MimeAnalyzer.php
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MimeAnalyzer.php
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	<?php
	/**
	* 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 Wikimedia\Mime;

	use Psr\Log\LoggerAwareInterface;
	use Psr\Log\LoggerInterface;
	use Psr\Log\NullLogger;
	use UnexpectedValueException;
	use Wikimedia\AtEase\AtEase;
	use ZipDirectoryReader;

	/**
	* @defgroup Mime Mime
	*
	* @ingroup Media
	*/

	/**
	* Detect MIME types of a file by mapping file extensions or parsing file contents.
	*
	* @since 1.28
	* @ingroup Mime
	*/
	class MimeAnalyzer implements LoggerAwareInterface {
	/** @var string */
	protected $typeFile;
	/** @var string */
	protected $infoFile;
	/** @var string */
	protected $xmlTypes;
	/** @var callable */
	protected $initCallback;
	/** @var callable */
	protected $detectCallback;
	/** @var callable */
	protected $guessCallback;
	/** @var callable */
	protected $extCallback;
	/** @var array Mapping of media types to arrays of MIME types */
	protected $mediaTypes = null;
	/** @var array Map of MIME type aliases */
	protected $mimeTypeAliases = null;
	/** @var array<string,string[]> Map of MIME types to file extensions */
	protected $mimeToExts = [];
	/** @var array<string,string[]> Map of file extensions to MIME types */
	protected $extToMimes = [];

	/** @var array Map of file extensions types to MIME types (as a space separated list) */
	public $mExtToMime = []; // legacy name; field accessed by hooks

	/** @var string Extra MIME types, set for example by media handling extensions */
	private $extraTypes = '';
	/** @var string Extra MIME info, set for example by media handling extensions */
	private $extraInfo = '';

	/** @var LoggerInterface */
	private $logger;

	/** @var string Use the full, built-in MIME mapping rather than load from a file */
	public const USE_INTERNAL = 'internal';

	/**
	* @param array $params Configuration map, includes:
	* - typeFile: path to file with the list of known MIME types
	* - infoFile: path to file with the MIME type info
	* - xmlTypes: map of root element names to XML MIME types
	* - initCallback: initialization callback that is passed this object [optional]
	* - detectCallback: alternative to finfo that returns the mime type for a file.
	* For example, the callback can return the output of "file -bi". [optional]
	* - guessCallback: callback to improve the guessed MIME type using the file data.
	* This is intended for fixing mistakes in fileinfo or "detectCallback". [optional]
	* - extCallback: callback to improve the guessed MIME type using the extension. [optional]
	* - logger: PSR-3 logger [optional]
	* @note Constructing these instances is expensive due to file reads.
	* A service or singleton pattern should be used to avoid creating instances again and again.
	*/
	public function __construct( array $params ) {
	$this->typeFile = $params['typeFile'];
	$this->infoFile = $params['infoFile'];
	$this->xmlTypes = $params['xmlTypes'];
	$this->initCallback = $params['initCallback'] ?? null;
	$this->detectCallback = $params['detectCallback'] ?? null;
	$this->guessCallback = $params['guessCallback'] ?? null;
	$this->extCallback = $params['extCallback'] ?? null;
	$this->logger = $params['logger'] ?? new NullLogger();

	$this->loadFiles();
	}

	protected function loadFiles(): void {
	# Allow media handling extensions adding MIME-types and MIME-info
	if ( $this->initCallback ) {
	call_user_func( $this->initCallback, $this );
	}

	$rawTypes = $this->extraTypes;
	if ( $this->typeFile === self::USE_INTERNAL ) {
	$this->mimeToExts = MimeMap::MIME_EXTENSIONS;
	} else {
	$this->mimeToExts = MimeMapMinimal::MIME_EXTENSIONS;
	if ( $this->typeFile ) {
	$rawTypes = file_get_contents( $this->typeFile ) . "\n" . $this->extraTypes;
	}
	}
	if ( $rawTypes ) {
	$this->parseMimeTypes( $rawTypes );
	}

	// Build the reverse mapping (extension => MIME type).
	foreach ( $this->mimeToExts as $mime => $exts ) {
	foreach ( $exts as $ext ) {
	$this->extToMimes[$ext][] = $mime;
	}
	}

	// Migrate items from the legacy $this->mExtToMime field.
	// TODO: Remove this when mExtToMime is finally removed.
	foreach ( $this->mExtToMime as $ext => $mimes ) {
	foreach ( explode( ' ', $mimes ) as $mime ) {
	$this->extToMimes[$ext][] = $mime;
	}
	}

