p10-2.c

SUN Solaris8平台下进程间通信

#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(void)
{
    int file_desc;
    int res;
    int byte_count;
    char *byte_to_write = "A";
    struct flock region_1,region_2;
     /* 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");
    /* 写入数据 */
    for(byte_count = 0; byte_count<100; byte_count++)
        write(file_desc, byte_to_write, 1);
    printf("Process %d locking file\n", getpid());
    /* 在区域1（从字节10至29）设置共享读锁 */
    if (READ_LOCK(file_desc, 10, SEEK_SET, 20) == -1)
        fprintf(stderr,"Failed to lock region 1\n");
    /* 在区域2（从字节40至49）设置互斥写锁 */
    if (WRITE_LOCK (file_desc, 40, SEEK_SET, 10) == -1)
        fprintf(stderr,"Failed to lock region 2\n");
    /* 等待以便另一个程序测试锁 */
    pause();
    printf("Process %d closeing file\n",getpid());
    close(file_desc);
}