includes/media/Exif.php

   1 <?php
   2 /**
   3  * Extraction and validation of image metadata.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @ingroup Media
  21  * @author Ævar Arnfjörð Bjarmason <avarab@gmail.com>
  22  * @copyright Copyright © 2005, Ævar Arnfjörð Bjarmason, 2009 Brent Garber
  23  * @license http://www.gnu.org/copyleft/gpl.html GNU General Public License
  24  * @see http://exif.org/Exif2-2.PDF The Exif 2.2 specification
  25  * @file
  26  */
  27
  28 /**
  29  * Class to extract and validate Exif data from jpeg (and possibly tiff) files.
  30  * @ingroup Media
  31  */
  32 class Exif {
  33
  34         const BYTE = 1; //!< An 8-bit (1-byte) unsigned integer.
  35         const ASCII = 2; //!< An 8-bit byte containing one 7-bit ASCII code. The final byte is terminated with NULL.
  36         const SHORT = 3; //!< A 16-bit (2-byte) unsigned integer.
  37         const LONG = 4; //!< A 32-bit (4-byte) unsigned integer.
  38         const RATIONAL = 5; //!< Two LONGs. The first LONG is the numerator and the second LONG expresses the denominator
  39         const SHORT_OR_LONG = 6; //!< A 16-bit (2-byte) or 32-bit (4-byte) unsigned integer.
  40         const UNDEFINED = 7; //!< An 8-bit byte that can take any value depending on the field definition
  41         const SLONG = 9; //!< A 32-bit (4-byte) signed integer (2's complement notation),
  42         const SRATIONAL = 10; //!< Two SLONGs. The first SLONG is the numerator and the second SLONG is the denominator.
  43         const IGNORE = -1; // A fake value for things we don't want or don't support.
  44
  45         //@{
  46         /* @var array
  47          * @private
  48          */
  49
  50         /**
  51          * Exif tags grouped by category, the tagname itself is the key and the type
  52          * is the value, in the case of more than one possible value type they are
  53          * separated by commas.
  54          */
  55         var $mExifTags;
  56
  57         /**
  58          * The raw Exif data returned by exif_read_data()
  59          */
  60         var $mRawExifData;
  61
  62         /**
  63          * A Filtered version of $mRawExifData that has been pruned of invalid
  64          * tags and tags that contain content they shouldn't contain according
  65          * to the Exif specification
  66          */
  67         var $mFilteredExifData;
  68
  69         /**
  70          * Filtered and formatted Exif data, see FormatMetadata::getFormattedData()
  71          */
  72         var $mFormattedExifData;
  73
  74         //@}
  75
  76         //@{
  77         /* @var string
  78          * @private
  79          */
  80
  81         /**
  82          * The file being processed
  83          */
  84         var $file;
  85
  86         /**
  87          * The basename of the file being processed
  88          */
  89         var $basename;
  90
  91         /**
  92          * The private log to log to, e.g. 'exif'
  93          */
  94         var $log = false;
  95
  96         /**
  97          * The byte order of the file. Needed because php's
  98          * extension doesn't fully process some obscure props.
  99          */
 100         private $byteOrder;
 101         //@}
 102
 103         /**
 104          * Constructor
 105          *
 106          * @param string $file filename.
 107          * @param string $byteOrder Type of byte ordering either 'BE' (Big Endian) or 'LE' (Little Endian). Default ''.
 108          * @throws MWException
 109          * @todo FIXME: The following are broke:
 110          * SubjectArea. Need to test the more obscure tags.
 111          *
 112          * DigitalZoomRatio = 0/0 is rejected. need to determine if that's valid.
 113          * possibly should treat 0/0 = 0. need to read exif spec on that.
 114          */
 115         function __construct( $file, $byteOrder = '' ) {
 116                 /**
 117                  * Page numbers here refer to pages in the EXIF 2.2 standard
 118                  *
 119                  * Note, Exif::UNDEFINED is treated as a string, not as an array of bytes
 120                  * so don't put a count parameter for any UNDEFINED values.
