序：引子
对话功能实际上就是利用管道见得通信。最原始的是一方发另一方收，不能进项交互，发送方的代码如下：
/*============================================
> Copyright (C) 2014 All rights reserved.
> FileName：send.c
> author：donald
> details：
==============================================*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#define N 1024
int main(int argc, const char *argv[])
{ if(- == mkfifo(argv[],)){//creat 2
perror("failed");
exit(-);
} printf("mkfifo over!\n");
int fd_send,fd_recev;
printf("open fifo...\n"); fd_send = open(argv[],O_WRONLY); if(fd_send == -){//必须另一方打开
perror("open failed");
unlink(argv[]);
exit(-);
}
printf("open success!\n"); char send_buf[N];
while(memset(send_buf,,N),fgets(send_buf,N,stdin) != NULL){
write(fd_send,send_buf,strlen(send_buf));
} printf("send over\n");
unlink(argv[]);
return ;
}
send.c
接收方的代码：
/*============================================
> Copyright (C) 2014 All rights reserved.
> FileName：recv.c
> author：donald
> details：
==============================================*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#define N 1024
int main(int argc, const char *argv[])
{
int fd_send,fd_recev;
printf("open fifo...\n");
fd_recev = open(argv[],O_RDONLY); if(fd_send == -){
perror("open failed");
unlink(argv[]);
exit(-);
}
printf("open success!\n"); char recev_buf[];
while(memset(recev_buf,,N),read(fd_recev,recev_buf,N) > ){
printf("%s",recev_buf);
} printf("recev over\n");
close(fd_recev);
unlink(argv[]);
return ;
}
recev.c
两人回话
对于两个程序之间的进行交互式对话有两种方式：
A.一问一答式，这是最简单的方式，但也是最不人性化的方法，运行后你就会产生一种回到上个世纪的错觉
B.没有固定的顺序，和QQ一样，想说就说，不用等到另一方说完一句才能说。
A方法比较简单，直接上代码：
启动方：
/*============================================
> Copyright (C) 2014 All rights reserved.
> FileName：send.c
> author：donald
> date：2014/08/22/ 14:45:45
> details：
==============================================*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#define N 1024
int main(int argc, const char *argv[])
{ if(- == mkfifo(argv[],)){//creat 1
perror("failed");
exit(-);
} printf("mkfifo over!\n");
int fd_send,fd_recev;
printf("open fifo...\n"); fd_send = open(argv[],O_WRONLY); if(fd_send == -){//必须另一方打开
perror("open failed");
unlink(argv[]);
// exit(-1);
}
printf("open success!\n"); char send_buf[N];
while(memset(send_buf,,N),fgets(send_buf,N,stdin) != NULL){
write(fd_send,send_buf,strlen(send_buf));
} printf("send over\n");
unlink(argv[]);
return ;
}
send.c
recev_send.c
B方法利用创建一个进程（fork）来实现交互，其代码为：
/*===========================================
> Copyright (C)2014All rights reserved
> File Name: fork_re_se.c
> Author: Donald
=============================================*/ #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#define N 1024
int main(int argc, const char *argv[])
{
#if 1
if(- == mkfifo(argv[],)){
perror("failed");
exit(-);
}
printf("mkfifo over!\n");
#endif
int fd_send,fd_recev;
printf("open fifo...\n");
fd_recev = open(argv[],O_RDONLY);
fd_send = open(argv[],O_WRONLY); if(fd_send == - || fd_recev == -){
perror("open failed");
unlink(argv[]);
exit(-);
}
printf("open success!\n"); char recev_buf[];
char send_buf[N];
if(fork() == ){//child recev
close(fd_send);
//while(memset(recev_buf,0,N),read(fd_recev,recev_buf,strlen(recev_buf)) != 0){这里不能用strlen（recev_buf在while中进行了初始化，所以长度为0）
