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hash vs. xmalloc [was: [PATCH 2/2] tests: drop unused link dependency]
From: |
Eric Blake |
Subject: |
hash vs. xmalloc [was: [PATCH 2/2] tests: drop unused link dependency] |
Date: |
Wed, 27 Apr 2011 15:26:52 -0600 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.15) Gecko/20110307 Fedora/3.1.9-0.39.b3pre.fc14 Lightning/1.0b3pre Mnenhy/0.8.3 Thunderbird/3.1.9 |
On 04/27/2011 12:24 AM, Jim Meyering wrote:
>> fdutimensat-tests still pulls in xalloc, via utimecmp (which
>> calls xalloc_die if it can't manage a hash table). So this
>> patch isn't quite perfect yet, but getting closer. Any ideas
>> on whether it would be possible to make utimecmp work without
>> xalloc?
>
> Looks feasible.
> The hash table is solely to avoid incurring the cost of calculating
> the time stamp resolution for every call. The alternative is simply
> to incur the cost when hash table initialization or insertion fails.
Even worse, I just noticed that there is a NULL dereference on low
memory conditions in utimecmp. The code tries to allocate ht, but then
blindly uses ht even if allocation failed.
I definitely agree that utimecmp's use of a hash-table is merely a
caching optimization, and therefore memory failure should not be fatal.
I'll have a patch shortly...
--
Eric Blake address@hidden +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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