	$rawInfo = $this->extraInfo;
	if ( $this->infoFile === self::USE_INTERNAL ) {
	$this->mimeTypeAliases = MimeMap::MIME_TYPE_ALIASES;
	$this->mediaTypes = MimeMap::MEDIA_TYPES;
	} else {
	$this->mimeTypeAliases = MimeMapMinimal::MIME_TYPE_ALIASES;
	$this->mediaTypes = MimeMapMinimal::MEDIA_TYPES;
	if ( $this->infoFile ) {
	$rawInfo = file_get_contents( $this->infoFile ) . "\n" . $this->extraInfo;
	}
	}
	if ( $rawInfo ) {
	$this->parseMimeInfo( $rawInfo );
	}
	}

	protected function parseMimeTypes( string $rawMimeTypes ): void {
	$rawMimeTypes = str_replace( [ "\r\n", "\n\r", "\n\n", "\r\r", "\r" ], "\n", $rawMimeTypes );
	$rawMimeTypes = str_replace( "\t", " ", $rawMimeTypes );

	$lines = explode( "\n", $rawMimeTypes );
	foreach ( $lines as $s ) {
	$s = trim( $s );
	if ( $s === '' \|\| str_starts_with( $s, '#' ) ) {
	continue;
	}

	$s = strtolower( $s );
	$i = strpos( $s, ' ' );

	if ( $i === false ) {
	continue;
	}

	$ext = trim( substr( $s, $i + 1 ) );

	if ( !$ext ) {
	continue;
	}

	$tokens = preg_split( '/\s+/', $s, -1, PREG_SPLIT_NO_EMPTY );
	if ( count( $tokens ) > 1 ) {
	$mime = array_shift( $tokens );
	$this->mimeToExts[$mime] = array_values( array_unique(
	array_merge( $this->mimeToExts[$mime] ?? [], $tokens ) ) );
	}
	}
	}

	protected function parseMimeInfo( string $rawMimeInfo ): void {
	$rawMimeInfo = str_replace( [ "\r\n", "\n\r", "\n\n", "\r\r", "\r" ], "\n", $rawMimeInfo );
	$rawMimeInfo = str_replace( "\t", " ", $rawMimeInfo );

	$lines = explode( "\n", $rawMimeInfo );
	foreach ( $lines as $s ) {
	$s = trim( $s );
	if ( $s === '' \|\| str_starts_with( $s, '#' ) ) {
	continue;
	}

	$s = strtolower( $s );
	$i = strpos( $s, ' ' );

	if ( $i === false ) {
	continue;
	}

	# print "processing MIME INFO line $s<br>";

	$match = [];
	if ( preg_match( '!\[\s(\w+)\s\]!', $s, $match ) ) {
	$s = preg_replace( '!\[\s(\w+)\s\]!', '', $s );
	$mtype = trim( strtoupper( $match[1] ) );
	} else {
	$mtype = MEDIATYPE_UNKNOWN;
	}

	$m = preg_split( '/\s+/', $s, -1, PREG_SPLIT_NO_EMPTY );

	if ( !isset( $this->mediaTypes[$mtype] ) ) {
	$this->mediaTypes[$mtype] = [];
	}

	foreach ( $m as $mime ) {
	$mime = trim( $mime );
	if ( !$mime ) {
	continue;
	}

	$this->mediaTypes[$mtype][] = $mime;
	}

	if ( count( $m ) > 1 ) {
	$main = $m[0];
	$mCount = count( $m );
	for ( $i = 1; $i < $mCount; $i += 1 ) {
	$mime = $m[$i];
	$this->mimeTypeAliases[$mime] = $main;
	}
	}
	}
	}

	public function setLogger( LoggerInterface $logger ) {
	$this->logger = $logger;
	}

	/**
	* Adds to the list mapping MIME to file extensions.
	*
	* As an extension author, you are encouraged to submit patches to
	* MediaWiki's core to add new MIME types to MimeMap.php.
	*
	* @param string $types
	*/
	public function addExtraTypes( string $types ): void {
	$this->extraTypes .= "\n" . $types;
	}

	/**
	* Adds to the list mapping MIME to media type.
	*
	* As an extension author, you are encouraged to submit patches to
	* MediaWiki's core to add new MIME info to MimeMap.php.
	*
	* @param string $info
	*/
	public function addExtraInfo( string $info ): void {
	$this->extraInfo .= "\n" . $info;
	}

	/**
	* Returns a list of file extensions for a given MIME type as a space
	* separated string or null if the MIME type was unrecognized. Resolves
	* MIME type aliases.
	*
	* @deprecated since 1.35 Use getExtensionsFromMimeType() instead.
	* @param string $mime
	* @return string\|null
	*/
	public function getExtensionsForType( $mime ) {
	$exts = $this->getExtensionsFromMimeType( $mime );
	return $exts ? implode( ' ', $exts ) : null;
	}

	/**
	* Returns an array of file extensions associated with a given MIME type.
	* The returned array is empty if the MIME type was unrecognized. Resolves
	* MIME type aliases.
	*
	* @since 1.35
	* @param string $mime
	* @return string[]
	*/
	public function getExtensionsFromMimeType( string $mime ): array {
	$mime = strtolower( $mime );
	if ( !isset( $this->mimeToExts[$mime] ) && isset( $this->mimeTypeAliases[$mime] ) ) {
	$mime = $this->mimeTypeAliases[$mime];
	}
	return $this->mimeToExts[$mime] ?? [];
	}