while(memset(recev_buf,,N),read(fd_recev,recev_buf,N) != ){
//write(1,recev_buf,N);
printf("%s",recev_buf);
}
exit();
}else{//parent send
close(fd_recev);
while(memset(send_buf,,N),fgets(send_buf,N,stdin) != NULL){
write(fd_send,send_buf,strlen(send_buf));
}
close(fd_send);
wait(NULL);
unlink(argv[]);
}
printf("recev over\n");
return ;
}
fork_re_se.c
/*===========================================
> Copyright (C)2014All rights reserved
> File Name: fork_se_re.c
> Author: Donald
=============================================*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#define N 1024
int main(int argc, const char *argv[])
{
#if 1
if(- == mkfifo(argv[],)){
perror("failed");
exit(-);
}
printf("mkfifo over!\n");
#endif
int fd_send,fd_recev;
printf("open fifo...\n");
fd_send = open(argv[],O_WRONLY);
fd_recev = open(argv[],O_RDONLY); if(fd_send == - || fd_recev == -){
perror("open failed");
unlink(argv[]);
exit(-);
}
printf("open success!\n"); char recev_buf[];
char send_buf[N];
if(fork() == ){//child recev
close(fd_send);
while(memset(recev_buf,,N),read(fd_recev,recev_buf,N) != ){
//write(1,recev_buf,N);
printf("%s",recev_buf);
}
exit();
}else{//parent send
close(fd_recev);
while(memset(send_buf,,N),fgets(send_buf,N,stdin) != NULL){
write(fd_send,send_buf,strlen(send_buf));
}
close(fd_send);
wait(NULL);
unlink(argv[]);
} printf("send over\n");
return ;
}
fork_se_re.c
三人无序对话
本程序主要通过父进程创建两个子进程，通过管道来实现，和两人无序对话的功能一样。只要逻辑清晰，并不难。共需要pipe（有名管道）六根，功能为用于读、写，为了使逻辑清晰，方便讨论，以下1、2、3分别代表程序1、2、3之间的管道，分别对程序之间的管道进项讨论分析：
| A | B | C | |||
| 1-2 | write | 1-2 | read | 1-3 | read |
| 1-3 | write | 2-1 | write | 3-1 | write |
| 2-1 | read | 2-3 | write | 2-3 | read |
| 3-1 | read | 3-2 | read | 3-2 | write |
以上表格表示的具体含义我在这里举例说明一下。eg：对于A（聊天猪头）而言共有四根管道与其相连，两根用于读，另外两根用于写，1-2管道代表A、B之间的管道A需要进行写操作，而B进行读操作。
- A:第一人
/*============================================
> Copyright (C) 2014 All rights reserved.
> FileName：1.c
> author：donald
> date：2014/08/22/ 20:28:53
> details：
==============================================*/ #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#define N 1024
int main(int argc, const char *argv[])//12,13,21,31
{
if(mkfifo(argv[],) == - || mkfifo(argv[],) == -){
perror("mkfifo");
exit();
} int fd_12,fd_13,fd_21,fd_31;
char buf[N];
fd_12 = open(argv[],O_WRONLY);
fd_13 = open(argv[],O_WRONLY);
fd_21 = open(argv[],O_RDONLY);
fd_31 = open(argv[],O_RDONLY); printf("open sucess\n"); if(fork() == ){//21 r
close(fd_13);
close(fd_12);
close(fd_31);
while(memset(buf,,N),read(fd_21,buf,N) != ){
printf("from 2:");
write(,buf,strlen(buf));
}
close(fd_21);
exit();
}
if(fork() == ){//31 r
close(fd_13);
close(fd_12);
close(fd_21);
while(memset(buf,,N),read(fd_31,buf,N) != ){
printf("from 3:");
write(,buf,strlen(buf));
}
close(fd_31);
exit();
} //12 13 w
close(fd_21);
close(fd_31);
while(memset(buf,,N),fgets(buf,N,stdin) != NULL){
write(fd_13,buf,strlen(buf));
write(fd_12,buf,strlen(buf));
}
close(fd_13);
close(fd_12);
wait(NULL);
wait(NULL); unlink(argv[]);
unlink(argv[]);
printf("program 1 over\n");
return ;
}
1.c
- B:第二人
/*============================================
> Copyright (C) 2014 All rights reserved.
