进程通信pipe, 输入输出，进程间互相读写

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#define MAXLINE	80


void *parent_read_proc(void *p)
{
	int p_fd_r = (int)p;
	char line[MAXLINE] = {0};
	int len = 0;
	int n = 0;
	while(1)
	{
		memset(line,0,MAXLINE);
		len = read(p_fd_r,line,MAXLINE);
		printf("\nparent read:%s %d\t\n",line,n);
		n++;
	}
	return 0;
}

void *child_read_proc(void *p)
{
	int c_fd_r = (int)p;
	char line[MAXLINE] = {0};
	int len = 0;
	int n = 0;
	while(1)
	{
		memset(line,0,MAXLINE);
		len = read(c_fd_r,line,MAXLINE);
		printf("\nchild read:%s %d\t\n",line,n);
		n++;
	}
	return 0;
}

void *parent_write_proc(void *p)
{
	int p_fd_w = (int)p;
	char line[MAXLINE] = {0};
	int len = 0;
	int n = 0;
	char msg[] = "this is parent";
	while (n < 10) {
		len = strlen(msg);
		int err = write(p_fd_w,msg,len);
		if (err != -1) {
			printf("\nparent write : %s %d",msg,n);
		}
		n++;
		sleep(2);
	}
	return 0;
}

void *child_write_proc(void *p)
{
	int c_fd_w = (int)p;
	
	char line[MAXLINE] = {0};
	int len = 0;
	int n = 0;
	char msg[] = "this is child";
	while (n < 10) {
		len = strlen(msg);
		int err = write(c_fd_w,msg,len);
		if (err != -1) {
			printf("\nchild write : %s %d",msg,n);
		}
		n++;
		sleep(2);
	}
	
}

int main(void)
{
	int fd_rw[2];
	int fd_wr[2];
	pid_t pid;
	pthread_t p_r_pid;/*parent read thread*/
	pthread_t c_r_pid;/*child read thread*/
	pthread_t p_w_pid;/*parent write thread*/
	pthread_t c_w_pid;/*child write thread*/	

	if (pipe(fd_rw) < 0) {
		printf("create pipe_rw fail!\n");
		return -1;
	}	
	if (pipe(fd_wr) < 0) {
		printf("create pipe_wr fail!\n");
	}

	pid = fork();
	if (pid < 0){
		printf("fork process fail! errno = %d\n",errno);
		return -1;
	}
	else if (pid == 0) {
		int err = pthread_create(&c_r_pid,NULL,child_read_proc,(void*)fd_rw[0]);
		if (err != 0){
			printf("create child read proc fail, errno = %d\n",err);
			return -1;
		}
		
		err = pthread_create(&c_w_pid,NULL,child_write_proc,(void*)fd_wr[1]);
		if (err != 0) {
			printf("create child write proc fail, errno = %d\n",err);
			return -1;
		}
		pthread_join(c_r_pid);
		pthread_join(c_w_pid);
	}
	else {
		int err = pthread_create(&p_r_pid, NULL, parent_read_proc,(void*)fd_wr[0]);
		if (err != 0){
			printf("create parent read proc fail, errno = %d\n",err);
			return -1;
		}
		
		err = pthread_create(&p_w_pid, NULL, parent_write_proc,(void*)fd_rw[1]);
		if (err != 0) {
			printf("create parent write proc fail, errno = %d\n",err);
			return -1;
		}
		pthread_join(p_r_pid);
		pthread_join(p_w_pid);
	}
	
	int n = 0;
	scanf("%d",&n);
	return 0;
}