rsync - Aug 2013 - [Bug 10081] New: Multiple rsync instances conflict

https://bugzilla.samba.org/show_bug.cgi?id=10081

           Summary: Multiple rsync instances conflict
           Product: rsync
           Version: 3.1.0
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: minor
          Priority: P5
         Component: core
        AssignedTo: wayned at samba.org
        ReportedBy: xaionaro at gmail.com
         QAContact: rsync-qa at samba.org


When running multiple instances of rsync with "--backup" option on
same file
(for example in case of intersecting include-files), few of them can exit with
exitcode "23".

It happens due to nonatomicity of robust_unlink()&do_open() operation in
copy_file(). While one of instances is proceeding between robust_unlink() and
do_open(), another instance can run do_open(). So the first instance will fail
on do_open() due to flag "O_EXCL".

I suggest to remove the flag "O_EXCL" if copy_file() is called from
make_backup() function.

Overwriting of "backuped" file is fine behavior, so why not to permit
it even
for this special case?

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https://bugzilla.samba.org/show_bug.cgi?id=10081

--- Comment #1 from Dmitry Yu Okunev <xaionaro at gmail.com> 2014-01-02
11:01:10 UTC ---
I can write a patch. Is this required? I can make my modification to be
optional, if this required.

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https://bugzilla.samba.org/show_bug.cgi?id=10081

--- Comment #2 from devurandom at gmx.net ---
I assume this is not being considered, because the backup needs to be restored
in case the new file is corrupted? So overwriting it would be bad?

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