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XSI semaphore locking
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| void semaphore_lock(int sem_id) | |
| { | |
| int res = 0 | |
| struct sembuf sops; | |
| sops.sem_num = 0; | |
| sops.sem_flg = SEM_UNDO; | |
| sops.sem_op = -1; | |
| do { | |
| res = semop(sem_id, &sops, 1); | |
| } while (res == -1 && errno == EINTR); | |
| } | |
| void semaphore_unlock(int sem_id) | |
| { | |
| int res = 0; | |
| struct sembuf sops; | |
| sops.sem_num = 0; | |
| sops.sem_op = 1; | |
| sops.sem_flg = SEM_UNDO; | |
| do { | |
| res = semop(sem_id, &sops, 1); | |
| } while (res == -1 && errno == EINTR); | |
| } | |
| int main(int argc, char *argv[]) | |
| { | |
| sem_id = semget(key, 1, IPC_CREATE); | |
| /* initialize semaphore #0 to 1 */ | |
| union semun arg; | |
| arg.val = 1; | |
| if (semctl(sem_id, 0, SETVAL, arg) == -1) { | |
| perror("semctl"); | |
| exit(1); | |
| } | |
| /* remove semaphore */ | |
| if (semctl(sem_id, 0, IPC_RMID, arg) == -1 ) { | |
| perror("semctl"); | |
| exit(1); | |
| } | |
| } |
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