meld throws exception when diffing against subversion repository

[Headless Platter]

Binary package hint: meld

Repro steps:

1- change to a directory in a checked-out subversion repository with changed files
2- meld .
3- double-click on one of the changed files
4- Observe that it does not show the diff as it should. The following stack-trace is printed to the console from which meld was executed:

Traceback (most recent call last):
  File "/usr/lib/meld/meld/task.py", line 130, in iteration
    ret = task()
  File "/usr/lib/meld/meld/vcview.py", line 385, in run_diff_iter
    self.show_patch(prefix, patch)
  File "/usr/lib/meld/meld/vcview.py", line 522, in show_patch
    if misc.write_pipe(patchcmd, patch) == 0:
  File "/usr/lib/meld/meld/misc.py", line 245, in write_pipe
    proc = subprocess.Popen(command, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
  File "/usr/lib/python2.7/subprocess.py", line 672, in __init__
    errread, errwrite)
  File "/usr/lib/python2.7/subprocess.py", line 1213, in _execute_child
    raise child_exception
OSError: [Errno 2] No such file or directory

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: meld 1.5.0-0ubuntu1
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 2.6.38.2
Uname: Linux 2.6.38-8-generic x86_64
Architecture: amd64
Date: Tue Jun 7 13:00:46 2011
InstallationMedia: Kubuntu 11.04 "Natty Narwhal" - Release amd64 (20110427)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: meld
UpgradeStatus: No upgrade log present (probably fresh install)

[Julian Taylor (jtaylor)]

I can't reproduce this, can you provide a example repository which reproduces the crash?

[Headless Platter (headlessplatter)]

My repository is at svn://gashler.com/meldtest. Here are the steps that
repro for me:

svn co svn://gashler.com/meldtest
cd meldtest
echo "changed" > hi.txt
meld .
double-click on hi.txt
observe the issue

This repository is quite minimalistic, so I doubt that it is part of the
problem. Here are the steps I used to create it:

svnadmin create ./meldtest
add the line "anon-access = write" to meldtest/conf/svnserve.conf
svnserve -d -r .
svn co svn://localhost/meldtest ./test
cd test
echo "original" > hi.txt
svn add hi.txt
svn commit -m "initial commit"

If the repository itself is not part of the problem, and I'm pretty-sure
it is not, then there must be some other difference between our
machines. It's a 64-bit machine. I did a fresh install of Kubuntu on a
newly-formatted machine just hours before I found and reported the bug,
so I didn't really have much time to do anything too unusual. Meld has
worked perfectly for me in the past on the same machine with at least 5
different versions of Ubuntu, so I'm pretty-sure the problem is related
to recent changes. I'm using ReiserFS for the first time instead of
Ext3, and I mounted /home on its own partition, but I'm pretty-sure none
of that should have any effect on how Python interacts with the file-system.

Would it help if I inserted a few lines that would print out some
additional information on my machine, perhaps near misc.py line 245? I
have never programmed in Python before, but I am capable in other
languages, so I'd be willing to try if you could give me some guidance
about what info would be helpful and how to express a print statement in
Python.

On 06/08/2011 01:40 AM, Julian Taylor wrote:
> I can't reproduce this, can you provide a example repository which
> reproduces the crash?
>
> ** Changed in: meld (Ubuntu)
> Status: New => Incomplete
>

[Julian Taylor (jtaylor)]

I can't reproduce it with that repository either.

do you have patch installed?
sudo apt-get install patch

if yes can you execute:
python -c 'import tempfile; print tempfile.mkdtemp("-meld")'
it should print a the location of a directory

if that works can you add a
print command
in /usr/lib/meld/meld/misc.py line 244 before proc = subprocess.Popen(command...)
and post what it prints before the crash

[Headless Platter (headlessplatter)]

Okay, I executed the command

python -c 'import tempfile; print tempfile.mkdtemp("-meld")'

then I added the following 2 lines to misc.py just before line 244:

     print tempfile.mkdtemp("-meld")
     print command

To my surprise, the problem did not repro. It printed

/tmp/tmp8Tx0aV-meld
['patch', '-p0', '-R', '-d', '/tmp/tmpcfanD4-meld']

and displayed the diff as expected. I then removed the two lines that I
had added, and it continued to work properly, so I think it was the
mkdtemp command that fixed it. Meld also works properly now with my
other repositories, where I originally discovered the issue. So, now I
can no longer repro the problem either. I do not understand why making a
temporary dir would fix anything. I hope this means more to you than it
does to me.

Thanks for your help!
--Mike

On 06/08/2011 10:21 AM, Julian Taylor wrote:
> I can't reproduce it with that repository either.
>
> do you have patch installed?
> sudo apt-get install patch
>
> if yes can you execute:
> python -c 'import tempfile; print tempfile.mkdtemp("-meld")'
> it should print a the location of a directory
>
> if that works can you add a
> print command
> in /usr/lib/meld/meld/misc.py line 244 before proc = subprocess.Popen(command...)
> and post what it prints before the crash
>

[Julian Taylor (jtaylor)]

did you install patch?
this probably solved the problem.

meld is missing a dependency on it.

[Headless Platter (headlessplatter)]

Yes, I did just install patch. That must have been it.

On 06/08/2011 11:10 AM, Julian Taylor wrote:
> did you install patch?
> this probably solved the problem.
>
> meld is missing a dependency on it.
>
> ** Changed in: meld (Ubuntu)
> Status: Incomplete => Confirmed
>

[Julian Taylor (jtaylor)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. I am closing it because the bug has been fixed in the latest development version of Ubuntu - Oneiric Ocelot.