Incorrect stack trace info for C++ exceptions

[remittor]

If C++ exceptions are used in the project, then to use __try/__except it is necessary to build the project with the /EHa option!
Proof: https://docs.microsoft.com/en-us/cpp/cpp/structured-exception-handling-c-cpp?view=msvc-160

When using C++ exceptions, the StackWalker cannot get information about the last call in which the exception occurred.

Here is the code to demonstrate this bug:
https://github.com/remittor-pr/StackWalker/blob/9be4790427145ba81adfd22188e591820f92a0ad/Main/StackWalker/main.cpp

Compiler: MSVC2015 (x64 Release)
Options with which the test project was built: /MT /Zi /O2 /EHa

DebugLog for: THROW_CPP_EXP = 0, CATCH_CPP_EXP = 0

THROW_CPP_EXP = 0, CATCH_CPP_EXP = 0
----- bar -----
===== main.__except =====
main.cpp (23): bar
main.cpp (30): foo
main.cpp (41): test
main.cpp (72): main
exe_common.inl (253): __scrt_common_main_seh
----- Foo destructor -----
***** END *****

DebugLog for: THROW_CPP_EXP = 1, CATCH_CPP_EXP = 0

THROW_CPP_EXP = 1, CATCH_CPP_EXP = 0
----- bar -----
===== main.__except =====
KERNELBASE: RaiseException
throw.cpp (136): _CxxThrowException
main.cpp (22): bar
main.cpp (30): foo
main.cpp (41): test
main.cpp (71): main
exe_common.inl (253): __scrt_common_main_seh
----- Foo destructor -----
***** END *****

DebugLog for: THROW_CPP_EXP = 0, CATCH_CPP_EXP = 1

THROW_CPP_EXP = 0, CATCH_CPP_EXP = 1
----- bar -----
----- Foo destructor -----
===== test.catch =====
stackwalker.cpp (1073): StackWalker::ShowCallstack
main.cpp (52): `test'::`1'::catch$1
handlers.asm (50): _CallSettingFrame
frame.cpp (1322): __CxxCallCatchBlock
ntdll: RtlRestoreContext
main.cpp (41): test
main.cpp (72): main
exe_common.inl (253): __scrt_common_main_seh
===== main.__except =====
KERNELBASE: RaiseException
frame.cpp (1342): __CxxCallCatchBlock
ntdll: RtlRestoreContext
main.cpp (41): test
main.cpp (72): main
exe_common.inl (253): __scrt_common_main_seh
***** END *****

DebugLog for: THROW_CPP_EXP = 1, CATCH_CPP_EXP = 1

THROW_CPP_EXP = 1, CATCH_CPP_EXP = 1
----- bar -----
----- Foo destructor -----
===== test.catch =====
stackwalker.cpp (1073): StackWalker::ShowCallstack
main.cpp (52): `test'::`1'::catch$1
handlers.asm (50): _CallSettingFrame
frame.cpp (1322): __CxxCallCatchBlock
ntdll: RtlRestoreContext
main.cpp (41): test
main.cpp (71): main
exe_common.inl (253): __scrt_common_main_seh
===== main.__except =====
KERNELBASE: RaiseException
frame.cpp (1342): __CxxCallCatchBlock
ntdll: RtlRestoreContext
main.cpp (41): test
main.cpp (71): main
exe_common.inl (253): __scrt_common_main_seh
***** END *****

DebugLog for: THROW_CPP_EXP = 1, CATCH_CPP_EXP = 2

THROW_CPP_EXP = 1, CATCH_CPP_EXP = 2
----- bar -----
----- Foo destructor -----
===== test.catch =====
KERNELBASE: RaiseException
throw.cpp (136): _CxxThrowException
main.cpp (22): bar
main.cpp (30): foo
main.cpp (41): test
main.cpp (71): main
exe_common.inl (253): __scrt_common_main_seh
===== main.__except =====
KERNELBASE: RaiseException
frame.cpp (1342): __CxxCallCatchBlock
ntdll: RtlRestoreContext
main.cpp (41): test
main.cpp (71): main
exe_common.inl (253): __scrt_common_main_seh
***** END *****

The last log shows how using the CATCH_CPP_EXP = 2 option allows you to fix the StackWalker bug.

But it is worth noting the following fact. If the test program is compiled with the /EHsc option, the StackWalker will work better (but not correctly). There will be an error in the line numbers (look to main and bar line numbers).