> FileName：2.c
> author：donald
> date：2014/08/22/ 20:29:02
> details：
==============================================*/ #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#define N 1024
int main(int argc, const char *argv[])
{ if(mkfifo(argv[],) == - || mkfifo(argv[],) == -){
perror("mkfifo");
exit();
} int fd_12,fd_21,fd_23,fd_32;
char buf[N];
fd_12 = open(argv[],O_RDONLY);
fd_21 = open(argv[],O_WRONLY);
fd_23 = open(argv[],O_WRONLY);
fd_32 = open(argv[],O_RDONLY); printf("open success\n"); if(fork() == ){//12 r
close(fd_32);
close(fd_21);
close(fd_23);
while(memset(buf,,N),read(fd_12,buf,N) != ){
printf("from 1:");
write(,buf,strlen(buf));
}
close(fd_12);
exit();
} if(fork() == ){//32 r
close(fd_12);
close(fd_21);
close(fd_23);
while(memset(buf,,N),read(fd_32,buf,N) != ){
printf("from 3:");
write(,buf,strlen(buf));
}
close(fd_32);
exit();
} //21 23 w
close(fd_12);
close(fd_32);
while(memset(buf,,N),fgets(buf,N,stdin) != NULL){
write(fd_21,buf,strlen(buf));
write(fd_23,buf,strlen(buf));
}
close(fd_21);
close(fd_23);
wait(NULL);
wait(NULL); unlink(argv[]);
unlink(argv[]);
printf("program 2 over\n");
return ;
}
2.c
- C:第三人
/*============================================
> Copyright (C) 2014 All rights reserved.
> FileName：3.c
> author：donald
> date：2014/08/22/ 20:29:13
> details：
==============================================*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#define N 1024
int main(int argc, const char *argv[])
{ if(mkfifo(argv[],) == - || mkfifo(argv[],) == -){
perror("mkfifo");
exit();
} int fd_13,fd_31,fd_23,fd_32;
char buf[N];
fd_13 = open(argv[],O_RDONLY);
fd_31 = open(argv[],O_WRONLY);
fd_23 = open(argv[],O_RDONLY);
fd_32 = open(argv[],O_WRONLY); printf("open success\n"); if(fork() == ){//13 r
close(fd_31);
close(fd_23);
close(fd_32);
while(memset(buf,,N),read(fd_13,buf,N) != ){
printf("from 1:");
write(,buf,strlen(buf));
}
close(fd_13);
exit();
}
if(fork() == ){//23 r
close(fd_13);
close(fd_31);
close(fd_32);
while(memset(buf,,N),read(fd_23,buf,N) != ){
printf("from 2:");
write(,buf,strlen(buf));
}
close(fd_23);
exit();
} //31 32 w
close(fd_13);
close(fd_23);
while(memset(buf,,N),fgets(buf,N,stdin) != NULL){
write(fd_31,buf,strlen(buf));
write(fd_32,buf,strlen(buf));
}
close(fd_31);
close(fd_32);
wait(NULL);
wait(NULL); unlink(argv[]);
unlink(argv[]);
printf("program 3 over\n");
return ;
}
3.c
PS:在命令行参数中还需注意的，假设1.c、2.c、3.c的可执行文件为A.out、B.out、C.out。命令行参数分别为：(其实和表格里分析的一样)
- ./A.out 12.fifo 13.fifo 21.fifo 31.fifo
- ./B.out 12.fifo 21.fifo 23.fifo 32.fifo
- ./C.out 13.fifo 31.fifo 23.fifo 32.fifo
三人以上的用fork就没必要了，需要另寻方，一般采用服务器的处理方式。