boinc/lib/synch.C

109 lines
2.4 KiB
C++
Raw Normal View History

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