sktfork.c

Porting the Simple Sockets Library Dr. Charles E. Campbell, Jr.

/* sktfork.c: this program illustrates use of fork under Unix SysV with a
 *            simple server.
 */
#include <stdio.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>
#include "xtdio.h"
#include "sockets.h"

/* ------------------------------------------------------------------------
 * Definitions:
 */
#define BUFSIZE	256

/* ------------------------------------------------------------------------
 * Globals:
 */
int childstat= 0;

/* ------------------------------------------------------------------------
 * Prototypes:
 */
int main( int, char **);      /* sktfork.c       */
void sigchld_handler(void);   /* sktfork.c       */

/* ------------------------------------------------------------------------
 * Source Code:
 */

/* main: */
int main(
  int    argc,
  char **argv)
{
int     sktcnt=0;
int     istat;
int     ret;
Socket *srvr;
Socket *nskt;

if(argc <= 1) {
	fprintf(stderr,"***usage*** sktfork srvrname\n");
	exit(1);
	}

srvr= Sopen(argv[1],"s");
if(!srvr) {
	fprintf(stderr,"***error*** unable to open <%s> server\n",argv[1]);
	exit(1);
	}

/* install a SIGCHLD handler */
sigset(SIGCHLD,sigchld_handler);

while(1) {
	printf("Wait for new socket to be accepted\n");
	nskt= Saccept(srvr);
	if(!nskt) {	/* presumably I just got a SIGCHLD */
		printf("WEXITSTATUS(childstat=%d)=%d\n",childstat,WEXITSTATUS(childstat));
		if(WEXITSTATUS(childstat) == 1) break;
		continue;
		}
	else {
		++sktcnt;
		printf("normal new skt: sktcnt=%d\n",sktcnt);
		}
	ret= fork();

	if(ret == 0) {
		/* child process */
		char    buf[BUFSIZE];
		Socket *skt;

		printf("child() skt<%s>",Sprtskt(nskt));
		skt = nskt;
		nskt= NULL;

		if(!Sgets(buf,BUFSIZE,skt)) {
			fprintf(stderr,"***error*** unable to Sgets\n");
			_exit(0);
			}
		Sputs("goodbye!",skt);
		printf("got <%s>, goodbye!\n",buf);
		Sclose(skt);
		skt= NULL;

		if(!strcmp(buf,"Q")) {
			printf("return: child 1");
			_exit(1);
			}
		printf("return: child 0");
		_exit(0);
		}

	else if(ret == -1) {
		fprintf(stderr,"***error*** unable to fork\n");
		if(nskt) Sclose(nskt);
		if(srvr) Sclose(srvr);
		srvr= nskt= NULL;
		break;
		}
	}

printf("closing down server: sktcnt=%d\n",sktcnt);
if(srvr) Sclose(srvr);
srvr= NULL;

return 0;
}

/* --------------------------------------------------------------------- */

/* sigchld_handler: this function */
void sigchld_handler()
{
wait(&childstat);
}

/* --------------------------------------------------------------------- */