	/**
	* Returns an array of MIME types associated with a given file extension.
	* The returned array is empty if the file extension is not associated with
	* any MIME types.
	*
	* @since 1.35
	* @param string $ext
	* @return string[]
	*/
	public function getMimeTypesFromExtension( string $ext ): array {
	$ext = strtolower( $ext );
	return $this->extToMimes[$ext] ?? [];
	}

	/**
	* Returns a single MIME type for a given file extension or null if unknown.
	* This is always the first type from the list returned by getMimeTypesFromExtension($ext).
	*
	* @since 1.35
	* @param string $ext
	* @return string\|null
	*/
	public function getMimeTypeFromExtensionOrNull( string $ext ): ?string {
	$types = $this->getMimeTypesFromExtension( $ext );
	return $types[0] ?? null;
	}

	/**
	* Returns a single file extension for a given MIME type or null if unknown.
	* This is always the first type from the list returned by getExtensionsFromMimeType($mime).
	*
	* @deprecated since 1.35 Use getMimeTypeFromExtensionOrNull() instead.
	* @param string $ext
	* @return string\|null
	*/
	public function guessTypesForExtension( $ext ) {
	return $this->getMimeTypeFromExtensionOrNull( $ext );
	}

	/**
	* Returns a list of MIME types for a given file extension as a space
	* separated string or null if the extension was unrecognized.
	*
	* @deprecated since 1.35 Use getMimeTypesFromExtension() instead.
	* @param string $ext
	* @return string\|null
	*/
	public function getTypesForExtension( $ext ) {
	$types = $this->getMimeTypesFromExtension( $ext );
	return $types ? implode( ' ', $types ) : null;
	}

	/**
	* Returns a single file extension for a given MIME type or null if unknown.
	* This is always the first type from the list returned by getExtensionsFromMimeType($mime).
	*
	* @since 1.35
	* @param string $mime
	* @return string\|null
	*/
	public function getExtensionFromMimeTypeOrNull( string $mime ): ?string {
	$exts = $this->getExtensionsFromMimeType( $mime );
	return $exts[0] ?? null;
	}

	/**
	* Tests if the extension matches the given MIME type. Returns true if a
	* match was found, null if the MIME type is unknown, and false if the
	* MIME type is known but no matches where found.
	*
	* @param string $extension
	* @param string $mime
	* @return bool\|null
	*/
	public function isMatchingExtension( string $extension, string $mime ): ?bool {
	$exts = $this->getExtensionsFromMimeType( $mime );

	if ( !$exts ) {
	return null; // Unknown MIME type
	}

	return in_array( strtolower( $extension ), $exts );
	}

	/**
	* Returns true if the MIME type is known to represent an image format
	* supported by the PHP GD library.
	*
	* @deprecated since 1.40
	* @param string $mime
	* @return bool
	*/
	public function isPHPImageType( string $mime ): bool {
	wfDeprecated( __METHOD__, '1.40' );
	// As defined by imagegetsize and image_type_to_mime
	static $types = [
	'image/gif', 'image/jpeg', 'image/png',
	'image/x-bmp', 'image/xbm', 'image/tiff',
	'image/jp2', 'image/jpeg2000', 'image/iff',
	'image/xbm', 'image/x-xbitmap',
	'image/vnd.wap.wbmp', 'image/vnd.xiff',
	'image/x-photoshop',
	'application/x-shockwave-flash',
	];

	return in_array( $mime, $types );
	}

	/**
	* Returns true if the extension represents a type which can
	* be reliably detected from its content. Use this to determine
	* whether strict content checks should be applied to reject
	* invalid uploads; if we can't identify the type we won't
	* be able to say if it's invalid.
	*
	* @todo Be more accurate when using fancy MIME detector plugins;
	* right now this is the bare minimum getimagesize() list.
	* @param string $extension
	* @return bool
	*/
	public function isRecognizableExtension( string $extension ): bool {
	static $types = [
	// Types recognized by getimagesize()
	'gif', 'jpeg', 'jpg', 'png', 'swf', 'psd',
	'bmp', 'tiff', 'tif', 'jpc', 'jp2',
	'jpx', 'jb2', 'swc', 'iff', 'wbmp',
	'xbm',

	// Formats we recognize magic numbers for
	'djvu', 'ogx', 'ogg', 'ogv', 'oga', 'spx', 'opus',
	'mid', 'pdf', 'wmf', 'xcf', 'webm', 'mkv', 'mka',
	'webp', 'mp3',

	// XML formats we sure hope we recognize reliably
	'svg',

	// 3D formats
	'stl', 'glb',
	];
	return in_array( strtolower( $extension ), $types );
	}

