fifo实现单服务器多客户端

费劲的折腾，好几次小细节没处理好，真是醉了，不说了

代码记录下

服务端:

//fifo(first in, first out)
//有名管道
#include <iostream>
#include <unistd.h>
#include <cstdio>
#include <sys/wait.h>
#include <signal.h>
#include <cstring>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <cstdlib>
using namespace std;
#define FILE_MODE (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)
#define FIFO_0 "/tmp/fifo0"
const int size=256;
			struct DATA
			{
			    int nLen;   //sBuf+pid的有效长度
			    pid_t pid;
			    char sBuf[size];
			};

int server(int &readfd,int &writefd);

//server
//作用：多个客户端通过FIFO向server传来文件路径名，server返回路径名的反序


int main()
{
		//start();
    int readfd,writefd;
    cout << FILE_MODE << endl;
    unlink(FIFO_0);
    if( (mkfifo(FIFO_0,FILE_MODE) < 0 ) )
    {
        if(errno = EEXIST)
            cout << "fifo is exist!" << endl;
        else
            perror("server create FIFO_0");
    }

    readfd=open(FIFO_0,O_RDONLY,0);
    writefd=open(FIFO_0,O_WRONLY,0);
    cout << "readfd=" << readfd << endl;
    cout << "writefd=" << writefd << endl;

    server(readfd,writefd);
    return 0;
}
int fifo_ret(DATA & data);
int server(int & readfd,int & writefd)
{
    struct DATA data={0};
    size_t n=0;
    size_t len=0;
    char sBuf[256]= {0};
    while(true)
    {
        //迭代式，一个个处理
        memset(&data,0x00,sizeof(data));
        n = read(readfd,&data,sizeof(data.nLen));
        if(n <= 0)
            break;
        else if(n != sizeof(data.nLen))
        {
            perror("readfifo");
            break; 
        }
        len = data.nLen;
        if(read(readfd,&data.pid,sizeof(pid_t)) == sizeof(pid_t) && \
           len == read(readfd,data.sBuf,len))
            {
            	cout << "server:" << data.nLen << data.pid << data.sBuf << endl;
            	fifo_ret(data);
            }
    }

}
void reverse(char * from, char * to)
{
    int n=strlen(from);
    int m=n;
    for(int i=0;i < n;i++)
    {
        to[i] = from[--m];
    }
}
int fifo_ret(DATA & data)
{
		//cout << "come" << endl;
    char pathname[size]="/tmp/fifo";
    int pid=(int)data.pid;
    //strcat(pathname,itoa(pid));			ubuntu,下没有itoa
    char sBuf[256];
    memset(sBuf,0x00,sizeof(sBuf));
    sprintf(sBuf,"%d",pid);
    strcat(pathname,sBuf);
    //cout <<"pathname"<< pathname << endl;
    if(mkfifo(pathname,FILE_MODE) < 0)
    {
        if(errno == EEXIST)
            cout << pathname << "exist" << endl;
        else
        {
            perror("mkfifo pathname");
            return -1;
        }
    }
    int writefd;
    sleep(3);
    if( (writefd=open(pathname,O_WRONLY,0)) < 0)
        perror("open fifo");
    char sTmp[256]={0};
    reverse(data.sBuf,sTmp);
    cout << sTmp << endl;
    write(writefd,sTmp,strlen(sTmp));
    close(writefd);
   

}

客户端:

#include <iostream>
#include <unistd.h>
#include <cstdio>
#include <sys/wait.h>
#include <signal.h>
#include <cstring>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <cstdlib>
using namespace std;
#define FILE_MODE (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)
#define FIFO_0 "/tmp/fifo0"  
const int size=256;

struct DATA
{
    int nLen;   //sBuf+pid的有效长度
    pid_t pid;
    char sBuf[size];
};

int main()
{
    if( (mkfifo(FIFO_0,FILE_MODE) < 0 ) )
    {
        if(errno = EEXIST)
            cout << "fifo is exist!" << endl;
        else
            perror("server create FIFO_0");
    }
    int readfd,writefd;
    char pathname[size]="/tmp/fifo";
    int pid=(int)getpid();
    char sBuf[256]={0}; 
    memset(sBuf,0x00,sizeof(sBuf));
    sprintf(sBuf,"%d",pid);
    strcat(pathname,sBuf);
    if(mkfifo(pathname,FILE_MODE) < 0)
    {
        if(errno == EEXIST)
            cout << pathname << "exist" << endl;
        else
        {
            perror("mkfifo pathname");
            return -1;
        }
    }
    //多客户端向服务端发送字符串，服务器返回反序
		writefd=open(FIFO_0,O_WRONLY,0);
		sprintf(sBuf,"%d",pid);
    char sTmp[256]={0};
    DATA data;
    while(1)	//与服务器通讯
    {
    	memset(sBuf,0x00,sizeof(sBuf));    	
    	memset(sTmp,0x00,sizeof(sTmp));
    	memset(&data,0x00,sizeof(data));
    	cout << "input:[# quit]" << endl;	
    	cin >> data.sBuf;
    	if(data.sBuf[0] == '#')
    			break;
	    data.pid=pid;
	    data.nLen=strlen(data.sBuf);
	    write(writefd,&data,data.nLen+sizeof(data.nLen)+sizeof(data.pid));
	    readfd=open(pathname,O_RDONLY,0);
    	read(readfd,sTmp,sizeof(sTmp));
    	cout << "recv:" <<sTmp << endl;
    }
    	
    close(writefd);
    close(readfd);
		unlink(pathname);
    exit(0);
}