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Re: [PATCH] Avoid concurrency problem in ldconfig (bug 23973)
- From: Florian Weimer <fweimer at redhat dot com>
- To: Andreas Schwab <schwab at suse dot de>
- Cc: libc-alpha at sourceware dot org
- Date: Thu, 18 Apr 2019 16:47:34 +0200
- Subject: Re: [PATCH] Avoid concurrency problem in ldconfig (bug 23973)
- References: <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org>
* Andreas Schwab:
> On Apr 18 2019, Florian Weimer <email@example.com> wrote:
>> * Andreas Schwab:
>>> Use a unique name for the temporary file when updating the ld.so cache, so
>>> that two concurrent runs of ldconfig don't write to the same file.
>>> * elf/cache.c (save_cache): Use unique temporary name.
>>> (save_aux_cache): Likewise.
>> The downside of this change is that if ldconfig is interrupted, the
>> temporary file never goes away.
>> Ideally, we would use O_TMPFILE if supported by the (file) system, but
>> that can get quite involved.
> That shortens the window, but won't close it, since we need a name to
> pass to rename in any case.
The difference is that with a fixed name, the next ldconfig run will use
the same name and rename, cleaning up. With a random, unique name, that
automatic cleanup is gone.