//static
bool OTString::vformat(const char * fmt, va_list * pvl, std::string & strOutput)
{
    OT_ASSERT(NULL != fmt);
    OT_ASSERT(NULL != pvl);
    // ------------------
    va_list args;
	int size;
	int nsize;
	char * buffer;


#ifdef _WIN32

	args = *pvl;
	nsize = _vscprintf(fmt,args);

#else

    size      = 512;
    buffer = new char[size+100];  // probably could just be size, not size+1. But harmless.
    OT_ASSERT(NULL != buffer);
    OTPassword::zeroMemory(buffer, size+100);
    // ------------------------------------
    // Here the buffer is 513 bytes but we tell vsnprintf that it's 512 bytes.
    // I guess only for wiggle-room.
    //

    va_copy(args, *pvl);
	nsize = vsnprintf(buffer,size,fmt,args);

	delete buffer; buffer = NULL;

#endif

    va_end(args);
    OT_ASSERT(nsize >= 0);

    // fail -- delete buffer and try again
    // If nsize was 1024 bytes, then that would mean that it printed 1024 characters,
    // even though the actual string must be 1025 in length (to have room for the null
    // terminator.)
    // If size, the ACTUAL buffer, was 1024 (that is, if size <= nsize) then size would
    // LACK the necessary space to store the 1025th byte containing the null terminator.
    // Therefore we are forced to delete the buffer and make one that is nsize+1, so that
    // it will be 1025 bytes and thus have the necessary space for the terminator
    //

	size  = nsize+1;
	buffer = new char[size+100];
	OT_ASSERT(NULL != buffer);
	OTPassword::zeroMemory(buffer, size+100);

	// ------------------------------------
#ifdef _WIN32
	nsize = vsnprintf_s(buffer,size,size,fmt,*pvl);
#else
	nsize = vsnprintf(buffer,size,fmt,*pvl)
#endif
	// ------------------------------------

	OT_ASSERT( nsize >= 0    );
	OT_ASSERT(  size >  nsize);

    // ------------------------------------
    // If nsize was 1024, that means the actual string is stored in
    // 0..1023 and the null terminator must be stored at index 1024,
    // in the 1025th byte. (Remember, we count from 0.)
    // (Therefore, since nsize is 1024 already, we can use it as the
    // index for adding the null terminator.)
    //
    // Update: Valgrind is complaining about a 1 byte issue in this function,
    // so I'm commenting this out for now. Anyway, vsnprintf should null-terminate.
    //
//  buffer[nsize] = '\0';
    // ------------------------------------
	strOutput = buffer;  // set buffer
    delete buffer; buffer = NULL;
    return true;
}