/*
 * tkUnixEvent.c --
 *
 *	This file implements an event source for X displays for the
 *	UNIX version of Tk.
 *
 * Copyright (c) 1995-1997 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tkUnixEvent.c,v 1.11.2.1 2003/07/16 01:20:13 mdejong Exp $
 */

#include "tkInt.h"
#include "tkUnixInt.h"
#include <sys/time.h>
#include <signal.h>

/*
 * The following static indicates whether this module has been initialized
 * in the current thread.
 */

typedef struct ThreadSpecificData {
    int initialized;
} ThreadSpecificData;
static Tcl_ThreadDataKey dataKey;

#if defined(TK_USE_INPUT_METHODS) && defined(PEEK_XCLOSEIM)
/*
 * Structure used to peek into internal XIM data structure.
 * This is only known to work with XFree86.
 */
struct XIMPeek {
    void *junk1, *junk2;
    XIC  ic_chain;
};
#endif

/*
 * Prototypes for procedures that are referenced only in this file:
 */

static void		DisplayCheckProc _ANSI_ARGS_((ClientData clientData,
			    int flags));
static void		DisplayExitHandler _ANSI_ARGS_((
			    ClientData clientData));
static void		DisplayFileProc _ANSI_ARGS_((ClientData clientData,
			    int flags));
static void		DisplaySetupProc _ANSI_ARGS_((ClientData clientData,
			    int flags));
static void		TransferXEventsToTcl _ANSI_ARGS_((Display *display));
#ifdef TK_USE_INPUT_METHODS
static void		OpenIM _ANSI_ARGS_((TkDisplay *dispPtr));
#endif


/*
 *----------------------------------------------------------------------
 *
 * TkCreateXEventSource --
 *
 *	This procedure is called during Tk initialization to create
 *	the event source for X Window events.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	A new event source is created.
 *
 *----------------------------------------------------------------------
 */

void
TkCreateXEventSource()
{
    ThreadSpecificData *tsdPtr = (ThreadSpecificData *)
            Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData));

    if (!tsdPtr->initialized) {
	tsdPtr->initialized = 1;
	Tcl_CreateEventSource(DisplaySetupProc, DisplayCheckProc, NULL);
	Tcl_CreateExitHandler(DisplayExitHandler, NULL);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * DisplayExitHandler --
 *
 *	This function is called during finalization to clean up the
 *	display module.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static void
DisplayExitHandler(clientData)
    ClientData clientData;	/* Not used. */
{
    ThreadSpecificData *tsdPtr = (ThreadSpecificData *)
            Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData));

    Tcl_DeleteEventSource(DisplaySetupProc, DisplayCheckProc, NULL);
    tsdPtr->initialized = 0;
}

/*
 *----------------------------------------------------------------------
 *
 * TkpOpenDisplay --
 *
 *	Allocates a new TkDisplay, opens the X display, and establishes
 *	the file handler for the connection.
 *
 * Results:
 *	A pointer to a Tk display structure.
 *
 * Side effects:
 *	Opens a display.
 *
 *----------------------------------------------------------------------
 */

TkDisplay *
TkpOpenDisplay(display_name)
    CONST char *display_name;
{
    TkDisplay *dispPtr;
    Display *display = XOpenDisplay(display_name);

    if (display == NULL) {
	return NULL;
    }
    dispPtr = (TkDisplay *) ckalloc(sizeof(TkDisplay));
    memset(dispPtr, 0, sizeof(TkDisplay));
    dispPtr->display = display;
#ifdef TK_USE_INPUT_METHODS
    OpenIM(dispPtr);
#endif
    Tcl_CreateFileHandler(ConnectionNumber(display), TCL_READABLE,
	    DisplayFileProc, (ClientData) dispPtr);
    return dispPtr;
}

/*
 *----------------------------------------------------------------------
 *
 * TkpCloseDisplay --
 *
 *	Cancels notifier callbacks and closes a display.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Deallocates the displayPtr and unix-specific resources.
 *
 *----------------------------------------------------------------------
 */

void
TkpCloseDisplay(dispPtr)
    TkDisplay *dispPtr;
{
    TkSendCleanup(dispPtr);

    TkFreeXId(dispPtr);

    TkWmCleanup(dispPtr);

