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genx Comments

From: Bjoern Hoehrmann <derhoermi@gmx.net>
Date: Fri, 12 Mar 2004 17:53:46 +0100
To: tbray@textuality.com
Cc: www-archive@w3.org
Message-ID: <4069db5a.1624314190@smtp.bjoern.hoehrmann.de>

Hi Tim,

  I think it would be helpful if genx provides means to ease the
creation of structured comments and processing instructions. The
existing routines genxPI(...) and genxComment(...) require precomposing
the string content which is quite inconvenient to do in C in a flexible,
secure and portable manner. I would thus prefer to be able to something
like:

  genxStartPI(w, "xml-stylesheet");
  if (styleType)
  {
    genxAddText(w, "type='");
    genxAddText(w, styleType);
    genxAddText(w, "' ");
  }
  genxAddText(w, "href='");
  genxAddText(w, styleUri);
  genxAddText(w, "'");
  genxEndPI(w);

Using sprintf/strcat/etc. to precompose the data would likely yield in
security issues on "reduced-mental-function days" or make developers use
non-portable library routines to circumvent such problems. The same
applies for comments, of course. Structured comments are often used for
meta data in template systems or mailing list archives, for example, so
I'd say there is some market for such an addition to genx.

I've in fact expected genx to provide only the start/end versions for
comments and processing instructions because it appears to be high-level
functionality to do this in one step (and there is no genxElement() to
create an element plus text node child in on step either).

Also, while I can gurantee that all my input to genx is UTF-8 encoded,
I would like to avoid pre-processing the text to handle illegal
characters such as U+0001. While genxScrubText() provides help, I would
prefer to have something to configure a replacement character rather
than stripping such values off the string. In my particular application,
this data is source code from foreign documents and I have line/column
pointers for this data, they would break if the line length changes. It
would also be helpful to have something visual for debugging. Since
genxScrubText() gurantees equal-or-less string length for the resulting
string, the choice of replacement characters is limited to US-ASCII, but
that would work for me (using '.' or '?').

Hmm, the documentation reads

  int genxScrubText(genxWriter w, utf8 in, utf8 out);

I think this should be

  int genxScrubText(genxWriter w, const utf8 in, utf8 out);

It would be helpful to know from the documentation whether in and out
must be distinct or whether I can use

  genxScrubText(w, s, s);

and whether I can safely assume that the return value is the number of
bytes scrubbed.

Since most of my untrusted text goes into text nodes, it would also be
helpful to have genxAdd*Text(...) routines that allow to scrub the text
more conveniently, say

  genxAddScrubbedText(...)

or

  genxSetAutoScrubText(...)

so I would have to worry less about the well-formedness of the output
(or, more precicely, genx runtime errors...) Hmm, now that I think about
this, genxScrubText(...) does not take care of U+0000 since it considers
the first occurence of such a character to terminate the string. Argl,
so I need to fix the text myself anyway...

regards.
Received on Friday, 12 March 2004 11:54:09 UTC

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