[PATCH] valgrind warning fixes in libX11

Daniel Stone daniel at fooishbar.org
Tue Feb 20 16:19:46 PST 2007

On Tue, Feb 20, 2007 at 03:47:21PM -0800, L. David Baron wrote:
> The two attached patches to libX11 fix valgrind warnings  that I see
> starting Mozilla.  The warnings are "syscall param write(buf) points
> to uninitialised byte(s)", with a stack showing data being sent to
> the X server.
> They are the only patches needed to get trunk Firefox (as of a few
> weeks ago) to start up without valgrind warnings at least some of
> the time (other than the warnings in the suppressions file that
> ships with valgrind on Fedora Core 6).  (The problem that causes
> warnings the remainder of the time is a Mozilla bug.)
> I think it would be quite useful for these bugs to be fixed in
> libX11, since it's basically impossible to suppress the warnings
> they cause without suppressing all warnings about sending
> uninitialized data to the X server unless you make everybody using
> valgrind run apps with --sync.  Fixing them would make it easier to
> catch cases where client apps are sending uninitialized data to the
> X server.  (Actually debugging such issues requires --sync, but
> noticing them does not.  Or at least, noticing them would not
> require --sync if these patches were incorporated into libX11, since
> otherwise real warnings cannot be distinguished from the warnings
> caused by the bugs patched here.)
> [...]
> I'm not sure what the process for getting patches considered is, but
> since attaching them to the bugs didn't work, I'm writing this
> email.

Attaching them to the bug is fine.  I've had them flagged (being the
closest thing I have to a TODO list[0]) for a while to review.
Unfortunately, because they touch a pretty critical section of code,
they have to be checked pretty thoroughly to make sure they don't
accidentally break anything doing something unexpected/incorrect.

Thanks for these, though, it'd be great to see them applied.  I'll let
you know when I check it out.


[0]: Okay, not strictly true anymore, but eh.
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