includes/json/FormatJson.php
<?php
/**
* Wrapper for json_encode and json_decode.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
*/
namespace MediaWiki\Json;
use MediaWiki\Status\Status;
/**
* JSON formatter wrapper class
*/
class FormatJson {
/**
* Skip escaping most characters above U+007F for readability and compactness.
* This encoding option saves 3 to 8 bytes (uncompressed) for each such character;
* however, it could break compatibility with systems that incorrectly handle UTF-8.
*
* @since 1.22
*/
public const UTF8_OK = 1;
/**
* Skip escaping the characters '<', '>', and '&', which have special meanings in
* HTML and XML.
*
* @warning Do not use this option for JSON that could end up in inline scripts.
* - HTML 5.2, §4.12.1.3 Restrictions for contents of script elements
* - XML 1.0 (5th Ed.), §2.4 Character Data and Markup
*
* @since 1.22
*/
public const XMLMETA_OK = 2;
/**
* Skip escaping as many characters as reasonably possible.
*
* @warning When generating inline script blocks, use FormatJson::UTF8_OK instead.
*
* @since 1.22
*/
public const ALL_OK = self::UTF8_OK | self::XMLMETA_OK;
/**
* If set, treat JSON objects '{...}' as associative arrays. Without this option,
* JSON objects will be converted to stdClass.
*
* @since 1.24
*/
public const FORCE_ASSOC = 0x100;
/**
* If set, attempt to fix invalid JSON.
*
* @since 1.24
*/
public const TRY_FIXING = 0x200;
/**
* If set, strip comments from input before parsing as JSON.
*
* @since 1.25
*/
public const STRIP_COMMENTS = 0x400;
/**
* Returns the JSON representation of a value.
*
* @note Empty arrays are encoded as numeric arrays, not as objects, so cast any associative
* array that might be empty to an object before encoding it.
*
* @note In pre-1.22 versions of MediaWiki, using this function for generating inline script
* blocks may result in an XSS vulnerability, and quite likely will in XML documents
* (cf. FormatJson::XMLMETA_OK). Use Xml::encodeJsVar() instead in such cases.
*
* @param mixed $value The value to encode. Can be any type except a resource.
* @param string|bool $pretty If a string, add non-significant whitespace to improve
* readability, using that string for indentation (must consist only of whitespace
* characters). If true, use the default indent string (four spaces).
* @param int $escaping Bitfield consisting of _OK class constants
* @return string|false String if successful; false upon failure
*/
public static function encode( $value, $pretty = false, $escaping = 0 ) {
// PHP escapes '/' to prevent breaking out of inline script blocks using '</script>',
// which is hardly useful when '<' and '>' are escaped (and inadequate), and such
// escaping negatively impacts the human readability of URLs and similar strings.
$options = JSON_UNESCAPED_SLASHES;
if ( $pretty || is_string( $pretty ) ) {
$options |= JSON_PRETTY_PRINT;
}
if ( $escaping & self::UTF8_OK ) {
$options |= JSON_UNESCAPED_UNICODE;
}
if ( !( $escaping & self::XMLMETA_OK ) ) {
$options |= JSON_HEX_TAG | JSON_HEX_AMP;
}
$json = json_encode( $value, $options );
if ( is_string( $pretty ) && $pretty !== ' ' && $json !== false ) {
// Change the four-space indent to the provided indent.
// The regex matches four spaces either at the start of a line or immediately
// after the previous match. $pretty should contain only whitespace characters,
// so there should be no need to call StringUtils::escapeRegexReplacement().
$json = preg_replace( '/ {4}|.*+\n\K {4}/A', $pretty, $json );
}
return $json;
}
/**
* Decodes a JSON string. It is recommended to use FormatJson::parse(),
* which returns more comprehensive result in case of an error, and has
* more parsing options.
*
* In PHP versions before 7.1, decoding a JSON string containing an empty key
* without passing $assoc as true results in a return object with a property
* named "_empty_" (because true empty properties were not supported pre-PHP-7.1).
* Instead, consider passing $assoc as true to return an associative array.
*
* But be aware that in all supported PHP versions, decoding an empty JSON object
* with $assoc = true returns an array, not an object, breaking round-trip consistency.
*
* See https://phabricator.wikimedia.org/T206411 for more details on these quirks.
*
* @param string $value The JSON string being decoded
* @param bool $assoc When true, returned objects will be converted into associative arrays.
*
* @return mixed The value encoded in JSON in appropriate PHP type.
* `null` is returned if $value represented `null`, if $value could not be decoded,
* or if the encoded data was deeper than the recursion limit.
* Use FormatJson::parse() to distinguish between types of `null` and to get proper error code.
*/
public static function decode( $value, $assoc = false ) {
return json_decode( $value, $assoc );
}
/**
* Decodes a JSON string.
* Unlike FormatJson::decode(), if $value represents null value, it will be
* properly decoded as valid.
