[Nix-dev] Hard-coded dlload paths in .so [was: Nix expression for closed-source scanner driver]

[Peter Jones]

Bjørn Forsman <bjorn.forsman at gmail.com> writes:
> On 16 December 2014 at 02:09, Peter Jones <mlists at pmade.com> wrote:
>> I'm working on a Nix expression to install a proprietary scanner driver
>> that is available as a Debian package.  After using `nix-env' to install
>> the package I'm still not able to see my scanner in the list produced by
>> `scanimage -L' or `sane-find-scanner'.
>>
>> Here's the expression (WIP):
>>
>>   https://github.com/pjones/nixpkgs/blob/pkg/brother/pkgs/misc/drivers/brother/dsseries.nix
>>
>> Something interesting to note is that device files for the scanner show
>> up in /dev/bsg/ instead of the usual /dev/sg*.  I think that has
>> something to do with the scanner being detected as a disk.
>>
>> I did have this working under Debian before switching to NixOS.  I also
>> still have a Debian install if I need to test anything or figure out
>> what's going on.
>>
>> Any hint/tips would be appreciated.  Thanks.
>
> Maybe you must patchelf some binaries? See if this finds something
> that points to (nonexisting) /usr/... or similar:
>
> find $out | while read f; do patchelf --print-rpath "$f"; done

None of the .so files in the binary package have an RPATH set.  I was
able to use strace and strings to discover that the main .so for the
scanner driver tries to dlload two other .so files using hard-coded
paths.  

Can I alter the strings in the .so or do I need to make some sort of
wrapper that intercepts the dlload calls and loads the correct
libraries?  If the latter, is there an example somewhere I can use as a
guide?

-- 
Peter Jones, Founder, Devalot.com
Defending the honor of good code