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Diffstat (limited to 'pthreads/src/sem_post.c')
| -rw-r--r-- | pthreads/src/sem_post.c | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/pthreads/src/sem_post.c b/pthreads/src/sem_post.c new file mode 100644 index 0000000..3483252 --- /dev/null +++ b/pthreads/src/sem_post.c @@ -0,0 +1,128 @@ +/* + * ------------------------------------------------------------- + * + * Module: sem_post.c + * + * Purpose: + * Semaphores aren't actually part of the PThreads standard. + * They are defined by the POSIX Standard: + * + * POSIX 1003.1b-1993 (POSIX.1b) + * + * ------------------------------------------------------------- + * + * -------------------------------------------------------------------------- + * + * Pthreads-win32 - POSIX Threads Library for Win32 + * Copyright(C) 1998 John E. Bossom + * Copyright(C) 1999,2005 Pthreads-win32 contributors + * + * Contact Email: rpj@callisto.canberra.edu.au + * + * The current list of contributors is contained + * in the file CONTRIBUTORS included with the source + * code distribution. The list can also be seen at the + * following World Wide Web location: + * http://sources.redhat.com/pthreads-win32/contributors.html + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library in the file COPYING.LIB; + * if not, write to the Free Software Foundation, Inc., + * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA + */ + +#include "pthread.h" +#include "semaphore.h" +#include "implement.h" + + +int +sem_post (sem_t * sem) + /* + * ------------------------------------------------------ + * DOCPUBLIC + * This function posts a wakeup to a semaphore. + * + * PARAMETERS + * sem + * pointer to an instance of sem_t + * + * DESCRIPTION + * This function posts a wakeup to a semaphore. If there + * are waiting threads (or processes), one is awakened; + * otherwise, the semaphore value is incremented by one. + * + * RESULTS + * 0 successfully posted semaphore, + * -1 failed, error in errno + * ERRNO + * EINVAL 'sem' is not a valid semaphore, + * ENOSYS semaphores are not supported, + * ERANGE semaphore count is too big + * + * ------------------------------------------------------ + */ +{ + int result = 0; + sem_t s = *sem; + + if (s == NULL) + { + result = EINVAL; + } + else if ((result = pthread_mutex_lock (&s->lock)) == 0) + { + /* See sem_destroy.c + */ + if (*sem == NULL) + { + (void) pthread_mutex_unlock (&s->lock); + result = EINVAL; + return -1; + } + + if (s->value < SEM_VALUE_MAX) + { +#if defined(NEED_SEM) + if (++s->value <= 0 + && !SetEvent(s->sem)) + { + s->value--; + result = EINVAL; + } +#else + if (++s->value <= 0 + && !ReleaseSemaphore (s->sem, 1, NULL)) + { + s->value--; + result = EINVAL; + } +#endif /* NEED_SEM */ + } + else + { + result = ERANGE; + } + + (void) pthread_mutex_unlock (&s->lock); + } + + if (result != 0) + { + errno = result; + return -1; + } + + return 0; + +} /* sem_post */ |