HTMLPurifier_Encoder Class Reference

Static Public Member Functions
static	cleanUTF8 ($str, $force_php=false)
	Cleans a UTF-8 string for well-formedness and SGML validity.
static	convertFromUTF8 ($str, $config, $context)
	Converts a string from UTF-8 based on configuration.
static	convertToASCIIDumbLossless ($str)
	Lossless (character-wise) conversion of HTML to ASCII.
static	convertToUTF8 ($str, $config, $context)
	Convert a string to UTF-8 based on configuration.
static	iconv ($in, $out, $text, $max_chunk_size=8000)
	iconv wrapper which mutes errors and works around bugs.
static	iconvAvailable ()
static	muteErrorHandler ()
	Error-handler that mutes errors, alternative to shut-up operator.
static	testEncodingSupportsASCII ($encoding, $bypass=false)
	This expensive function tests whether or not a given character encoding supports ASCII.
static	testIconvTruncateBug ()
	glibc iconv has a known bug where it doesn't handle the magic //IGNORE stanza correctly.
static	unichr ($code)
	Translates a Unicode codepoint into its corresponding UTF-8 character.
static	unsafeIconv ($in, $out, $text)
	iconv wrapper which mutes errors, but doesn't work around bugs.

Public Attributes
const	ICONV_OK = 0
	No bugs detected in iconv.
const	ICONV_TRUNCATES = 1
	Iconv truncates output if converting from UTF-8 to another character set with //IGNORE, and a non-encodable character is found.
const	ICONV_UNUSABLE = 2
	Iconv does not support //IGNORE, making it unusable for transcoding purposes.

Member Function Documentation

cleanUTF8()

static HTMLPurifier_Encoder::cleanUTF8 ( $str, $force_php = false )

static

Cleans a UTF-8 string for well-formedness and SGML validity.

It will parse according to UTF-8 and return a valid UTF8 string, with non-SGML codepoints excluded.

Specifically, it will permit: x{9}x{A}x{D}x{20}-x{7E}x{A0}-x{D7FF}x{E000}-x{FFFD}x{10000}-x{10FFFF} Source: https://www.w3.org/TR/REC-xml/#NT-Char Arguably this function should be modernized to the HTML5 set of allowed characters: https://www.w3.org/TR/html5/syntax.html#preprocessing-the-input-stream which simultaneously expand and restrict the set of allowed characters.

Parameters

string	$str	The string to clean
bool	$force_php

Return values

string

Note

Just for reference, the non-SGML code points are 0 to 31 and 127 to 159, inclusive. However, we allow code points 9, 10 and 13, which are the tab, line feed and carriage return respectively. 128 and above the code points map to multibyte UTF-8 representations.

Fallback code adapted from utf8ToUnicode by Henri Sivonen and hsivo.nosp@m.nen@.nosp@m.iki.f.nosp@m.i at http://iki.fi/hsivonen/php-utf8/ under the LGPL license. Notes on what changed are inside, but in general, the original code transformed UTF-8 text into an array of integer Unicode codepoints. Understandably, transforming that back to a string would be somewhat expensive, so the function was modded to directly operate on the string. However, this discourages code reuse, and the logic enumerated here would be useful for any function that needs to be able to understand UTF-8 characters. As of right now, only smart lossless character encoding converters would need that, and I'm probably not going to implement them.

convertFromUTF8()

static HTMLPurifier_Encoder::convertFromUTF8 ( $str, $config, $context )

static

Converts a string from UTF-8 based on configuration.

Parameters

string	$str	The string to convert
HTMLPurifier_Config	$config
HTMLPurifier_Context	$context

Return values

string

Note

Currently, this is a lossy conversion, with unexpressable characters being omitted.

convertToASCIIDumbLossless()

static HTMLPurifier_Encoder::convertToASCIIDumbLossless ( $str )

static

Lossless (character-wise) conversion of HTML to ASCII.

Parameters

string

$str

UTF-8 string to be converted to ASCII

Return values

string

ASCII encoded string with non-ASCII character entity-ized

Warning

Adapted from MediaWiki, claiming fair use: this is a common algorithm. If you disagree with this license fudgery, implement it yourself.

Note

Uses decimal numeric entities since they are best supported.

This is a DUMB function: it has no concept of keeping character entities that the projected character encoding can allow. We could possibly implement a smart version but that would require it to also know which Unicode codepoints the charset supported (not an easy task).

Sort of with cleanUTF8() but it assumes that $str is well-formed UTF-8

convertToUTF8()

static HTMLPurifier_Encoder::convertToUTF8 ( $str, $config, $context )

static

Convert a string to UTF-8 based on configuration.

Parameters

string	$str	The string to convert
HTMLPurifier_Config	$config
HTMLPurifier_Context	$context

Return values

string

iconv()

static HTMLPurifier_Encoder::iconv ( $in, $out, $text, $max_chunk_size = 8000 )

static

iconv wrapper which mutes errors and works around bugs.

Parameters

string	$in	Input encoding
string	$out	Output encoding
string	$text	The text to convert
int	$max_chunk_size

Return values

string

iconvAvailable()

static HTMLPurifier_Encoder::iconvAvailable ( )

static

Return values

bool

testEncodingSupportsASCII()

static HTMLPurifier_Encoder::testEncodingSupportsASCII ( $encoding, $bypass = false )

static

This expensive function tests whether or not a given character encoding supports ASCII.

7/8-bit encodings like Shift_JIS will fail this test, and require special processing. Variable width encodings shouldn't ever fail.

Parameters

string	$encoding	Encoding name to test, as per iconv format
bool	$bypass	Whether or not to bypass the precompiled arrays.

Return values

Array

of UTF-8 characters to their corresponding ASCII, which can be used to "undo" any overzealous iconv action.

testIconvTruncateBug()

static HTMLPurifier_Encoder::testIconvTruncateBug ( )

static

glibc iconv has a known bug where it doesn't handle the magic //IGNORE stanza correctly.

In particular, rather than ignore characters, it will return an EILSEQ after consuming some number of characters, and expect you to restart iconv as if it were an E2BIG. Old versions of PHP did not respect the errno, and returned the fragment, so as a result you would see iconv mysteriously truncating output. We can work around this by manually chopping our input into segments of about 8000 characters, as long as PHP ignores the error code. If PHP starts paying attention to the error code, iconv becomes unusable.

Return values

int	Error code indicating severity of bug.

unichr()

static HTMLPurifier_Encoder::unichr ( $code )

static

Translates a Unicode codepoint into its corresponding UTF-8 character.

Note

Based on Feyd's function at http://forums.devnetwork.net/viewtopic.php?p=191404#191404, which is in public domain.

While we're going to do code point parsing anyway, a good optimization would be to refuse to translate code points that are non-SGML characters. However, this could lead to duplication.

This is very similar to the unichr function in maintenance/generate-entity-file.php (although this is superior, due to its sanity checks).

unsafeIconv()

static HTMLPurifier_Encoder::unsafeIconv ( $in, $out, $text )

static

iconv wrapper which mutes errors, but doesn't work around bugs.

Parameters

string	$in	Input encoding
string	$out	Output encoding
string	$text	The text to convert

Return values

string

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The documentation for this class was generated from the following file:

• lib/htmlpurifier/HTMLPurifier/Encoder.php