// 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__