*
* @param string $value The JSON string being decoded
* @param int $options A bit field that allows FORCE_ASSOC, TRY_FIXING,
* STRIP_COMMENTS
* @return Status If valid JSON, the value is available in $result->getValue()
*/
public static function parse( $value, $options = 0 ) {
if ( $options & self::STRIP_COMMENTS ) {
$value = self::stripComments( $value );
}
$assoc = ( $options & self::FORCE_ASSOC ) !== 0;
$result = json_decode( $value, $assoc );
$code = json_last_error();
if ( $code === JSON_ERROR_SYNTAX && ( $options & self::TRY_FIXING ) !== 0 ) {
// The most common error is the trailing comma in a list or an object.
// We cannot simply replace /,\s*[}\]]/ because it could be inside a string value.
// But we could use the fact that JSON does not allow multi-line string values,
// And remove trailing commas if they are et the end of a line.
// JSON only allows 4 control characters: [ \t\r\n]. So we must not use '\s' for matching.
// Regex match ,]<any non-quote chars>\n or ,\n] with optional spaces/tabs.
$count = 0;
$value =
preg_replace( '/,([ \t]*[}\]][^"\r\n]*([\r\n]|$)|[ \t]*[\r\n][ \t\r\n]*[}\]])/', '$1',
$value, -1, $count );
if ( $count > 0 ) {
$result = json_decode( $value, $assoc );
if ( json_last_error() === JSON_ERROR_NONE ) {
// Report warning
$st = Status::newGood( $result );
$st->warning( wfMessage( 'json-warn-trailing-comma' )->numParams( $count ) );
return $st;
}
}
}
// JSON_ERROR_RECURSION, JSON_ERROR_INF_OR_NAN, JSON_ERROR_UNSUPPORTED_TYPE,
// are all encode errors that we don't need to care about here.
switch ( $code ) {
case JSON_ERROR_NONE:
return Status::newGood( $result );
default:
return Status::newFatal( wfMessage( 'json-error-unknown' )->numParams( $code ) );
case JSON_ERROR_DEPTH:
$msg = 'json-error-depth';
break;
case JSON_ERROR_STATE_MISMATCH:
$msg = 'json-error-state-mismatch';
break;
case JSON_ERROR_CTRL_CHAR:
$msg = 'json-error-ctrl-char';
break;
case JSON_ERROR_SYNTAX:
$msg = 'json-error-syntax';
break;
case JSON_ERROR_UTF8:
$msg = 'json-error-utf8';
break;
case JSON_ERROR_INVALID_PROPERTY_NAME:
$msg = 'json-error-invalid-property-name';
break;
case JSON_ERROR_UTF16:
$msg = 'json-error-utf16';
break;
}
return Status::newFatal( $msg );
}
/**
* Remove multiline and single line comments from an otherwise valid JSON
* input string. This can be used as a preprocessor, to allow JSON
* formatted configuration files to contain comments.
*
* @param string $json
* @return string JSON with comments removed
*/
public static function stripComments( $json ) {
// Ensure we have a string
$str = (string)$json;
$buffer = '';
$maxLen = strlen( $str );
$mark = 0;
$inString = false;
$inComment = false;
$multiline = false;
for ( $idx = 0; $idx < $maxLen; $idx++ ) {
switch ( $str[$idx] ) {
case '"':
$lookBehind = ( $idx - 1 >= 0 ) ? $str[$idx - 1] : '';
if ( !$inComment && $lookBehind !== '\\' ) {
// Either started or ended a string
$inString = !$inString;
}
break;
case '/':
$lookAhead = ( $idx + 1 < $maxLen ) ? $str[$idx + 1] : '';
$lookBehind = ( $idx - 1 >= 0 ) ? $str[$idx - 1] : '';
if ( $inString ) {
break;
} elseif ( !$inComment &&
( $lookAhead === '/' || $lookAhead === '*' )
) {
// Transition into a comment
// Add characters seen to buffer
$buffer .= substr( $str, $mark, $idx - $mark );
// Consume the look ahead character
$idx++;
// Track state
$inComment = true;
$multiline = $lookAhead === '*';
} elseif ( $multiline && $lookBehind === '*' ) {
// Found the end of the current comment
$mark = $idx + 1;
$inComment = false;
$multiline = false;
}
break;
case "\n":
if ( $inComment && !$multiline ) {
// Found the end of the current comment
$mark = $idx + 1;
$inComment = false;
}
break;
}
}
if ( $inComment ) {
// Comment ends with input
// Technically we should check to ensure that we aren't in
// a multiline comment that hasn't been properly ended, but this
// is a strip filter, not a validating parser.
$mark = $maxLen;
}
// Add final chunk to buffer before returning
return $buffer . substr( $str, $mark, $maxLen - $mark );
}
}
/** @deprecated class alias since 1.43 */
class_alias( FormatJson::class, 'FormatJson' );