3 * Copyright 2019 Wikimedia Foundation
5 * Licensed under the Apache License, Version 2.0 (the "License"); you may
6 * not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
9 * http://www.apache.org/licenses/LICENSE-2.0
11 * Unless required by applicable law or agreed to in writing, software distributed
12 * under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
13 * OF ANY KIND, either express or implied. See the License for the
14 * specific language governing permissions and limitations under the License.
18 * Read the directory of a Microsoft Compound File Binary file, a.k.a. an OLE
19 * file, and detect the MIME type.
22 * - MS-CFB https://msdn.microsoft.com/en-us/library/dd942138.aspx
23 * - MS-XLS https://msdn.microsoft.com/en-us/library/cc313154.aspx
24 * - MS-PPT https://msdn.microsoft.com/en-us/library/cc313106.aspx
25 * - MS-DOC https://msdn.microsoft.com/en-us/library/cc313153.aspx
26 * - Python olefile https://github.com/decalage2/olefile
27 * - OpenOffice.org's Documentation of the Microsoft Compound Document
28 * File Format https://www.openoffice.org/sc/compdocfileformat.pdf
32 class MSCompoundFileReader
{
36 private $mimeFromClsid;
39 private $valid = false;
41 private $sectorLength;
46 const TYPE_UNALLOCATED
= 0;
47 const TYPE_STORAGE
= 1;
48 const TYPE_STREAM
= 2;
51 const ERROR_FILE_OPEN
= 1;
54 const ERROR_INVALID_SIGNATURE
= 4;
55 const ERROR_READ_PAST_END
= 5;
56 const ERROR_INVALID_FORMAT
= 6;
58 private static $mimesByClsid = [
59 // From http://justsolve.archiveteam.org/wiki/Microsoft_Compound_File
60 '00020810-0000-0000-C000-000000000046' => 'application/vnd.ms-excel',
61 '00020820-0000-0000-C000-000000000046' => 'application/vnd.ms-excel',
62 '00020906-0000-0000-C000-000000000046' => 'application/msword',
63 '64818D10-4F9B-11CF-86EA-00AA00B929E8' => 'application/vnd.ms-powerpoint',
69 * @param string $fileName The full path to the file
70 * @return array An associative array of information about the file:
71 * - valid: true if the file is valid, false otherwise
72 * - error: An error message in English, should be present if valid=false
73 * - errorCode: One of the self::ERROR_* constants
74 * - mime: The MIME type detected from the directory contents
75 * - mimeFromClsid: The MIME type detected from the CLSID on the root
78 public static function readFile( $fileName ) {
79 $handle = fopen( $fileName, 'r' );
80 if ( $handle === false ) {
83 'error' => 'file does not exist',
84 'errorCode' => self
::ERROR_FILE_OPEN
87 return self
::readHandle( $handle );
91 * Read from an open seekable handle
93 * @param resource $fileHandle The file handle
94 * @return array An associative array of information about the file:
95 * - valid: true if the file is valid, false otherwise
96 * - error: An error message in English, should be present if valid=false
97 * - errorCode: One of the self::ERROR_* constants
98 * - mime: The MIME type detected from the directory contents
99 * - mimeFromClsid: The MIME type detected from the CLSID on the root
102 public static function readHandle( $fileHandle ) {
103 $reader = new self( $fileHandle );
105 'valid' => $reader->valid
,
106 'mime' => $reader->mime
,
107 'mimeFromClsid' => $reader->mimeFromClsid
109 if ( $reader->error
) {
110 $info['error'] = $reader->error
;
111 $info['errorCode'] = $reader->errorCode
;
116 private function __construct( $fileHandle ) {
117 $this->file
= $fileHandle;
120 } catch ( RuntimeException
$e ) {
121 $this->valid
= false;
122 $this->error
= $e->getMessage();
123 $this->errorCode
= $e->getCode();
127 private function init() {
128 $this->header
= $this->unpackOffset( 0, [
129 'header_signature' => 8,
130 'header_clsid' => 16,
131 'minor_version' => 2,
132 'major_version' => 2,
135 'mini_sector_shift' => 2,
137 'num_dir_sectors' => 4,
138 'num_fat_sectors' => 4,
139 'first_dir_sector' => 4,
140 'transaction_signature_number' => 4,
141 'mini_stream_cutoff_size' => 4,
142 'first_mini_fat_sector' => 4,
143 'num_mini_fat_sectors' => 4,
144 'first_difat_sector' => 4,
145 'num_difat_sectors' => 4,
148 if ( $this->header
['header_signature'] !== "\xd0\xcf\x11\xe0\xa1\xb1\x1a\xe1" ) {
149 $this->error( 'invalid signature: ' . bin2hex( $this->header
['header_signature'] ),
150 self
::ERROR_INVALID_SIGNATURE
);
152 // @phan-suppress-next-line PhanTypeInvalidRightOperandOfIntegerOp
153 $this->sectorLength
= 1 << $this->header
['sector_shift'];
155 $this->readDirectory();
160 private function sectorOffset( $sectorId ) {
161 return $this->sectorLength
* ( $sectorId +
1 );
164 private function decodeClsid( $binaryClsid ) {
165 $parts = unpack( 'Va/vb/vc/C8d', $binaryClsid );
