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Re: Patch to the way BFD reads overlaid ELF sections
On Thu, May 02, 2002 at 04:14:15PM +0100, Richard Sandiford wrote:
> then we end up with two segments that have the same file offset,
> file size (0), VMA, and memory size. Is it reasonable to expect
> BFD to get the mapping right in this case?
This is getting difficult. I don't think you can.
> The only way I can think of making it work is to have the
> file offsets for zeroed sections and segments point to the
> segment structure itself. Would that go against the ELF spec?
Yes, I believe it violates the ELF spec.
> I notice (for the section case) it says:
>
> One section type, SHT_NOBITS described below, occupies no
> space in the file, and its sh_offset member locates the
> conceptual placement in the file
>
> but I don't really understand what "conceptual placement" is,
> or how it affects things.
Well, if they _did_ occupy space, that's where they would be in the
file.
> Checking
>
> hdr->sh_offset + hdr->sh_size against both
> phdr->p_offset + phdr->p_memsz and
> phdr->p_offset + phdr->p_filesz
>
> seems to be redundant, since p_memsz can't be smaller than p_filesz.
Err, since p_filesz must be smaller, it's the more restrictive
limit, no?
--
Alan Modra
IBM OzLabs - Linux Technology Centre