linux c select函数使用求解释

时间:2023-01-07 11:01:12

      代码非常easy,就是发送c语言发送http请求。但 i= read(sockfd, buf, BUFSIZE-1); 能够正常执行, 

替换为i= Read(sockfd, buf, BUFSIZE-1);后程序退出,不知什么原因,求解答。

#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <time.h>
#include <errno.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <arpa/inet.h> #define IPSTR "180.97.33.107"
#define PORT 80
#define BUFSIZE 1024 * 1024 * 2 int Read(int fd, char *buf, int count) {
int nread, totlen = 0; while (totlen != count) {
nread = read(fd, buf, count - totlen);
if (nread == 0)
return totlen;
if (nread == -1)
return -1;
totlen += nread;
buf += nread;
}
return totlen;
} int main(int argc, char **argv)
{
int sockfd, ret, i, h;
struct sockaddr_in servaddr;
char str1[4096], buf[BUFSIZE];
socklen_t len;
fd_set t_set1;
struct timeval tv; if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 ) {
printf("---socket error!\n");
exit(0);
}; bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(PORT);
if (inet_pton(AF_INET, IPSTR, &servaddr.sin_addr) <= 0 ){
printf("--inet_pton error!\n");
exit(0);
}; if (connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0){
printf("connect error!\n");
exit(0);
} memset(str1, 0, 4096);
strcat(str1, "GET / HTTP/1.1\n");
strcat(str1, "Host: www.baidu.com\n");
strcat(str1, "\n\n");
printf("%s",str1); ret = write(sockfd,str1,strlen(str1));
if (ret < 0) {
printf("errno = %d strerror = %s\n",errno, strerror(errno));
exit(0);
}else{
printf("send %d size\n", ret);
} FD_ZERO(&t_set1);
FD_SET(sockfd, &t_set1); while(1){
tv.tv_sec= 2;
tv.tv_usec= 0;
h= 0;
printf("--------------->1\n");
h= select(sockfd +1, &t_set1, NULL, NULL, &tv);
printf("--------------->2\n"); printf("h =================== %d\n", h);
//if (h == 0) continue;
if (h < 0) {
close(sockfd);
printf("select error \n");
return -1;
} if (h > 0){
memset(buf, 0, BUFSIZE);
i= read(sockfd, buf, BUFSIZE-1);
//i= Read(sockfd, buf, BUFSIZE-1);
printf("i ========================== %d", i);
if (i==0){
close(sockfd);
printf("stop .................\n");
return -1;
}
printf("%s\n", buf);
}
}
close(sockfd);
return 0;
}