	/**
	* Improves a MIME type using the file extension. Some file formats are very generic,
	* so their MIME type is not very meaningful. A more useful MIME type can be derived
	* by looking at the file extension. Typically, this method would be called on the
	* result of guessMimeType().
	*
	* XXX: Null-returning behavior is probably an accident and definitely confusing (T253483).
	*
	* @param string $mime The MIME type, typically guessed from a file's content.
	* @param string $ext The file extension, as taken from the file name
	* @return string\|null The improved MIME type, or null if the MIME type is
	* unknown/unknown and the extension is not recognized.
	*/
	public function improveTypeFromExtension( string $mime, string $ext ): ?string {
	if ( $mime === 'unknown/unknown' ) {
	if ( $this->isRecognizableExtension( $ext ) ) {
	$this->logger->info( __METHOD__ . ': refusing to guess mime type for .' .
	"$ext file, we should have recognized it" );
	} else {
	// Not something we can detect, so simply
	// trust the file extension
	$mime = $this->getMimeTypeFromExtensionOrNull( $ext );
	}
	} elseif ( $mime === 'application/x-opc+zip'
	\|\| $mime === 'application/vnd.oasis.opendocument'
	) {
	if ( $this->isMatchingExtension( $ext, $mime ) ) {
	// A known file extension for an OPC/ODF file,
	// find the proper MIME type for that file extension
	$mime = $this->getMimeTypeFromExtensionOrNull( $ext );
	} else {
	$this->logger->info( __METHOD__ .
	": refusing to guess better type for $mime file, " .
	".$ext is not a known OPC/ODF extension." );
	$mime = 'application/zip';
	}
	} elseif ( $mime === 'text/plain' && $this->findMediaType( ".$ext" ) === MEDIATYPE_TEXT ) {
	// Textual types are sometimes not recognized properly.
	// If detected as text/plain, and has an extension which is textual
	// improve to the extension's type. For example, csv and json are often
	// misdetected as text/plain.
	$mime = $this->getMimeTypeFromExtensionOrNull( $ext );
	}

	# Media handling extensions can improve the MIME detected
	$callback = $this->extCallback;
	if ( $callback ) {
	$callback( $this, $ext, $mime /* by reference */ );
	}

	if ( $mime !== null && isset( $this->mimeTypeAliases[$mime] ) ) {
	$mime = $this->mimeTypeAliases[$mime];
	}

	$this->logger->info( __METHOD__ . ": improved mime type for .$ext: $mime" );
	return $mime;
	}

	/**
	* MIME type detection. This uses detectMimeType to detect the MIME type
	* of the file, but applies additional checks to determine some well known
	* file formats that may be missed or misinterpreted by the default MIME
	* detection (namely XML based formats like XHTML or SVG, as well as ZIP
	* based formats like OPC/ODF files).
	*
	* @param string $file The file to check
	* @param string\|bool $ext The file extension, or true (default) to extract
	* it from the filename. Set it to false to ignore the extension. DEPRECATED!
	* Set to false, use improveTypeFromExtension($mime, $ext) later to improve MIME type.
	* @return string The MIME type of $file
	*/
	public function guessMimeType( string $file, $ext = true ): string {
	if ( $ext ) { // TODO: make $ext default to false. Or better, remove it.
	$this->logger->info( __METHOD__ .
	": WARNING: use of the \$ext parameter is deprecated. " .
	"Use improveTypeFromExtension(\$mime, \$ext) instead." );
	}

	$mime = $this->doGuessMimeType( $file );

	if ( !$mime ) {
	$this->logger->info( __METHOD__ .
	": internal type detection failed for $file (.$ext)..." );
	$mime = $this->detectMimeType( $file, $ext );
	}

	if ( isset( $this->mimeTypeAliases[$mime] ) ) {
	$mime = $this->mimeTypeAliases[$mime];
	}

	$this->logger->info( __METHOD__ . ": guessed mime type of $file: $mime" );
	return $mime;
	}

	/**
	* Guess the MIME type from the file contents.
	*
	* @param string $file
	* @return bool\|string
	* @throws UnexpectedValueException
	*/
	private function doGuessMimeType( string $file ) {
	// Read a chunk of the file
	AtEase::suppressWarnings();
	$f = fopen( $file, 'rb' );
	AtEase::restoreWarnings();

	if ( !$f ) {
	return 'unknown/unknown';
	}

	$fsize = filesize( $file );
	if ( $fsize === false ) {
	return 'unknown/unknown';
	}

	$head = fread( $f, 1024 );
	$head16k = $head . fread( $f, 16384 - 1024 ); // some WebM files have big headers
	$tailLength = min( 65558, $fsize ); // 65558 = maximum size of a zip EOCDR
	if ( fseek( $f, -1 * $tailLength, SEEK_END ) === -1 ) {
	throw new UnexpectedValueException(
	"Seeking $tailLength bytes from EOF failed in " . __METHOD__ );
	}
	$tail = $tailLength ? fread( $f, $tailLength ) : '';

	$this->logger->info( __METHOD__ .
	": analyzing head and tail of $file for magic numbers." );

