C++ – C/C++ with GCC: Statically add resource files to executable/library

celfgcclinuxshared-libraries

Does anybody have an idea how to statically compile any resource file right into the executable or the shared library file using GCC?

For example I'd like to add image files that never change (and if they do, I'd have to replace the file anyway) and wouldn't want them to lie around in the file system.

If this is possible (and I think it is because Visual C++ for Windows can do this, too), how can I load the files which are stored in the own binary? Does the executable parse itself, find the file and extract the data out of it?

Maybe there's an option for GCC which I haven't seen yet. Using search engines didn't really spit out the right stuff.

I would need this to work for shared libraries and normal ELF-executables.

Best Answer

Update I have grown to prefer the control John Ripley's assembly .incbin based solution offers and now use a variant on that.

I have used objcopy (GNU binutils) to link the binary data from a file foo-data.bin into the data section of the executable:

objcopy -B i386 -I binary -O elf32-i386 foo-data.bin foo-data.o

This gives you a foo-data.o object file which you can link into your executable. The C interface looks something like

/** created from binary via objcopy */
extern uint8_t foo_data[]      asm("_binary_foo_data_bin_start");
extern uint8_t foo_data_size[] asm("_binary_foo_data_bin_size");
extern uint8_t foo_data_end[]  asm("_binary_foo_data_bin_end");

so you can do stuff like

for (uint8_t *byte=foo_data; byte<foo_data_end; ++byte) {
    transmit_single_byte(*byte);
}

or

size_t foo_size = (size_t)((void *)foo_data_size);
void  *foo_copy = malloc(foo_size);
assert(foo_copy);
memcpy(foo_copy, foo_data, foo_size);

If your target architecture has special constraints as to where constant and variable data is stored, or you want to store that data in the .text segment to make it fit into the same memory type as your program code, you can play with the objcopy parameters some more.

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