/*
 * $Header: /afs/sipb.mit.edu/project/sipb-athena/repository/src/moira/gdb/gdb_fserv.c,v 1.2 1994/08/07 19:02:49 svalente Exp $
 */

#ifndef lint
static char *rcsid_gdb_fserv_c = "$Header: /afs/sipb.mit.edu/project/sipb-athena/repository/src/moira/gdb/gdb_fserv.c,v 1.2 1994/08/07 19:02:49 svalente Exp $";
#endif	lint


/************************************************************************
 *	
 *			   gdb_fserv.c
 *	
 *	      GDB - Routines to implement forking servers.
 *	
 *	Author: Noah Mendelsohn
 *	Copyright: 1986 MIT Project Athena 
 *		For copying and distribution information, please see
 *	  	the file <mit-copyright.h>.
 *	
 ************************************************************************/

#include <mit-copyright.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <sys/signal.h>
#include "gdb.h"
#include <sys/resource.h>


/************************************************************************
 *	
 *			create_forking_server (create_forking_server)
 *	
 *	Called by an application to turn itself into a forking model
 *	server.  Returns from this routine occur only in the forked
 *	children.  The parent lives in this routine forever, waiting
 *	for incoming connection requests and doing the appropriate
 *	forking.
 *	
 *	Children are expected to do their own cleanup, but this routine
 *	does do the work of reaping the resulting zombie processes.
 *	
 *	ARGUMENTS:
 *	----------
 *	
 *		service-id	identifies the port to be used for
 *				listening.  Same rules as for
 *				create_listening_connection.
 *	
 *		validate-rtn	pointer to a function to be called to
 *				validate the incoming client.  Should
 *				return TRUE if client is acceptable,
 *				else false.  If this is NULL, all clients
 *				are accepted.
 *	
 *	GLOBAL VARIABLES
 *	----------------
 *	
 *	Children created by this routine inherit the global variables
 *	gdb_sockaddr_of_client, which is of type sockaddr_in and 
 *	gdb_socklen, which is the returned length of the sockaddr.
 *	These are the Berkeley identifiers of the clients as accepted.
 *	Use of this interface is non-portable to other than Berkeley 
 *	systems.
 *	
 *	The client's request tuple may be found in gdb_client_tuple.
 *	
 ************************************************************************/


CONNECTION
create_forking_server(service, validate)
char *service;
int (*validate)();
{
	void start_accepting_client();
	CONNECTION incoming;			/* listen for incoming */
						/* children here */
	CONNECTION client = NULL;		/* connection to client */
						/* is created here */
	OPERATION listenop;			/* used to asynchronously */
						/* listen for a child */
						/* connection request */
	GDB_INIT_CHECK

	/*----------------------------------------------------------*/
	/*	
	/*	Set up parent execution environment
	/*	
	/*----------------------------------------------------------*/

	g_do_signals();				/* set up signal handling */

	incoming = create_listening_connection(service);
	if (incoming == NULL || connection_status(incoming) != CON_UP)
		GDB_GIVEUP("create_forking_server: can't create listening connection")

	/*----------------------------------------------------------*/
	/*	
	/*	Repeatedly listen for incoming
	/*	
	/*----------------------------------------------------------*/

	listenop = create_operation();
	while (TRUE) {
		gdb_socklen = sizeof(gdb_sockaddr_of_client);
		client = NULL;
		(void) start_accepting_client(incoming, listenop, &client, 
				       gdb_sockaddr_of_client, &gdb_socklen,
				       &gdb_client_tuple);
		if(complete_operation(listenop) != OP_COMPLETE ||
		   client == NULL) {
		    gdb_perror("GDB create_forking_server: failed to accept client");
		    reset_operation(listenop);
		    (void) sever_connection(client);
		    continue;
		  }
		

                /*
                 * Call the validate routine, if it fails, 
                 * refuse the client.
                 */
		if (validate != NULL && !(*validate)()) {
			reset_operation(listenop);
			start_replying_to_client(listenop, client, 
						 GDB_REFUSED, "","");
			(void) complete_operation(listenop); 
			reset_operation(listenop);
			(void) sever_connection(client);
			continue;			
		}
                /*
                 * Create  the child for this client
                 */
		if ((gdb_Debug & GDB_NOFORK) || fork() == 0) {
                       /*
                        * This is the child, or we're in noforking
                        * debug mode.
                        */
			reset_operation(listenop);
			start_replying_to_client(listenop, client, 
						 GDB_ACCEPTED, "","");
			if (complete_operation(listenop) != OP_COMPLETE) 
				exit(8);
			return client;		/* return to application */
						/* program */
		}
               /*
                * Still in the parent
                */
		(void) sever_connection(client);
		reset_operation(listenop);
	}
}

/************************************************************************/
/*	
/*				gdb_reaper
/*	
/*	Called on SIGCHILD to reap all dead children.
/*	
/************************************************************************/
#ifndef POSIX
int
#else
void
#endif
gdb_reaper()
{
#ifdef POSIX
	int status;
	while (waitpid(-1, &status, WNOHANG) >0);
#else
	union wait status;
	while (wait3(&status, WNOHANG, (struct rusage *)0) >0);
#endif
}

/************************************************************************/
/*	
/*				g_do_signals
/*	
/*	Set up signal handling for a forking server.
/*	
/************************************************************************/

int
g_do_signals()
{
#ifdef POSIX
    struct sigaction act;

    act.sa_handler = gdb_reaper;
    sigemptyset(&act.sa_mask);
    act.sa_flags = 0;
    (void) sigaction(SIGCHLD, &act, (struct sigaction *)0);
#else /* sun */
    (void) signal(SIGCHLD, gdb_reaper);
#endif 
}