p10-3.c

来自「SUN Solaris8平台下进程间通信」· C语言 代码 · 共 65 行

#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include "filelock.h"
#include "err_exit.h"
const char *test_file = "/tmp/test_lock";
int main() 
{
    int file_desc;
    struct flock region_to_lock;
    int res;
    /* 打开文件描述字*/
    file_desc = open(test_file, O_RDWR | O_CREAT, 0666);
    if (!file_desc) 
        err_exit("Unable to open file: test_file");
    /* 对区域[10－14]设置读锁 */
    printf("Process %d, trying F_RDLCK, region %d to %d\n", getpid(),
           10, 14);
    if (READ_LOCK(file_desc,10,SEEK_SET,5) == -1) {
        printf("Process %d - failed to lock region\n", getpid());
    } else 
        printf("Process %d - obtained lock region\n", getpid());    
    /* 对区域[10-14]解锁 */   
    printf("Process %d, trying F_UNLCK, region %d to %d\n", getpid(),
           10,14);
    if (UN_LOCK(file_desc,10,SEEK_SET,5) == -1) {
        printf("Process %d - failed to unlock region\n", getpid());
    } else 
        printf("Process %d - unlocked region\n", getpid());
    /* 对区域[0-49]解锁 */
    printf("Process %d, trying F_UNLCK, region %d to %d\n", getpid(),
           0, 49);
    if (UN_LOCK(file_desc,0,SEEK_SET,50) == -1) {
        printf("Process %d - failed to unlock region\n", getpid());
    } else 
        printf("Process %d - unlocked region\n", getpid());
    /* 对区域[15-20]加写锁 */    
    printf("Process %d, trying F_WRLCK, region %d to %d\n", getpid(),
           15, 15+5);
    if (WRITE_LOCK(file_desc,15,SEEK_SET,6) == -1) {
        printf("Process %d - failed to lock region\n", getpid());
    } else {
        printf("Process %d - obtained lock on region\n", getpid());
    }
    /* 对区域[40-49]加读锁 */
    printf("Process %d, trying F_RDLCK, region %d to %d\n", getpid(),
           40, 49);
    if (READ_LOCK(file_desc,40,SEEK_SET,10) == -1) {
        printf("Process %d - failed to lock region\n", getpid());
    } else {
        printf("Process %d - obtained lock on region\n", getpid());
    }
    /* 对区域[16-20]加写锁并等待 */   
    printf("Process %d, trying F_WRLCK with wait, region %d to %d\n", getpid(),
           16, 20);
    if (WRITEW_LOCK(file_desc,16,SEEK_SET,5) == -1) {
        printf("Process %d - failed to lock region\n", getpid());
    } else {
        printf("Process %d - obtained lock on region\n", getpid());
    }
    printf("Process %d ending\n", getpid());    
    close(file_desc);
}