config changes, xmldiff (was: Re: CRITICAL Shibboleth Security Advisory 20110725)

[Chad La Joie]

Thanks Peter,

One thing you might want to consider now that we have, I think, all
the MIME types on our files correct is to use that instead of checking
to see if the file ends in .xml.  Just use 'svn propget svn:mime-type
FILE'.

On Thu, Aug 18, 2011 at 09:43, Peter Schober <peter.schober at univie.ac.at> wrote:
> * Chad La Joie <lajoie at itumi.biz> [2011-07-27 16:30]:
>> This was the result of running the files through line ending
>> normalization process which was part of us switching to SVN's "native"
>> eol-style.
>>
>> As Scott said, if you want to diff XML files you need to use xmldiff.
>> Anything else is likely to give you too many false positives if more
>> than just a single line changes.
>
> I usually `svn merge` changes from one release to the other to a
> working copy of my own configuration. With normal diff tools this of
> course has the problems mentioned above (namespace declarations,
> whitespace, comments, etc.) but then I usually want to track upstream
> config files closely in order to easier spot changed defaults,
> configration settings required to enable new functionality, etc.
> So I usually also migrate comments, xmlns decls and whatnot to my own
> config to keep diffs to upstream minimal.
>
> Anyway, based on your and Scott's comment I had a look at xmldiff,
> assuming you're referring to the eponymous Python tool (but possibly
> you're just using it as a pars-pro-toto in a more generic sense; I
> mean the Logilab tool).
> I hacked up a small wrapper script based on the Subversion book[1] to
> allow use of xmldiff as an external diff tool with `svn --diff-cmd`.
> The wrapper also ignores all files not ending in .xml since xmldiff
> would barf on those anyway.
> But xmldiff's output is of course rather unpleasant to read (for
> humans and probably for most programs as well) and not suitable for
> merging with `svn merge` as is. I haven't yet cooked up a wrapper for
> `svn merge --diff3-cmd` which would make this more/actually useful.
>
> Anyway, with the attached script you can xmldiff the config between
> all shib releases (or any other xml files, of course), e.g. for the
> IdP (arbitrarily picking releases where actual differences occured):
>
>  $ svn diff --diff-cmd sxdw \
>  https://svn.shibboleth.net/java-shib-idp2/tags/2.2.1/src/installer/resources/conf-tmpl/ \
>  https://svn.shibboleth.net/java-shib-idp2/tags/2.3.0/src/installer/resources/conf-tmpl/
>
> Or for the SP:
>
>  $ svn diff --diff-cmd sxdw \
>  https://svn.shibboleth.net/cpp-sp/tags/2.4.2/configs/
>  https://svn.shibboleth.net/cpp-sp/tags/2.4.3/configs/
>
> With 'sxdw" being the local filename of the attached "Subversion
> XmlDiff Wrapper" script, which would need be made executable and put
> somewhere in your $PATH (or provide the full path to the script).
> Usage would probably be easiest setting up an alias in your $SHELL
> called 'svnxmldiff', e.g.:
>
>  $ alias svnxmldiff="svn diff --diff-cmd /path/to/sxdw"
>
> to be able to just call `svnxmldiff PATH1 PATH2`.
> Note sure this is actually helpful yet, probably more so with the
> `xmldiff -x` output (historic XUpdate specs), which could then be
> merged using Perl's XML::Update::LibXML, for example.
> -peter
>
> [1] http://svnbook.red-bean.com/nightly/en/svn.advanced.externaldifftools.html
>
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>



-- 
Chad La Joie
www.itumi.biz
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