unix网络编程笔记---6.TCP的C/S实例2处理SIGCHLD与EINTR

1. 说明
1.1 功能
  第5章的第一个程序
   client从终端读入一行,写到socket中
   server从socket中读入一行，并将读到的data写到socket中
   client从socket中读取一行，并显示到终端
1.2 问题
在unix网络编程笔记---4.时间获取server与client 中ps命令显示server有僵死进程,
同时对慢系统调用函数accept的EINTR没有处理
1.3 主要修改了server端，client端没有变化

---

2. 源码
server.c

cong@msi:/work/test/tcpip/6tcp/serv1$ cat tcpserv.c
#include "utils.h"

#define LISTENQ 10
void sig_chld(int signo)     //问题1.处理sigchld
{
    pid_t pid;
    int stat;
    pid = wait(&stat);
    dbmsg("child %d terminated", pid);
    return ;
}
void str_echo(int sockfd)
{
    ssize_t n;
    char buf[MAXLINE];
again:
    while( (n=read(sockfd, buf, MAXLINE)) > 0)
        write(sockfd, buf, n);

    if( (n<0) && (errno==EINTR) )
        goto again;
    else if(n < 0)
        dbmsg("read_error");
}

int main ( int argc, char *argv[] )
{
    int listenfd, connfd;
    struct sockaddr_in servaddr, cliaddr;
    signal(SIGCHLD, sig_chld);     //问题1.捕获信号sigchld
    pid_t childpid;
    char buf[1024];
    int len;
    listenfd = socket(AF_INET, SOCK_STREAM, 0);
    if(listenfd< 0)
        return -1;
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(13999);
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    //inet_pton(AF_INET, TIME_SERV_ADDR, &servaddr.sin_addr);

    bind(listenfd, (const struct sockaddr*)&servaddr, sizeof(servaddr));
    listen(listenfd, LISTENQ);
    while(1)
    {
        len = sizeof(cliaddr);
        //connfd = accept(listenfd, (struct sockaddr*)NULL, NULL);
        connfd = accept(listenfd, (struct sockaddr*)&cliaddr,(socklen_t*)&len);
        dbmsg("accept:%s,port=%d", inet_ntop(AF_INET,&cliaddr.sin_addr,buf, sizeof(buf)), ntohs(cliaddr.sin_port));
        if(errno == EINTR)           //问题2.慢系统调用accept返回eintr时,需要重启accept
        {
            dbmsg("EINTR");
            continue;
        }
        if( (childpid=fork()) == 0)
        {
            close(listenfd);
            str_echo(connfd);
            exit(0);                  //问题1.子进程exit时会产生信号sigchld
        }
        dbmsg("close connfd");
        close(connfd);
    }

    return EXIT_SUCCESS;
}

client.c

cong@msi:/work/test/tcpip/6tcp/client$ cat client.c
#include "utils.h"

//#define TIME_SERV_ADDR "192.168.4.98"
#define TIME_SERV_ADDR "127.0.0.1"
#if 0
//这段readline有bug
//buf的末尾没有加'\0',导致显示时出错
ssize_t readline(int fd, void* vptr, size_t maxlen)
{
    ssize_t n, rc;
    char c,*ptr;
    ptr = vptr;
    for(n=1; n<maxlen; n++)
    {
again:
        if((rc=read(fd,&c,1)) == 1)
        {
            *ptr++ = c;
            if(c == '\n')
                break;
        } else if(rc == 0) {
            *ptr = 0;
            return (n-1);
        }else {
            if( errno == EINTR)
                goto again;
            return -1;
        }
    }
}
#endif
ssize_t readline(int fd, void* vptr, size_t maxlen)
{
    ssize_t n, rc; 
    char c,*ptr;
    ptr = vptr;
    for(n=0; n
again:
        if((rc=read(fd,&c,1)) == 1)
        {
            *ptr++ = c;
            if(c == '\n')
                break;
        } else if(rc == 0) {
            *ptr = 0;
            return n;
        }else {
            if( errno == EINTR)
                goto again;
            return -1; 
        }
    }   
    *ptr = '\0';
    return n;
}
void str_cli(FILE* fp, int sockfd)
{
    char sendline[MAXLINE], recvline[MAXLINE];
    while(fgets(sendline, MAXLINE, fp) != NULL)
    {
        write(sockfd, sendline, strlen(sendline));
        if(readline(sockfd, recvline, MAXLINE) == 0)
            dbmsg("server terminated");
        fputs(recvline, stdout);
    }

}

int main ( int argc, char *argv[] )
{
    int sockfd, n;
    struct sockaddr_in servaddr;
    char recvline[1024];
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if(sockfd < 0)
        return -1;
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(13999);
    inet_pton(AF_INET, TIME_SERV_ADDR, &servaddr.sin_addr);
    dbmsg("next connect");
    connect(sockfd, (const struct sockaddr*)&servaddr, sizeof(servaddr));
    dbmsg("connect success");

    str_cli(stdin, sockfd);
    return EXIT_SUCCESS;
}

utils.h

cong@msi:/work/test/tcpip/6tcp/serv$ cat utils.h
#ifndef UTILS_H__
#define UTILS_H__
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <time.h>
#include <string.h>
#include <errno.h>
#include <signal.h>

#define MAXLINE 1024

#define dbmsg(fmt, args ...) printf("%s:%s[%d]: "fmt"\n", __FILE__,__FUNCTION__, __LINE__,##args)

#endif

client.rar  (下载后改名为client.tar.gz)
serv.rar   (下载后改名为serv.tar.gz)