166 return sprintf( "%08X-%04X-%04X-%02X%02X-%02X%02X%02X%02X%02X%02X",
183 * @param int[] $struct
186 private function unpackOffset( $offset, $struct ) {
187 $block = $this->readOffset( $offset, array_sum( $struct ) );
188 return $this->unpack( $block, 0, $struct );
192 * @param string $block
194 * @param int[] $struct
197 private function unpack( $block, $offset, $struct ) {
199 foreach ( $struct as $key => $length ) {
201 $data[$key] = substr( $block, $offset, $length );
203 $data[$key] = $this->bin2dec( $block, $offset, $length );
210 private function bin2dec( $str, $offset, $length ) {
212 for ( $i = $length - 1; $i >= 0; $i-- ) {
214 $value +
= ord( $str[$offset +
$i] );
219 private function readOffset( $offset, $length ) {
220 $this->fseek( $offset );
221 Wikimedia\
suppressWarnings();
222 $block = fread( $this->file
, $length );
223 Wikimedia\restoreWarnings
();
224 if ( $block === false ) {
225 $this->error( 'error reading from file', self
::ERROR_READ
);
227 if ( strlen( $block ) !== $length ) {
228 $this->error( 'unable to read the required number of bytes from the file',
229 self
::ERROR_READ_PAST_END
);
234 private function readSector( $sectorId ) {
235 // @phan-suppress-next-line PhanTypeInvalidRightOperandOfIntegerOp
236 return $this->readOffset( $this->sectorOffset( $sectorId ), 1 << $this->header
['sector_shift'] );
239 private function error( $message, $code ) {
240 throw new RuntimeException( $message, $code );
243 private function fseek( $offset ) {
244 Wikimedia\
suppressWarnings();
245 $result = fseek( $this->file
, $offset );
246 Wikimedia\restoreWarnings
();
247 if ( $result !== 0 ) {
248 $this->error( "unable to seek to offset $offset", self
::ERROR_SEEK
);
252 private function readDifat() {
253 $binaryDifat = $this->header
['difat'];
254 $nextDifatSector = $this->header
['first_difat_sector'];
255 for ( $i = 0; $i < $this->header
['num_difat_sectors']; $i++
) {
256 $block = $this->readSector( $nextDifatSector );
257 $binaryDifat .= substr( $block, 0, $this->sectorLength
- 4 );
258 $nextDifatSector = $this->bin2dec( $block, $this->sectorLength
- 4, 4 );
259 if ( $nextDifatSector == 0xFFFFFFFE ) {
265 for ( $pos = 0; $pos < strlen( $binaryDifat ); $pos +
= 4 ) {
266 $fatSector = $this->bin2dec( $binaryDifat, $pos, 4 );
267 if ( $fatSector < 0xFFFFFFFC ) {
268 $this->difat
[] = $fatSector;
275 private function getNextSectorIdFromFat( $sectorId ) {
276 $entriesPerSector = intdiv( $this->sectorLength
, 4 );
277 $fatSectorId = intdiv( $sectorId, $entriesPerSector );
278 $fatSectorArray = $this->getFatSector( $fatSectorId );
279 return $fatSectorArray[$sectorId %
$entriesPerSector];
282 private function getFatSector( $fatSectorId ) {
283 if ( !isset( $this->fat
[$fatSectorId] ) ) {
285 if ( !isset( $this->difat
[$fatSectorId] ) ) {
286 $this->error( 'FAT sector requested beyond the end of the DIFAT', self
::ERROR_INVALID_FORMAT
);
288 $absoluteSectorId = $this->difat
[$fatSectorId];
289 $block = $this->readSector( $absoluteSectorId );
290 for ( $pos = 0; $pos < strlen( $block ); $pos +
= 4 ) {
291 $fat[] = $this->bin2dec( $block, $pos, 4 );
293 $this->fat
[$fatSectorId] = $fat;
295 return $this->fat
[$fatSectorId];
298 private function readDirectory() {
299 $dirSectorId = $this->header
['first_dir_sector'];
302 while ( $dirSectorId !== 0xFFFFFFFE ) {
303 if ( isset( $seenSectorIds[$dirSectorId] ) ) {
304 $this->error( 'FAT loop detected', self
::ERROR_INVALID_FORMAT
);
306 $seenSectorIds[$dirSectorId] = true;
308 $binaryDir .= $this->readSector( $dirSectorId );
309 $dirSectorId = $this->getNextSectorIdFromFat( $dirSectorId );
322 'create_time_low' => 4,
323 'create_time_high' => 4,
324 'modify_time_low' => 4,
325 'modify_time_high' => 4,
330 $entryLength = array_sum( $struct );
332 for ( $pos = 0; $pos < strlen( $binaryDir ); $pos +
= $entryLength ) {
333 $entry = $this->unpack( $binaryDir, $pos, $struct );
335 // According to [MS-CFB] size_high may contain garbage due to a
336 // bug in a writer, it's best to pretend it is zero
337 $entry['size_high'] = 0;
339 $type = $entry['object_type'];
340 if ( $type == self
::TYPE_UNALLOCATED
) {
344 $name = iconv( 'UTF-16LE', 'UTF-8', substr( $entry['name_raw'], 0, $entry['name_length'] - 2 ) );
346 $clsid = $this->decodeClsid( $entry['clsid'] );
347 if ( $type == self
::TYPE_ROOT
&& isset( self
::$mimesByClsid[$clsid] ) ) {
348 $this->mimeFromClsid
= self
::$mimesByClsid[$clsid];
351 if ( $name === 'Workbook' ) {
352 $this->mime
= 'application/vnd.ms-excel';
353 } elseif ( $name === 'WordDocument' ) {
354 $this->mime
= 'application/msword';
355 } elseif ( $name === 'PowerPoint Document' ) {
356 $this->mime
= 'application/vnd.ms-powerpoint';