EXCEPTION_DISPOSITION
__GSHandlerCheck_EH4(
IN PEXCEPTION_RECORD ExceptionRecord,
IN PVOID EstablisherFrame,
IN OUT PCONTEXT ContextRecord,
IN OUT PDISPATCHER_CONTEXT DispatcherContext
)
{
PGS_HANDLER_DATA GSHandlerData;
ULONG GSUnwindInfo;
EXCEPTION_DISPOSITION Disposition;
//
// Retrieve a pointer to the start of that part of the handler data used
// to locate the local security cookie in the local frame. That is found
// following the image-relative offset to the FuncInfo table used by
// __CxxFrameHandler3.
//
GSHandlerData = (PGS_HANDLER_DATA)((PULONG)DispatcherContext->HandlerData + 1);
//
// Perform the actual cookie check.
//
__GSHandlerCheckCommon(
EstablisherFrame,
DispatcherContext,
GSHandlerData
);
//
// If the cookie check succeeds, call the normal C++ EH handler if we're
// supposed to on this exception pass. Find the EHANDLER/UHANDLER flags
// controlling that in the first ULONG of our part of the handler data.
//
GSUnwindInfo = *(PULONG)GSHandlerData;
if (IS_DISPATCHING(ExceptionRecord->ExceptionFlags)
? (GSUnwindInfo & UNW_FLAG_EHANDLER)
: (GSUnwindInfo & UNW_FLAG_UHANDLER))
{
Disposition = __CxxFrameHandler4(
ExceptionRecord,
EstablisherFrame,
ContextRecord,
DispatcherContext
);
}
else
{
Disposition = ExceptionContinueSearch;
}
return Disposition;
}
DECLSPEC_GUARD_SUPPRESS
EXCEPTION_DISPOSITION
__C_specific_handler (
_In_ PEXCEPTION_RECORD ExceptionRecord,
_In_ PVOID EstablisherFrame,
_Inout_ PCONTEXT ContextRecord,
_Inout_ PDISPATCHER_CONTEXT DispatcherContext
)
/*++
Routine Description:
This function scans the scope tables associated with the specified
procedure and calls exception and termination handlers as necessary.
Arguments:
ExceptionRecord - Supplies a pointer to an exception record.
EstablisherFrame - Supplies a pointer to frame of the establisher function.
ContextRecord - Supplies a pointer to a context record.
DispatcherContext - Supplies a pointer to the exception dispatcher or
unwind dispatcher context.
N.B. SHRINK WRAPPING MUST BE DISABLED FOR THIS FUNCTION.
Return Value:
If an exception is being dispatched and the exception is handled by one
of the exception filter routines, then there is no return from this
routine and RtlUnwind is called. Otherwise, an exception disposition
value of continue execution or continue search is returned.
If an unwind is being dispatched, then each termination handler is called
and a value of continue search is returned.
--*/
{
ULONG_PTR ControlPc;
PEXCEPTION_FILTER ExceptionFilter;
EXCEPTION_POINTERS ExceptionPointers;
ULONG_PTR ImageBase;
ULONG_PTR Handler;
ULONG Index;
PSCOPE_TABLE ScopeTable;
ULONG TargetIndex;
ULONG_PTR TargetPc;
PTERMINATION_HANDLER TerminationHandler;
LONG Value;
DISABLE_SHRINK_WRAPPING();
#if defined(_M_AMD64)
//
// Validate integrity of context record.
//
__except_validate_context_record(ContextRecord);
#endif
//
// Get the image base address. compute the relative address of where
// control left the establisher, and get the address of the scope table.
//
ImageBase = DispatcherContext->ImageBase;
ControlPc = DispatcherContext->ControlPc - ImageBase;
ScopeTable = (PSCOPE_TABLE)(DispatcherContext->HandlerData);
#if defined(_M_ARM_NT) || defined(_M_ARM64) || defined(_CHPE_X86_ARM64_EH_)
//
// Do we have an indirect scope table?
//
if ((ScopeTable->Count & (1 << 31)) != 0) {
ScopeTable = (PSCOPE_TABLE)(ImageBase + (ScopeTable->Count & ~(1 << 31)));
}
//
// If this context came from an unwind to a call, then the ControlPc points
// to a return address, which could put us at the start of a neighboring
// scope. To correct for this, back the PC up by the minimum instruction
// size to ensure we are in the same scope as the original branch opcode.
