Midterm ex6

Please add a signal handler to the above server so that there won't be any zombie process.

/* 修改 ex5 部分用藍色表示 */

//-------------------------------------------------------------------------------------------
//tcpcli01.c
#include "unp.h"

struct ans
{
　int answer;
};

void　guess(FILE *fp, int sockfd)
{
　char sendline[MAXLINE], recvline[MAXLINE];
　struct ans ans;

　printf("Please guess a number between 1 and 100:\n");
　do {
　　if (Fgets(sendline, MAXLINE, fp) != NULL) {
　　　if (sscanf(sendline, "%d", &ans.answer)!=1)
　　　　printf("Invalid input: %s", sendline);
　　　else if (ans.answer>100 || ans.answer<1) sockfd =" Socket(AF_INET," sin_family =" AF_INET;" sin_port =" htons(SERV_PORT);" style="color: rgb(0, 153, 0);">/* do it all */
　exit(0);
}
//-------------------------------------------------------------------------------------------


//------------------------------------------------------------------------------------------- //tcpserv01.c
#include "unp.h"

struct ans
{
　int answer;
};

void　sig_chld(int signo)
{
　pid_t pid;
　int stat;

　while ( (pid = waitpid(-1, &stat, WNOHANG)) > 0)
　　printf("child %d terminated\n", pid);
　return;
}

void　retrt(int sockfd)
{
　char buf[MAXLINE];
　ssize_t n;
　struct ans ans;
　int result;

　srand(time(NULL));
　result=rand()%100+1;
　printf("The answer is %d\n",result);
　do {
　　if ( (n = Readn(sockfd, &ans, sizeof(ans))) == 0)
　　　return; /* connection closed by other end */
　　if (ans.answer>result) strcpy(buf,"Guess a smaller number!\n");
　　else if (ans.answer
　　else strcpy(buf,"You got the answer!\n");
　　Writen(sockfd, buf, strlen(buf));
　} while (strcmp(buf,"You got the answer!\n")!=0);
}

int　main(int argc, char **argv)
{
　int listenfd, connfd;
　pid_t childpid;
　socklen_t clilen;
　struct sockaddr_in cliaddr, servaddr;

　listenfd = Socket(AF_INET, SOCK_STREAM, 0);

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

　Bind(listenfd, (SA *) &servaddr, sizeof(servaddr));

　Listen(listenfd, LISTENQ);

　Signal(SIGCHLD, sig_chld);
　
　for ( ; ; ) {
　　clilen = sizeof(cliaddr);
　　connfd = Accept(listenfd, (SA *) &cliaddr, &clilen);

　　if ( (childpid = Fork()) == 0) { /* child process */
　　　Close(listenfd); /* close listening socket */
　　　retrt(connfd); /* process the request */
　　　exit(0);
　　}
　　
　　Close(connfd); /* parent closes connected socket */
　}
}
//-------------------------------------------------------------------------------------------