How to skip invalid characters in XML file using PHP

Question

I'm trying to parse an XML file using PHP, but I get an error message:

parser error : Char 0x0 out of allowed range in

I think it's because of the content of the XML, I think there is a speical symbol "☆", any ideas what I can do to fix it?

I also get:

parser error : Premature end of data in tag item line

What might be causing that error?

I'm using simplexml_load_file.

Update:

I try to find the error line and paste its content as single xml file and it can work!! so I still cannot figure out what makes xml file parse fails. PS it's a huge xml file over 100M, will it makes parse error?

Answer 1

Do you have control over the XML? If so, ensure the data is enclosed in <![CDATA[ .. ]]> blocks.

Answer 2

If you have control over the data, ensure that it is encoded correctly (i.e. is in the encoding that you promised in the xml tag, e.g. if you have:

<?xml version="1.0" encoding="UTF-8"?>

then you'll need to ensure your data is in UTF-8.

If you don't have control over the data, yell at those who do.

Answer 3

Not all valid utf-8 characters are allowed in XML documents. E.g. for xml 1.0 the standard says:

Char ::= #x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF]

which doesn't include 0x0.

You can skip those characters e.g. with a (read) filter that is applied to the input stream for simplexml_load_file, see php://filter at http://docs.php.net/wrappers.php

<?php
stream_filter_register('xmlutf8', 'ValidUTF8XMLFilter');

// file_put_contents('test.xml', '<a>foo'.chr(0).'</a>');
// $doc = simplexml_load_file('test.xml'); => Char 0x0 out of allowed range

$doc = simplexml_load_file("php://filter/read=xmlutf8/resource=test.xml");
echo $doc->asXML();

class ValidUTF8XMLFilter extends php_user_filter {
  protected static $pattern = '/[^\x{0009}\x{000a}\x{000d}\x{0020}-\x{D7FF}\x{E000}-\x{FFFD}]+/u';
  function filter($in, $out, &$consumed, $closing)
  {
    while ($bucket = stream_bucket_make_writeable($in)) {
      $bucket->data = preg_replace(self::$pattern, '', $bucket->data);
      $consumed += $bucket->datalen;
      stream_bucket_append($out, $bucket);
    }
    return PSFS_PASS_ON;
  }
}

Answer 4

Make sure your XML source is valid. See http://en.wikipedia.org/wiki/List_of_XML_and_HTML_character_entity_references