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From: Bart Schaefer <schaefer@brasslantern.com>
To: zsh-workers@zsh.org
Subject: Re: Substitution ${...///} slows down when certain UTF character occurs
Date: Wed, 30 Sep 2015 14:19:37 -0700	[thread overview]
Message-ID: <150930141937.ZM22962@torch.brasslantern.com> (raw)
In-Reply-To: <20150930150433.21f70e13@pwslap01u.europe.root.pri>

On Sep 30,  3:04pm, Peter Stephenson wrote:
} Subject: Re: Substitution ${...///} slows down when certain UTF character 
}
} In some complex git completion --- reproducible only in one set up ---
} the heap allocation is apparently going out of bounds.  Yet I've checked
} and nothing seems able to happen that can affect this.  If I add
} debugging, the same pointer is reported as returned from zhalloc() that
} is later claimed to be out of bounds.  Yet with more debugging there's
} no popheap() or switch_heap() happening, as by eye there can't be.  I'm
} a bit stuck; how can a piece of memory returned by zhalloc() suddenly go
} invalid?
} 
} valgrind agrees with gdb but doesn't give any more help.

Did you --enable-zsh-heap-debug and --enable-zsh-valgrind ?  I always
forget at least the latter of those ...

} Maybe we're just running out of memory after all?

That seems really unlikely, unless the explicit zalloc version shows a
similar issue.  But I suppose if the heap is never popped it might be
possible to run out of memory on a deep recursive glob.  Perhaps a
call to freeheap() is needed somewhere prior to the popheap()?  Or
maybe there *is* a freeheap() happening where it isn't any longer safe
to do so -- did you check for that?

Even if out of memory, I wouldn't expect an existing pointer to go bad.
You'd just fail to get a new one.  And heaps are mmap()d if possible so
in that case you'd have to be out of address space, not just out of
memory?


  reply	other threads:[~2015-09-30 21:19 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-09-26 12:19 Sebastian Gniazdowski
2015-09-26 20:44 ` Bart Schaefer
2015-09-27  8:13   ` Sebastian Gniazdowski
2015-09-27 16:11     ` Bart Schaefer
2015-09-28  8:51       ` Peter Stephenson
2015-09-28 11:30         ` Peter Stephenson
2015-09-28 19:23         ` Peter Stephenson
2015-09-29  8:44           ` Peter Stephenson
2015-09-29 18:37             ` Peter Stephenson
2015-09-29 19:23               ` Bart Schaefer
2015-09-30  8:59                 ` Peter Stephenson
2015-09-30 14:04                   ` Peter Stephenson
2015-09-30 21:19                     ` Bart Schaefer [this message]
2015-10-01  8:41                       ` Peter Stephenson
2015-10-01 14:28                         ` Heap corruption [the thread formerly known as substitution] Peter Stephenson
2015-10-01 15:07                           ` Bart Schaefer
2015-10-01 15:13                           ` Peter Stephenson
2015-10-03 18:59                             ` Peter Stephenson
2015-10-01 13:45       ` Substitution ${...///} slows down when certain UTF character occurs Sebastian Gniazdowski

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