diff options
Diffstat (limited to 'sem_trywait.c')
| -rw-r--r-- | sem_trywait.c | 226 |
1 files changed, 108 insertions, 118 deletions
diff --git a/sem_trywait.c b/sem_trywait.c index 640d190..2116222 100644 --- a/sem_trywait.c +++ b/sem_trywait.c @@ -1,118 +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" - -#include <stdio.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. - * - * ------------------------------------------------------ - */ -{ -#ifdef NEED_SEM - - /* - * not yet implemented! - */ - errno = ENOTSUP; - return -1; - -#else /* NEED_SEM */ - - 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++; - result = EAGAIN; - } - - (void) pthread_mutex_unlock (&s->lock); - } - - if (result != 0) - { - errno = result; - return -1; - } - - return 0; - -#endif /* NEED_SEM */ - -} /* 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 */
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