	// Hardcode a few magic number checks...
	$headers = [
	// Multimedia...
	'MThd' => 'audio/midi',
	'OggS' => 'application/ogg',
	'ID3' => 'audio/mpeg',
	"\xff\xfb" => 'audio/mpeg', // MPEG-1 layer 3
	"\xff\xf3" => 'audio/mpeg', // MPEG-2 layer 3 (lower sample rates)
	"\xff\xe3" => 'audio/mpeg', // MPEG-2.5 layer 3 (very low sample rates)

	// Image formats...
	// Note that WMF may have a bare header, no magic number.
	"\x01\x00\x09\x00" => 'application/x-msmetafile', // Possibly prone to false positives?
	"\xd7\xcd\xc6\x9a" => 'application/x-msmetafile',
	'%PDF' => 'application/pdf',
	'gimp xcf' => 'image/x-xcf',

	// 3D
	"glTF" => 'model/gltf-binary',

	// Some forbidden fruit...
	'MZ' => 'application/octet-stream', // DOS/Windows executable
	"\xca\xfe\xba\xbe" => 'application/octet-stream', // Mach-O binary
	"\x7fELF" => 'application/octet-stream', // ELF binary
	];

	foreach ( $headers as $magic => $candidate ) {
	if ( str_starts_with( $head, $magic ) ) {
	$this->logger->info( __METHOD__ .
	": magic header in $file recognized as $candidate" );
	return $candidate;
	}
	}

	/* Look for WebM and Matroska files */
	if ( str_starts_with( $head16k, pack( "C4", 0x1a, 0x45, 0xdf, 0xa3 ) ) ) {
	$doctype = strpos( $head16k, "\x42\x82" );
	if ( $doctype ) {
	// Next byte is datasize, then data (sizes larger than 1 byte are stupid muxers)
	$data = substr( $head16k, $doctype + 3, 8 );
	if ( str_starts_with( $data, "matroska" ) ) {
	$this->logger->info( __METHOD__ . ": recognized file as video/x-matroska" );
	return "video/x-matroska";
	}

	if ( str_starts_with( $data, "webm" ) ) {
	// XXX HACK look for a video track, if we don't find it, this is an audio file
	// This detection is very naive and doesn't parse the actual fields
	// 0x86 byte indicates start of codecname field
	// next byte is a variable length integer (vint) for the size of the value following it
	// 8 (first bit is 1) indicates the smallest size vint, a single byte
	// (unlikely we see larger vints here)
	// 5 indicates a length of 5 ( V_VP8 or V_VP9 or V_AV1 )
	// Sometimes we see 0x86 instead of 0x85 because a
	// non-conforming muxer wrote a null terminated string
	$videotrack = str_contains( $head16k, "\x86\x85V_VP8" ) \|\|
	str_contains( $head16k, "\x86\x85V_VP9" ) \|\|
	str_contains( $head16k, "\x86\x85V_AV1" ) \|\|
	str_contains( $head16k, "\x86\x86V_VP8\x0" ) \|\|
	str_contains( $head16k, "\x86\x86V_VP9\x0" ) \|\|
	str_contains( $head16k, "\x86\x86V_AV1\x0" );

	if ( $videotrack ) {
	// There is a video track, so this is a video file.
	$this->logger->info( __METHOD__ . ": recognized file as video/webm" );
	return "video/webm";
	}

	$this->logger->info( __METHOD__ . ": recognized file as audio/webm" );
	return "audio/webm";
	}
	}
	$this->logger->info( __METHOD__ . ": unknown EBML file" );
	return "unknown/unknown";
	}

	/* Look for WebP */
	if ( str_starts_with( $head, "RIFF" ) && substr( $head, 8, 7 ) === "WEBPVP8" ) {
	$this->logger->info( __METHOD__ . ": recognized file as image/webp" );
	return "image/webp";
	}

	/* Look for JPEG2000 */
	if ( str_starts_with( $head, "\x00\x00\x00\x0cjP\x20\x20\x0d\x0a\x87\x0a" ) ) {
	$this->logger->info( __METHOD__ . ": recognized as JPEG2000" );
	// we skip 4 bytes
	if ( substr( $head, 16, 8 ) === "ftypjp2 " ) {
	$this->logger->info( __METHOD__ . ": recognized file as image/jp2" );
	return 'image/jp2';
	} elseif ( substr( $head, 16, 8 ) === "ftypjpx " ) {
	$this->logger->info( __METHOD__ . ": recognized file as image/jpx" );
	return 'image/jpx';
	}
	}

	/* Look for MS Compound Binary (OLE) files */
	if ( str_starts_with( $head, "\xd0\xcf\x11\xe0\xa1\xb1\x1a\xe1" ) ) {
	$this->logger->info( __METHOD__ . ': recognized MS CFB (OLE) file' );
	return $this->detectMicrosoftBinaryType( $f );
	}