//
if (DispatcherContext->ControlPcIsUnwound != FALSE) {
#if defined(_M_ARM_NT)
ControlPc -= 2;
#else
ControlPc -= 4;
#endif
}
#endif // defined(_M_ARM_NT) || defined(_M_ARM64) || defined(_CHPE_X86_ARM64_EH_)
//
// If an unwind is not in progress, then scan the scope table and call
// the appropriate exception filter routines. Otherwise, scan the scope
// table and call the appropriate termination handlers using the target
// PC obtained from the dispatcher context.
//
if (IS_DISPATCHING(ExceptionRecord->ExceptionFlags)) {
//
// Scan the scope table and call the appropriate exception filter
// routines.
//
ExceptionPointers.ExceptionRecord = ExceptionRecord;
ExceptionPointers.ContextRecord = ContextRecord;
for (Index = DispatcherContext->ScopeIndex; Index < ScopeTable->Count; Index += 1) {
if ((ControlPc >= ScopeTable->ScopeRecord[Index].BeginAddress) &&
(ControlPc < ScopeTable->ScopeRecord[Index].EndAddress) &&
(ScopeTable->ScopeRecord[Index].JumpTarget != 0)) {
//
// If the filter function address is the distinguished value
// one, then set the disposition value to execute handler.
// Otherwise, call the exception filter function to get the
// disposition value.
//
if (ScopeTable->ScopeRecord[Index].HandlerAddress == 1) {
Value = EXCEPTION_EXECUTE_HANDLER;
} else {
ExceptionFilter =
(PEXCEPTION_FILTER)(ScopeTable->ScopeRecord[Index].HandlerAddress + ImageBase);
Value = EXECUTE_EXCEPTION_FILTER(&ExceptionPointers,
EstablisherFrame,
ExceptionFilter,
DispatcherContext);
}
//
// If the return value is less than zero, then dismiss the
// exception. Otherwise, if the value is greater than zero,
// then unwind to the target exception handler. Otherwise,
// continue the search for an exception filter.
//
if (Value < 0) {
return ExceptionContinueExecution;
} else if (Value > 0) {
//
// If a thrown C++ exception is being handled, then let
// the C++ exception handler destruct the thrown object.
//
#ifndef _NTSUBSET_
if ((ExceptionRecord->ExceptionCode == EH_EXCEPTION_NUMBER) &&
(_pDestructExceptionObject != NULL) &&
(_IsNonwritableInCurrentImage(&_pDestructExceptionObject))) {
(*_pDestructExceptionObject)(ExceptionRecord, TRUE);
}
#endif
//
// Inform the debugger that control is about to be passed
// to an exception handler and pass the handler's address
// to NLG_Notify.
//
Handler = ImageBase + ScopeTable->ScopeRecord[Index].JumpTarget;
_NLG_Notify((PVOID)Handler, EstablisherFrame, 0x1);
RtlUnwindEx(EstablisherFrame,
(PVOID)(ScopeTable->ScopeRecord[Index].JumpTarget + ImageBase),
ExceptionRecord,
(PVOID)((ULONG_PTR)ExceptionRecord->ExceptionCode),
(PCONTEXT)DispatcherContext->ContextRecord,
DispatcherContext->HistoryTable);
//
// Notify debugger : return from exception handler
//
__NLG_Return2();
}
}
}
} else {
//
// Scan the scope table and call the appropriate termination handler
// routines.
//
TargetPc = DC_TARGETPC(DispatcherContext) - ImageBase;
for (Index = DispatcherContext->ScopeIndex; Index < ScopeTable->Count; Index += 1) {
if ((ControlPc >= ScopeTable->ScopeRecord[Index].BeginAddress) &&
(ControlPc < ScopeTable->ScopeRecord[Index].EndAddress)) {
if (IS_TARGET_UNWIND(ExceptionRecord->ExceptionFlags)) {
//
// If the target PC is within the same scope as the control PC,
// then this is an uplevel goto out of an inner try scope or a
// long jump back into a try scope. Terminate the scan for a
// termination handler.
//
// N.B. Due to a bug in the AMD64 compiler, try scopes may
// be split into multiple regions, requiring a scan
// of the earlier region of the table to verify that
// the target PC is not within the same try scope.
// The split scopes could reside both before or after
// the currently searched scope in the scope table.
//
// N.B. The target PC can be just beyond the end of the
// scope in which case it is a leave from a scope.
// The "leave from a scope" case is subsequently
// handled before control is transferred.
