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Re: [PATCH] Avoid concurrency problem in ldconfig (bug 23973)
- From: Florian Weimer <fweimer at redhat dot com>
- To: Christian Brauner <christian at brauner dot io>
- Cc: Andreas Schwab <schwab at suse dot de>, libc-alpha at sourceware dot org
- Date: Thu, 18 Apr 2019 14:11:13 +0200
- Subject: Re: [PATCH] Avoid concurrency problem in ldconfig (bug 23973)
- References: <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org>
* Christian Brauner:
> On Thu, Apr 18, 2019 at 02:01:55PM +0200, Florian Weimer 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.
> Just saw this fly by so sorry if I miss the the necessary context: If
> there doesn't need to be a file on disk what about using memfd_create()
> on kernels that support it?
The file needs to be on disk because it's used as part of the atomic
file replacement pattern.