[sane-devel] [sane-pixma] Canon MF4150 v. PIXMA_CAP_LINEART
Samuel Adam
adam at certifound.com
Wed Aug 28 06:55:17 UTC 2013
On Tue, 27 Aug 2013 13:11:40 -0400, Samuel Adam <adam at certifound.com>
wrote:
> I applied your patch against git version af107912. It segfaults
> without producing any noticeable activity in the scanner; and the
> segfault occurs whether --mode is set to "Lineart", "Gray", or
> "Color". I find this baffling, as on a brief glance the new lineart
> code path *seems* to be largely branched over in other modes (at
> least
> in the logical beginning thereof).
[...]
> Compiling without the patch, git af107912 seeks to work (with some
> flakiness).
Skimming the code, I am about 80% certain that:
(1) It is dying between these two points in the codepath:
(a) pixma_imageclass.c: iclass_check_param()
(b) pixma.c: start_reader_task()
(Viz.: Successfully completes the former; segfaults at an undetermined
point before reaching or completing the latter.)
(2) Up to that point, the *only* substantive changes induced by the
patch are alterations to the values of various data structures.
===> Therefore: Is there anything which jumps out to those familiar
with the code between point (a) and point (b) which would or could choke
upon a change in the size, shape, or contents of pixma_scan_param_t
structure? (There is one other blackmagic blob of bit-stuffing changed
before that. The change is only effective if the "--mode" is set to
"Lineart", however; whereas the segfault occurs regardless.)
Yes, I am aware that I may get some "wtf" for not simply attaching a
debugger.
Samuel Adam
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