tkError.c revision 3f54fd611f536639ec30dd53c48e5ec1897cc7d9
/*
* 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.
*
* SCCS: @(#) tkError.c 1.20 96/02/15 18:53:17
*/
#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.
*/
/*
* Forward references to procedures declared later in this file:
*/
/*
*--------------------------------------------------------------
*
* 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(clientData, errorEventPtr)
* 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.
*
*--------------------------------------------------------------
*/
* 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). */
* matching error occurs. NULL means
* just ignore matching errors. */
* errorProc. */
{
register TkErrorHandler *errorPtr;
/*
* Find the display. If Tk doesn't know about this display then
* it's an error: panic.
*/
panic("Unknown display passed to Tk_CreateErrorHandler");
}
/*
* Make sure that X calls us whenever errors occur.
*/
if (defaultHandler == NULL) {
}
/*
* Create the handler record.
*/
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
* was previous return value from
* Tk_CreateErrorHandler. */
{
/*
* 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).
*/
register TkErrorHandler *prevPtr;
int lastSerial;
dispPtr->deleteCount = 0;
} else {
}
continue;
}
}
}
}
/*
*--------------------------------------------------------------
*
* 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
* occurred. */
{
register TkErrorHandler *errorPtr;
/*
* See if we know anything about the display. If not, then
* invoke the default error handler.
*/
goto couldntHandle;
}
/*
* Otherwise invoke any relevant handlers for the error, in order.
*/
continue;
}
return 0;
} else {
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.
*/
return 0;
}
/*
* We couldn't handle the error. Use the default handler.
*/
}