linux下使用select异步IO模式实现客户端
【linux下使用select异步IO模式实现客户端】目的：使用select fd_set FD_SET FD_ISSET FD_ZERO
#include// memset
#include
#include
#include
#ifdef HAVE_NETINET_IN_H
#include
#endif#define ERR_EXIT(m)\
do\
{\
perror(m);
\
exit(EXIT_FAILURE);
\
}while(0)struct packet
{
int len;
char buf[1024];
};
ssize_t readn(int fd,void *buf,size_t count)
{
size_t nleft = count;
ssize_t nread;
char *bufp = (char*)buf;
while(nleft>0)
{
nread = read(fd,bufp,nleft);
if(nread <0)
{
if(errno = EINTR)
{
return -1;
}
}
else if(nread == 0)
{
break;
}
else
{
bufp += nread;
nleft -= nread;
}}
}ssize_t written(int fd,void *buf,size_t count)
{
//printf("%d",count);
size_t nleft = count;
ssize_t nwritten;
char *bufp = (char*)buf;
//fputs(bufp,stdout);
while(nleft>0)
{
nwritten = write(fd,bufp,nleft);
if(nwritten <0)
{
if(errno = EINTR)
{
return -1;
}
}
else if(nwritten == 0)
{
continue;
}
else
{
bufp += nwritten;
nleft= nleft -nwritten;
//printf("%d",nleft);
}}
}
ssize_t recv_peek(int sockfd,void *buf,size_t len)
{
while(1)
{
int ret = recv(sockfd,buf,len,MSG_PEEK);
if(ret == -1 && errno==EINTR)
{
continue;
}
else
{
return ret;
}
}
}ssize_t readline(int sockfd,void *buf,size_t maxline)
{
int ret;
int nread;
char *bufp =(char*)buf;
int nleft = maxline;
while(1)
{
ret = recv_peek(sockfd,bufp,nleft);
if(ret < 0)
{
return ret;
}
else if(ret ==0)
{
return ret;
}
else
{
nread = ret;
int i;
for(i=0;
i nleft)
{
exit(EXIT_FAILURE);
}
nleft -= nread;
ret = readn(sockfd,bufp,nread);
if(ret != nread)
{
exit(EXIT_FAILURE);
}bufp += nread;
}
return -1;
}}int main(void)
{
int sock;
if((sock =socket(PF_INET,SOCK_STREAM,IPPROTO_TCP))<0)
{
ERR_EXIT("ERROR");
}
struct sockaddr_in servaddr;
memset(&servaddr,0,sizeof(servaddr));
servaddr.sin_family=AF_INET;
servaddr.sin_port = htons(5188);
servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");
if(connect(sock,(struct sockaddr*)&servaddr,sizeof(servaddr))< 0)
{
ERR_EXIT("connect");
}
fd_set rset;
FD_ZERO(&rset);
int nready;
int maxfd;
int fd_stdin = fileno(stdin);
if(fd_stdin > sock)
maxfd = fd_stdin;
else
maxfd = sock;
char sendbuf[1024] ={0};
char recvbuf[1024] ={0};
while(1)
{
FD_SET(fd_stdin,&rset);
FD_SET(sock,&rset);
nready = select(maxfd+1,&rset,NULL,NULL,NULL);
if(nready ==-1)
ERR_EXIT("SELECT");
if(nready==0)
continue;
if(FD_ISSET(sock,&rset))
{
int ret = readline(sock,recvbuf,sizeof(recvbuf));
if(ret == -1)
ERR_EXIT("readline");
else if(ret ==0)
{
printf("server close\n");
break;
}
fputs(recvbuf,stdout);
memset(recvbuf,0,sizeof(recvbuf));
}
if(FD_ISSET(fd_stdin,&rset))
{
if( fgets(sendbuf,sizeof(sendbuf),stdin)==NULL)
break;
written(sock,sendbuf,strlen(sendbuf));
memset(sendbuf,0,sizeof(sendbuf));
}
}return 0;
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