[sane-devel] Avision bug (was: Re: Suicidal Child Process - SANE)

m. allan noah kitno455 at gmail.com
Mon Dec 22 01:31:23 UTC 2008

> On Tue, Dec 9, 2008 at 10:48 AM, Mattias Ellert
> <mattias.ellert at fysast.uu.se> wrote:
>> mån 2008-12-08 klockan 09:46 -0500 skrev m. allan noah:
>>> After some private mails with Ian, it seems this is a bug in sane-avision:
>>> during sane_cancel(), the backend calls: sanei_thread_kill
>>> (s->reader_pid), but s->reader_pid is 0, which signals the entire
>>> group. There is a test to try and avoid this, but it relies on prior
>>> code to have set s->reader_pid = -1, which has not happened in the
>>> case of no paper.
>>> I just expanded the test to require a positive value, since the pid
>>> should never be negative anyway? My fix has just been commited to CVS
>>> (backend version 289 nice round number for Ford and Studebaker fans).
>>> Ian and Rene- please test.
>>> allan
>> This breaks the MacOS X port. The PID number (being a pointer) can be
>> arbitrary large, and when cast to an integer it can easily overflow to a
>> negative value. The code was fixed for this problem by removing all
>> places where the code was checking for a PID > 0. For the avision
>> backend this was done here:
>> https://alioth.debian.org/plugins/scmcvs/cvsweb.php/sane-backends/backend/avision.c.diff?r1=1.38;r2=1.39;cvsroot=sane
>> Your commit:
>> https://alioth.debian.org/plugins/scmcvs/cvsweb.php/sane-backends/backend/avision.c.diff?r1=1.43;r2=1.44;cvsroot=sane
>> reintroduces the problem fixed by the earlier commit. Please revert it
>> and fix the new problem in a way that doesn't break the MacOS X port.

Ok, so what is the correct fix? If OSX is using pthread, is it enough
to make SANE_Pid pthread_t?

"The truth is an offense, but not a sin"

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