2002-09-26 18:11:06 +00:00
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// The contents of this file are subject to the Mozilla Public License
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// Version 1.0 (the "License"); you may not use this file except in
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// compliance with the License. You may obtain a copy of the License at
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// http://www.mozilla.org/MPL/
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//
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// Software distributed under the License is distributed on an "AS IS"
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// basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
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// License for the specific language governing rights and limitations
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// under the License.
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//
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// The Original Code is the Berkeley Open Infrastructure for Network Computing.
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//
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// The Initial Developer of the Original Code is the SETI@home project.
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// Portions created by the SETI@home project are Copyright (C) 2002
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// University of California at Berkeley. All Rights Reserved.
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//
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// Contributor(s):
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//
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// interfaces for accessing sempahores
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2002-05-24 04:29:10 +00:00
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#include <stdio.h>
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#include <string.h>
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#include "synch.h"
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union semun {
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int val;
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struct semid_ds *buf;
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unsigned short int *arra;
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struct seminfo *__buf;
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};
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int create_semaphore(key_t key){
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int id, retval;
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semun s;
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id = semget(key, 1, IPC_CREAT|IPC_EXCL|0777);
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if (id < 0) {
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perror("create_semaphore: semget");
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return -1;
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}
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memset(&s, 0, sizeof(s));
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s.val = 1;
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retval = semctl(id, 0, SETVAL, s);
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if (retval) {
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perror("create_semaphore: semctl");
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return -1;
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}
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return 0;
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}
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int destroy_semaphore(key_t key){
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int id, retval;
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id = semget(key, 0, 0);
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if (id < 0) {
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perror("destroy_semaphore: semget");
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return -1;
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}
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retval = semctl(id, 1, IPC_RMID, 0);
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if (retval) {
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perror("destroy_semaphore: semctl");
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return -1;
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}
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return 0;
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}
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int lock_semaphore(key_t key) {
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struct sembuf s;
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int id, retval;
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id = semget(key, 0, 0);
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if (id < 0) {
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perror("lock_semaphore: semget");
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return -1;
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}
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s.sem_num = 0;
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s.sem_op = -1;
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s.sem_flg = SEM_UNDO;
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retval = semop(id, &s, 1);
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if (retval) {
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perror("lock_semaphore: semctl");
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return -1;
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}
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return 0;
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}
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int unlock_semaphore(key_t key) {
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struct sembuf s;
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int id, retval;
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id = semget(key, 0, 0);
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if (id < 0) {
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perror("unlock_semaphore: semget");
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return -1;
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}
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s.sem_num = 0;
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s.sem_op = 1;
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s.sem_flg = SEM_UNDO;
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retval = semop(id, &s, 1);
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if (retval) {
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perror("unlock_semaphore: semctl");
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return -1;
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}
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return 0;
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}
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