 121                  *
 122                  * @link http://exif.org/Exif2-2.PDF The Exif 2.2 specification
 123                  */
 124                 $this->mExifTags = array(
 125                         # TIFF Rev. 6.0 Attribute Information (p22)
 126                         'IFD0' => array(
 127                                 # Tags relating to image structure
 128                                 'ImageWidth' => Exif::SHORT_OR_LONG,            # Image width
 129                                 'ImageLength' => Exif::SHORT_OR_LONG,           # Image height
 130                                 'BitsPerSample' => array( Exif::SHORT, 3 ),             # Number of bits per component
 131                                 # "When a primary image is JPEG compressed, this designation is not"
 132                                 # "necessary and is omitted." (p23)
 133                                 'Compression' => Exif::SHORT,                           # Compression scheme #p23
 134                                 'PhotometricInterpretation' => Exif::SHORT,             # Pixel composition #p23
 135                                 'Orientation' => Exif::SHORT,                           # Orientation of image #p24
 136                                 'SamplesPerPixel' => Exif::SHORT,                       # Number of components
 137                                 'PlanarConfiguration' => Exif::SHORT,                   # Image data arrangement #p24
 138                                 'YCbCrSubSampling' => array( Exif::SHORT, 2 ),          # Subsampling ratio of Y to C #p24
 139                                 'YCbCrPositioning' => Exif::SHORT,                      # Y and C positioning #p24-25
 140                                 'XResolution' => Exif::RATIONAL,                        # Image resolution in width direction
 141                                 'YResolution' => Exif::RATIONAL,                        # Image resolution in height direction
 142                                 'ResolutionUnit' => Exif::SHORT,                        # Unit of X and Y resolution #(p26)
 143
 144                                 # Tags relating to recording offset
 145                                 'StripOffsets' => Exif::SHORT_OR_LONG,                  # Image data location
 146                                 'RowsPerStrip' => Exif::SHORT_OR_LONG,                  # Number of rows per strip
 147                                 'StripByteCounts' => Exif::SHORT_OR_LONG,               # Bytes per compressed strip
 148                                 'JPEGInterchangeFormat' => Exif::SHORT_OR_LONG,         # Offset to JPEG SOI
 149                                 'JPEGInterchangeFormatLength' => Exif::SHORT_OR_LONG,   # Bytes of JPEG data
 150
 151                                 # Tags relating to image data characteristics
 152                                 'TransferFunction' => Exif::IGNORE,                     # Transfer function
 153                                 'WhitePoint' => array( Exif::RATIONAL, 2 ),             # White point chromaticity
 154                                 'PrimaryChromaticities' => array( Exif::RATIONAL, 6 ),  # Chromaticities of primarities
 155                                 'YCbCrCoefficients' => array( Exif::RATIONAL, 3 ),      # Color space transformation matrix coefficients #p27
 156                                 'ReferenceBlackWhite' => array( Exif::RATIONAL, 6 ),    # Pair of black and white reference values
 157
 158                                 # Other tags
 159                                 'DateTime' => Exif::ASCII,                              # File change date and time
 160                                 'ImageDescription' => Exif::ASCII,                      # Image title
 161                                 'Make' => Exif::ASCII,                                  # Image input equipment manufacturer
 162                                 'Model' => Exif::ASCII,                                 # Image input equipment model
 163                                 'Software' => Exif::ASCII,                              # Software used
 164                                 'Artist' => Exif::ASCII,                                # Person who created the image
 165                                 'Copyright' => Exif::ASCII,                             # Copyright holder
 166                         ),
 167
 168                         # Exif IFD Attribute Information (p30-31)
 169                         'EXIF' => array(
 170                                 # TODO: NOTE: Nonexistence of this field is taken to mean nonconformance
 171                                 # to the EXIF 2.1 AND 2.2 standards
 172                                 'ExifVersion' => Exif::UNDEFINED,                       # Exif version
 173                                 'FlashPixVersion' => Exif::UNDEFINED,                   # Supported Flashpix version #p32
 174
 175                                 # Tags relating to Image Data Characteristics
 176                                 'ColorSpace' => Exif::SHORT,                            # Color space information #p32
 177
 178                                 # Tags relating to image configuration
 179                                 'ComponentsConfiguration' => Exif::UNDEFINED,                   # Meaning of each component #p33
 180                                 'CompressedBitsPerPixel' => Exif::RATIONAL,                     # Image compression mode
 181                                 'PixelYDimension' => Exif::SHORT_OR_LONG,               # Valid image width
 182                                 'PixelXDimension' => Exif::SHORT_OR_LONG,               # Valid image height
 183
 184                                 # Tags relating to related user information
 185                                 'MakerNote' => Exif::IGNORE,                            # Manufacturer notes
 186                                 'UserComment' => Exif::UNDEFINED,                       # User comments #p34
 187
 188                                 # Tags relating to related file information
 189                                 'RelatedSoundFile' => Exif::ASCII,                      # Related audio file
 190
 191                                 # Tags relating to date and time
 192                                 'DateTimeOriginal' => Exif::ASCII,                      # Date and time of original data generation #p36
 193                                 'DateTimeDigitized' => Exif::ASCII,                     # Date and time of original data generation
 194                                 'SubSecTime' => Exif::ASCII,                            # DateTime subseconds
 195                                 'SubSecTimeOriginal' => Exif::ASCII,                    # DateTimeOriginal subseconds
 196                                 'SubSecTimeDigitized' => Exif::ASCII,                   # DateTimeDigitized subseconds
 197
 198                                 # Tags relating to picture-taking conditions (p31)
 199                                 'ExposureTime' => Exif::RATIONAL,                       # Exposure time
 200                                 'FNumber' => Exif::RATIONAL,                            # F Number
 201                                 'ExposureProgram' => Exif::SHORT,                       # Exposure Program #p38
 202                                 'SpectralSensitivity' => Exif::ASCII,                   # Spectral sensitivity
 203                                 'ISOSpeedRatings' => Exif::SHORT,                       # ISO speed rating
 204                                 'OECF' => Exif::IGNORE,
 205                                 # Optoelectronic conversion factor. Note: We don't have support for this atm.