DebugLog for: /EHsc, THROW_CPP_EXP = 0, CATCH_CPP_EXP = 0

THROW_CPP_EXP = 0, CATCH_CPP_EXP = 0
----- bar -----
===== main.__except =====
main.cpp (23): bar
main.cpp (30): foo
main.cpp (41): test
main.cpp (72): main
exe_common.inl (253): __scrt_common_main_seh
***** END *****

DebugLog for: /EHsc, THROW_CPP_EXP = 0, CATCH_CPP_EXP = 1

THROW_CPP_EXP = 0, CATCH_CPP_EXP = 1
----- bar -----
===== main.__except =====
main.cpp (23): bar
main.cpp (30): foo
main.cpp (41): test
main.cpp (72): main
exe_common.inl (253): __scrt_common_main_seh
***** END *****

DebugLog for: /EHsc, THROW_CPP_EXP = 1, CATCH_CPP_EXP = 0
Same as for /EHa

DebugLog for: /EHsc, THROW_CPP_EXP = 1, CATCH_CPP_EXP = 1
Same as for /EHa

DebugLog for: /EHsc, THROW_CPP_EXP = 1, CATCH_CPP_EXP = 2
Same as for /EHa

It is necessary to explicitly write about this problem in the documentation!

[JochenKalmbach]

Please make a PR. Von: Oleg S. <notifications@github.com> Gesendet: Donnerstag, 26. November 2020 12:42 An: JochenKalmbach/StackWalker <StackWalker@noreply.github.com> Cc: Subscribed <subscribed@noreply.github.com> Betreff: [JochenKalmbach/StackWalker] Incorrect stack trace info for C++ exceptions (Win64) (#41) If C++ exceptions are used in the project, then to use __except it is necessary to build the project with the /EHa option! Proof: https://docs.microsoft.com/en-us/cpp/cpp/structured-exception-handling-c-cpp?view=msvc-160 When using C++ exceptions, the StackWalker cannot get information about the last call in which the exception occurred. Here is the code to demonstrate this bug: #include "stackwalker.h" #include <stdio.h> #include <stdexcept> #define THROW_CPP_EXCEPTION 1 #define CATCH_CPP_EXCEPTION 1 #define NOINLINE __declspec(noinline) NOINLINE int bar(int * pi = nullptr) { #if THROW_CPP_EXCEPTION == 1 throw(std::exception("Bar error")); /* line 13 */ #else *pi = 0xBADDEAD; /* line 15 */ #endif return 0; } NOINLINE void foo() { int x = bar(nullptr); /* line 22 */ printf("bar = %d \n", x); } extern "C" void** __cdecl __current_exception_context(); NOINLINE void test() { try { foo(); /* line 31 */ } catch(...) { #if CATCH_CPP_EXCEPTION == 1 PCONTEXT ctx = *(PCONTEXT *)__current_exception_context(); StackWalker sw(StackWalker::RetrieveVerbose); sw.ShowCallstack(GetCurrentThread(), ctx); #endif throw; } } LONG WINAPI ExpFilter(EXCEPTION_POINTERS * pExp, DWORD dwExpCode) { StackWalker sw(StackWalker::RetrieveVerbose); sw.ShowCallstack(GetCurrentThread(), pExp->ContextRecord); return EXCEPTION_EXECUTE_HANDLER; } int main() {

…

__try { test(); /* line 53 */ }

__except( ExpFilter(GetExceptionInformation(), GetExceptionCode()) ) { // nothing } return 0; } Compiler: MSVC2015 (x64 Release) Options with which the test project was built: /MT /Zi /O2 /EHa DebugLog for: THROW_CPP_EXCEPTION = 0, CATCH_CPP_EXCEPTION = 0 KERNELBASE: RaiseException frame.cpp (1342): __CxxCallCatchBlock ntdll: RtlRestoreContext main.cpp (31): test main.cpp (54): main exe_common.inl (253): __scrt_common_main_seh DebugLog for: THROW_CPP_EXCEPTION = 1, CATCH_CPP_EXCEPTION = 0 KERNELBASE: RaiseException frame.cpp (1342): __CxxCallCatchBlock ntdll: RtlRestoreContext main.cpp (31): test main.cpp (53): main exe_common.inl (253): __scrt_common_main_seh DebugLog for: THROW_CPP_EXCEPTION = 1, CATCH_CPP_EXCEPTION = 1 KERNELBASE: RaiseException throw.cpp (136): _CxxThrowException main.cpp (13): bar main.cpp (22): foo main.cpp (31): test main.cpp (53): main exe_common.inl (253): __scrt_common_main_seh KERNELBASE: RaiseException frame.cpp (1342): __CxxCallCatchBlock ntdll: RtlRestoreContext main.cpp (31): test main.cpp (53): main exe_common.inl (253): __scrt_common_main_seh The last log shows how using the CATCH_CPP_EXCEPTION = 1 option allows you to fix the StackWalker bug. But it is worth noting the following fact. If the test program is compiled with the /EHsc option, the StackWalker will work almost correctly. There will only be an error in the line numbers (look to main and foo line numbers). DebugLog for: /EHsc, THROW_CPP_EXCEPTION = 0, CATCH_CPP_EXCEPTION = 0 main.cpp (11): bar main.cpp (23): foo main.cpp (31): test main.cpp (54): main exe_common.inl (253): __scrt_common_main_seh And this bug is very serious! Need to fix! — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub<#41>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/ACP35X5O5IEHWDBB4JEI2SDSRY5HTANCNFSM4UDT2Y4Q>.