Get source location for address at runtime using debug information

Question

In my C program, I have an instruction pointer that points to some address in virtual memory, e.g., a function pointer. I would like to map this address to the corresponding source location (file path, line number) using the debug information in the executed binary at runtime. I know that GDB implements something like this, but am unsure how to approach this for my project.

I'm aware of addr2line and llvm-symbolizer, but both of those tools analyze addresses in ELF files, not binaries that are already loaded into virtual memory. Similarly, this is not a duplicate of How do I access the addr2line functionality within my C++ program?

Answer 1

Thanks to Yakov Galka's comment, I found a solution for what I want to do:

#define __USE_GNU
#include <dlfcn.h>

// instruction address for which I want the source location
const void* code_addr = 0xabcdef;

// call dladdr to figure out base address in virtual memory
Dl_info info;
dladdr(code_addr, &info);

size_t base_address = (size_t) info.dli_fbase;
size_t relative_address = ((size_t) code_addr) - base_address;
// in my case: relative_address == 0x126c

Then, I can call addr2line to determine the source location. In my case, everything is liked into a.out, so I can just call

addr2line --basenames -i -e tasks.out 0x126c

which then prints something like:

filename.c:42