2004-04-09 11:59:02 +00:00
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/*
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Mutex implementation for SnapScan backend
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Copyright (C) 2000, 2004 Henrik Johansson, Oliver Schwartz
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful, but
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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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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330, Boston,
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MA 02111-1307, USA.
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As a special exception, the authors of SANE give permission for
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additional uses of the libraries contained in this release of SANE.
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The exception is that, if you link a SANE library with other files
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to produce an executable, this does not by itself cause the
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resulting executable to be covered by the GNU General Public
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License. Your use of that executable is in no way restricted on
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account of linking the SANE library code into it.
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This exception does not, however, invalidate any other reasons why
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the executable file might be covered by the GNU General Public
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License.
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If you submit changes to SANE to the maintainers to be included in
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a subsequent release, you agree by submitting the changes that
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those changes may be distributed with this exception intact.
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If you write modifications of your own for SANE, it is your choice
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whether to permit this exception to apply to your modifications.
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If you do not wish that, delete this exception notice.*/
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2004-04-15 20:33:53 +00:00
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#if defined USE_PTHREAD || defined HAVE_OS2_H
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2004-04-09 11:59:02 +00:00
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#include <pthread.h>
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#define snapscan_mutex_t pthread_mutex_t
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static int snapscani_mutex_open(snapscan_mutex_t* sem_id, const char* dev UNUSEDARG)
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{
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pthread_mutex_init(sem_id, NULL);
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return 1;
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}
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static void snapscani_mutex_close(snapscan_mutex_t* sem_id)
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{
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pthread_mutex_destroy(sem_id);
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}
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static void snapscani_mutex_lock(snapscan_mutex_t* sem_id)
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{
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pthread_mutex_lock(sem_id);
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}
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static void snapscani_mutex_unlock(snapscan_mutex_t* sem_id)
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{
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pthread_mutex_unlock(sem_id);
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}
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2004-04-15 20:33:53 +00:00
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#else /* defined USE_PTHREAD || defined HAVE_OS2_H */
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2004-04-09 11:59:02 +00:00
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#include <sys/ipc.h>
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#include <sys/sem.h>
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#define snapscan_mutex_t int
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/* check for union semun */
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#if defined(HAVE_UNION_SEMUN)
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/* union semun is defined by including <sys/sem.h> */
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#else
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/* according to X/OPEN we have to define it ourselves */
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union semun {
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int val; /* value for SETVAL */
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struct semid_ds *buf; /* buffer for IPC_STAT, IPC_SET */
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unsigned short int *array; /* array for GETALL, SETALL */
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struct seminfo *__buf; /* buffer for IPC_INFO */
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};
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#endif /* defined HAVE_UNION_SEMUN */
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static struct sembuf sem_wait = { 0, -1, 0 };
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static struct sembuf sem_signal = { 0, 1, 0 };
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static int snapscani_mutex_open(snapscan_mutex_t* sem_id, const char* dev)
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{
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*sem_id = semget( ftok(dev,0x12), 1, IPC_CREAT | 0660 );
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if (*sem_id != -1)
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{
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semop(*sem_id, &sem_signal, 1);
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return 1;
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}
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return 0;
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}
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static void snapscani_mutex_close(snapscan_mutex_t* sem_id)
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{
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static union semun dummy_semun_arg;
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semctl(*sem_id, 0, IPC_RMID, dummy_semun_arg);
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}
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static void snapscani_mutex_lock(snapscan_mutex_t* sem_id)
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{
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semop(*sem_id, &sem_wait, 1);
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}
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static void snapscani_mutex_unlock(snapscan_mutex_t* sem_id)
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{
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semop(*sem_id, &sem_signal, 1);
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}
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2004-04-15 20:33:53 +00:00
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#endif /* defined USE_PTHREAD || defined HAVE_OS2_H */
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