[PATCH] Save/restore file offset while reading notes in core file

[Alan Modra]

On Thu, Mar 18, 2021 at 08:40:26AM -0700, Keith Seitz via Binutils wrote:
> 	* elfcore.h (_bfd_elf_core_find_build_id): Save and restore
> 	file offset when calling elf_read_notes.

Looks OK to me, but you could avoid the ftell with

	  /* Make sure ABFD returns to processing the program headers.  */
	  if (bfd_seek (abfd, (file_ptr) (offset + i_ehdr.e_phoff
					  + (i + 1) * sizeof (x_phdr)),
			SEEK_SET) != 0)
	    goto fail;

Either way is fine.

> ---
>  bfd/ChangeLog |  5 +++++
>  bfd/elfcore.h | 10 ++++++++++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/bfd/elfcore.h b/bfd/elfcore.h
> index 3015e582ef0..d5d1555ac03 100644
> --- a/bfd/elfcore.h
> +++ b/bfd/elfcore.h
> @@ -408,8 +408,18 @@ NAME(_bfd_elf, core_find_build_id)
>  
>        if (i_phdr->p_type == PT_NOTE && i_phdr->p_filesz > 0)
>  	{
> +	  /* elf_read_notes will seek to the file offset of the
> +	     note segment.  Save the current location in case
> +	     this program header contains multiple note segments.  */
> +	  file_ptr origin = bfd_tell (abfd);
> +
>  	  elf_read_notes (abfd, offset + i_phdr->p_offset,
>  			  i_phdr->p_filesz, i_phdr->p_align);
> +
> +	  /* Make sure ABFD returns to processing the program
> +	     headers.  */
> +	  if (bfd_seek (abfd, origin, SEEK_SET) != 0)
> +	    goto fail;
>  	  if (abfd->build_id != NULL)
>  	    return TRUE;
>  	}
> -- 
> 2.29.2

-- 
Alan Modra
Australia Development Lab, IBM