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Re: deadlock caused by gettext usage in a signal handler
- X-seq: zsh-workers 24154
- From: Peter Stephenson <pws@xxxxxxx>
- To: Guillaume Chazarain <guichaz@xxxxxxxx>, zsh-workers@xxxxxxxxxx
- Subject: Re: deadlock caused by gettext usage in a signal handler
- Date: Tue, 04 Dec 2007 18:24:50 +0000
- In-reply-to: <20071204190219.037a5400@xxxxxxxx>
- Mailing-list: contact zsh-workers-help@xxxxxxxxxx; run by ezmlm
- References: <20071130203534.1d1ea29c@xxxxxxxx> <20071203224324.247fb30f.p.w.stephenson@xxxxxxxxxxxx> <20071204190219.037a5400@xxxxxxxx>
Guillaume Chazarain wrote:
> Zsh seems to use dlerror though, hopefully not in a signal handler.
No, the shell is quite cautious what it executes in signal handlers;
system errors are pretty much inevitable, but there's no module handling
there so no call to dlerror.
> strerror_r also calls into gettext, so I don't see how this solves the
strerror_r() is the way of ensuring thread safety in printing the
message by providing a buffer into which data is written. The GNU
library manual entry does actually claim it's thread-safe; that
means that any hidden back-end functions it uses are thread-safe too.
To put it another way, I don't really care how it solves the problem; if
it doesn't it's broken.
There is a possible problem that strerror_r() might need more memory
than we pass it if it's doing random additional things, I suppose, but
the manual doesn't give any guidance.
> > To get diff output for a test failure while I was writing this I needed
> Does that mean you managed to make a reproducible test case?
No, I was testing I hadn't broken anything.
> > to use "diff -a" in ztst.zsh. I'm not sure if the option is universal,
> > however.
> Confused, I can't see any diff invocation in your patch.
There isn't; I was referring to an existing test that failed while I was
writing the patch: diff assumed the difference in output was binary and
didn't show it.
> It seems to me a possible solution would be to rewrite strerror() in Zsh
> to initially build a static table of translated error messages as
> well as the translation of "Unknown error ". Don't know how much this
> would delay the Zsh startup though.
If strerror_r() really doesn't do what it's supposed to then it needs
Peter Stephenson <pws@xxxxxxx> Software Engineer
CSR PLC, Churchill House, Cambridge Business Park, Cowley Road
Cambridge, CB4 0WZ, UK Tel: +44 (0)1223 692070
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