// Copyright (c) 2004-2009 Nokia Corporation and/or its subsidiary(-ies).

 // All rights reserved.

 // This component and the accompanying materials are made available

 // under the terms of the License "Eclipse Public License v1.0"

 // which accompanies this distribution, and is available

 // at the URL "http://www.eclipse.org/legal/epl-v10.html".

 //

 // Initial Contributors:

 // Nokia Corporation - initial contribution.

 //

 // Contributors:

 //

 // Description:

 // e32\common\win32\seh.cpp

 // 

 //

 #include "seh.h"

 // Fill in the blank types for TWin32SEHTrap

 #define __WIN32_SEH_TYPES_KNOWN__

 #define __UnknownWindowsType1 EXCEPTION_RECORD

 #define __UnknownWindowsType2 CONTEXT

 // Pretend we're tools to avoid clashes with Win32 headers

 #define __TOOLS__

 #define __IN_SEH_CPP__

 #include <e32cmn.h>

 #include <e32cmn_private.h>

 #include <emulator.h>

 #include <e32panic.h>

 GLREF_C void Panic(TCdtPanic);

 // magic value denoting the end of the SEH handler list

 static const TWin32SEHTrap* const KFencePost = (TWin32SEHTrap*)-1;

 //

 // Class TWin32SEHTrap

 //

 #ifdef __KERNEL_MODE__

 extern DWORD CallFinalSEHHandler(EXCEPTION_RECORD* aException, CONTEXT* aContext)

 	{

 	// Get the final SEH entry on the chain

 	TWin32SEHTrap* finalHandler = TWin32SEHTrap::IterateForFinal();

 	// Call the handler - ignoring return value

 	(void)(*finalHandler->ExceptionHandler())(aException, finalHandler, aContext);

 	// Explicitly tell Win32 the exception has been handled

 	return ExceptionContinueExecution;

 	}

 TWin32SEHTrap* TWin32SEHTrap::IterateForFinal()

 	{

 	TWin32SEHTrap* p = (TWin32SEHTrap*)Tib()->ExceptionList;

 	// Iterate through the SEH chain to find the final SEH record that we wish to skip to

     for (; p && p!=KFencePost && p->iPrevExceptionRegistrationRecord!=KFencePost; p=p->iPrevExceptionRegistrationRecord)

 		{}

 	return p;

 	}

 TWin32SEHExceptionHandler* TWin32SEHTrap::ExceptionHandler()

 	{

 	return iExceptionHandler;

 	}

 #else // !__KERNEL_MODE__

 #include <u32exec.h>

 extern "C" void trap_check(TWin32SEHTrap* a)

 	{

 	TWin32SEHTrap* p = a->iPrevExceptionRegistrationRecord;

 	if (p && p!=KFencePost && a->iExceptionHandler == p->iExceptionHandler && a->iExceptionHandler == &TWin32SEHTrap::ExceptionHandler)

 		Exec::PushTrapFrame((TTrap*)p);

 	else

 		Exec::PushTrapFrame(0);

 	}

 extern "C" void untrap_check()

 	{

 	// search back for consecutive TWin32SEHTrap and remember the second one

 	TWin32SEHTrap* p = (TWin32SEHTrap*)Tib()->ExceptionList;

 	TWin32SEHTrap* q = 0;

 	TWin32SEHTrap* s = 0;

 	if (p && p!=KFencePost)

 		{

 		for(;;)

 			{

 			q = p->iPrevExceptionRegistrationRecord;

 			if (!q || q==KFencePost)

 				break;

 			if (p->iExceptionHandler == &TWin32SEHTrap::ExceptionHandler && q->iExceptionHandler == &TWin32SEHTrap::ExceptionHandler)

 				{

 				s = q;

 				break;

 				}

 			p = q;

 			}

 		}

 	Exec::PushTrapFrame((TTrap*)s);

 	}

 // Use assembler to ensure no extra SEH frame is created by the compiler

 UEXPORT_C __NAKED__ void TWin32SEHTrap::Trap()

 	{

 	_asm mov eax, fs:[0]

 	_asm mov [ecx], eax

 	_asm mov fs:[0], ecx

 	_asm push ecx

 	_asm call trap_check

 	_asm pop ecx

 	_asm ret

 	}

 extern "C" void panic_chain_corrupt()

 	{

 	Panic(EWin32SEHChainCorrupt);

 	}

 // Use assembler to ensure no extra SEH frame is created by the compiler

 UEXPORT_C __NAKED__ void TWin32SEHTrap::UnTrap()

 	{

 	_asm mov eax, fs:[0]