#ifdef TK_USE_INPUT_METHODS
#if TK_XIM_SPOT
    if (dispPtr->inputXfs) {
	XFreeFontSet(dispPtr->display, dispPtr->inputXfs);
    }
#endif
    if (dispPtr->inputMethod) {
	/*
	 * Calling XCloseIM with an input context that has not
	 * been freed can cause a crash. This crash has been
	 * reproduced under Linux systems with XFree86 3.3
	 * and may have also been seen under Solaris 2.3.
	 * The crash is caused by a double free of memory
	 * inside the X library. Memory that was already
	 * deallocated may be accessed again inside XCloseIM.
	 * This bug can be avoided by making sure that a
	 * call to XDestroyIC is made for each XCreateIC call.
	 * This bug has been fixed in XFree86 4.2.99.2.
	 * The internal layout of the XIM structure changed
	 * in the XFree86 4.2 release so the test should
	 * not be run for with these new releases.
	 */

#if defined(TK_USE_INPUT_METHODS) && defined(PEEK_XCLOSEIM)
	int do_peek = 0;
	struct XIMPeek *peek;

	if (strstr(ServerVendor(dispPtr->display), "XFree86")) {
	    int vendrel = VendorRelease(dispPtr->display);
	    if (vendrel < 336) {
	        /* 3.3.4 and 3.3.5 */
	        do_peek = 1;
	    } else if (vendrel < 3900) {
	        /* Other 3.3.x versions */
	        do_peek = 1;
	    } else if (vendrel < 40000000) {
	        /* 4.0.x versions */
	        do_peek = 1;
	    } else {
	        /* Newer than 4.0 */
	        do_peek = 0;
	    }
	}

	if (do_peek) {
	    peek = (struct XIMPeek *) dispPtr->inputMethod;
	    if (peek->ic_chain != NULL)
	        panic("input contexts not freed before XCloseIM");
	}
#endif
	XCloseIM(dispPtr->inputMethod);
    }
#endif

    if (dispPtr->display != 0) {
	Tcl_DeleteFileHandler(ConnectionNumber(dispPtr->display));
	(void) XSync(dispPtr->display, False);
	(void) XCloseDisplay(dispPtr->display);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * DisplaySetupProc --
 *
 *	This procedure implements the setup part of the UNIX X display
 *	event source.  It is invoked by Tcl_DoOneEvent before entering
 *	the notifier to check for events on all displays.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	If data is queued on a display inside Xlib, then the maximum
 *	block time will be set to 0 to ensure that the notifier returns
 *	control to Tcl even if there is no more data on the X connection.
 *
 *----------------------------------------------------------------------
 */

static void
DisplaySetupProc(clientData, flags)
    ClientData clientData;	/* Not used. */
    int flags;
{
    TkDisplay *dispPtr;
    static Tcl_Time blockTime = { 0, 0 };

    if (!(flags & TCL_WINDOW_EVENTS)) {
	return;
    }

    for (dispPtr = TkGetDisplayList(); dispPtr != NULL;
	 dispPtr = dispPtr->nextPtr) {

	/*
	 * Flush the display. If data is pending on the X queue, set
	 * the block time to zero.  This ensures that we won't block
	 * in the notifier if there is data in the X queue, but not on
	 * the server socket.
	 */

	XFlush(dispPtr->display);
	if (QLength(dispPtr->display) > 0) {
	    Tcl_SetMaxBlockTime(&blockTime);
	}
    }
}

/*
 *----------------------------------------------------------------------
 *
 *  TransferXEventsToTcl
 *
 *      Transfer events from the X event queue to the Tk event queue.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Moves queued X events onto the Tcl event queue.
 *
 *----------------------------------------------------------------------
 */

static void
TransferXEventsToTcl(display)
    Display *display;
{
    int numFound;
    XEvent event;

    numFound = QLength(display);

    /*
     * Transfer events from the X event queue to the Tk event queue.
     */

    while (numFound > 0) {
	XNextEvent(display, &event);
	Tk_QueueWindowEvent(&event, TCL_QUEUE_TAIL);
	numFound--;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * DisplayCheckProc --
 *
 *	This procedure checks for events sitting in the X event
 *	queue.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Moves queued events onto the Tcl event queue.
 *
 *----------------------------------------------------------------------
 */

static void
DisplayCheckProc(clientData, flags)
    ClientData clientData;	/* Not used. */
    int flags;
{
    TkDisplay *dispPtr;

    if (!(flags & TCL_WINDOW_EVENTS)) {
	return;
    }

    for (dispPtr = TkGetDisplayList(); dispPtr != NULL;
	 dispPtr = dispPtr->nextPtr) {
	XFlush(dispPtr->display);
	TransferXEventsToTcl(dispPtr->display);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * DisplayFileProc --
 *
 *	This procedure implements the file handler for the X connection.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Makes entries on the Tcl event queue for all the events available
 *	from all the displays.
 *
 *----------------------------------------------------------------------
 */

static void
DisplayFileProc(clientData, flags)
    ClientData clientData;		/* The display pointer. */
    int flags;				/* Should be TCL_READABLE. */
{
    TkDisplay *dispPtr = (TkDisplay *) clientData;
    Display *display = dispPtr->display;
    int numFound;

