`p_offset` in ELF binary

Question

I'm trying to learn the ELF format and am implementing an ELF parser. So far, I've implemented the ELF header parser, and I'm working on parsing segments, especially the .text segment. I'm stuck here because of the following reasons:

1. When I build a go binary, the program header with LOAD type with readable and executable flags (which to my understanding points to the .text segment has a p_offset of 0). It must mean that the entire file is readable and executable (as the p_filesz is almost the same size as that of the binary.)

2. When I compile a C or Rust program, the problem is not there and the p_offset field is properly set with a non-zero value.

3. I don't want to use the section information to parse the .text segment from the go binary as it works with all the sections information stripped, so I must be missing something.

In short, How do I find the .text segment in a ELF binary with p_offset value 0 in a loadable program header with readable and executable flags.

Also, here is the abridged readelf dump of the go binary that I'm working with:

Program Headers:
  Type           Offset             VirtAddr           PhysAddr
                 FileSiz            MemSiz              Flags  Align
  PHDR           0x0000000000000040 0x0000000000400040 0x0000000000400040
                 0x0000000000000150 0x0000000000000150  R      0x1000
  NOTE           0x0000000000000f9c 0x0000000000400f9c 0x0000000000400f9c
                 0x0000000000000064 0x0000000000000064  R      0x4
  LOAD           0x0000000000000000 0x0000000000400000 0x0000000000400000
                 0x000000000007adfa 0x000000000007adfa  R E    0x1000

Thanks!

I've tried reading the System V ELF specification, the x86-64 supplement, tried looking for articles on this topic and asked help from ChatGPT and Bard.

Answer 1

In short, How do I find the .text segment in a ELF binary with p_offset value 0 in a loadable program header with readable and executable flags.

There is not a .text segment -- it simply doesn't exist (.text section does, but you are not interested in it).

Instead, multiple sections are grouped together, and are "covered" by a single LOAD segment.

When I build a go binary, the program header with LOAD type with readable and executable flags (which to my understanding points to the .text segment has a p_offset of 0). It must mean that the entire file is readable and executable (as the p_filesz is almost the same size as that of the binary.)

Yes, it means exactly that, and there is nothing wrong with that. The linker chose to put everything into one segment (you can see section to segment mapping in readelf -Wl a.out output).

See also this answer.