169 lines
4.4 KiB
C
169 lines
4.4 KiB
C
/*
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* -------------------------------------------------------------
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*
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* Module: sem_init.c
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*
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* Purpose:
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* Semaphores aren't actually part of PThreads.
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* They are defined by the POSIX Standard:
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*
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* POSIX 1003.1-2001
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*
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* -------------------------------------------------------------
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*
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* Pthreads-win32 - POSIX Threads Library for Win32
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* Copyright(C) 1998 John E. Bossom
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* Copyright(C) 1999,2005 Pthreads-win32 contributors
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*
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* Contact Email: rpj@callisto.canberra.edu.au
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*
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* The current list of contributors is contained
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* in the file CONTRIBUTORS included with the source
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* code distribution. The list can also be seen at the
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* following World Wide Web location:
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* http://sources.redhat.com/pthreads-win32/contributors.html
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library in the file COPYING.LIB;
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* if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
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*/
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#include "pthread.h"
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#include "semaphore.h"
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#include "implement.h"
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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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* DOCPUBLIC
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* This function initializes a semaphore. The
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* initial value of the semaphore is 'value'
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*
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* PARAMETERS
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* sem
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* pointer to an instance of sem_t
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*
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* pshared
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* if zero, this semaphore may only be shared between
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* threads in the same process.
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* if nonzero, the semaphore can be shared between
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* processes
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*
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* value
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* initial value of the semaphore counter
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*
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* DESCRIPTION
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* This function initializes a semaphore. The
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* initial value of the semaphore is set to 'value'.
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*
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* RESULTS
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* 0 successfully created semaphore,
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* -1 failed, error in errno
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* ERRNO
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* EINVAL 'sem' is not a valid semaphore, or
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* 'value' >= SEM_VALUE_MAX
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* ENOMEM out of memory,
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* ENOSPC a required resource has been exhausted,
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* ENOSYS semaphores are not supported,
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* EPERM the process lacks appropriate privilege
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*
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* ------------------------------------------------------
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*/
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{
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int result = 0;
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sem_t s = NULL;
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if (pshared != 0)
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{
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/*
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* Creating a semaphore that can be shared between
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* processes
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*/
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result = EPERM;
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}
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else if (value > (unsigned int)SEM_VALUE_MAX)
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{
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result = EINVAL;
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}
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else
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{
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s = (sem_t) calloc (1, sizeof (*s));
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if (NULL == s)
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{
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result = ENOMEM;
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}
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else
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{
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s->value = value;
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if (pthread_mutex_init(&s->lock, NULL) == 0)
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{
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#if defined(NEED_SEM)
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s->sem = CreateEvent (NULL,
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PTW32_FALSE, /* auto (not manual) reset */
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PTW32_FALSE, /* initial state is unset */
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NULL);
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if (0 == s->sem)
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{
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free (s);
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(void) pthread_mutex_destroy(&s->lock);
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result = ENOSPC;
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}
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else
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{
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s->leftToUnblock = 0;
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}
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#else /* NEED_SEM */
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if ((s->sem = CreateSemaphore (NULL, /* Always NULL */
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(long) 0, /* Force threads to wait */
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(long) SEM_VALUE_MAX, /* Maximum value */
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NULL)) == 0) /* Name */
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{
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(void) pthread_mutex_destroy(&s->lock);
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result = ENOSPC;
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}
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#endif /* NEED_SEM */
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}
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else
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{
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result = ENOSPC;
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}
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if (result != 0)
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{
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free(s);
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}
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}
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}
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if (result != 0)
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{
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errno = result;
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return -1;
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}
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*sem = s;
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return 0;
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} /* sem_init */
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