我一直在尝试编写一些错误保护条款,用于识别第三方提供给我们的dll中的问题。这个DLL可能存在问题(内存异常,浮点错误等),并且能够在不访问源代码的情况下识别这些错误是有利的。
我从各种SEH错误处理例程中收集了一些东西,但是虽然它有效,但它有几个......不一致。我试图隔离每一个,我会逐个问一个问题。
这与在SEH __try / __ except子句中使用的GetExceptionCode有关,以识别错误。它似乎没有可靠地这样做。
这是一个明确的除零情况:
#include <float.h> // defines of _EM_OVERFLOW, etc.
#include <string.h> // strncpy_s & strncat_s
#include <stdlib.h> // malloc
#include <excpt.h> // EXCEPTION_EXECUTE_HANDLER
#include <iostream> // cout
#include <bitset> // bitset
#include <conio.h> // _kbhit
#pragma fenv_access (on)
const unsigned int SERIOUS_FP_EXCEPTIONS = _EM_DENORMAL | _EM_ZERODIVIDE | _EM_INVALID;
const unsigned int MINOR_FP_EXCEPTIONS = _EM_OVERFLOW | _EM_UNDERFLOW | _EM_INEXACT;
int main(int argc, char[])
{
double numerator = 1.0;
double denominator = 0.0;
double result = 0.0;
unsigned int _previous_floating_point_control;
_controlfp_s(&_previous_floating_point_control, 0, 0);
_controlfp_s(nullptr, MINOR_FP_EXCEPTIONS, _MCW_EM);
__try {
result = numerator / denominator;
_controlfp_s(NULL, _previous_floating_point_control, _MCW_EM);
}
__except (EXCEPTION_EXECUTE_HANDLER)
{
std::cout << "_EM_INEXACT = " << std::bitset<32>(_EM_INEXACT) << std::endl;
std::cout << "_EM_UNDERFLOW = " << std::bitset<32>(_EM_UNDERFLOW) << std::endl;
std::cout << "_EM_OVERFLOW = " << std::bitset<32>(_EM_OVERFLOW) << std::endl;
std::cout << "_EM_ZERODIVIDE = " << std::bitset<32>(_EM_ZERODIVIDE) << std::endl;
std::cout << "_EM_INVALID = " << std::bitset<32>(_EM_INVALID) << std::endl;
std::cout << "_EM_DENORMAL = " << std::bitset<32>(_EM_DENORMAL) << std::endl;
std::cout << "_EM_AMBIGUOUS = " << std::bitset<32>(_EM_AMBIGUOUS) << std::endl;
std::cout << std::endl;
std::cout << " divide-by-zero" << std::endl;
std::cout << " |" << std::endl;
std::cout << " ambiguous code? underflow" << std::endl;
std::cout << " | : |" << std::endl;
std::cout << " v v v" << std::endl;
std::cout << "Exception code = " << std::bitset<32>(GetExceptionCode()) << std::endl;
std::cout << " ^ ^ ^ ^" << std::endl;
std::cout << " | : : |" << std::endl;
std::cout << " denormal number inexact number" << std::endl;
std::cout << " : |" << std::endl;
std::cout << " overflow" << std::endl;
std::cout << " |" << std::endl;
std::cout << " invalid number" << std::endl;
if (GetExceptionCode() & _EM_ZERODIVIDE)
std::cout << "ERROR! Divide By Zero!" << std::endl;
else
std::cout << "No divide by zero found here!" << std::endl;
_controlfp_s(NULL, _previous_floating_point_control, _MCW_EM);
}
std::cout << "result = " << result << std::endl;
while (!_kbhit()) // Wait until a key is pressed to close console.
{ }
}
这将打印以下内容:
_EM_INEXACT = 00000000000000000000000000000001
_EM_UNDERFLOW = 00000000000000000000000000000010
_EM_OVERFLOW = 00000000000000000000000000000100
_EM_ZERODIVIDE = 00000000000000000000000000001000
_EM_INVALID = 00000000000000000000000000010000
_EM_DENORMAL = 00000000000010000000000000000000
_EM_AMBIGUOUS = 10000000000000000000000000000000
divide-by-zero
|
ambiguous code? underflow
| : |
v v v
Exception code = 11000000000000000000001010110101
^ ^ ^ ^
| : : |
denormal number inexact number
: |
overflow
|
invalid number
No divide by zero found here!
result = 0
它确定了一个问题(很棒),但没有正确诊断出来。
更糟糕的是,当用一个缺少依赖的dll调用替换该子句时,我得到:
f.p. exceptions
denormal number |
| _|_
v / \
11000000011011010000000001111110
^^ ^ ^ ^^
|| | | ||
\________________/
unknown codes
在SIGSEV错误(分段错误)的情况下返回类似的结果。这意味着我们将其他问题误认为是浮点异常。
所以我的问题是:
PS:请不要发表评论或回复说我应该检查分母是否为0 - 我知道,我在我控制的所有代码中都这样做。
答案 0 :(得分:2)
你需要的东西是
DWORD exception_filter(DWORD dwExceptionCode)
{
// use dwExceptionCode to handle only the types of exceptions you want
// if you want to use it inside your handler, you'll need to save it.
return EXCEPTION_EXECUTE_HANDLER; // or other value depending on ExceptionCode
}
Your exception handler...
__try
{
something();
}
__except (exception_filter(GetExceptionCode())
{
// DO NOT CALL GetExceptionCode() or GetExceptionInfo() here. If you need
// Exception Info as well, pass it to the filter, and save the values you need.
switch (dwSavedExceptionCode)
{
case EXCEPTION_FLT_OVERFLOW:
ItWasAFloatingPointOverflow();
break;
case EXCEPTION_FLT_DIVIDE_BY_ZERO:
ItWasAFloatingDivideByZero();
break;
case ***Other Exception Types You Want handled (==the ones you returned execute_handler for in the filter) ***
break;
}
}
答案 1 :(得分:1)
例外代码= 11000000000000000000001010110101
该值为0xC00002B5
,又名STATUS_FLOAT_MULTIPLE_TRAPS
。
请参阅Why after enabling floating point exceptions I got multiple traps error。