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Re: Extract static object from dynamic one

From: Brian Dessent <brian at dessent dot net>
To: Thomas Köppe <t dot koeppe at ed dot ac dot uk>
Cc: gcc-help at gcc dot gnu dot org, Tom Browder <tom dot browder at gmail dot com>
Date: Tue, 04 Dec 2007 06:19:06 -0800
Subject: Re: Extract static object from dynamic one
References: <47548F85.8040002@ed.ac.uk> <8bc817ee0712040358o4e3d8d85vf9afafa25fe5eea@mail.gmail.com> <4755509F.847B5017@dessent.net> <47555F19.1060501@ed.ac.uk>
Reply-to: gcc-help at gcc dot gnu dot org

Thomas Köppe wrote:

> Is there an obstruction in principle (that some vital information is
> lost in the shared library), or is it simply that no such tool has been
> written?

It's not just a matter of extracting something.  You'd have to rewrite
all accesses through the GOT and PLT (for ELF) or indirections through
.idata (for PE) to be regular symbol references.  You'd have to undo
relocs and make them into regular labels.  With things like relaxation
this becomes extremely nontrivial.  In a sense this is going backwards,
like a disassembler, because a static library is just a collection of
unlinked .o files, whereas a shared library is fully linked.

Brian

Follow-Ups:
- Re: Extract static object from dynamic one
  - From: Ian Lance Taylor

References:
- Extract static object from dynamic one
  - From: Thomas Köppe
- Re: Extract static object from dynamic one
  - From: Tom Browder
- Re: Extract static object from dynamic one
  - From: Brian Dessent
- Re: Extract static object from dynamic one
  - From: Thomas Köppe

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