100 lines
3.0 KiB
PHP
100 lines
3.0 KiB
PHP
<?php
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/**
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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*/
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namespace Wikimedia\Reflection;
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/**
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* Trait for accessing "ghost fields".
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*
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* Ghost fields are fields that have been created in an object instance
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* by PHP's unserialize() mechanism, though they no longer exist
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* in the current version of the corresponding class.
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*
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* Accessing non-public ghost fields offers some challenges due to
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* how they are handled by PHP internally.
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*
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* @see https://www.php.net/manual/en/language.types.array.php#language.types.array.casting
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* @since 1.36
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*/
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trait GhostFieldAccessTrait {
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/**
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* Get the value of the ghost field named $name,
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* or null if the field does not exist.
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*
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* @param string $name
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* @param class-string ...$aliases
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* @return mixed|null
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*/
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private function getGhostFieldValue( string $name, string ...$aliases ) {
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if ( isset( $this->$name ) ) {
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return $this->$name;
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}
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$data = (array)$this;
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// Protected variables have a '*' prepended to the variable name.
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// These prepended values have null bytes on either side.
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$protectedName = "\x00*\x00{$name}";
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if ( isset( $data[$protectedName] ) ) {
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return $data[$protectedName];
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}
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// Private variables have the class name prepended to the variable name.
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// These prepended values have null bytes on either side.
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$thisClass = get_class( $this );
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$privateName = "\x00{$thisClass}\x00{$name}";
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if ( isset( $data[$privateName] ) ) {
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return $data[$privateName];
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}
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// Check old aliased class names as well.
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foreach ( $aliases as $thisClass ) {
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$privateName = "\x00{$thisClass}\x00{$name}";
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if ( isset( $data[$privateName] ) ) {
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return $data[$privateName];
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}
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}
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return null;
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}
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/**
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* In PHP <= 8.1, private fields of a class are not properly restored
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* when the class is aliased to a new name, since the private fields are
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* prefixed with the *old* name of the class. This method can be used
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* to restore them if present after deserialization.
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*
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* @param string $name
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* @param class-string ...$aliases
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*/
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private function restoreAliasedGhostField( string $name, string ...$aliases ): void {
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$data = (array)$this;
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foreach ( $aliases as $thisClass ) {
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$privateName = "\x00{$thisClass}\x00{$name}";
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if ( isset( $data[$privateName] ) ) {
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$this->$name = $data[$privateName];
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unset( $data[$privateName] );
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return;
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}
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}
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}
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}
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