Linux 进程通信之FIFO的实现

FIFO通信(first in first out)

FIFO 有名管道,实现无血缘关系进程通信。

  • 创建一个管道的伪文件
    • a.mkfifo testfifo 命令创建
    • b.也可以使用函数int mkfifo(const char *pathname, mode_t mode);
  • 内核会针对fifo文件开辟一个缓冲区,操作fifo文件,可以操作缓冲区,实现进程间通信C实际上就是文件读写

man 3 mkfifo

  #include <sys/types.h>  #include <sys/stat.h>  int mkfifo(const char *pathname, mode_t mode);

注意事项:

FIFOs
Opening the read or write end of a FIFO blocks until the other end is also opened (by another process or thread). See
fifo(7) for further details.

打开fifo文件时候,read端会阻塞等待write端open,write端同理,也会阻塞等待另外一段打开。

代码示例:
file_w.c 写端

  #include <stdio.h>  #include <stdlib.h>  #include <sys/wait.h>  #include <sys/types.h>  #include <sys/stat.h>  #include <unistd.h>  #include <fcntl.h>  #include <string.h>    int main(int argc, char *argv[]) {    if(argc != 2) {      printf("./a.out filename1n");      return -1;    }    printf("begin open wn");    int o_ret = open(argv[1], O_WRONLY);    printf("end open wn");    char buf[256];    int num = 0;    while (1) {      memset(buf, '', sizeof(buf));      sprintf(buf, "xiaoming--%d", num++);      printf("strlen(buf) = %dn", strlen(buf));      write(o_ret, buf, strlen(buf));      sleep(1);    }    close(o_ret);    return 0;  }       

file_r.c 读端

  #include <stdio.h>  #include <stdlib.h>  #include <sys/wait.h>  #include <sys/types.h>  #include <sys/stat.h>  #include <unistd.h>  #include <fcntl.h>  #include <string.h>    int main(int argc, char *argv[]) {    if(argc != 2) {      printf("./a.out filename1n");      return -1;    }    printf("begin open rn");    int o_ret = open(argv[1], O_RDONLY);    printf("end open rn");    char buf[256];    int num = 0;    while (1) {      memset(buf, '', sizeof(buf));      read(o_ret, buf, sizeof(buf));      printf("strlen(buf) = %dn", strlen(buf));      printf("read is%sn", buf);    }    close(o_ret);    return 0;  }    

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