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Re: [PATCH] issue #2147 - v1

From: VK Sameer <sameer_at_collab.net>
Date: 2005-01-28 13:08:19 CET

Julian Foad wrote on 01/26/2005 09:07 AM:
> Julian Foad wrote:
>> VK Sameer wrote:
>>> SVN_ERR( dav_svn__send_xml(lrb->bb, lrb->output,
>>> "<D:comment>%s</D:comment>" DEBUG_CR,
>>> - apr_xml_quote_string(pool, msg, 0)) );
>>> + svn_xml_fuzzy_escape (
>>> + apr_xml_quote_string (pool, msg, 0),
>>> + pool)) );
>> No. You should strip control characters before you XML-quote it,
>> otherwise you are relying on (1) your function producing validly
>> quoted XML (which it may do at present but is not documented to do),
>> and (2) the XML-quoting function accepting and passing through control
>> characters (which such a function need not be expected to do).
> (1)
> Thinking some more about this, I see now that you originally intended
> svn_xml_fuzzy_escape to accept nearly-well-formed XML text (but with
> some control characters) and return well-formed XML text, and that's why
> it is named "svn_xml_...". Ideally you wanted it to perform some sort
> of XML quoting which would encode the control characters in XML such
> that they would be decoded by the XML receiver, but you have found that
> this is not possible. (I agree: the XML spec says control characters
> cannot be represented, encoded or otherwise.) Therefore you have had to
> settle for performing an ad-hoc, mostly human-readable, non-reversible
> encoding. Because of this, I stand by what I wrote above: your fuzzy
> function is not, and should not be documented for use on well-formed XML
> text; it should be applied to the actual (non-escaped) log message.

Wouldn't that cause unnecessary encoding for those transport layers that
_can_ handle control characters? Control characters in a log message are
not a problem when using file:// or svn://.

> Whether the fuzzy function's name and/or doc-string should change to
> reflect that it doesn't produce XML but does produce XML-safe text, I
> don't know.

I'm a little lost now. Why shouldn't the output be considered XML?

> (2)
> Now I'm confused about what you are escaping. You are escaping all
> ASCII control characters (as defined by svn_ctype_iscntrl). That
> includes valid XML characters CR, LF and TAB. Shouldn't you be escaping
> only non-XML control characters?

Fixed, thanks for pointing that out.


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Received on Fri Jan 28 13:09:48 2005

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