 |
int val, retval; |
| 391 |
|
| 392 |
if (sem_check_validity(sem) != 0) |
| 393 |
return (-1); |
| 394 |
|
| 395 |
retval = 0; |
| 396 |
for (;;) { |
| 397 |
while ((val = sem->_kern._count) > 0) { |
| 398 |
if (atomic_cmpset_acq_int(&sem->_kern._count, val, val - 1)) |
| 399 |
return (0); |
| 400 |
} |
| 401 |
|
| 402 |
if (retval) { |
| 403 |
_pthread_testcancel(); |
| 404 |
break; |
| 405 |
} |
| 406 |
|
| 407 |
/* |
| 408 |
* The timeout argument is only supposed to |
| 409 |
* be checked if the thread would have blocked. |
| 410 |
*/ |
| 411 |
if (abstime != NULL) { |
| 412 |
if (abstime->tv_nsec >= 1000000000 || abstime->tv_nsec < 0) { |
| 413 |
errno = EINVAL; |
| 414 |
return (-1); |
| 415 |
} |
| 416 |
clock_gettime(CLOCK_REALTIME, &ts); |
| 417 |
TIMESPEC_SUB(&ts2, abstime, &ts); |
| 418 |
} |
| 419 |
_pthread_cancel_enter(1); |
| 420 |
retval = usem_wait(&sem->_kern, abstime ? &ts2 : NULL); |
| 421 |
_pthread_cancel_leave(0); |
| 422 |
} |
| 423 |
return (retval); |
| 424 |
} |
| 425 |
|
| 426 |
int |
| 427 |
_sem_wait(sem_t *sem) |
| 428 |
{ |
| 429 |
return _sem_timedwait(sem, NULL); |
| 430 |
} |
| 431 |
|
| 432 |
/* |
| 433 |
* POSIX: |
| 434 |
* The sem_post() interface is reentrant with respect to signals and may be |
| 435 |
* invoked from a signal-catching function. |
| 436 |
* The implementation does not use lock, so it should be safe. |
| 437 |
*/ |
| 438 |
int |
| 439 |
_sem_post(sem_t *sem) |
| 440 |
{ |
| 441 |
|
| 442 |
if (sem_check_validity(sem) != 0) |
| 443 |
return (-1); |
| 444 |
|
| 445 |
atomic_add_rel_int(&sem->_kern._count, 1); |
| 446 |
return usem_wake(&sem->_kern); |
| 447 |
} |