 	_asm cmp eax, ecx

 	_asm ja untrap_0

 	_asm jb untrap_error

 	_asm mov eax, [ecx]

 	_asm mov fs:[0], eax

 	_asm xor eax, eax

 	_asm mov [ecx], eax

 	_asm call untrap_check

 untrap_0:

 	_asm ret

 untrap_error:

 	_asm jmp panic_chain_corrupt

 	}

 UEXPORT_C TWin32SEHTrap::TWin32SEHTrap()

 	:	iPrevExceptionRegistrationRecord(NULL),

 		iExceptionHandler(&ExceptionHandler)

 	{

 	}

 // Handler called whilst Win32 is walking the SEH chain

 DWORD TWin32SEHTrap::ExceptionHandler(EXCEPTION_RECORD* aException, TWin32SEHTrap* /*aRegistrationRecord*/, CONTEXT* aContext)

 	{

 	if (aException->ExceptionCode != EXCEPTION_MSCPP)

 		{

 		return Emulator::Win32SEHException(aException, aContext);

 		}

 	else

 		{

 		return ExceptionContinueSearch;

 		}

 	}

 #if defined(__LEAVE_EQUALS_THROW__) && defined(__WINS__)

 extern "C" TWin32SEHTrap* pop_trap_frame()

 	{

 	return (TWin32SEHTrap*)Exec::PopTrapFrame();

 	}

 extern "C" void leave_end()

 	{

 	Exec::LeaveEnd();

 	}

 EXPORT_C __NAKED__ TInt XLeaveException::GetReason() const

 	{

 	_asm push ecx

 	_asm call pop_trap_frame

 	_asm test eax, eax

 	_asm jz no_nested_trap

 	// eax points to TWin32SEHTrap to be restored

 	// if current exception record is above eax on the stack just restore eax

 	_asm cmp eax, esp

 	_asm jbe nested_trap_error

 	_asm mov edx, fs:[0]

 	_asm cmp eax, edx

 	_asm ja nested_trap_insert_in_middle

 	_asm je no_nested_trap	// we haven't been unwound after all

 	// check we eventually reach current exception record from eax

 	_asm mov ecx, eax

 	_asm mov edx, [eax+4]	// &TWin32SEHTrap::ExceptionHandler

 nested_trap_check:

 	_asm mov ecx, [ecx]

 	_asm cmp ecx, 0

 	_asm jz nested_trap_error

 	_asm cmp ecx, 0ffffffffh

 	_asm jz nested_trap_error

 	_asm cmp ecx, fs:[0]

 	_asm jz nested_trap_check_ok

 	_asm cmp edx, [ecx+4]	// all intervening entries should be TWin32SEHTrap

 	_asm jz nested_trap_check

 	_asm jmp nested_trap_error

 	// other SEH handlers have been added after we were unwound so we need to insert eax 'in the middle'

 nested_trap_insert_in_middle:

 	_asm cmp eax, [edx]

 	_asm je no_nested_trap	// eax is still in the chain

 	_asm jb nested_trap_insert_in_middle_found

 	_asm mov edx, [edx]

 	_asm jmp nested_trap_insert_in_middle

 nested_trap_insert_in_middle_found:

 	_asm mov ecx, [edx]		// first SEH above eax on stack

 	_asm cmp ecx, 0ffffffffh

 	_asm je nested_trap_error	// reached end of SEH list

 	_asm push edx

 	// ECX should be reachable from EAX

 	_asm mov edx, eax

 nested_trap_insert_in_middle_check:

 	_asm mov edx, [edx]

 	_asm cmp ecx, edx

 	_asm je nested_trap_insert_in_middle_ok

 	_asm cmp edx, 0ffffffffh

 	_asm je nested_trap_error	// reached end of SEH list

 	_asm test edx, edx

 	_asm jnz nested_trap_insert_in_middle_check

 	_asm jmp nested_trap_error

 nested_trap_insert_in_middle_ok:

 	_asm pop edx

 	_asm mov [edx], eax		// insert eax back into chain

 	_asm jmp no_nested_trap

 nested_trap_check_ok:

 	_asm mov fs:[0], eax	// reinstall nested trap SEH handlers

 no_nested_trap:

 	_asm call untrap_check	// check for other nested TRAPs

 	_asm call leave_end

 	_asm pop ecx

 	_asm mov eax, [ecx]XLeaveException.iR

 	_asm ret

 nested_trap_error:

 	_asm jmp panic_chain_corrupt

 	}

 #endif	// defined(__LEAVE_EQUALS_THROW__) && defined(__WINS__)

 #endif //__KERNEL_MODE__