    XFlush(display);
    numFound = XEventsQueued(display, QueuedAfterReading);
    if (numFound == 0) {

	/*
	 * Things are very tricky if there aren't any events readable
	 * at this point (after all, there was supposedly data
	 * available on the connection).  A couple of things could
	 * have occurred:
	 *
	 * One possibility is that there were only error events in the
	 * input from the server.  If this happens, we should return
	 * (we don't want to go to sleep in XNextEvent below, since
	 * this would block out other sources of input to the
	 * process).
	 *
	 * Another possibility is that our connection to the server
	 * has been closed.  This will not necessarily be detected in
	 * XEventsQueued (!!), so if we just return then there will be
	 * an infinite loop.  To detect such an error, generate a NoOp
	 * protocol request to exercise the connection to the server,
	 * then return.  However, must disable SIGPIPE while sending
	 * the request, or else the process will die from the signal
	 * and won't invoke the X error function to print a nice (?!)
	 * message.
	 */

	void (*oldHandler)();

	oldHandler = (void (*)()) signal(SIGPIPE, SIG_IGN);
	XNoOp(display);
	XFlush(display);
	(void) signal(SIGPIPE, oldHandler);
    }

    TransferXEventsToTcl(display);
}

/*
 *----------------------------------------------------------------------
 *
 * TkUnixDoOneXEvent --
 *
 *	This routine waits for an X event to be processed or for
 *	a timeout to occur.  The timeout is specified as an absolute
 *	time.  This routine is called when Tk needs to wait for a
 *	particular X event without letting arbitrary events be
 *	processed.  The caller will typically call Tk_RestrictEvents
 *	to set up an event filter before calling this routine.  This
 *	routine will service at most one event per invocation.
 *
 * Results:
 *	Returns 0 if the timeout has expired, otherwise returns 1.
 *
 * Side effects:
 *	Can invoke arbitrary Tcl scripts.
 *
 *----------------------------------------------------------------------
 */

int
TkUnixDoOneXEvent(timePtr)
    Tcl_Time *timePtr;		/* Specifies the absolute time when the
				 * call should time out. */
{
    TkDisplay *dispPtr;
    static fd_mask readMask[MASK_SIZE];
    struct timeval blockTime, *timeoutPtr;
    Tcl_Time now;
    int fd, index, bit, numFound, numFdBits = 0;

    /*
     * Look for queued events first.
     */

    if (Tcl_ServiceEvent(TCL_WINDOW_EVENTS)) {
	return 1;
    }

    /*
     * Compute the next block time and check to see if we have timed out.
     * Note that HP-UX defines tv_sec to be unsigned so we have to be
     * careful in our arithmetic.
     */

    if (timePtr) {
	Tcl_GetTime(&now);
	blockTime.tv_sec = timePtr->sec;
	blockTime.tv_usec = timePtr->usec - now.usec;
	if (blockTime.tv_usec < 0) {
	    now.sec += 1;
	    blockTime.tv_usec += 1000000;
	}
	if (blockTime.tv_sec < now.sec) {
	    blockTime.tv_sec = 0;
	    blockTime.tv_usec = 0;
	} else {
	    blockTime.tv_sec -= now.sec;
	}
	timeoutPtr = &blockTime;
    } else {
	timeoutPtr = NULL;
    }

