/*
 * xdm - display manager daemon
 *
 * $XConsortium: dm.c,v 1.18 89/09/08 14:34:00 keith Exp $
 *
 * Copyright 1988 Massachusetts Institute of Technology
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose and without fee is hereby granted, provided
 * that the above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation, and that the name of M.I.T. not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  M.I.T. makes no representations about the
 * suitability of this software for any purpose.  It is provided "as is"
 * without express or implied warranty.
 *
 * Author:  Keith Packard, MIT X Consortium
 */

/*
 * display manager
 */

# include	<stdio.h>
# include	<X11/Xos.h>
# include	<sys/signal.h>
# include	<sys/stat.h>
# include	<varargs.h>
# include	"dm.h"

extern void	exit (), abort ();

static void	RescanServers ();
int		Rescan;
static long	ServersModTime, ConfigModTime;
static void	TerminateAll (), RescanNotify ();

#ifndef NOXDMTITLE
static char *Title;
static int TitleLen;
#endif

main (argc, argv)
int	argc;
char	**argv;
{
#ifndef SYSV
    void	ChildNotify ();
#endif

#ifndef NOXDMTITLE
    Title = argv[0];
    TitleLen = (argv[argc - 1] + strlen(argv[argc - 1])) - Title;
#endif

    /*
     * Step 1 - load configuration parameters
     */
    InitResources (argc, argv);
    LoadDMResources ();
    if (debugLevel == 0 && daemonMode)
	    BecomeDaemon ();
    CreateWellKnownSockets ();
    InitErrorLog ();
    StorePid ();
    (void) signal (SIGTERM, TerminateAll);
    (void) signal (SIGINT, TerminateAll);
    /*
     * Step 2 - Read /etc/Xservers and set up
     *	    the socket.
     *
     *	    Keep a sub-daemon running
     *	    for each entry
     */
    ScanServers ();
    StartDisplays ();
    (void) signal (SIGHUP, RescanNotify);
#ifndef SYSV
    (void) signal (SIGCHLD, ChildNotify);
#endif
    while (AnyWellKnownSockets() || AnyDisplaysLeft ())
    {
	if (Rescan)
	{
	    RescanServers ();
	    Rescan = 0;
	}
#ifdef SYSV
	WaitForChild ();
#else
	WaitForSomething ();
#endif
    }
    Debug ("Nothing left to do, exiting\n");
}

static void
RescanNotify ()
{
    void	RescanNotify ();

    Debug ("Caught SIGHUP\n");
    Rescan = 1;
#ifdef SYSV
    signal (SIGHUP, RescanNotify);
#endif
}

ScanServers ()
{
    char	lineBuf[10240];
    int		len;
    FILE	*serversFile;
    struct stat	statb;
    static DisplayType	acceptableTypes[] =
	    { { Local, Permanent, FromFile },
	      { Foreign, Permanent, FromFile },
	    };

#define NumTypes    (sizeof (acceptableTypes) / sizeof (acceptableTypes[0]))

    if (servers[0] == '/')
    {
	serversFile = fopen (servers, "r");
	if (serversFile == NULL)
 	{
	    LogError ("cannot access servers file %s\n", servers);
	    return;
	}
	if (ServersModTime == 0)
	{
	    fstat (fileno (serversFile), &statb);
	    ServersModTime = statb.st_mtime;
	}
	while (fgets (lineBuf, sizeof (lineBuf)-1, serversFile))
	{
	    len = strlen (lineBuf);
	    if (lineBuf[len-1] == '\n')
		lineBuf[len-1] = '\0';
	    ParseDisplay (lineBuf, acceptableTypes, NumTypes);
	}
	fclose (serversFile);
    }
    else
    {
	ParseDisplay (lineBuf, acceptableTypes, NumTypes);
    }
}

static void
MarkDisplay (d)
struct display	*d;
{
    d->state = MissingEntry;
}

static void
RescanServers ()
{
    Debug ("rescanning servers\n");
    LogInfo ("Rescanning both config and servers files\n");
    ForEachDisplay (MarkDisplay);
    ReinitResources ();
    LoadDMResources ();
    ScanServers ();
    StartDisplays ();
}

static
RescanIfMod ()
{
    struct stat	statb;

    if (stat (config, &statb) != -1)
    {
	if (statb.st_mtime > ConfigModTime)
	{
	    Debug ("Config file %s has changed, rereading\n", config);
	    LogInfo ("Rereading configuration file %s\n", config);
	    ConfigModTime = statb.st_mtime;
	    ReinitResources ();
	    LoadDMResources ();
	}
    }
    if (servers[0] == '/' && stat(servers, &statb) != -1)
    {
	if (statb.st_mtime > ServersModTime)
	{
	    Debug ("Servers file %s has changed, rescanning\n", servers);
	    LogInfo ("Rereading servers file %s\n", servers);
	    ServersModTime = statb.st_mtime;
	    ForEachDisplay (MarkDisplay);
	    ScanServers ();
	}
    }
    