	/**
	* Look for PHP. Check for this before HTML/XML... Warning: this is a
	* heuristic, and won't match a file with a lot of non-PHP before. It
	* will also match text files which could be PHP. :)
	*
	* @todo FIXME: For this reason, the check is probably useless -- an attacker
	* could almost certainly just pad the file with a lot of nonsense to
	* circumvent the check in any case where it would be a security
	* problem. On the other hand, it causes harmful false positives (bug
	* 16583). The heuristic has been cut down to exclude three-character
	* strings like "<? ", but should it be axed completely?
	*/
	if ( ( strpos( $head, '<?php' ) !== false ) \|\|
	( strpos( $head, "<\x00?\x00p\x00h\x00p" ) !== false ) \|\|
	( strpos( $head, "<\x00?\x00 " ) !== false ) \|\|
	( strpos( $head, "<\x00?\x00\n" ) !== false ) \|\|
	( strpos( $head, "<\x00?\x00\t" ) !== false ) \|\|
	( strpos( $head, "<\x00?\x00=" ) !== false )
	) {
	$this->logger->info( __METHOD__ . ": recognized $file as application/x-php" );
	return 'application/x-php';
	}

	/**
	* look for XML formats (XHTML and SVG)
	*/
	AtEase::suppressWarnings();
	$xml = new XmlTypeCheck( $file );
	AtEase::restoreWarnings();
	if ( $xml->wellFormed ) {
	$xmlTypes = $this->xmlTypes;
	// @phan-suppress-next-line PhanTypeMismatchDimFetch False positive
	return $xmlTypes[$xml->getRootElement()] ?? 'application/xml';
	}

	/**
	* look for shell scripts
	*/
	$script_type = null;

	# detect by shebang
	if ( str_starts_with( $head, "#!" ) ) {
	$script_type = "ASCII";
	} elseif ( str_starts_with( $head, "\xef\xbb\xbf#!" ) ) {
	$script_type = "UTF-8";
	} elseif ( str_starts_with( $head, "\xfe\xff\x00#\x00!" ) ) {
	$script_type = "UTF-16BE";
	} elseif ( str_starts_with( $head, "\xff\xfe#\x00!" ) ) {
	$script_type = "UTF-16LE";
	}

	if ( $script_type ) {
	if ( $script_type !== "UTF-8" && $script_type !== "ASCII" ) {
	// Quick and dirty fold down to ASCII!
	$pack = [ 'UTF-16BE' => 'n', 'UTF-16LE' => 'v' ];
	$chars = unpack( $pack[$script_type], substr( $head, 2 ) );
	$head = '';
	foreach ( $chars as $codepoint ) {
	if ( $codepoint < 128 ) {
	$head .= chr( $codepoint );
	} else {
	$head .= '?';
	}
	}
	}

	$match = [];

	if ( preg_match( '%/?([^\s]+/)(\w+)%', $head, $match ) ) {
	$mime = "application/x-{$match[2]}";
	$this->logger->info( __METHOD__ . ": shell script recognized as $mime" );
	return $mime;
	}
	}

	// Check for ZIP variants (before getimagesize)
	$eocdrPos = strpos( $tail, "PK\x05\x06" );
	if ( $eocdrPos !== false && $eocdrPos <= strlen( $tail ) - 22 ) {
	$this->logger->info( __METHOD__ . ": ZIP signature present in $file" );
	// Check if it really is a ZIP file, make sure the EOCDR is at the end (T40432)
	$commentLength = unpack( "n", substr( $tail, $eocdrPos + 20 ) )[1];
	if ( $eocdrPos + 22 + $commentLength !== strlen( $tail ) ) {
	$this->logger->info( __METHOD__ . ": ZIP EOCDR not at end. Not a ZIP file." );
	} else {
	return $this->detectZipTypeFromFile( $f );
	}
	}

	// Check for STL (3D) files
	// @see https://en.wikipedia.org/wiki/STL_(file_format)
	if ( $fsize >= 15 &&
	stripos( $head, 'SOLID ' ) === 0 &&
	preg_match( '/\RENDSOLID .*$/i', $tail ) ) {
	// ASCII STL file
	return 'application/sla';
	} elseif ( $fsize > 84 ) {
	// binary STL file
	$triangles = substr( $head, 80, 4 );
	$triangles = unpack( 'V', $triangles );
	$triangles = reset( $triangles );
	if ( $triangles !== false && $fsize === 84 + ( $triangles * 50 ) ) {
	return 'application/sla';
	}
	}

	AtEase::suppressWarnings();
	$gis = getimagesize( $file );
	AtEase::restoreWarnings();

	if ( $gis && isset( $gis['mime'] ) ) {
	$mime = $gis['mime'];
	$this->logger->info( __METHOD__ . ": getimagesize detected $file as $mime" );
	return $mime;
	}

	# Media handling extensions can guess the MIME by content
	# It's intentionally here so that if core is wrong about a type (false positive),
	# people will hopefully nag and submit patches :)
	$mime = false;
	# Some strings by reference for performance - assuming well-behaved hooks
	$callback = $this->guessCallback;
	if ( $callback ) {
	$callback( $this, $head, $tail, $file, $mime /* by reference */ );
	}

	return $mime;
	}

	/**
	* Detect application-specific file type of a given ZIP file.
	* If it can't tell, return 'application/zip'.
	*
	* @internal
	* @param resource $handle
	* @return string
	*/
	public function detectZipTypeFromFile( $handle ) {
	$types = [];
	$status = ZipDirectoryReader::readHandle(
	$handle,
	static function ( $entry ) use ( &$types ) {
	$name = $entry['name'];
	$names = [ $name ];

