зеркало из https://github.com/mozilla/gecko-dev.git
added Jump instruction for safe removal. this is a dead-end, because update events can't be gotten reliably.
This commit is contained in:
Родитель
7684bc079c
Коммит
3ea5b551a6
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@ -27,41 +27,106 @@
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#include "jGNE.h"
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#include <MixedMode.h>
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#include <Memory.h>
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#include <LowMem.h>
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#include <TextUtils.h>
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/**
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* A 68K jump vector.
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*/
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#pragma options align=mac68k
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struct Jump {
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unsigned short jmp;
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UniversalProcPtr addr;
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};
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#pragma options align=reset
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static void GNEFilter(EventRecord *event, Boolean* result);
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static RoutineDescriptor theGNEFilterUPP = BUILD_ROUTINE_DESCRIPTOR(uppGetNextEventFilterProcInfo, GNEFilter);
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static GetNextEventFilterUPP theGetNextEventFilterUPP = NULL;
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static RoutineDescriptor theGNEFilterDescriptor = BUILD_ROUTINE_DESCRIPTOR(uppGetNextEventFilterProcInfo, GNEFilter);
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static Jump* theGNEFilterJump;
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static GetNextEventFilterUPP theOldGNEFilterUPP = NULL;
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static EventFilterProcPtr theEventFilter = NULL;
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static Str63 theAppName;
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OSStatus InstallEventFilter(EventFilterProcPtr filter)
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{
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theEventFilter = filter;
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if (theEventFilter == NULL) {
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theEventFilter = filter;
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// get previous event filter routine.
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theGetNextEventFilterUPP = LMGetGNEFilter();
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LMSetGNEFilter(&theGNEFilterUPP);
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return noErr;
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// record the current application's name.
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StringPtr currentAppName = LMGetCurApName();
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::BlockMoveData(currentAppName, theAppName, 1 + currentAppName[0]);
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// allocate a jump vector in the System heap, so it will be retained after termination.
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if (theGNEFilterJump == NULL) {
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theGNEFilterJump = (Jump*) NewPtrSys(sizeof(Jump));
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if (theGNEFilterJump == NULL)
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return MemError();
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theGNEFilterJump->jmp = 0x4EF9;
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theGNEFilterJump->addr = &theGNEFilterDescriptor;
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// get previous event filter routine.
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theOldGNEFilterUPP = LMGetGNEFilter();
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LMSetGNEFilter(GetNextEventFilterUPP(theGNEFilterJump));
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} else {
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// our previously allocated Jump is still installed, use it.
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theOldGNEFilterUPP = theGNEFilterJump->addr;
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theGNEFilterJump->addr = &theGNEFilterDescriptor;
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}
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return noErr;
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}
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return paramErr;
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}
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OSStatus RemoveEventFilter()
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{
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// should really check to see if somebody else has installed a filter proc as well.
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LMSetGNEFilter(theGetNextEventFilterUPP);
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theGetNextEventFilterUPP = NULL;
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theEventFilter = NULL;
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return noErr;
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if (theEventFilter != NULL) {
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// It's only truly safe to remove our filter, if nobody else installed one after us.
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if (LMGetGNEFilter() == GetNextEventFilterUPP(theGNEFilterJump)) {
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// can safely restore the old filter.
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LMSetGNEFilter(theOldGNEFilterUPP);
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DisposePtr(Ptr(theGNEFilterJump));
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theGNEFilterJump = NULL;
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} else {
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// modify the jump instruction to point to the previous filter.
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theGNEFilterJump->addr = theOldGNEFilterUPP;
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}
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theOldGNEFilterUPP = NULL;
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theEventFilter = NULL;
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return noErr;
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}
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return paramErr;
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}
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static void GNEFilter(EventRecord *event, Boolean* result)
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{
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// call next filter in chain first.
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if (theGetNextEventFilterUPP)
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CallGetNextEventFilterProc(theGetNextEventFilterUPP, event, result);
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if (theOldGNEFilterUPP != NULL)
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CallGetNextEventFilterProc(theOldGNEFilterUPP, event, result);
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// now, let the filter proc have a crack at the event.
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if (*result)
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*result = !theEventFilter(event);
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if (*result) {
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// only call the filter if called in the current application's context.
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/* if (::EqualString(theAppName, LMGetCurApName(), true, true)) */
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{
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// prevent recursive calls to the filter.
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static Boolean inFilter = false;
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if (! inFilter) {
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inFilter = true;
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Boolean filteredEvent = theEventFilter(event);
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if (filteredEvent) {
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// consume the event by making it a nullEvent.
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event->what = nullEvent;
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*result = false;
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}
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inFilter = false;
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}
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}
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}
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}
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