DebugTrapHandler Class Reference

Default SIGTRAP handler. More...

#include <trap.h>

Inheritance diagram for DebugTrapHandler:

Additional Inherited Members
Public Member Functions inherited from SignalHandler< SIGTRAP, false >
	SignalHandler (SignalHandlerFn pfn=NULL, int flags=0)
	Construct a signal handler.

Detailed Description

Default SIGTRAP handler.

DebugTrapHandler() can be used by a program to install an empty SIGTRAP handler. If present, the handler ensures there is a signal handler in place for SIGTRAP raised by CRYPTOPP_ASSERT. If CRYPTOPP_ASSERT raises SIGTRAP without a handler, then one of two things can occur. First, the OS might allow the program to continue. Second, the OS might terminate the program. OS X allows the program to continue, while some Linuxes terminate the program.

If DebugTrapHandler detects another handler in place, then it will not install a handler. This ensures a debugger can gain control of the SIGTRAP signal without contention. It also allows multiple DebugTrapHandler to be created without contentious or unusual behavior. Though multiple DebugTrapHandler can be created, a program should only create one, if needed.

A DebugTrapHandler is subject to C++ static initialization [dis]order. If you need to install a handler and it must be installed early, then reference the code associated with CRYPTOPP_INIT_PRIORITY in cryptlib.cpp and cpu.cpp.

If you want to ensure CRYPTOPP_ASSERT is inert, then do not define CRYPTOPP_DEBUG, DEBUG or _DEBUG. Avoiding the defines means CRYPTOPP_ASSERT is processed into ((void)0).

The traditional Posix define NDEBUG has no effect on CRYPTOPP_DEBUG, CRYPTOPP_ASSERT or DebugTrapHandler.

An example of using CRYPTOPP_ASSERT and DebugTrapHandler is shown below. The library's test program, cryptest.exe (from test.cpp), exercises the structure:

  #if defined(CRYPTOPP_DEBUG) && defined(UNIX_SIGNALS_AVAILABLE)
  const DebugTrapHandler g_dummyHandler;
  #endif

  int main(int argc, char* argv[])
  {
     CRYPTOPP_ASSERT(argv != nullptr);
     ...
  }
 

Since

Crypto++ 5.6.5

See also

CRYPTOPP_ASSERT, SignalHandler, Issue 277, CVE-2016-7420

Definition at line 154 of file trap.h.

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The documentation for this class was generated from the following file:

• trap.h