	// If there is a null character, cut off the name at it, because JDK's
	// ZIP_GetEntry() uses strcmp() if the name hashes match. If a file name
	// were constructed which had ".class\0" followed by a string chosen to
	// make the hash collide with the truncated name, that file could be
	// returned in response to a request for the .class file.
	$nullPos = strpos( $entry['name'], "\000" );
	if ( $nullPos !== false ) {
	$names[] = substr( $entry['name'], 0, $nullPos );
	}

	// If there is a trailing slash in the file name, we have to strip it,
	// because that's what ZIP_GetEntry() does.
	if ( preg_grep( '!\.class/?$!', $names ) ) {
	$types[] = 'application/java';
	}

	if ( $name === '[Content_Types].xml' ) {
	$types[] = 'application/x-opc+zip';
	} elseif ( $name === 'mimetype' ) {
	$types[] = 'application/vnd.oasis.opendocument';
	}
	}
	);
	if ( !$status->isOK() ) {
	$this->logger->info( "Error reading zip file: " . (string)$status );
	// This could be unknown/unknown but we have some weird phpunit test cases
	return 'application/zip';
	}
	if ( in_array( 'application/java', $types ) ) {
	// For security, java detection takes precedence
	return 'application/java';
	} elseif ( count( $types ) ) {
	return $types[0];
	} else {
	return 'application/zip';
	}
	}

	/**
	* Detect the type of a Microsoft Compound Binary a.k.a. OLE file.
	* These are old style pre-ODF files such as .doc and .xls
	*
	* @param resource $handle An opened seekable file handle
	* @return string The detected MIME type
	*/
	private function detectMicrosoftBinaryType( $handle ): string {
	$info = MSCompoundFileReader::readHandle( $handle );
	if ( !$info['valid'] ) {
	$this->logger->info( __METHOD__ . ': invalid file format' );
	return 'unknown/unknown';
	}
	if ( !$info['mime'] ) {
	$this->logger->info( __METHOD__ . ": unrecognised document subtype" );
	return 'unknown/unknown';
	}
	return $info['mime'];
	}

	/**
	* Internal MIME type detection. Detection is done using the fileinfo
	* extension if it is available. It can be overridden by callback, which could
	* use an external program, for example. If detection fails and $ext is not false,
	* the MIME type is guessed from the file extension, using getMimeTypeFromExtensionOrNull.
	*
	* If the MIME type is still unknown, getimagesize is used to detect the
	* MIME type if the file is an image. If no MIME type can be determined,
	* this function returns 'unknown/unknown'.
	*
	* @param string $file The file to check
	* @param string\|bool $ext The file extension, or true (default) to extract it from the filename.
	* Set it to false to ignore the extension. DEPRECATED! Set to false, use
	* improveTypeFromExtension($mime, $ext) later to improve MIME type.
	* @return string The MIME type of $file
	*/
	private function detectMimeType( string $file, $ext = true ): string {
	/** @todo Make $ext default to false. Or better, remove it. */
	if ( $ext ) {
	$this->logger->info( __METHOD__ .
	": WARNING: use of the \$ext parameter is deprecated. "
	. "Use improveTypeFromExtension(\$mime, \$ext) instead." );
	}

	$callback = $this->detectCallback;
	if ( $callback ) {
	$m = $callback( $file );
	} else {
	$m = mime_content_type( $file );
	}

	if ( $m ) {
	# normalize
	$m = preg_replace( '![;, ].*$!', '', $m ); # strip charset, etc
	$m = trim( $m );
	$m = strtolower( $m );

	if ( !str_contains( $m, 'unknown' ) ) {
	$this->logger->info( __METHOD__ . ": magic mime type of $file: $m" );
	return $m;
	}
	}

	// If desired, look at extension as a fallback.
	if ( $ext === true ) {
	$i = strrpos( $file, '.' );
	$ext = strtolower( $i ? substr( $file, $i + 1 ) : '' );
	}
	if ( $ext ) {
	if ( $this->isRecognizableExtension( $ext ) ) {
	$this->logger->info( __METHOD__ . ": refusing to guess mime type for .$ext file, "
	. "we should have recognized it" );
	} else {
	$m = $this->getMimeTypeFromExtensionOrNull( $ext );
	if ( $m ) {
	$this->logger->info( __METHOD__ . ": extension mime type of $file: $m" );
	return $m;
	}
	}
	}

	// Unknown type
	$this->logger->info( __METHOD__ . ": failed to guess mime type for $file!" );
	return 'unknown/unknown';
	}

