testfifo.c

入门程序

/***********************************************
 * Simple pipe demo program for linuxforum.net
 *
 * Edward Jiang <[e-mail]>
 * July 17, 2001
 ***********************************************/

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

#define BUFFERSIZE 1024

int main(int argc, char *argv[])
{
	int fdp[2], rdfd, wtfd;
	int r, pid;
	unsigned char buffer[BUFFERSIZE];

	if (argc != 3) {
		fprintf(stderr, "Usage: %s <input_file> <output_file>\n",argv[0]);
		exit(-1);
	}

	if ((r = pipe(fdp))<0) {
		perror("Open pipe error");
		exit(-2);
	}

	if ((rdfd = open(argv[1], O_RDONLY)) < 0) {
		perror("Read file error");
		exit(-3);
	}

	if ((wtfd = open(argv[2], O_CREAT | O_WRONLY | O_TRUNC)) < 0) {
		perror("Write file error");
		exit(-4);
	}

	if ((pid = fork())>0) {
		close(wtfd);
		close(fdp[0]);
		while ((r = read(rdfd, buffer, BUFFERSIZE)) > 0) {
			write(fdp[1], buffer, r);
		}
		close(rdfd);
		close(fdp[1]);
		waitpid(pid, NULL, 0);
		printf("Parent process exit\n");
		exit(0);
	}
	else if (pid == 0) {
		close(rdfd);
		close(fdp[1]);
		while ((r = read(fdp[0], buffer, BUFFERSIZE)) > 0) {
			write(wtfd, buffer, r);
		}
		close(wtfd);
		close(fdp[0]);
		printf("Child process exit\n");
		_exit(0);
	}
	else {
		perror("Fork error");
		exit(-5);
	}
}