    /*
     * Set up the select mask for all of the displays.  If a display has
     * data pending, then we want to poll instead of blocking.
     */

    memset((VOID *) readMask, 0, MASK_SIZE*sizeof(fd_mask));
    for (dispPtr = TkGetDisplayList(); dispPtr != NULL;
	 dispPtr = dispPtr->nextPtr) {
	XFlush(dispPtr->display);
	if (QLength(dispPtr->display) > 0) {
	    blockTime.tv_sec = 0;
	    blockTime.tv_usec = 0;
	}
	fd = ConnectionNumber(dispPtr->display);
	index = fd/(NBBY*sizeof(fd_mask));
	bit = 1 << (fd%(NBBY*sizeof(fd_mask)));
	readMask[index] |= bit;
	if (numFdBits <= fd) {
	    numFdBits = fd+1;
	}
    }

    numFound = select(numFdBits, (SELECT_MASK *) &readMask[0], NULL, NULL,
	    timeoutPtr);
    if (numFound <= 0) {
	/*
	 * Some systems don't clear the masks after an error, so
	 * we have to do it here.
	 */

	memset((VOID *) readMask, 0, MASK_SIZE*sizeof(fd_mask));
    }

    /*
     * Process any new events on the display connections.
     */

    for (dispPtr = TkGetDisplayList(); dispPtr != NULL;
	 dispPtr = dispPtr->nextPtr) {
	fd = ConnectionNumber(dispPtr->display);
	index = fd/(NBBY*sizeof(fd_mask));
	bit = 1 << (fd%(NBBY*sizeof(fd_mask)));
	if ((readMask[index] & bit) || (QLength(dispPtr->display) > 0)) {
	    DisplayFileProc((ClientData)dispPtr, TCL_READABLE);
	}
    }
    if (Tcl_ServiceEvent(TCL_WINDOW_EVENTS)) {
	return 1;
    }

    /*
     * Check to see if we timed out.
     */

    if (timePtr) {
	Tcl_GetTime(&now);
	if ((now.sec > timePtr->sec) || ((now.sec == timePtr->sec)
		&& (now.usec > timePtr->usec))) {
	    return 0;
	}
    }

    /*
     * We had an event but we did not generate a Tcl event from it. Behave
     * as though we dealt with it. (JYL&SS)
     */

    return 1;
}

/*
 *----------------------------------------------------------------------
 *
 * TkpSync --
 *
 *	This routine ensures that all pending X requests have been
 *	seen by the server, and that any pending X events have been
 *	moved onto the Tk event queue.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Places new events on the Tk event queue.
 *
 *----------------------------------------------------------------------
 */

void
TkpSync(display)
    Display *display;		/* Display to sync. */
{
    XSync(display, False);

    /*
     * Transfer events from the X event queue to the Tk event queue.
     */
    TransferXEventsToTcl(display);
}
#ifdef TK_USE_INPUT_METHODS

/*
 *--------------------------------------------------------------
 *
 * OpenIM --
 *
 *	Tries to open an X input method, associated with the
 *	given display.  Right now we can only deal with a bare-bones
 *	input style:  no preedit, and no status.
 *
 * Results:
 *	Stores the input method in dispPtr->inputMethod;  if there isn't
 *	a suitable input method, then NULL is stored in dispPtr->inputMethod.
 *
 * Side effects:
 *	An input method gets opened.
 *
 *--------------------------------------------------------------
 */

static void
OpenIM(dispPtr)
    TkDisplay *dispPtr;		/* Tk's structure for the display. */
{
    unsigned short i;
    XIMStyles *stylePtr;

    if (XSetLocaleModifiers("") == NULL) {
	goto error;
    }

    dispPtr->inputMethod = XOpenIM(dispPtr->display, NULL, NULL, NULL);
    if (dispPtr->inputMethod == NULL) {
	return;
    }

    if ((XGetIMValues(dispPtr->inputMethod, XNQueryInputStyle, &stylePtr,
	    NULL) != NULL) || (stylePtr == NULL)) {
	goto error;
    }
#if TK_XIM_SPOT
    /*
     * If we want to do over-the-spot XIM, we have to check that this
     * mode is supported.  If not we will fall-through to the check below.
     */
    for (i = 0; i < stylePtr->count_styles; i++) {
	if (stylePtr->supported_styles[i]
		== (XIMPreeditPosition | XIMStatusNothing)) {
	    dispPtr->flags |= TK_DISPLAY_XIM_SPOT;
	    XFree(stylePtr);
	    return;
	}
    }
#endif
    for (i = 0; i < stylePtr->count_styles; i++) {
	if (stylePtr->supported_styles[i]
		== (XIMPreeditNothing | XIMStatusNothing)) {
	    XFree(stylePtr);
	    return;
	}
    }
    XFree(stylePtr);

    error:

    if (dispPtr->inputMethod) {
	/*
	 * This call should not suffer from any core dumping problems
	 * since we have not allocated any input contexts.
	 */
	XCloseIM(dispPtr->inputMethod);
	dispPtr->inputMethod = NULL;
    }
}
#endif /* TK_USE_INPUT_METHODS */

