openssh bugs - Apr 2010 - [Bug 1761] New: sftp exits on 2nd terminal resize after a transfer

https://bugzilla.mindrot.org/show_bug.cgi?id=1761

           Summary: sftp exits on 2nd terminal resize after a transfer
           Product: Portable OpenSSH
           Version: 5.5p1
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: sftp
        AssignedTo: unassigned-bugs at mindrot.org
        ReportedBy: ejsheldrake at googlemail.com


Created attachment 1844
  --> https://bugzilla.mindrot.org/attachment.cgi?id=1844
remove progress meter signal handlers in stop_progress_meter

sftp, when built with libedit (editline) support enabled, may exit
unexpectedly if you resize the terminal window after a transfer.

This is with libedit 20100424-3.0 (which fixed the resize problem in
libedit 20090923), but this appears to be a separate bug in sftp.

sftp handles any number of terminal resizes before a transfer, but
after a file transfer, it exits after 2 consecutive terminal resizes.

I think the problem may due to signal handlers (one for SIGWINCH, the
terminal resize signal) being set up in the progress meter code, but
these don't seem to be removed on disposing of the progress meter.
Well, at least the patch appears to fix the problem for me.

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https://bugzilla.mindrot.org/show_bug.cgi?id=1761

Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |djm at mindrot.org

--- Comment #1 from Damien Miller <djm at mindrot.org>  ---
I can't replicate this on either OpenBSD of Ubuntu Lucid. Your patch
makes sense, but I'd like to see how it crashes before applying it. Is
there any change you could capture a debug/gdb trace of it crashing?

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https://bugzilla.mindrot.org/show_bug.cgi?id=1761

--- Comment #2 from Edward Sheldrake <ejsheldrake at googlemail.com>  ---
Created attachment 1887
  --> https://bugzilla.mindrot.org/attachment.cgi?id=1887
strace, sftp closing after resizes

The trouble is sftp doesn't crash, it exits normally. I need to work
out where to put some useful breakpoints or something.

I've attached the output from strace, with several resizes before a
transfer, then a transfer, and sftp closing after some more resizes.
It's probably not very helpful.

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Darren Tucker <dtucker at zip.com.au> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dtucker at zip.com.au
             Blocks|                            |1708

--- Comment #3 from Darren Tucker <dtucker at zip.com.au>  ---
I can reproduce it locally (fedora 10).  I'd like to understand to root
cause first before making any changes though.

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--- Comment #4 from Edward Sheldrake <ejsheldrake at googlemail.com>  ---
Created attachment 1904
  --> https://bugzilla.mindrot.org/attachment.cgi?id=1904
fix for libedit

I now think this is more likely to be a libedit bug, since when running
sftp, libedit's sig_handler() function only gets called on the first
SIGWINCH during a read, any more seem to be ignored.

Fixing that seems to solve the problem (although I don't really know
why it causes sftp to close only after a progress bar has been shown).
I've emailed the libedit maintainers with my new findings.

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Edward Sheldrake <ejsheldrake at googlemail.com> changed:

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

--- Comment #5 from Edward Sheldrake <ejsheldrake at googlemail.com>  ---
libedit is now fixed in cvs, so this isn't an sftp bug.

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Darren Tucker <dtucker at zip.com.au> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |CLOSED

--- Comment #6 from Darren Tucker <dtucker at zip.com.au>  ---
With the release of OpenSSH 5.6p1 this bug is now considered closed. 
If you have further problems please reopen or file a new bug as
appropriate.

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