How to Embed Resources into Executables and Shared Libraries using GCC?

Embedding Resources into Executables and Shared Libraries with GCC

Problem Statement:

How to statically embed resource files into executable and shared library files using the GCC compiler?

Solution:

To embed resource files into binary programs using GCC, follow these steps:

1. Create the object file: Use the objcopy utility from the GNU binutils package to create an object file containing the binary data of the resource file. For instance, to convert the binary file foo-data.bin into an object file:

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

2. Link the object file: Link the object file containing the resource data into your executable or shared library.
3. C Interface: Define appropriate C symbols in the binary, such as foo_data, foo_data_size, and foo_data_end. These symbols represent the start, size, and end of the embedded resource data, allowing for convenient access within the program.
4. Usage: You can interact with the embedded resource data using the defined symbols. For example, you can iterate through the data or copy it into a buffer.

Additional Considerations:

• Adjusting objcopy parameters can address specific data placement requirements for your target architecture.
• If required, you can embed the resource data into other segments, such as the .text segment, to optimize memory allocation.

Example Usage:

The following code snippet demonstrates how to use the embedded resource data:

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");

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);

This code reads the embedded foo-data resource, determines its size, and makes a copy in the program memory.

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