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Diffstat (limited to 'backend/snapscan-mutex.c')
| -rw-r--r-- | backend/snapscan-mutex.c | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/backend/snapscan-mutex.c b/backend/snapscan-mutex.c new file mode 100644 index 0000000..0321741 --- /dev/null +++ b/backend/snapscan-mutex.c @@ -0,0 +1,183 @@ +/* + Mutex implementation for SnapScan backend + + Copyright (C) 2000, 2004 Henrik Johansson, Oliver Schwartz + + This program is free software; you can redistribute it and/or + modify it under the terms of the GNU General Public License as + published by the Free Software Foundation; either version 2 of the + License, or (at your option) any later version. + + This program 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 + General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 59 Temple Place - Suite 330, Boston, + MA 02111-1307, USA. + + As a special exception, the authors of SANE give permission for + additional uses of the libraries contained in this release of SANE. + + The exception is that, if you link a SANE library with other files + to produce an executable, this does not by itself cause the + resulting executable to be covered by the GNU General Public + License. Your use of that executable is in no way restricted on + account of linking the SANE library code into it. + + This exception does not, however, invalidate any other reasons why + the executable file might be covered by the GNU General Public + License. + + If you submit changes to SANE to the maintainers to be included in + a subsequent release, you agree by submitting the changes that + those changes may be distributed with this exception intact. + + If you write modifications of your own for SANE, it is your choice + whether to permit this exception to apply to your modifications. + If you do not wish that, delete this exception notice.*/ + +#if defined __BEOS__ + +#include <OS.h> +#define snapscan_mutex_t sem_id + +static int snapscani_mutex_open(snapscan_mutex_t* a_sem, const char* dev UNUSEDARG) +{ + *a_sem = create_sem(1, "snapscan_mutex"); + return 1; +} + +static void snapscani_mutex_close(snapscan_mutex_t* a_sem) +{ + delete_sem(*a_sem); +} + +static void snapscani_mutex_lock(snapscan_mutex_t* a_sem) +{ + acquire_sem(*a_sem); +} + +static void snapscani_mutex_unlock(snapscan_mutex_t* a_sem) +{ + release_sem(*a_sem); +} + + + +#elif defined USE_PTHREAD || defined HAVE_OS2_H + +#include <pthread.h> +#define snapscan_mutex_t pthread_mutex_t + +static int snapscani_mutex_open(snapscan_mutex_t* sem_id, const char* dev UNUSEDARG) +{ + pthread_mutex_init(sem_id, NULL); + return 1; +} + +static void snapscani_mutex_close(snapscan_mutex_t* sem_id) +{ + pthread_mutex_destroy(sem_id); +} + +static void snapscani_mutex_lock(snapscan_mutex_t* sem_id) +{ + pthread_mutex_lock(sem_id); +} + +static void snapscani_mutex_unlock(snapscan_mutex_t* sem_id) +{ + pthread_mutex_unlock(sem_id); +} + +#else /* defined USE_PTHREAD || defined HAVE_OS2_H */ + +#include <sys/ipc.h> +#include <sys/sem.h> +#include <sys/types.h> +#include <unistd.h> + +#define snapscan_mutex_t int + +/* check for union semun */ +#if defined(HAVE_UNION_SEMUN) +/* union semun is defined by including <sys/sem.h> */ +#else +/* according to X/OPEN we have to define it ourselves */ +union semun { + int val; /* value for SETVAL */ + struct semid_ds *buf; /* buffer for IPC_STAT, IPC_SET */ + unsigned short int *array; /* array for GETALL, SETALL */ + struct seminfo *__buf; /* buffer for IPC_INFO */ +}; +#endif /* defined HAVE_UNION_SEMUN */ + +static struct sembuf sem_wait = { 0, -1, 0 }; +static struct sembuf sem_signal = { 0, 1, 0 }; + +static unsigned int snapscani_bernstein(const unsigned char* str) +{ + unsigned int hash = 5381; /* some arbitrary number */ + int c; + + while (*str) + { + c = *str++; + hash = ((hash << 5) + hash) + c; + } + return hash; +} + +static int snapscani_mutex_open(snapscan_mutex_t* sem_id, const char* dev) +{ + static const char *me = "snapscani_mutex_open"; + key_t ipc_key = -1; + + if (strstr(dev, "libusb:") == dev) + { + key_t ipc_key = (key_t) snapscani_bernstein((const unsigned char*) dev+7); + DBG (DL_INFO, "%s: using IPC key 0x%08x for device %s\n", + me, ipc_key, dev); + } + else + { + ipc_key = ftok(dev, 0x12); + + if (ipc_key == -1) + { + DBG (DL_MAJOR_ERROR, "%s: could not obtain IPC key for device %s: %s\n", me, dev, strerror(errno)); + return 0; + } + } + + *sem_id = semget( ipc_key, 1, IPC_CREAT | 0660 ); + if (*sem_id == -1) + { + DBG (DL_MAJOR_ERROR, "%s: semget failed: %s\n", me, strerror(errno)); + return 0; + } + + semop(*sem_id, &sem_signal, 1); + return 1; +} + +static void snapscani_mutex_close(snapscan_mutex_t* sem_id) +{ + static union semun dummy_semun_arg; + semctl(*sem_id, 0, IPC_RMID, dummy_semun_arg); +} + +static void snapscani_mutex_lock(snapscan_mutex_t* sem_id) +{ + semop(*sem_id, &sem_wait, 1); +} + +static void snapscani_mutex_unlock(snapscan_mutex_t* sem_id) +{ + semop(*sem_id, &sem_signal, 1); +} + +#endif /* defined USE_PTHREAD || defined HAVE_OS2_H */ |