Re: [Patch] Fix race with signals in signal_block()

[Peter Stephenson <pws@csr.com>]

Guillaume Chazarain <guichaz@yahoo.fr> wrote:
> Here is patch to fix a bug where zsh can become unkillable (except of 
> course with SIGKILL), I use Linux-2.6/i386 so the POSIX_SIGNALS macro
> is defined.
> 
> signal_block() and signal_unblock() use two global variables 
> dummy_sigset1 and dummy_sigset2. I observed a race between
> child_block() and
> oldmask = signal_block(newmask); /* Block all signals temporarily */
> called in the zhandler() signal handler.
> 
> The attached patch fixes the problem by getting rid of the global 
> variables, and instead using the signal_block() and signal_unblock() 
> functions.

Looking at your patch, it's hard to see what it wasn't done that way
before... I couldn't see anything obviously wrong and I've committed it.

Thanks.

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR PLC, Churchill House, Cambridge Business Park, Cowley Road
Cambridge, CB4 0WZ, UK                          Tel: +44 (0)1223 692070


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