Embedding resources in executable using GCC

Question

I'm looking for a way to easily embed any external binary data in a C/C++ application compiled by GCC.

A good example of what I'd like to do is handling shader code - I can just keep it in source files like const char* shader = "source here"; but that's extremely impractical.

I'd like the compiler to do it for me: upon compilation (linking stage), read file "foo.bar" and link its content to my program, so that I'd be able to access the contents as binary data from the code.

Could be useful for small applications which I'd like to distribute as a single .exe file.

Does GCC support something like this?

Answer 1

There are a couple possibilities:

• use ld's capability to turn any file into an object (Embedding binary blobs using gcc mingw):

  ld -r -b binary -o binary.o foo.bar  # then link in binary.o
  

• use a bin2c/bin2h utility to turn any file into an array of bytes (Embed image in code, without using resource section or external images)

---

Update: Here's a more complete example of how to use data bound into the executable using ld -r -b binary:

#include <stdio.h>

// a file named foo.bar with some example text is 'imported' into 
// an object file using the following command:
//
//      ld -r -b binary -o foo.bar.o foo.bar
//
// That creates an bject file named "foo.bar.o" with the following 
// symbols:
//
//      _binary_foo_bar_start
//      _binary_foo_bar_end
//      _binary_foo_bar_size
//
// Note that the symbols are addresses (so for example, to get the 
// size value, you have to get the address of the _binary_foo_bar_size
// symbol).
//
// In my example, foo.bar is a simple text file, and this program will
// dump the contents of that file which has been linked in by specifying
// foo.bar.o as an object file input to the linker when the progrma is built

extern char _binary_foo_bar_start[];
extern char _binary_foo_bar_end[];

int main(void)
{
    printf( "address of start: %p\n", &_binary_foo_bar_start);
    printf( "address of end: %p\n", &_binary_foo_bar_end);

    for (char* p = _binary_foo_bar_start; p != _binary_foo_bar_end; ++p) {
        putchar( *p);
    }

    return 0;
}

---

Update 2 - Getting the resource size: I could not read the _binary_foo_bar_size correctly. At runtime, gdb shows me the right size of the text resource by using display (unsigned int)&_binary_foo_bar_size. But assigning this to a variable gave always a wrong value. I could solve this issue the following way:

unsigned int iSize =  (unsigned int)(&_binary_foo_bar_end - &_binary_foo_bar_start)

It is a workaround, but it works good and is not too ugly.

Answer 2

As well as the suggestions already mentioned, under linux you can use the hex dump tool xxd, which has a feature to generate a C header file:

xxd -i mybinary > myheader.h