第四版str_cli(多进程版)

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <sys/types.h>
#include <sys/select.h>

#define SERV_ADDR "127.0.0.1"
#define SERV_PORT 5358
#define BUF_LEN 1024

#define MAX(a, b) (a)>(b)?(a):(b)

ssize_t writen(int fd, const void *vptr, size_t n)
{
    size_t nleft;
    ssize_t nwriten;
    const char *ptr;

    ptr = vptr;
    nleft = n;
    while(nleft>0) {
        if((nwriten = write(fd, ptr, nleft)) <= 0) {
            if(nwriten < 0 && errno == EINTR) {
                nwriten = 0;        /*interrupt by signal*/
            } else {
                return -1;
            }
        }

        nleft -= nwriten;
        ptr += nwriten;
    }
    return n;
}

void str_cli(FILE *fp, int sockfd)
{
    pid_t pid;
    char sendbuf[BUF_LEN], recvbuf[BUF_LEN];

    if((pid = fork()) ==0) {
        while(read(sockfd, recvbuf, BUF_LEN) > 0) {
            fputs(recvbuf, stdout);
            bzero(recvbuf, BUF_LEN);
        }
        kill(getpid(), SIGTERM);
        exit(0);
    }

    while(fgets(sendbuf, BUF_LEN, fp) != NULL) {
        writen(sockfd, sendbuf, strlen(sendbuf));
        bzero(sendbuf, BUF_LEN);
    }
    shutdown(sockfd, SHUT_WR);
    pause();
    return;
}

int main(int argc, char **argv)
{
    int fd;
    struct sockaddr_in servaddr;

    fd = socket(AF_INET, SOCK_STREAM, 0);

    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = inet_addr(SERV_ADDR);
    servaddr.sin_port = htons(SERV_PORT);

    if (connect(fd, (struct sockaddr *)&servaddr, sizeof(servaddr)) == -1) {
        printf("connect error: %s\n", strerror(errno));
        return 0;
    }

    str_cli(stdin, fd);
    return 0;
}



 

要点:

父子进程共享一个套接口，父进程写，子进程读。尽管套接口只有一个，接收区缓冲和发送区缓冲也分别只有一个，但却有两个描述字在引用它。