User forums > Using Code::Blocks

strlen() fails when the code is compiled with mingw gcc

(1/3) > >>

sylwa:
Hi !

I've just installed code::block bundled with mingw.
To test the compiler/debugger tools, I've compiled this snippet :


--- Code: ---#include <tchar.h>
#include <memory.h> // for memset
#include <string>

using namespace std;

const unsigned kuiConfigFileNameMaxLength = 128;

int _tmain(int argc, _TCHAR* argv[])
{
  int iErr = 0;
  char cConfigFileName [kuiConfigFileNameMaxLength];
  memset( (void*)cConfigFileName , 0, kuiConfigFileNameMaxLength );

  // Get input file name
  if ( strlen( (const char *) argv[1] ) > kuiConfigFileNameMaxLength )
  {
    iErr = 1;
  }
  else
  {
    memcpy( (void*)cConfigFileName, (const void*)argv[1], strlen( (const char *) argv[1] ));
  }

  string strConfigFileName( (const char*)(cConfigFileName), strlen( (const char *)cConfigFileName) );

  return iErr;
}


--- End code ---

While debugging, the program crahses @ line :

--- Code: ---  if ( strlen( (const char *) argv[1] ) > kuiConfigFileNameMaxLength )

--- End code ---

Here the debugger messages :
Program received signal SIGSEGV, Segmentation fault.
In std::string::c_str() const () ()
Program received signal SIGSEGV, Segmentation fault.

Still, this works perfectly when compiled with Visual Studio.

Any hints ?

Regards

Sylvain

ollydbg:
Maybe, you have the same issue like Watching std::string in debugger causes segfault?!?

sylwa:
Dear OllyDbg,

Many thanks for your reply.

I went through the post link you provided to me.
Nevertheless, I'am not expert enough to understand why, in my case, calling the C function strlen() triggers std::string::c_str() C++ method which in turn makes my program crash !

May I ask you some enlightenments or some biblio references about that behaviour ?

Best Regards

jarod42:
I would say that argv[1] is NULL. (Do you provide debug args, and do you have a project ?)
and with some optimisation, crash "occurs" in string constructor.

sylwa:
Dear jarod42,

yes, I provided some non null string into argv[1].
Moreover, following memcpy works fine !

You talk about string constructor crash, but it's invoked / executed later in the code.
The Seg fault that I pointed out occurs at the strlen() code line.

Regards

Sylvain

Navigation

[0] Message Index

[#] Next page