 206                                 'ShutterSpeedValue' => Exif::SRATIONAL,                 # Shutter speed
 207                                 'ApertureValue' => Exif::RATIONAL,                      # Aperture
 208                                 'BrightnessValue' => Exif::SRATIONAL,                   # Brightness
 209                                 'ExposureBiasValue' => Exif::SRATIONAL,                 # Exposure bias
 210                                 'MaxApertureValue' => Exif::RATIONAL,                   # Maximum land aperture
 211                                 'SubjectDistance' => Exif::RATIONAL,                    # Subject distance
 212                                 'MeteringMode' => Exif::SHORT,                          # Metering mode #p40
 213                                 'LightSource' => Exif::SHORT,                           # Light source #p40-41
 214                                 'Flash' => Exif::SHORT,                                 # Flash #p41-42
 215                                 'FocalLength' => Exif::RATIONAL,                        # Lens focal length
 216                                 'SubjectArea' => array( Exif::SHORT, 4 ),               # Subject area
 217                                 'FlashEnergy' => Exif::RATIONAL,                        # Flash energy
 218                                 'SpatialFrequencyResponse' => Exif::IGNORE,             # Spatial frequency response. Not supported atm.
 219                                 'FocalPlaneXResolution' => Exif::RATIONAL,              # Focal plane X resolution
 220                                 'FocalPlaneYResolution' => Exif::RATIONAL,              # Focal plane Y resolution
 221                                 'FocalPlaneResolutionUnit' => Exif::SHORT,              # Focal plane resolution unit #p46
 222                                 'SubjectLocation' => array( Exif::SHORT, 2 ),           # Subject location
 223                                 'ExposureIndex' => Exif::RATIONAL,                      # Exposure index
 224                                 'SensingMethod' => Exif::SHORT,                         # Sensing method #p46
 225                                 'FileSource' => Exif::UNDEFINED,                        # File source #p47
 226                                 'SceneType' => Exif::UNDEFINED,                         # Scene type #p47
 227                                 'CFAPattern' => Exif::IGNORE,                           # CFA pattern. not supported atm.
 228                                 'CustomRendered' => Exif::SHORT,                        # Custom image processing #p48
 229                                 'ExposureMode' => Exif::SHORT,                          # Exposure mode #p48
 230                                 'WhiteBalance' => Exif::SHORT,                          # White Balance #p49
 231                                 'DigitalZoomRatio' => Exif::RATIONAL,                   # Digital zoom ration
 232                                 'FocalLengthIn35mmFilm' => Exif::SHORT,                 # Focal length in 35 mm film
 233                                 'SceneCaptureType' => Exif::SHORT,                      # Scene capture type #p49
 234                                 'GainControl' => Exif::SHORT,                           # Scene control #p49-50
 235                                 'Contrast' => Exif::SHORT,                              # Contrast #p50
 236                                 'Saturation' => Exif::SHORT,                            # Saturation #p50
 237                                 'Sharpness' => Exif::SHORT,                             # Sharpness #p50
 238                                 'DeviceSettingDescription' => Exif::IGNORE,
 239                                 # Device settings description. This could maybe be supported. Need to find an
 240                                 # example file that uses this to see if it has stuff of interest in it.
