[sane-devel] XSANE fails to detect any scanner.

[Olaf Meeuwissen]

Hi Aveek,

Aveek Basu writes:

> *1. libusb version 0.1-4 is not installed:*
>
> It has been observed in Ubuntu 17.10 (x86) / (x64) & Ubuntu 18.04 that libusb
> version 0.1-4  is not installed properly. Lexmark Scanner drivers
> require libusb
> version 0.1-4 for the scanners to get detected.

In which case the debian/control file for the Lexmark Scanner driver
should say so.  APT can then pull it in, if needed, without any effort
required from the user when they install your driver.

> This seems to be a Ubuntu issue and nothing specific to any application.
>
> *Bug logged:* https://bugs.launchpad.net/ubuntu/+source/xsane/+bug/1770653.

This is not an Ubuntu (or any other Debian distro) bug.  This is a bug
in the Lexmark Scanner driver .deb.

Please read, understand and follow the Debian[1] and Ubuntu[2] packaging
documentation[1].

 [1]: https://www.debian.org/devel/#packaging
 [2]: http://packaging.ubuntu.com/

And as Allan mentioned in another follow-up, distributions are free to
stop providing old, deprecated libraries whenever they want to.  That
said, libusb-0.1-4 is still available.

> *2.* *XSANE looking for driver files in different paths:*
>
> Usually XSANE used to look for the driver files in  /usr/lib/sane for 32
> bit version of the Ubuntu OS and /usr/lib64/sane for the 64 bit version of
> the Ubuntu OS. This was the case at-least till Ubuntu 14.10. After that
> there seems to be discrepancies in the locations XSANE is trying to find
> the driver files. Details mentioned below:
>
> OS
> OS locations searched by XSANE for the Driver Files
> Ubuntu 14.10 Ubuntu 16.04 Ubuntu 16.10 Ubuntu 17.10/18.04
> x86 /usr/lib/sane /usr/lib/sane /usr/lib/sane /usr/lib/i386-linux-gnu/sane
> x64 /usr/lib64/sane /usr/lib/sane /usr/lib/sane
> /usr/lib/x86_64-linux-gnu/sane

So things changed over time.  It's called progress ;-)
Like it or not, you will have to follow these changes.

> So now the question is which should be the perfect path for XSANE to look
> for the driver files. If "*/usr/lib/i386-linux-gnu/sane*" and "
> */usr/lib/x86_64-linux-gnu/sane*" are the confirmed new locations then the
> driver has to change. Need a confirmation on the same.
>
> *Bug logged: *https://bugs.launchpad.net/ubuntu/+source/xsane/+bug/1770656

This is not a bug and the answer to your question is wherever they are
supposed to be installed on each version of each distribution and each
architecture that you target.

And I fully second Allan's suggestion about open sourcing your driver.
It will allow distribution's to do the packaging for you.  That is,
after a bit of lead-time and hand-holding on your side, likely to lead
to more up-to-date, better integrated packages for more versions of more
distribution and more architectures than Lexmark could ever hope to
support by itself.

Hope this helps,
--
Olaf Meeuwissen, LPIC-2            FSF Associate Member since 2004-01-27
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