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Re: svn 1.4.5 bug with diff on binary files

From: Wade Carpenter <wade.carpenter_at_gmail.com>
Date: 2007-08-30 03:15:47 CEST

I was just noticing that there is a difference in the output when
using the internal and external diff because the internal diff, that's
all.

Thanks for the info!

On 8/29/07, Ben Collins-Sussman <sussman@red-bean.com> wrote:
> Hi Wade,
>
> I'm not sure what you're calling a bug.
>
> The svn client tries to 'guess' if a file is text or binary before
> running it through a line-based diff program. If it guesses that the
> file is binary, it doesn't attempt to do a line-based diff. This
> logic holds the same, whether it's using the internal diff algorithm
> or an external diff tool.
>
> The *only* criteria it uses to make this guess is by looking at the
> svn:mime-type property. If the property isn't present at all, it
> assumes it's a text file. If the property is present, and doesn't
> have a value which is obviously text-y (e.g. text/*, html/*, ...), it
> assumes it's a binary file.
>
> So as far as I can tell, everything is working exactly as designed. :-)
>
> If your expectation is that 'svn diff' have a more sophisticated way
> of guessing at binary-ness, that's a whole separate conversation full
> of thorns...
>
> On 8/29/07, Wade Carpenter <wade.carpenter@gmail.com> wrote:
> > Hi Ben,
> >
> > Thanks for the reply.
> >
> > I was actually able to reproduce the problem on 1.4.2. I built 1.4.5
> > to check the latest release as well, which I configured with
> > --enable-maintainer-mode --disable-shared, so I think I just ran the
> > wrong 'svn' binary to retrieve the version =)
> >
> > I looked at the diff.c and it needs both the old and new fles to have
> > no svn:mime-type property. It's obviously not a smart thing to have
> > for binary files, but the behaviour is different between internal diff
> > and external diff for this case.
> >
> > Here's what I did (with diff-cmd=/usr/bin/diff):
> >
> > $ svn --version
> > svn, version 1.4.5 (r25188)
> > compiled Aug 29 2007, 14:59:42
> > $ dd if=/dev/urandom of=test.bin count=5
> > $ svn add test.bin
> > A (bin) test.bin
> > $ svn pd svn:mime-type test.bin
> > property 'svn:mime-type' deleted from 'test.bin'.
> > $ svn ci -m "..." test.bin
> > Adding test.bin
> > Transmitting file data .
> > Committed revision 12470.
> > $ svn st test.bin
> > $ dd if=/dev/urandom of=test.bin count=5
> > $ svn diff test.bin
> > Index: test.bin
> > ===================================================================
> > Binary files test.bin (revision 12470) and test.bin (working copy) differ
> > ../svn_1.4.5/subversion/libsvn_subr/io.c:2230: (apr_err=200012)
> > svn: '/usr/bin/diff' returned 2
> >
> > With diff-cmd unset, I get this a diff showing the binary contents of
> > the change.
> >
> > I couldn't think of anything easy to do for this. I guess it would be
> > nice if GNU diff returned more than 2 for its various error
> > conditions, or if it returned 1 for binary files that differ as well.
> > Unfortunately, that's not happening. The next thing I thought of
> > would be to add filetype magic, but that's no small change either.
> >
> > Then I decided I would turn off the diff-cmd option or use the
> > svn:mime-type property as intended =)
> >
> > So it seems like a bug, but I wouldn't call it a high priority issue,
> > that's for sure!
> >
> > Let me know if you think I should report it or not, and then maybe
> > I'll have some time to work on fixing it soon.
> >
> > Thanks!
> > Wade
> >
> > On 8/29/07, Ben Collins-Sussman <sussman@red-bean.com> wrote:
> > > On 8/28/07, Wade Carpenter <wade.carpenter@gmail.com> wrote:
> > > > This seems to be related to 1019:
> > > > http://subversion.tigris.org/issues/show_bug.cgi?id=1019
> > > >
> > > > I'm running svn client 1.4.5:
> > > > svn --version
> > > > svn, version 1.4.2 (r22196)
> > > > compiled Jan 18 2007, 11:56:49
> > >
> > > Uh, it says 1.4.2, not 1.4.5. :-)
> > >
> > > >
> > > > If I use svn internal diff, this problem is not present.
> > > >
> > > > For external diff, I set diff-cmd=/usr/bin/diff in my .subversion/config file.
> > > > /usr/bin/diff --version
> > > > diff (GNU diffutils) 2.8.1
> > > >
> > > > Example output:
> > > > svn diff -r11827 subidr/
> > > > Index: subidr/file.bin
> > > > ===================================================================
> > > > Binary files subidr/file.bin (revision 11827) and
> > > > subidr/file.bin (working copy) differ
> > > > ../svn_1.4.5/subversion/libsvn_subr/io.c:2230: (apr_err=200012)
> > > > svn: '/usr/bin/diff' returned 2
> > >
> > > Using the latest trunk code, and setting my diff-cmd runtime config
> > > variable to '/usr/bin/diff' (which is also gnu diff 2.8.1), I can't
> > > reproduce this problem:
> > >
> > > $ svn diff win32.png
> > > Index: win32.png
> > > ===================================================================
> > > Cannot display: file marked as a binary type.
> > >
> > >
> > > ...though maybe something is up with your installation. The error
> > > message is printing an error from your svn_1.4.5 libsvn_subr library,
> > > while your 'svn --version' claims to be 1.4.2. Perhaps you've got
> > > some odd linkage going on, a mixture of library versions?
> > >
> >
>

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Received on Thu Aug 30 03:12:59 2007

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