 241                                 'SubjectDistanceRange' => Exif::SHORT,                  # Subject distance range #p51
 242
 243                                 'ImageUniqueID' => Exif::ASCII,                         # Unique image ID
 244                         ),
 245
 246                         # GPS Attribute Information (p52)
 247                         'GPS' => array(
 248                                 'GPSVersion' => Exif::UNDEFINED,
 249                                 # Should be an array of 4 Exif::BYTE's. However php treats it as an undefined
 250                                 # Note exif standard calls this GPSVersionID, but php doesn't like the id suffix
 251                                 'GPSLatitudeRef' => Exif::ASCII,                        # North or South Latitude #p52-53
 252                                 'GPSLatitude' => array( Exif::RATIONAL, 3 ),            # Latitude
 253                                 'GPSLongitudeRef' => Exif::ASCII,                       # East or West Longitude #p53
 254                                 'GPSLongitude' => array( Exif::RATIONAL, 3 ),           # Longitude
 255                                 'GPSAltitudeRef' => Exif::UNDEFINED,
 256                                 # Altitude reference. Note, the exif standard says this should be an EXIF::Byte,
 257                                 # but php seems to disagree.
 258                                 'GPSAltitude' => Exif::RATIONAL,                        # Altitude
 259                                 'GPSTimeStamp' => array( Exif::RATIONAL, 3 ),           # GPS time (atomic clock)
 260                                 'GPSSatellites' => Exif::ASCII,                         # Satellites used for measurement
 261                                 'GPSStatus' => Exif::ASCII,                             # Receiver status #p54
 262                                 'GPSMeasureMode' => Exif::ASCII,                        # Measurement mode #p54-55
 263                                 'GPSDOP' => Exif::RATIONAL,                             # Measurement precision
 264                                 'GPSSpeedRef' => Exif::ASCII,                           # Speed unit #p55
 265                                 'GPSSpeed' => Exif::RATIONAL,                           # Speed of GPS receiver
 266                                 'GPSTrackRef' => Exif::ASCII,                           # Reference for direction of movement #p55
 267                                 'GPSTrack' => Exif::RATIONAL,                           # Direction of movement
 268                                 'GPSImgDirectionRef' => Exif::ASCII,                    # Reference for direction of image #p56
 269                                 'GPSImgDirection' => Exif::RATIONAL,                    # Direction of image
 270                                 'GPSMapDatum' => Exif::ASCII,                           # Geodetic survey data used
 271                                 'GPSDestLatitudeRef' => Exif::ASCII,                    # Reference for latitude of destination #p56
 272                                 'GPSDestLatitude' => array( Exif::RATIONAL, 3 ),        # Latitude destination
 273                                 'GPSDestLongitudeRef' => Exif::ASCII,                   # Reference for longitude of destination #p57
 274                                 'GPSDestLongitude' => array( Exif::RATIONAL, 3 ),       # Longitude of destination
 275                                 'GPSDestBearingRef' => Exif::ASCII,                     # Reference for bearing of destination #p57
 276                                 'GPSDestBearing' => Exif::RATIONAL,                     # Bearing of destination
 277                                 'GPSDestDistanceRef' => Exif::ASCII,                    # Reference for distance to destination #p57-58
 278                                 'GPSDestDistance' => Exif::RATIONAL,                    # Distance to destination
 279                                 'GPSProcessingMethod' => Exif::UNDEFINED,               # Name of GPS processing method
 280                                 'GPSAreaInformation' => Exif::UNDEFINED,                # Name of GPS area
 281                                 'GPSDateStamp' => Exif::ASCII,                          # GPS date
 282                                 'GPSDifferential' => Exif::SHORT,                       # GPS differential correction
 283                         ),
 284                 );
 285
 286                 $this->file = $file;
 287                 $this->basename = wfBaseName( $this->file );
 288                 if ( $byteOrder === 'BE' || $byteOrder === 'LE' ) {
 289                         $this->byteOrder = $byteOrder;
 290                 } else {
 291                         // Only give a warning for b/c, since originally we didn't
 292                         // require this. The number of things affected by this is
 293                         // rather small.
 294                         wfWarn( 'Exif class did not have byte order specified. ' .
 295                                 'Some properties may be decoded incorrectly.' );
 296                         $this->byteOrder = 'BE'; // BE seems about twice as popular as LE in jpg's.
 297                 }
 298
 299                 $this->debugFile( $this->basename, __FUNCTION__, true );
 300                 if( function_exists( 'exif_read_data' ) ) {
 301                         wfSuppressWarnings();
 302                         $data = exif_read_data( $this->file, 0, true );
 303                         wfRestoreWarnings();
 304                 } else {
 305                         throw new MWException( "Internal error: exif_read_data not present. \$wgShowEXIF may be incorrectly set or not checked by an extension." );
 306                 }
 307                 /**
 308                  * exif_read_data() will return false on invalid input, such as
 309                  * when somebody uploads a file called something.jpeg
 310                  * containing random gibberish.
