Re: Cygport and auto-manifestize compatibility manifest

[Corinna Vinschen <corinna-cygwin at cygwin dot com>]

On Nov 20 19:14, Corinna Vinschen wrote:
> On Nov 20 18:32, Corinna Vinschen wrote:
> > On Nov 20 18:22, Achim Gratz wrote:
> > > Corinna Vinschen writes:
> > > > Well, perhaps.  I'm just not sure it's the right thing to do it at
> > > > postinstall time.  I mean, it's not impossible, obviously, but it's
> > > > a lot of stuff per executable and running this for a few thousand .exe
> > > > files could take some time.
> > > 
> > > Yes, it does... but ever since I've switched to doing incremental
> > > autorebases that time has shrunk a lot.
> > > 
> > > > We would also have to make sure that the sections with long section
> > > > names are recreated after adding the .rsrc section, which is something
> > > > I don't quite see how to accomplish, right now.
> > > 
> > > Hmm.  I'm out of my depths on this, but would it be possible to excise
> > > those sections, do whatever changes are necessary to the rest of the
> > > executable and then add them back?
> > 
> > I don't know.  It's apparently more complicated than just calling
> > objcopy.  For instance, objcopy can export sections from a file in
> > whatever format you want, but it can only add back sections if they are
> > given as binary blobs.  If you add such a binary blob it's missing
> > relocation information.  Also, you have to make sure all the sections
> > start at the right address, thanks to the harebrained PE/COFF format.
> > 
> > This is apparently a big deal, otherwise it should have been no problem
> > to add a resource binary blob into an executable without making Windows
> > choke on it (ERROR_BAD_EXE_FORMAT).  Maybe I did something wrong, but I
> > would have no idea what option I missed.
> 
> I just made a quick test for the sake of creating a generic script to
> add the manifests.
> [...]

For the records and to all interested in this.  I have a script now
which works, provided the executables are stripped and the
.gnu_debuglink section is the only section with a long section name.

The sources of the script called "add-mani.sh" and the sources of
the Windows tool necessary to update the manifest are attached.

The downside:

If you add a manifest to, say, tcsh, the tcsh.exe.dbg file from the
tcsh-debuginfo package will not have the .rsrc section, and due to the
Dwarf2 debug sections you will not be able to add the .rsrc section
successfully *and* keep the tcsh.exe.dbg file debuggable.  This in turn
results in a warning in GDB:

  warning: section .rsrc not found in /usr/lib/debug/bin/tcsh.exe.dbg

The tcsh binary is still debuggable, apparently, but still...

Therefore I think this script is only a temporary measure, until the
time the binutils package allows to accomplish this by itself.  We're
working on that.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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