//
for (TargetIndex = 0; TargetIndex < ScopeTable->Count; TargetIndex += 1) {
if ((TargetPc >= ScopeTable->ScopeRecord[TargetIndex].BeginAddress) &&
(TargetPc < ScopeTable->ScopeRecord[TargetIndex].EndAddress) &&
(ScopeTable->ScopeRecord[TargetIndex].JumpTarget == ScopeTable->ScopeRecord[Index].JumpTarget) &&
(ScopeTable->ScopeRecord[TargetIndex].HandlerAddress == ScopeTable->ScopeRecord[Index].HandlerAddress)) {
break;
}
}
if (TargetIndex != ScopeTable->Count) {
break;
}
}
//
// If the scope table entry describes an exception filter
// and the associated exception handler is the target of
// the unwind, then terminate the scan for termination
// handlers. Otherwise, if the scope table entry describes
// a termination handler, then record the address of the
// end of the scope as the new control PC address and call
// the termination handler.
//
if (ScopeTable->ScopeRecord[Index].JumpTarget != 0) {
if ((TargetPc == ScopeTable->ScopeRecord[Index].JumpTarget) &&
(IS_TARGET_UNWIND(ExceptionRecord->ExceptionFlags))) {
break;
}
} else {
DispatcherContext->ScopeIndex = Index + 1;
TerminationHandler =
(PTERMINATION_HANDLER)(ScopeTable->ScopeRecord[Index].HandlerAddress + ImageBase);
EXECUTE_TERMINATION_HANDLER(TRUE,
EstablisherFrame,
TerminationHandler,
DispatcherContext);
}
}
}
}
//
// Continue search for exception or termination handlers.
//
ENABLE_SHRINK_WRAPPING();
return ExceptionContinueSearch;
}
EXCEPTION_DISPOSITION
__C_specific_handler (
IN struct _EXCEPTION_RECORD *ExceptionRecord,
IN void *EstablisherFrame,
IN OUT struct _CONTEXT *ContextRecord,
IN OUT struct _DISPATCHER_CONTEXT *DispatcherContext
)
/*++
Routine Description:
This function scans the scope tables associated with the specified
procedure and calls exception and termination handlers as necessary.
This language specific exception handler function is called on a
per-frame basis and in two different cases:
First, the IS_DISPATCHING case, it is called by the exception
dispatcher, RtlDispatchException, via the short assembler routine,
__C_ExecuteHandlerForException, when trying to locate exception
filters within the given frame.
Second, the IS_UNWINDING case, it is called by the frame unwinder,
RtlUnwind, via the short assembler routine, __C_ExecuteHandlerForUnwind,
when unwinding the stack and trying to locate termination handlers
within the given frame.
Arguments:
ExceptionRecord - Supplies a pointer to an exception record.
EstablisherFrame - Supplies a pointer to frame of the establisher function.
ContextRecord - Supplies a pointer to a context record.
DispatcherContext - Supplies a pointer to the exception dispatcher or
unwind dispatcher context.
Return Value:
If the exception is handled by one of the exception filter routines, then
there is no return from this routine and RtlUnwind is called. Otherwise,
an exception disposition value of continue execution or continue search is
returned.
--*/
{
ULONG_PTR ControlPc;
EXCEPTION_FILTER ExceptionFilter;
EXCEPTION_POINTERS ExceptionPointers;
PRUNTIME_FUNCTION FunctionEntry;
ULONG Index;
PSCOPE_TABLE ScopeTable;
ULONG_PTR TargetPc;
TERMINATION_HANDLER TerminationHandler;
LONG Value;
//
// Get the address of where control left the establisher, the address of
// the function table entry that describes the function, and the address of
// the scope table.
//
ControlPc = DispatcherContext->ControlPc;
FunctionEntry = DispatcherContext->FunctionEntry;
ScopeTable = (PSCOPE_TABLE)(FunctionEntry->HandlerData);
//
// The scope table HandlerAddress is either the address of an exception
// filter or a termination handler. The C compiler wraps the code in the
// exception filter expression or the termination handler clause within
// an internal C function. The value of the scope table JumpTarget field
// is used to distinguish an exception filter function (JumpTarget non zero)
// from a termination handler function (JumpTarget is zero).
//
//
// If an unwind is not in progress, then scan the scope table and call
// the appropriate exception filter routines. Otherwise, scan the scope
// table and call the appropriate termination handlers using the target
// PC obtained from the context record.
//
if (IS_DISPATCHING(ExceptionRecord->ExceptionFlags)) {
//
// Set up the ExceptionPointers structure that is passed as the argument
// to the exception filter. It is used by the compiler to implement the
// intrinsic functions exception_code() and exception_info().