	/**
	* Determine the media type code for a file, using its MIME type, name and
	* possibly its contents.
	*
	* This function relies on the findMediaType(), mapping extensions and MIME
	* types to media types.
	*
	* @todo analyse file if need be
	* @todo look at multiple extension, separately and together.
	*
	* @param string\|null $path Full path to the image file, in case we have to look at the contents
	* (if null, only the MIME type is used to determine the media type code).
	* @param string\|null $mime MIME type. If null it will be guessed using guessMimeType.
	* @return string A value to be used with the MEDIATYPE_xxx constants.
	*/
	public function getMediaType( ?string $path = null, ?string $mime = null ): string {
	if ( !$mime && !$path ) {
	return MEDIATYPE_UNKNOWN;
	}

	// If MIME type is unknown, guess it
	if ( !$mime ) {
	// @phan-suppress-next-line PhanTypeMismatchArgumentNullable False positive
	$mime = $this->guessMimeType( $path, false );
	}

	// Special code for ogg - detect if it's video (theora),
	// else label it as sound.
	if ( $mime == 'application/ogg' && is_string( $path ) && file_exists( $path ) ) {
	// Read a chunk of the file
	$f = fopen( $path, "rt" );
	if ( !$f ) {
	return MEDIATYPE_UNKNOWN;
	}
	$head = fread( $f, 256 );
	fclose( $f );

	$head = str_replace( 'ffmpeg2theora', '', strtolower( $head ) );

	// This is an UGLY HACK, file should be parsed correctly
	if ( strpos( $head, 'theora' ) !== false ) {
	return MEDIATYPE_VIDEO;
	} elseif ( strpos( $head, 'vorbis' ) !== false ) {
	return MEDIATYPE_AUDIO;
	} elseif ( strpos( $head, 'flac' ) !== false ) {
	return MEDIATYPE_AUDIO;
	} elseif ( strpos( $head, 'speex' ) !== false ) {
	return MEDIATYPE_AUDIO;
	} elseif ( strpos( $head, 'opus' ) !== false ) {
	return MEDIATYPE_AUDIO;
	} else {
	return MEDIATYPE_MULTIMEDIA;
	}
	}

	$type = null;
	// Check for entry for full MIME type
	if ( $mime ) {
	$type = $this->findMediaType( $mime );
	if ( $type !== MEDIATYPE_UNKNOWN ) {
	return $type;
	}
	}

	// Check for entry for file extension
	if ( $path ) {
	$i = strrpos( $path, '.' );
	$e = strtolower( $i ? substr( $path, $i + 1 ) : '' );

	// TODO: look at multi-extension if this fails, parse from full path
	$type = $this->findMediaType( '.' . $e );
	if ( $type !== MEDIATYPE_UNKNOWN ) {
	return $type;
	}
	}

	// Check major MIME type
	if ( $mime ) {
	$i = strpos( $mime, '/' );
	if ( $i !== false ) {
	$major = substr( $mime, 0, $i );
	$type = $this->findMediaType( $major );
	if ( $type !== MEDIATYPE_UNKNOWN ) {
	return $type;
	}
	}
	}

	if ( !$type ) {
	$type = MEDIATYPE_UNKNOWN;
	}

	return $type;
	}

	/**
	* Returns a media code matching the given MIME type or file extension.
	*
	* File extensions are represented by a string starting with a dot (.) to
	* distinguish them from MIME types.
	*
	* @param string $extMime
	* @return int\|string
	*/
	private function findMediaType( string $extMime ) {
	if ( strpos( $extMime, '.' ) === 0 ) {
	// If it's an extension, look up the MIME types
	$m = $this->getMimeTypesFromExtension( substr( $extMime, 1 ) );
	if ( !$m ) {
	return MEDIATYPE_UNKNOWN;
	}
	} else {
	// Normalize MIME type
	if ( isset( $this->mimeTypeAliases[$extMime] ) ) {
	$extMime = $this->mimeTypeAliases[$extMime];
	}

	$m = [ $extMime ];
	}

	foreach ( $m as $mime ) {
	foreach ( $this->mediaTypes as $type => $codes ) {
	if ( in_array( $mime, $codes, true ) ) {
	return $type;
	}
	}
	}

	return MEDIATYPE_UNKNOWN;
	}

	/**
	* Returns an array of media types (MEDIATYPE_xxx constants)
	*
	* @return string[]
	*/
	public function getMediaTypes(): array {
	return array_keys( $this->mediaTypes );
	}

	/**
	* Check if major_mime has a value accepted by enum in a database schema.
	*
	* @since 1.42.0 (also backported to 1.39.7, 1.40.3 and 1.41.1)
	*
	* @param string $type
	* @return bool
	*/
	public function isValidMajorMimeType( string $type ): bool {
	// From maintenance/tables-generated.sql => img_major_mime
	$types = [
	'unknown',
	'application',
	'audio',
	'image',
	'text',
	'video',
	'message',
	'model',
	'multipart',
	'chemical',
	];

	return in_array( $type, $types );
	}
	}

	/** @deprecated class alias since 1.43 */
	class_alias( MimeAnalyzer::class, 'MimeAnalyzer' );

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