linux进程间的通信之管道通信

发送端

#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <limits.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <string.h>

int main()
{
const char *fifo_name = "my_fifo";
int pipe_fd = -1;
int data_fd = -1;
int res = 0;
const int open_mode = O_WRONLY;
int bytes_sent = 0;
char buffer[PIPE_BUF + 1];

if(access(fifo_name, F_OK) == -1)
{
//管道文件不存在
//创建命名管道
res = mkfifo(fifo_name, 0777);//目测这个0777是权限设置，但改成0000权限然后删除原来的.pipe然后就无法访问了，所以最好0777
if(res != 0)
{
fprintf(stderr, "Could not create fifo %s\n", fifo_name);
exit(EXIT_FAILURE);
}
}

printf("Process %d opening FIFO O_WRONLY\n", getpid());
//以只写阻塞方式打开FIFO文件，以只读方式打开数据文件
pipe_fd = open(fifo_name, open_mode);
data_fd = open("Data.txt", O_RDONLY);
printf("Process %d result %d\n", getpid(), pipe_fd);

if(pipe_fd != -1)
{
int bytes_read = 0;
//向数据文件读取数据
bytes_read = read(data_fd, buffer, PIPE_BUF);
buffer[bytes_read] = '\0';
while(bytes_read > 0)
{
//向FIFO文件写数据
res = write(pipe_fd, buffer, bytes_read);
if(res == -1)
{
fprintf(stderr, "Write error on pipe\n");
exit(EXIT_FAILURE);
}
//累加写的字节数，并继续读取数据，之所以要在while里面发送，是防止一次cpu时间片用完了，没有发送完，下次来继续发送
bytes_sent += res;
bytes_read = read(data_fd, buffer, PIPE_BUF);
buffer[bytes_read] = '\0';
printf("%d\n",res);
//cout<<"dd"<<endl;
}
close(pipe_fd);
close(data_fd);
}
else
exit(EXIT_FAILURE);

printf("Process %d finished\n", getpid());
exit(EXIT_SUCCESS);
}

接收端

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <limits.h>
#include <string.h>

int main()
{
const char *fifo_name = "my_fifo";
int pipe_fd = -1;
int data_fd = -1;
int res = 0;
int open_mode = O_RDONLY;
char buffer[PIPE_BUF + 1];
int bytes_read = 0;
int bytes_write = 0;
//清空缓冲数组
memset(buffer, '\0', sizeof(buffer));

printf("Process %d opening FIFO O_RDONLY\n", getpid());
//以只读阻塞方式打开管道文件，注意与fifowrite.c文件中的FIFO同名
pipe_fd = open(fifo_name, open_mode);
//以只写方式创建保存数据的文件
data_fd = open("DataFormFIFO.txt", O_WRONLY|O_CREAT, 0644);
printf("Process %d result %d\n",getpid(), pipe_fd);

if(pipe_fd != -1)
{
do
{
//读取FIFO中的数据，并把它保存在文件DataFormFIFO.txt文件中
res = read(pipe_fd, buffer, PIPE_BUF);
printf("%d\n",res);
bytes_write = write(data_fd, buffer, res);
bytes_read += res;
//printf("%d\n",bytes_read);
}while(res > 0);
close(pipe_fd);
close(data_fd);
}
else
exit(EXIT_FAILURE);

printf("Process %d finished, %d bytes read\n", getpid(), bytes_read);
exit(EXIT_SUCCESS);
}


第一个p就表示管道