c++ - 在什么情况下EXCEPTION_RECORD链接到另一个嵌套异常？

Question

_EXCEPTION_RECORD的documentation说明了其中一个成员struct _EXCEPTION_RECORD *ExceptionRecord

A pointer to an associated EXCEPTION_RECORD structure. Exception records can be chained together to provide additional information when nested exceptions occur.

但是，我无法引发这种嵌套结构异常的情况。到目前为止，这是我尝试过的:

#include <iostream>
#include <windows.h>

void Handle0(LPEXCEPTION_POINTERS pex) {
    std::cout << "chain0 = " << pex->ExceptionRecord->ExceptionRecord << std::endl;
}

void Handle1(LPEXCEPTION_POINTERS pex) {
    std::cout << "chain1 = " << pex->ExceptionRecord->ExceptionRecord << std::endl;
    __try {
        throw 3;
    } __except( Handle0(GetExceptionInformation()), EXCEPTION_EXECUTE_HANDLER ) {}
}

int main() {
    __try {
        throw 3;
    } __except( Handle1(GetExceptionInformation()), EXCEPTION_EXECUTE_HANDLER ) {}
    return 0;
}

pex->ExceptionRecord->ExceptionRecord始终是nullptr。在什么情况下我可以在那里找到嵌套的_EXCEPTION_RECORD的链接？

Answer 1

根据MSDN:

When an exception is raised during the processing of an exception filter within ... native code ... a nested exception is raised, the ExceptionRecord field in the EXCEPTION_RECORD structure (as returned by GetExceptionInformation) is set, and the ExceptionFlags field sets the 0x10 bit. The following example illustrates this difference in behavior:

#include <windows.h>
#include <stdio.h>
#include <assert.h>

#ifndef false
#define false 0
#endif

int *p;

int filter(PEXCEPTION_POINTERS ExceptionPointers) {
   PEXCEPTION_RECORD ExceptionRecord =
                     ExceptionPointers->ExceptionRecord;

   if ((ExceptionRecord->ExceptionFlags & 0x10) == 0) {
      // not a nested exception, throw one
      *p = 0; // throw another AV
   }
   else {
      printf("Caught a nested exception\n");
      return 1;
    }

   assert(false);

   return 0;
}

void f(void) {
   __try {
      *p = 0;   // throw an AV
   }
   __except(filter(GetExceptionInformation())) {
      printf_s("We should execute this handler if "
                 "compiled to native\n");
    }
}

int main() {
   __try {
      f();
   }
   __except(1) {
      printf_s("The handler in main caught the "
               "exception\n");
    }
}

我相信如果您尝试继续不可延续的异常，它也会被设置。在这种情况下，EXCEPTION_RECORD将表示EXCEPTION_NONCONTINUABLE_EXCEPTION，而其ExceptionRecord将指向原始异常。