}

/*
 * catch a SIGTERM, kill all displays and exit
 */

static void
TerminateAll ()
{
    void    TerminateDisplay ();

    DestroyWellKnownSockets ();
    ForEachDisplay (TerminateDisplay);
}

/*
 * notice that a child has died and may need another
 * sub-daemon started
 */

int	ChildReady;

void
ChildNotify ()
{
    ChildReady = 1;
}

WaitForChild ()
{
    int		pid;
    struct display	*d;
    waitType	status;
    int		mask;

#ifdef SYSV
    /* XXX classic sysV signal race condition here with RescanNotify */
    if ((pid = wait (&status)) != -1)
#else
    mask = sigblock (sigmask (SIGCHLD) | sigmask (SIGHUP));
    Debug ("signals blocked, mask was 0x%x\n", mask);
    if (!ChildReady && !Rescan)
	sigpause (mask);
    ChildReady = 0;
    sigsetmask (mask);
    while ((pid = wait3 (&status, WNOHANG, (struct rusage *) 0)) > 0)
#endif
    {
	Debug ("Manager wait returns pid: %d\n", pid);
	if (autoRescan)
	    RescanIfMod ();
	d = FindDisplayByPid (pid);
	if (d) {
	    d->status = notRunning;
	    switch (waitVal (status)) {
	    case UNMANAGE_DISPLAY:
		Debug ("Display exited with UNMANAGE_DISPLAY\n");
		RemoveDisplay (d);
		break;
	    case OBEYSESS_DISPLAY:
		Debug ("Display exited with OBEYSESS_DISPLAY\n");
		if (d->displayType.lifetime != Permanent)
		    RemoveDisplay (d);
		break;
	    default:
		Debug ("Display exited with unknown status %d\n", waitVal(status));
		break;
	    case REMANAGE_DISPLAY:
		Debug ("Display exited with REMANAGE_DISPLAY\n");
		break;
	    }
	}
    }
    StartDisplays ();
}

static void
CheckDisplayStatus (d)
struct display	*d;
{
    void	TerminateDisplay ();

    if (d->displayType.origin == FromFile)
    {
	switch (d->state) {
	case MissingEntry:
	    TerminateDisplay (d);
	    break;
	case NewEntry:
	    d->state = OldEntry;
	case OldEntry:
	    if (d->status == notRunning)
		StartDisplay (d);
	    break;
	}
    }
}

StartDisplays ()
{
    ForEachDisplay (CheckDisplayStatus);
}

StartDisplay (d)
struct display	*d;
{
    int	pid;

    Debug ("StartDisplay %s\n", d->name);
    switch (pid = fork ())
    {
    case 0:
	CleanUpChild ();
	LoadDisplayResources (d);
	if (d->authName)
		d->authNameLen = strlen (d->authName);
	ManageDisplay (d);
	exit (REMANAGE_DISPLAY);
    case -1:
	break;
    default:
	Debug ("pid: %d\n", pid);
	d->pid = pid;
	d->status = running;
	break;
    }
}

void
TerminateDisplay (d)
struct display	*d;
{
    DisplayStatus	status;
    int		pid;

    status = d->status;
    pid = d->pid;
    RemoveDisplay (d);
    if (status == running) {
	if (pid < 2)
	    abort ();
	kill (pid, SIGTERM);
    }
}

static FD_TYPE	CloseMask;
static int	max;

RegisterCloseOnFork (fd)
int	fd;
{
	FD_SET (fd, &CloseMask);
	if (fd > max)
		max = fd;
}

ClearCloseOnFork (fd)
int	fd;
{
	FD_CLR (fd, &CloseMask);
	if (fd == max) {
		while (--fd >= 0)
			if (FD_ISSET (fd, &CloseMask))
				break;
		max = fd;
	}
}

CloseOnFork ()
{
	int	fd;

	for (fd = 0; fd < max; fd++)
		if (FD_ISSET (fd, &CloseMask))
			close (fd);
	FD_ZERO (&CloseMask);
	max = 0;
}

StorePid ()
{
	FILE	*f;

	if (pidFile[0] != '\0') {
		f = fopen (pidFile, "w");
		if (!f) {
			LogError ("process-id file %s cannot be opened\n",
				  pidFile);
		} else {
			fprintf (f, "%d\n", getpid ());
			fclose (f);
		}
	}
}

SetTitle (va_alist)
va_dcl
{
#ifndef NOXDMTITLE
	char	*p = Title;
	int	left = TitleLen;
	int	len;
	char	*s;
	va_list	args;

	va_start(args);
	*p++ = '-';
	--left;
	while (s = va_arg (args, char *)) {
	    while (*s && left > 0)
	    {
		*p++ = *s++;
		left--;
	    }
	}
	while (left > 0)
	{
	    *p++ = ' ';
	    --left;
	}
	va_end(args);
#endif	
}