From owner-freebsd-hackers Mon Feb 24 10:40: 0 2003 Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 7E39237B401 for ; Mon, 24 Feb 2003 10:39:55 -0800 (PST) Received: from ghostwheel.tribble.net (ghostwheel.tribble.net [198.49.247.40]) by mx1.FreeBSD.org (Postfix) with ESMTP id BB10743FAF for ; Mon, 24 Feb 2003 10:39:54 -0800 (PST) (envelope-from gder@ghostwheel.tribble.net) Received: from ghostwheel.tribble.net (gder@localhost.tribble.net [127.0.0.1]) by ghostwheel.tribble.net (8.12.6/8.12.6) with ESMTP id h1OIdrOq081337 for ; Mon, 24 Feb 2003 11:39:53 -0700 (MST) (envelope-from gder@ghostwheel.tribble.net) Received: (from gder@localhost) by ghostwheel.tribble.net (8.12.6/8.12.7/Submit) id h1OIdrr8081336 for freebsd-hackers@freebsd.org; Mon, 24 Feb 2003 11:39:53 -0700 (MST) Date: Mon, 24 Feb 2003 11:39:53 -0700 From: G-der To: freebsd-hackers@freebsd.org Subject: Properly reaping children from a fork() Message-ID: <20030224183953.GB80651@gder.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4i Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG I wasn't sure which group to send this too but -hackers seemed more appropriate than -questions. I've started to play with sockets under FreeBSD and have created a very simple server. All it does is listens (on port 2525 by default) and when it receives a connection fork()s. The only purpose it is accept a string, print it to stdout along with the number of bytes received. This is a first attempt for me but I seem to have problems when it comes to ensuring that all the children exit like they should. What happens is that each child process remains in a zombied state (as seen through ps). Also if you check sockstat you can see that each zombied process still has a connection open. I'm not sure if the problem is how I am trying to close the socket or if it is with my signal handling. I'm currently reading through intro(2) to see if there is something simple I've missed. I've attached the code for your enjoyment...I'm sure someone will be able to point out my mistake pretty quickly. Also I've found a couple of web pages that kind of explain socket handling but am looking for other resources that I can consult. Thanks in advance, I'm not a normal subscriber to -hackers so a cc to gder@gder.net would be appreciated. Regards Gene Dinkey gder@gder.net --CUT HERE-- #include #include #include #include #include #include #include #include #define MYPORT 2525 #define MAXRECV 5 #define MAXBUFSIZE 50 int main ( void ); int establish ( unsigned short portnum ); int get_connect ( int sockfd ); int get_data ( int sockfd ); void sigchld_handler ( int s ); int main ( void ) { int s; // struct sigaction sa; if ((s=establish(MYPORT)) < 0) //establish the socket exit(-1); s = get_connect(s); //wait for a connection /* The commented code was supposed to reap the children in but it didn't the call to signal() is supposed to do the same thing, but it doesn't */ /* sa.sa_handler = sigchld_handler; sigemptyset(&sa.sa_mask); sa.sa_flags = SA_RESTART; if (sigaction(SIGCHLD, &sa, NULL) == -1) { perror("main:sigaction"); exit(-1); } */ signal(SIGCHLD, sigchld_handler); if (s != -1) { get_data(s); // get the incoming data close(s); // finally close the socket } exit(0); } /*handles zombied processes*/ void sigchld_handler ( int s ) { while(waitpid(-1, NULL, WNOHANG) > 0); } /* Establishses a socket and starts to listen */ int establish ( unsigned short portnum ) { int sockfd; struct sockaddr_in my_addr; if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) { //establish the socket perror("establish:socket"); return(-1); } /* host information */ my_addr.sin_family = AF_INET; my_addr.sin_port = htons(portnum); my_addr.sin_addr.s_addr = htonl(INADDR_ANY); memset(&(my_addr.sin_zero), '\0', 8); /* bid the socket to a port */ if (bind(sockfd, (struct sockaddr *) &my_addr, sizeof(struct sockaddr)) < 0) { perror("establish:bind"); return(-1); } /* finally tell the socket to start listening */ if (listen(sockfd, MAXRECV) < 0) { perror("establish:listen"); close(sockfd); return(-1); } return(sockfd); // return the socket handler } /*accepts connections*/ int get_connect ( int sockfd ) { int sin_size, new_fd; struct sockaddr_in their_addr; sin_size = sizeof(struct sockaddr_in); for(;;) { //begin the accept loop /* accept the new connection and get the new socket id */ if ((new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size)) < 0) { perror("get_connect:accept"); return(-1); } printf("Server got connection\n"); /* fork the new connection */ if(!fork()) { close(sockfd); // close the listener, child doesn't need it return(new_fd); // return the new active socket } } return(-1); } /*gets some data and prints it out*/ int get_data ( int sockfd ) { char buffer[MAXBUFSIZE]; int datain; for (;;) { //begin the retreival loop /* get the incoming data and check a few things */ if ((datain = recv(sockfd, buffer, MAXBUFSIZE, 0)) < 0) { perror("get_data:recv"); return(-1); } else if (datain > 0) { //print number of bytes received printf("Received %d bytes\n", datain); buffer[datain] = '\0'; } else if (datain == 0) //if 0 then return and close the socket return(0); printf("%s", buffer); //otherwise print the buffer } return(0); } --EOF-- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message