rsync - Aug 2011 - [Bug 8423] New: Listing a non-existent remote directory hangs

https://bugzilla.samba.org/show_bug.cgi?id=8423

           Summary: Listing a non-existent remote directory hangs
           Product: rsync
           Version: 3.1.0
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P5
         Component: core
        AssignedTo: wayned at samba.org
        ReportedBy: chris at onthe.net.au
         QAContact: rsync-qa at samba.org


Listing a non-existent remote directory causes rsync to "hang"
(it's
not really hung, it's very busy doing nothing...).

Current git (5561c14).

Listing non-existent file fails as expected:

   local$ ./rsync-3.1.0dev-5561c14-x64
--rsync-path=/tmp/rsync-3.1.0dev-5561c14-x64 remote:/tmp/foo
   rsync: link_stat "/tmp/foo" failed: No such file or directory (2)
   rsync error: some files/attrs were not transferred (see previous errors)
(code 23) at ../rsync/main.c(1635) [Receiver=3.1.0dev-5561c14]
   rsync: [Receiver] write error: Broken pipe (32)
   local$

Listing non-existent directory doesn't return:

   local$ ./rsync-3.1.0dev-5561c14-x64
--rsync-path=/tmp/rsync-3.1.0dev-5561c14-x64 remote:/tmp/foo/
   rsync: change_dir "/tmp/foo" failed: No such file or directory (2)

Strace of local side:

   local$ strace -p ${pid}
   select(0, NULL, NULL, NULL, {0, 20000}) = 0 (Timeout)
   wait4(20466, 0x7fffe3bd3f7c, WNOHANG, NULL) = 0
   select(0, NULL, NULL, NULL, {0, 20000}) = 0 (Timeout)
   wait4(20466, 0x7fffe3bd3f7c, WNOHANG, NULL) = 0
   select(0, NULL, NULL, NULL, {0, 20000}) = 0 (Timeout)
   wait4(20466, 0x7fffe3bd3f7c, WNOHANG, NULL) = 0
   select(0, NULL, NULL, NULL, {0, 20000}) = 0 (Timeout)
   wait4(20466, 0x7fffe3bd3f7c, WNOHANG, NULL) = 0
   select(0, NULL, NULL, NULL, {0, 20000}) = 0 (Timeout)
   wait4(20466, 0x7fffe3bd3f7c, WNOHANG, NULL) = 0
   select(0, NULL, NULL, NULL, {0, 20000}) = 0 (Timeout)
   wait4(20466, 0x7fffe3bd3f7c, WNOHANG, NULL) = 0
   select(0, NULL, NULL, NULL, {0, 20000}) = 0 (Timeout)
   wait4(20466, 0x7fffe3bd3f7c, WNOHANG, NULL) = 0
   select(0, NULL, NULL, NULL, {0, 20000}) = 0 (Timeout)
   wait4(20466, 0x7fffe3bd3f7c, WNOHANG, NULL) = 0
   [...continues very quicky]

Strace of remote side:

   remote$ strace -p ${pid}
   Process 8398 attached - interrupt to quit
   select(1, [0], [], [0], {11, 434460})   = 0 (Timeout)
   select(2, [0], [1], [0], {30, 0})       = 1 (out [1], left {29, 999997})
   write(1, "\0\0\0\7", 4)                 = 4
   select(1, [0], [], [0], {30, 0} (Timeout)
   select(2, [0], [1], [0], {30, 0})       = 1 (out [1], left {29, 999997})
   write(1, "\0\0\0\7", 4)                 = 4
   select(1, [0], [], [0], {30, 0}
   [...continues slowly]

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https://bugzilla.samba.org/show_bug.cgi?id=8423

Wayne Davison <wayned at samba.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED

--- Comment #1 from Wayne Davison <wayned at samba.org> 2011-09-11
18:15:55 UTC ---
In the case where the chdir failed, rsync was setting an I/O error prior to
aborting (due to an empty file list), and that would trigger an attempt to
stick around waiting for a clean exit, even though it hadn't output enough
protocol data to tell the remote side everything was done.

I have changed the code to force this premature exit to exit w/o delay.  I
should probably revisit this empty-flist abnormal exit sequence in order to
make the protocol behave more cleanly, but this fix is good enough for now.

Thanks for the report!

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