Category: C++

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Shuffling function addresses in C/C++ with MSVC

The Microsoft C/C++ compiler allows you to specify link order of functions or variables. Using the #pragma directive with either code_seg or data_seg and specifying the segment name and its sorting key, you can tell the linker how to place the object code in the final executable.

Let’s start with a simple example:

#pragma code_seg(push, ".text$EB009")
__declspec(noinline) void f1()
{
    printf("this is f1()\n");
}
#pragma code_seg(pop)


#pragma code_seg(push, ".text$EB005")
__declspec(noinline) void f2()
{
    printf("this is f2()\n");
}
#pragma code_seg(pop)


#pragma code_seg(push, ".text$EB001")
__declspec(noinline) void f3()
{
    printf("this is f3()\n");
}
#pragma code_seg(pop)

int main()
{
    f1();
    f2();
    f3();
    return 0;
}

When the code_seg pragma is used, we can specify where the subsequent code should lie (in which section in the PE file). When the section name contains the “$” sign, then the subsequent text is not part of the section name (the string prior to the “$”) and instead is used as a sorting key. Continue reading “Shuffling function addresses in C/C++ with MSVC”

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Batchography: Polyglot Batch files and C++ – Self compiling C++ script

This article is part of the Batchography articles series and today, I am going to show you how to write a valid Batch file that is also a valid C/C++ file. The Batch file part of the source can do anything, however in this article, its sole purpose will be to compile itself and run the compile C++ program.

Let’s get started with the Polyglot source code:

Continue reading “Batchography: Polyglot Batch files and C++ – Self compiling C++ script”

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Programming with Emojis

I ran into the EmojiCode website. Emojicode is an open-source, full-blown programming language consisting of emojis.

I personally did not like that language, but it is worthwhile mentioning:

No idea what that code does…I don’t care 😉

Meanwhile, if you are a C++ programmer, enjoy the following, legitimate, piece of code that redefine keywords into emojis and then the fun starts:

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strtok() C++ wrapper

In this article, I share with you a simple C++ class that wraps the string tokenization function strtok(). The QuickTokenizer class makes it easy to tokenize and enumerate the tokens in a thread-safe manner.

The class code

//////////////////////////////////////////////////////////////////////////
class QuickTokenizer
{
private:
  char *buf;
  char *token;
  char *ctx;

  void FreeBuffers()
  {
    if (this->token != NULL)
    {
      free(this->token);
      this->token = NULL;
    }
    if (this->buf != NULL)
    {
      free(this->buf);
      this->buf = NULL;
    }
  }

public:
  QuickTokenizer() : buf(NULL), token(NULL)
  {

  }

  const char *Tokenize(
    const char *str,
    const char *tok)
  {

    this->buf = _strdup(str);
    this->token = _strdup(tok);

    return strtok_s(buf, token, &ctx);
  }

  const char *NextToken()
  {
    return strtok_s(NULL, token, &ctx);
  }

  ~QuickTokenizer()
  {
    FreeBuffers();
  }
};

Continue reading “strtok() C++ wrapper”