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/*
* tkError.c --
*
* This file provides a high-performance mechanism for selectively
* dealing with errors that occur in talking to the X server. This is
* useful, for example, when communicating with a window that may not
* exist.
*
* Copyright (c) 1990-1994 The Regents of the University of California.
* Copyright (c) 1994-1995 Sun Microsystems, Inc.
*
* See the file "license.terms" for information on usage and redistribution of
* this file, and for a DISCLAIMER OF ALL WARRANTIES.
*/
#include "tkInt.h"
/*
* The default X error handler gets saved here, so that it can be invoked if
* an error occurs that we can't handle.
*/
typedef int (*TkXErrorHandler)(Display *display, XErrorEvent *eventPtr);
static TkXErrorHandler defaultHandler = NULL;
/*
* Forward references to procedures declared later in this file:
*/
static int ErrorProc(Display *display, XErrorEvent *errEventPtr);
/*
*--------------------------------------------------------------
*
* Tk_CreateErrorHandler --
*
* Arrange for all a given procedure to be invoked whenever certain
* errors occur.
*
* Results:
* The return value is a token identifying the handler; it must be passed
* to Tk_DeleteErrorHandler to delete the handler.
*
* Side effects:
* If an X error occurs that matches the error, request, and minor
* arguments, then errorProc will be invoked. ErrorProc should have the
* following structure:
*
* int
* errorProc(caddr_t clientData, XErrorEvent *errorEventPtr) {
* }
*
* The clientData argument will be the same as the clientData argument to
* this procedure, and errorEvent will describe the error. If errorProc
* returns 0, it means that it completely "handled" the error: no further
* processing should be done. If errorProc returns 1, it means that it
* didn't know how to deal with the error, so we should look for other
* error handlers, or invoke the default error handler if no other
* handler returns zero. Handlers are invoked in order of age: youngest
* handler first.
*
* Note: errorProc will only be called for errors associated with X
* requests made AFTER this call, but BEFORE the handler is deleted by
* calling Tk_DeleteErrorHandler.
*
*--------------------------------------------------------------
*/
Tk_ErrorHandler
Tk_CreateErrorHandler(
Display *display, /* Display for which to handle errors. */
int error, /* Consider only errors with this error_code
* (-1 means consider all errors). */
int request, /* Consider only errors with this major
* request code (-1 means consider all major
* codes). */
int minorCode, /* Consider only errors with this minor
* request code (-1 means consider all minor
* codes). */
Tk_ErrorProc *errorProc, /* Procedure to invoke when a matching error
* occurs. NULL means just ignore matching
* errors. */
ClientData clientData) /* Arbitrary value to pass to errorProc. */
{
register TkErrorHandler *errorPtr;
register TkDisplay *dispPtr;
/*
* Find the display. If Tk doesn't know about this display then it's an
* error: panic.
*/
dispPtr = TkGetDisplay(display);
if (dispPtr == NULL) {
Tcl_Panic("Unknown display passed to Tk_CreateErrorHandler");
}
/*
* Make sure that X calls us whenever errors occur.
*/
if (defaultHandler == NULL) {
defaultHandler = XSetErrorHandler(ErrorProc);
}
/*
* Create the handler record.
*/
errorPtr = ckalloc(sizeof(TkErrorHandler));
errorPtr->dispPtr = dispPtr;
errorPtr->firstRequest = NextRequest(display);
errorPtr->lastRequest = (unsigned) -1;
errorPtr->error = error;
errorPtr->request = request;
errorPtr->minorCode = minorCode;
errorPtr->errorProc = errorProc;
errorPtr->clientData = clientData;
errorPtr->nextPtr = dispPtr->errorPtr;
dispPtr->errorPtr = errorPtr;
return (Tk_ErrorHandler) errorPtr;
}
/*
*--------------------------------------------------------------
*
* Tk_DeleteErrorHandler --
*
* Do not use an error handler anymore.
*
* Results:
* None.
*
* Side effects:
* The handler denoted by the "handler" argument will not be invoked for
* any X errors associated with requests made after this call. However,
* if errors arrive later for requests made BEFORE this call, then the
* handler will still be invoked. Call XSync if you want to be sure that
* all outstanding errors have been received and processed.
