多進程服務端

多進程的服務端，在主進程裏面調用accept操作，由於fork創建的子進程與主進程擁有相同的內存空間，也就是服務端和客戶端的套接字描述符在子進程的內存空間裏面存在相同的一份拷貝，因此，子進程的處理函數首先就要關閉服務端的套接字描述符，避免多個描述符指向同一個套接字，然後再做相關的操作，代碼如下所示：

include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd,h>
#include<signal.h>
#include<sys/wait.h>
#include<arpa/inet.h>
#include<sys/socket.h>


#define BUF_SIZE 30

void error_handing(char* message);
void read_childproc(int sig);

int main(int argc,char* argv[])
{
    int serv_lock,clnt_sock;
    struct sockaddr_in serv_adr,clnt_adr;
    
    pid_t pid;

    struct sigaction act;
    socklen_t adr_sz;
    int str_len,state;
    char buf[BUF_SIZE];
    if(argc!=2)
    {
        printf("Usage :%s <port> \n",argc[0]);
        exit(1);
    }
    act.sa_handler = read_childproc;
    sigemptyset(&act.sa_mask);
    act.sa_flags = 0;
    state = sigaction(SIGCHLD,&act,0);
    serv_sock = socket(PF_INET,SOCK_STREAM,0);   // create a socket
    memset(&serv_adr,0,sizeof(serv_adr));    //initialize memory
    serv_adr,sin_family = AF_INET;
    serv_adr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_adr,sin_port = htons(atoi(argv[1]));

    if(bind(serv_sock,(struct   sockaddr*)&serv_adr,sizeof()serv_adr))==-1)
        error_handling("bind() error");
    if(listen(serv_sock,5)==-1)
        error_handling("listen() error");

    while(1)
    {
        adr_sz = sizeof(clnt_adr);
        clnt_sock = accept(serv_sock,(struct sockaddr*)&clnt_adr,&adr_sz);
        if(clnt_sock == -1)
            continue;
        else
            puts("new client connected...");
        pid = fork();
        if(pid == -1)
        {
            close(clnt_sock);
            continue;
        }
        if(pid == 0)
        {
            close(serv_sock);
            while(str_len = read(clnt_sock,buf,BUF_SIZE)!=0)
                write(clnt_sock,buf,str_len);
            close(clnt_sock);
        }
    } 
    close(serv_sock);
    return 0;
}


void read_childproc(int sig)
{
    pid_t pid;
    int status;
    pid =waitpid(-1,&status,WNOHANG);
    printf("removed proc id: %d \n",pid);
}

void error_handling(char* message)
{
    fputs(message,stderr);
    fputc('\n',stderr);
    exit(1);
}