rsync - Aug 2009 - DO NOT REPLY [Bug 6672] New: mtim.tv_nsec not used when reading time of a file

https://bugzilla.samba.org/show_bug.cgi?id=6672

           Summary: mtim.tv_nsec not used when reading time of a file
           Product: rsync
           Version: 3.0.6
          Platform: Other
        OS/Version: All
            Status: NEW
          Severity: major
          Priority: P3
         Component: core
        AssignedTo: wayned at samba.org
        ReportedBy: antonio at dellelce.com
         QAContact: rsync-qa at samba.org


tv_nsec field in stat structure is not used (source code I checked does not
refer to it) if available. 

This results in files being not "completely" aligned because the
original file
will have  nanoseconds set all other destinations have this portion of file
information set to 0.

A pratical example of when this might become a problem is Apache's ETag 
generation, Apache HTTPD correctly reads tv_nsec when available (Solaris,Cygwin
have that feature for example) and puts the value of tv_nsec in the ETag.

A cluster of Etag-generating httpds behind a load balancer would generate all
the same ETag but the "master" source which would have an ETag with no
microseconds (ETags are limited to microseconds..) so defeating the ETag
purpose.


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https://bugzilla.samba.org/show_bug.cgi?id=6672


wayned at samba.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|major                       |enhancement
             Status|NEW                         |ASSIGNED
            Summary|mtim.tv_nsec not used when  |transfer & set nano-second
                   |reading time of a file      |times on files
            Version|3.0.6                       |3.1.0




------- Comment #1 from wayned at samba.org  2009-09-07 16:21 CST -------
The latest git repository has support for nanosecond timestamp values.  The
values are transferred as part of the file-list (when both sides are speaking
the most recent (dev-version) protocol 31), and the receiver will attempt to
set it.  Probably only works on Linux at the moment.

Things to enhance:

 * Figure out if there are other nanosecond setting functions that should be
supported besides utimensat().
 * Figure out a good heuristic for allowing the nanoseconds to be compared
(when determining if a file is up-to-date) without getting tripped up by those
filesystems that round/truncate time values.

The current code leaves the quick-check algorithm unchanged, as it only checks
the file's size, and the seconds portion of the modtime.


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samba-bugs at samba.org (samba-bugs at samba.org) wrote on 7 September 2009
16:21:
 >
 >wayned at samba.org changed:
 >
 >           What    |Removed                     |Added
 >----------------------------------------------------------------------------
 >           Severity|major                       |enhancement
 >             Status|NEW                         |ASSIGNED
 >            Summary|mtim.tv_nsec not used when  |transfer & set
nano-second
 >                   |reading time of a file      |times on files
 >            Version|3.0.6                       |3.1.0
 >
 >
 >
 >
 >------- Comment #1 from wayned at samba.org  2009-09-07 16:21 CST -------
 >The latest git repository has support for nanosecond timestamp values.  The
 >values are transferred as part of the file-list (when both sides are
speaking
 >the most recent (dev-version) protocol 31), and the receiver will attempt
to
 >set it.  Probably only works on Linux at the moment.

What will happen to the listing produced by --list-only?

https://bugzilla.samba.org/show_bug.cgi?id=6672

--- Comment #2 from Teodor Milkov <zimage at icdsoft.com> 2014-08-04
08:24:25 UTC ---
Maybe the easiest fix here would be, to extend cmp_time() in util.c to receive
two more parameters: file1_st_mtimensec and file2_st_mtimensec? I guess this is
not going to be portable...

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