//
ExceptionPointers.ExceptionRecord = ExceptionRecord;
ExceptionPointers.ContextRecord = ContextRecord;
//
// Scan the scope table and call the appropriate exception filter
// routines. The scope table entries are known to be sorted by
// increasing EndAddress order. Thus a linear scan will naturally
// hit inner scope exception clauses before outer scope clauses.
//
for (Index = 0; Index < ScopeTable->Count; Index += 1) {
if ((ControlPc >= ScopeTable->ScopeRecord[Index].BeginAddress) &&
(ControlPc < ScopeTable->ScopeRecord[Index].EndAddress) &&
(ScopeTable->ScopeRecord[Index].JumpTarget != 0)) {
//
// Call the exception filter routine.
//
ExceptionFilter =
(EXCEPTION_FILTER)ScopeTable->ScopeRecord[Index].HandlerAddress;
Value = __C_ExecuteExceptionFilter(&ExceptionPointers,
ExceptionFilter,
(ULONG_PTR)EstablisherFrame);
//
// If the return value is less than zero, then dismiss the
// exception. Otherwise, if the value is greater than zero,
// then unwind to the target exception handler corresponding
// to the exception filter. Otherwise, continue the search for
// an exception filter.
//
//
// Exception filters will usually return one of the following
// defines, although the decision below is made only by sign:
//
// #define EXCEPTION_EXECUTE_HANDLER 1
// #define EXCEPTION_CONTINUE_SEARCH 0
// #define EXCEPTION_CONTINUE_EXECUTION -1
//
if (Value < 0) {
return ExceptionContinueExecution;
} else if (Value > 0) {
//
// Set the return value for the unwind to the exception
// code so the exception handler clause can retrieve it
// from v0. This is how GetExceptionCode() is implemented
// in exception handler clauses.
//
RtlUnwind2(EstablisherFrame,
(PVOID)ScopeTable->ScopeRecord[Index].JumpTarget,
ExceptionRecord,
ULongToPtr( ExceptionRecord->ExceptionCode ),
ContextRecord);
}
}
}
} else {
//
// Scan the scope table and call the appropriate termination handler
// routines.
//
TargetPc = (ULONG_PTR)ContextRecord->Fir;
for (Index = 0; Index < ScopeTable->Count; Index += 1) {
if ((ControlPc >= ScopeTable->ScopeRecord[Index].BeginAddress) &&
(ControlPc < ScopeTable->ScopeRecord[Index].EndAddress)) {
//
// If the target PC is within the same scope the control PC
// is within, then this is an uplevel goto out of an inner try
// scope or a long jump back into a try scope. Terminate the
// scan for termination handlers - because any other handlers
// will be outside the scope of both the goto and its label.
//
// N.B. The target PC can be just beyond the end of the scope,
// in which case it is a leave from the scope.
//
if ((TargetPc >= ScopeTable->ScopeRecord[Index].BeginAddress) &&
(TargetPc <= ScopeTable->ScopeRecord[Index].EndAddress)) {
break;
} else {
//
// If the scope table entry describes an exception filter
// and the associated exception handler is the target of
// the unwind, then terminate the scan for termination
// handlers. Otherwise, if the scope table entry describes
// a termination handler, then record the address of the
// end of the scope as the new control PC address and call
// the termination handler.
//
// Recording a new control PC is necessary to ensure that
// termination handlers are called only once even when a
// collided unwind occurs.
//
if (ScopeTable->ScopeRecord[Index].JumpTarget != 0) {
//
// try/except - exception filter (JumpTarget != 0).
// After the exception filter is called, the exception
// handler clause is executed by the call to unwind
// above. Having reached this point in the scan of the
// scope tables, any other termination handlers will
// be outside the scope of the try/except.
//
if (TargetPc == ScopeTable->ScopeRecord[Index].JumpTarget) {
break;
}
} else {
//
// try/finally - termination handler (JumpTarget == 0).
//
//
// Unless the termination handler results in a long
// jump, execution will resume at the instruction after
// the exception handler clause.
//
// ## tvb - I'm still suspicious of the +4 below.
DispatcherContext->ControlPc =
ScopeTable->ScopeRecord[Index].EndAddress + 4;
TerminationHandler =
(TERMINATION_HANDLER)ScopeTable->ScopeRecord[Index].HandlerAddress;
__C_ExecuteTerminationHandler(TRUE,
TerminationHandler,
(ULONG_PTR)EstablisherFrame);
}
}
}
}
}
//
// Continue search for exception filters or termination handlers.
//
return ExceptionContinueSearch;
}
