[sane-devel] SANE_CAP_ALWAYS_SETTABLE (was Re: Preparing for a sane-backends release)

Olaf Meeuwissen olaf.meeuwissen at avasys.jp
Wed Aug 5 23:34:41 UTC 2015

Hi Johannes,

Sorry if my reply hit a raw nerve.  Didn't mean to.

I just wanted to point out that SANE_CAP_ALWAYS_SETTABLE is not part of
the specification and therefore your suggestion to add it to sane.h was
a bit misguided.  You are of course free to keep that patch in the SUSE
packaging of sane-backends.

Alternatively, the SANE standard could be extended to add this symbol.

# Maybe after the release would be a good time to blow the dust of the
# SANE 2 draft document and see what parts can be safely added to SANE 1
# without breaking API or ABI but that's food for sane-standard.

Johannes Meixner writes:

> Hello,
> On Aug 5 08:21 Olaf Meeuwissen wrote (excerpt):
>> Johannes Meixner writes:
> ...
>>> to sane.h which was erroneously removed in sane-backends-1.0.20 so that
>>> sane-frontends and xsane can no longer build, see
>>> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=527675
>> Hmm, SANE_CAP_ALWAYS_SETTABLE is not part of the SANE Standard.
> And what should a Linux distributor do when other programs
> (in this case sane-frontends and xsane) use something
> against the SANE Standard?

The Right Thing to do would be to fix those other programs.  Yes, I
know that may be a time consuming, lengthy and frustrating process.
Until complete you just keep using your patch.

> [...]
>>> I did not verify whether or not meanwhile all SANE frontends
>>> also no longer use SANE_CAP_ALWAYS_SETTABLE so that it could
>>> meanwhile be really removed in sane-backends.
>> The sane-frontends have it in an #ifdef conditional (in src/gtkglue.c)
>> that was added in 5e96223, apparently to switch to SANE 1.1 which never
>> materialized.
> I meant "all SANE frontends" - not only sane-frontends.
> I.e. also xsane and whatever else there is nowadays, cf.
> http://www.sane-project.org/sane-frontends.html

I didn't mean to imply all SANE frontends, just point out the
sane-frontends is OK.  The "fix" there should port fairly easily to
other SANE frontends (once you take toolkit differences into account).

> [...]
> Accordingly xsane should have been fixed since a long time.
> But I cannot tell about the other SANE frontends and
> right now I do not have the spare time to check them all.
> Should I now just remove my old patch to see what happens?

You could and when you get "bug" reports about compile time breakage you
can just point out the SANE_CAP_ALWAYS_SETTABLE is not part of the SANE
standard and tell people to fix *their* bugs.

> But I really do not like it when then I get blamed if something
> does no longer work so that for me personally it would be better
> to just keep that old patch.

As mentioned, you are free to do so.

Hope this helps,
Olaf Meeuwissen, LPIC-2     FLOSS Engineer -- EPSON AVASYS CORPORATION
FSF Associate Member #1962               Help support software freedom

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