Re: Adding a NOTE section after a copy ..

[Roland McGrath <roland at redhat dot com>]

You cannot add an SHF_ALLOC section to an already-final (non-ET_REL) ELF
file without doing a lot more work.  If you want a non-allocated section
created with the compiler, you have to play some games with asm () to get
the section flags right.  For adding a simple string or binary blob, it is
easier to write or generate assembly source where you write exactly the
section directive you want (.section .note.foo, "", @note).

If you use ELF_F_LAYOUT (which you must unless you recompute the phdrs
too), then you have to set sh_offset manually in your new section.

Indeed you do not have to adjust e_shnum; that is automatic in elf_update
after you have used elf_newscn.  Of course, you do need to add your
section's name to .shstrtab.

You may find it easier to write a script using objcopy --add-section
(binutils) rather than writing your own tool with libelf.


Thanks,
Roland