*grumble, grumble* There has got to be a GMail extension that makes
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On Mon, Mar 21, 2011 at 9:11 PM, Peter Hutterer
<[email protected]> wrote:
> On Fri, Mar 18, 2011 at 06:01:16PM -0700, Jason Gerecke wrote:
>> Crash first appears in ab311bf20535acd6e7201e024bc311e0e15b5b6b.
>> This commit rewrote wcmUpdateButtonKeyActions with one-indexed
>> arrays in mind and extended the 'keys' array in _WacomDeviceRec
>> to make room. However, the 'wheel_keys' and 'strip_keys' were
>> not updated.
>>
>> Running e.g. `xsetwacom --set pad StripLeftDown button 4` results
>> in a call to wcmUpdateButtonKeyActions. Its call to memset oversteps
>> the array bounds and just happens to zero the 'common' pointer. The
>> next tablet event results in a segfault as the driver tries to
>> dereference the pointer.
>
> doh. i think some audit in the driver is needed to switch to either
> one-indexed or zero-indexed buttons everywhere. right now, we seem to have
> both mixed and that's rather fatal.
>

That would probably be good a good idea. Any idea why one-indexing was
switched to? I guess it'd make writing user interface code easier (you
just index into the button array at the number they give), but
violates the principle of least astonishment...

> are you sure this is the right patch though? wcmCommon.c seems to use the
> right indices (minus the patch I've just CC'd you on). so it looks like
> there's more out of whack than just the array size.
>

wcmCommon.c might be using the right indicies, or it might not. It's
difficult to say at the moment since strip mapping (and I assume wheel
mapping since they're virtually identical) stopped working back in
August with commit eea34fad. Between fixing that and switching
everything to use zero- or one-indexed arrays, this bit of code needs
some love.

This patch was more of a stop-gap to fix the crash before I got around
to restoring mapping functionality. Hopefully I can have everything
done before the April 1 freeze (not sure how much code I'll need to
touch, so I'd rather not try to slip it in after...) but I'm not sure
I have the time.

Jason

---
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nuu-wee-ya' duu-xan' 'vm-nvshtlh-ts'it.
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