linux socket网络编程：fcntl select（多个客户端连接服务器端情形）的代码

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fcntl select（多个客户端连接服务器端情形）的代码，希望能对大家有所好处。



#include <sys/types.h>  
#include <sys/socket.h>  
#include <sys/wait.h>  
#include <stdio.h>  
#include <stdlib.h>  
#include <errno.h>  
#include <string.h>  
#include <sys/un.h>  
#include <sys/time.h>  
#include <sys/ioctl.h>  
#include <unistd.h>  
#include <netinet/in.h>  
#include <fcntl.h>  
#include <unistd.h>  
  
#define SERVPORT 3333  
#define BACKLOG 10  
#define MAX_CONNECTED_NO 10  
#define MAXDATASIZE 100  
  
int main()  
{  
    struct sockaddr_in server_sockaddr,client_sockaddr;  
    int sin_size,recvbytes,flags;  
    int sockfd,client_fd;  
    char buf[MAXDATASIZE];  
    if((sockfd = socket(AF_INET,SOCK_STREAM,0))==-1){  
        perror("socket");  
        exit(1);  
    }  
    printf("socket success!,sockfd=%dn",sockfd);  
  
    server_sockaddr.sin_family=AF_INET;  
    server_sockaddr.sin_port=htons(SERVPORT);  
    server_sockaddr.sin_addr.s_addr=INADDR_ANY;  
    bzero(&(server_sockaddr.sin_zero),8);  
  
        perror("bind");  
        exit(1);  
    }  
    printf("bind success!n");  
  
    if(listen(sockfd,BACKLOG)==-1){  
        perror("listen");  
        exit(1);  
    }  
    printf("listening....n");  
  
    if((flags=fcntl( sockfd, F_SETFL, 0))<0)  
            perror("fcntl F_SETFL");  
        flags |= O_NONBLOCK;  
        if(fcntl( sockfd, F_SETFL,flags)<0)  
            perror("fcntl");  
    while(1){  
        sin_size=sizeof(struct sockaddr_in);  
            perror("accept");  
            exit(1);  
        }  
        if((recvbytes=recv(client_fd,buf,MAXDATASIZE,0))==-1){  
            perror("recv");  
            exit(1);  
        }  
        if(read(client_fd,buf,MAXDATASIZE)<0){  
            perror("read");  
            exit(1);  
        }  
        printf("received a connection :%s",buf);  
  
    close(client_fd);  
    exit(1);  
}  



                                
                        
                                
运行该程序：[root@localhostnet]#./fcntlsocketsuccess!,sockfd=3bindsuccess!listening....accept:Resourcetemporarilyunavailable可以看到，当accept的资源不可用时，程序会自动返回。若将红色加粗代码替换为：
                                
                        
                                

  if((flags=fcntl( sockfd, F_SETFL, 0))<0)  
            perror("fcntl F_SETFL");  
        flags |= O_ASYNC;
        if(fcntl( sockfd, F_SETFL,flags)<0)  
            perror("fcntl");

                                
                        
                                
运行结果如下：[root@localhostnet]#./fcntl1socketsuccess!,sockfd=3bindsuccess!listening...可以看到，进程一直处于等待中，直到另一相关信号驱动它为止。三、select
                                
                        
                                


#include <sys/types.h>  
#include <sys/socket.h>  
#include <sys/wait.h>  
#include <stdio.h>  
#include <stdlib.h>  
#include <errno.h>  
#include <string.h>  
#include <sys/un.h>  
#include <sys/time.h>  
#include <sys/ioctl.h>  
#include <unistd.h>  
#include <netinet/in.h>  
#define SERVPORT 3333  
#define BACKLOG 10  
#define MAX_CONNECTED_NO 10  
#define MAXDATASIZE 100  
int main()  
{  
    struct sockaddr_in server_sockaddr,client_sockaddr;  
    int sin_size,recvbytes;  
    fd_set readfd;  
    fd_set writefd;  
    int sockfd,client_fd;  
    char buf[MAXDATASIZE];  
    if((sockfd = socket(AF_INET,SOCK_STREAM,0))==-1){  
        perror("socket");  
        exit(1);  
    }  
    printf("socket success!,sockfd=%dn",sockfd);  
    server_sockaddr.sin_family=AF_INET;  
    server_sockaddr.sin_port=htons(SERVPORT);  
    server_sockaddr.sin_addr.s_addr=INADDR_ANY;  
    bzero(&(server_sockaddr.sin_zero),8);  
        perror("bind");  
        exit(1);  
    }  
    printf("bind success!n");  
    if(listen(sockfd,BACKLOG)==-1){  
        perror("listen");  
        exit(1);  
    }  
    printf("listening....n");  
    while(1){  
    sin_size=sizeof(struct sockaddr_in);  
                perror("accept");  
                exit(1);  
            }  
            if((recvbytes=recv(client_fd,buf,MAXDATASIZE,0))==-1){  
                perror("recv");  
                exit(1);  
            }  
            if(read(client_fd,buf,MAXDATASIZE)<0){  
                perror("read");  
                exit(1);  
            }  
            printf("received a connection :%s",buf);  
        close(client_fd);  
}  

                                
                        
                                
运行结果如下：[root@localhostnet]#gccselect1.c-oselect1[root@localhostnet]#./select1socketcreatesuccess!bindsuccess!listening...