*
*--------------------------------------------------------------
*/
void
Tk_DeleteErrorHandler(
Tk_ErrorHandler handler) /* Token for handler to delete; was previous
* return value from Tk_CreateErrorHandler. */
{
register TkErrorHandler *errorPtr = (TkErrorHandler *) handler;
register TkDisplay *dispPtr = errorPtr->dispPtr;
errorPtr->lastRequest = NextRequest(dispPtr->display) - 1;
/*
* Every once-in-a-while, cleanup handlers that are no longer active. We
* probably won't be able to free the handler that was just deleted (need
* to wait for any outstanding requests to be processed by server), but
* there may be previously-deleted handlers that are now ready for garbage
* collection. To reduce the cost of the cleanup, let a few dead handlers
* pile up, then clean them all at once. This adds a bit of overhead to
* errors that might occur while the dead handlers are hanging around, but
* reduces the overhead of scanning the list to clean up (particularly if
* there are many handlers that stay around forever).
*/
dispPtr->deleteCount += 1;
if (dispPtr->deleteCount >= 10) {
register TkErrorHandler *prevPtr;
TkErrorHandler *nextPtr;
int lastSerial;
dispPtr->deleteCount = 0;
lastSerial = LastKnownRequestProcessed(dispPtr->display);
errorPtr = dispPtr->errorPtr;
for (prevPtr = NULL; errorPtr != NULL; errorPtr = nextPtr) {
nextPtr = errorPtr->nextPtr;
if ((errorPtr->lastRequest != (unsigned long) -1)
&& (errorPtr->lastRequest <= (unsigned long) lastSerial)) {
if (prevPtr == NULL) {
dispPtr->errorPtr = nextPtr;
} else {
prevPtr->nextPtr = nextPtr;
}
ckfree(errorPtr);
continue;
}
prevPtr = errorPtr;
}
}
}
/*
*--------------------------------------------------------------
*
* ErrorProc --
*
* This procedure is invoked by the X system when error events arrive.
*
* Results:
* If it returns, the return value is zero. However, it is possible that
* one of the error handlers may just exit.
*
* Side effects:
* This procedure does two things. First, it uses the serial # in the
* error event to eliminate handlers whose expiration serials are now in
* the past. Second, it invokes any handlers that want to deal with the
* error.
*
*--------------------------------------------------------------
*/
static int
ErrorProc(
Display *display, /* Display for which error occurred. */
register XErrorEvent *errEventPtr)
/* Information about error. */
{
register TkDisplay *dispPtr;
register TkErrorHandler *errorPtr;
/*
* See if we know anything about the display. If not, then invoke the
* default error handler.
*/
dispPtr = TkGetDisplay(display);
if (dispPtr == NULL) {
goto couldntHandle;
}
/*
* Otherwise invoke any relevant handlers for the error, in order.
*/
for (errorPtr = dispPtr->errorPtr; errorPtr != NULL;
errorPtr = errorPtr->nextPtr) {
if ((errorPtr->firstRequest > errEventPtr->serial)
|| ((errorPtr->error != -1)
&& (errorPtr->error != errEventPtr->error_code))
|| ((errorPtr->request != -1)
&& (errorPtr->request != errEventPtr->request_code))
|| ((errorPtr->minorCode != -1)
&& (errorPtr->minorCode != errEventPtr->minor_code))
|| ((errorPtr->lastRequest != (unsigned long) -1)
&& (errorPtr->lastRequest < errEventPtr->serial))) {
continue;
}
if (errorPtr->errorProc == NULL ||
errorPtr->errorProc(errorPtr->clientData, errEventPtr) == 0) {
return 0;
}
}
/*
* See if the error is a BadWindow error. If so, and it refers to a window
* that still exists in our window table, then ignore the error. Errors
* like this can occur if a window owned by us is deleted by someone
* externally, like a window manager. We'll ignore the errors at least
* long enough to clean up internally and remove the entry from the window
* table.
*
* NOTE: For embedding, we must also check whether the window was recently
* deleted. If so, it may be that Tk generated operations on windows that
* were deleted by the container. Now we are getting the errors
* (BadWindow) after Tk already deleted the window itself.
*/
if (errEventPtr->error_code == BadWindow) {
Window w = (Window) errEventPtr->resourceid;
if (Tk_IdToWindow(display, w) != NULL) {
return 0;
}
}
/*
* We couldn't handle the error. Use the default handler.
*/
couldntHandle:
return defaultHandler(display, errEventPtr);
}
/*
* Local Variables:
* mode: c
* c-basic-offset: 4
* fill-column: 78
* End:
*/