diff options
author | rpj <rpj> | 2005-04-25 14:42:37 +0000 |
---|---|---|
committer | rpj <rpj> | 2005-04-25 14:42:37 +0000 |
commit | 3ef98898333255b8000e9ab4801652c42fd5aacc (patch) | |
tree | 58fbe722c2011a392ffb47ad56b97fe44e2fe59c /sem_trywait.c | |
parent | 75a3015fd7412637a02b1b016b367f5deadfde94 (diff) |
''
Diffstat (limited to 'sem_trywait.c')
-rw-r--r-- | sem_trywait.c | 216 |
1 files changed, 108 insertions, 108 deletions
diff --git a/sem_trywait.c b/sem_trywait.c index 2116222..4d1451d 100644 --- a/sem_trywait.c +++ b/sem_trywait.c @@ -1,108 +1,108 @@ -/*
- * -------------------------------------------------------------
- *
- * Module: sem_trywait.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_trywait (sem_t * sem)
- /*
- * ------------------------------------------------------
- * DOCPUBLIC
- * This function tries to wait on a semaphore.
- *
- * PARAMETERS
- * sem
- * pointer to an instance of sem_t
- *
- * DESCRIPTION
- * This function tries to wait on a semaphore. If the
- * semaphore value is greater than zero, it decreases
- * its value by one. If the semaphore value is zero, then
- * this function returns immediately with the error EAGAIN
- *
- * RESULTS
- * 0 successfully decreased semaphore,
- * -1 failed, error in errno
- * ERRNO
- * EAGAIN the semaphore was already locked,
- * EINVAL 'sem' is not a valid semaphore,
- * ENOTSUP sem_trywait is not supported,
- * EINTR the function was interrupted by a signal,
- * EDEADLK a deadlock condition was detected.
- *
- * ------------------------------------------------------
- */
-{
- int result = 0;
- sem_t s = *sem;
-
- if (s == NULL)
- {
- result = EINVAL;
- }
- else if ((result = pthread_mutex_lock (&s->lock)) == 0)
- {
- if (s->value > 0)
- {
- s->value--;
- }
- else
- {
- result = EAGAIN;
- }
-
- (void) pthread_mutex_unlock (&s->lock);
- }
-
- if (result != 0)
- {
- errno = result;
- return -1;
- }
-
- return 0;
-
-} /* sem_trywait */
+/* + * ------------------------------------------------------------- + * + * Module: sem_trywait.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_trywait (sem_t * sem) + /* + * ------------------------------------------------------ + * DOCPUBLIC + * This function tries to wait on a semaphore. + * + * PARAMETERS + * sem + * pointer to an instance of sem_t + * + * DESCRIPTION + * This function tries to wait on a semaphore. If the + * semaphore value is greater than zero, it decreases + * its value by one. If the semaphore value is zero, then + * this function returns immediately with the error EAGAIN + * + * RESULTS + * 0 successfully decreased semaphore, + * -1 failed, error in errno + * ERRNO + * EAGAIN the semaphore was already locked, + * EINVAL 'sem' is not a valid semaphore, + * ENOTSUP sem_trywait is not supported, + * EINTR the function was interrupted by a signal, + * EDEADLK a deadlock condition was detected. + * + * ------------------------------------------------------ + */ +{ + int result = 0; + sem_t s = *sem; + + if (s == NULL) + { + result = EINVAL; + } + else if ((result = pthread_mutex_lock (&s->lock)) == 0) + { + if (s->value > 0) + { + s->value--; + } + else + { + result = EAGAIN; + } + + (void) pthread_mutex_unlock (&s->lock); + } + + if (result != 0) + { + errno = result; + return -1; + } + + return 0; + +} /* sem_trywait */ |