 311                  */
 312                 $this->mRawExifData = $data ? $data : array();
 313                 $this->makeFilteredData();
 314                 $this->collapseData();
 315                 $this->debugFile( __FUNCTION__, false );
 316         }
 317
 318         /**
 319          * Make $this->mFilteredExifData
 320          */
 321         function makeFilteredData() {
 322                 $this->mFilteredExifData = Array();
 323
 324                 foreach ( array_keys( $this->mRawExifData ) as $section ) {
 325                         if ( !in_array( $section, array_keys( $this->mExifTags ) ) ) {
 326                                 $this->debug( $section, __FUNCTION__, "'$section' is not a valid Exif section" );
 327                                 continue;
 328                         }
 329
 330                         foreach ( array_keys( $this->mRawExifData[$section] ) as $tag ) {
 331                                 if ( !in_array( $tag, array_keys( $this->mExifTags[$section] ) ) ) {
 332                                         $this->debug( $tag, __FUNCTION__, "'$tag' is not a valid tag in '$section'" );
 333                                         continue;
 334                                 }
 335
 336                                 $this->mFilteredExifData[$tag] = $this->mRawExifData[$section][$tag];
 337                                 // This is ok, as the tags in the different sections do not conflict.
 338                                 // except in computed and thumbnail section, which we don't use.
 339
 340                                 $value = $this->mRawExifData[$section][$tag];
 341                                 if ( !$this->validate( $section, $tag, $value ) ) {
 342                                         $this->debug( $value, __FUNCTION__, "'$tag' contained invalid data" );
 343                                         unset( $this->mFilteredExifData[$tag] );
 344                                 }
 345                         }
 346                 }
 347         }
 348
 349         /**
 350          * Collapse some fields together.
 351          * This converts some fields from exif form, to a more friendly form.
 352          * For example GPS latitude to a single number.
 353          *
 354          * The rationale behind this is that we're storing data, not presenting to the user
 355          * For example a longitude is a single number describing how far away you are from
 356          * the prime meridian. Well it might be nice to split it up into minutes and seconds
 357          * for the user, it doesn't really make sense to split a single number into 4 parts
 358          * for storage. (degrees, minutes, second, direction vs single floating point number).
 359          *
 360          * Other things this might do (not really sure if they make sense or not):
 361          * Dates -> mediawiki date format.
 362          * convert values that can be in different units to be in one standardized unit.
 363          *
 364          * As an alternative approach, some of this could be done in the validate phase
 365          * if we make up our own types like Exif::DATE.
 366          */
 367         function collapseData() {
 368
 369                 $this->exifGPStoNumber( 'GPSLatitude' );
 370                 $this->exifGPStoNumber( 'GPSDestLatitude' );
 371                 $this->exifGPStoNumber( 'GPSLongitude' );
 372                 $this->exifGPStoNumber( 'GPSDestLongitude' );
 373
 374                 if ( isset( $this->mFilteredExifData['GPSAltitude'] ) && isset( $this->mFilteredExifData['GPSAltitudeRef'] ) ) {
 375
 376                         // We know altitude data is a <num>/<denom> from the validation functions ran earlier.
 377                         // But multiplying such a string by -1 doesn't work well, so convert.
 378                         list( $num, $denom ) = explode( '/', $this->mFilteredExifData['GPSAltitude'] );
 379                         $this->mFilteredExifData['GPSAltitude'] = $num / $denom;
 380
 381                         if ( $this->mFilteredExifData['GPSAltitudeRef'] === "\1" ) {
 382                                 $this->mFilteredExifData['GPSAltitude'] *= - 1;
 383                         }
 384                         unset( $this->mFilteredExifData['GPSAltitudeRef'] );
 385                 }
 386
 387                 $this->exifPropToOrd( 'FileSource' );
 388                 $this->exifPropToOrd( 'SceneType' );
 389
 390                 $this->charCodeString( 'UserComment' );
 391                 $this->charCodeString( 'GPSProcessingMethod' );
 392                 $this->charCodeString( 'GPSAreaInformation' );
 393
 394                 //ComponentsConfiguration should really be an array instead of a string...
 395                 //This turns a string of binary numbers into an array of numbers.
 396
 397                 if ( isset ( $this->mFilteredExifData['ComponentsConfiguration'] ) ) {
 398                         $val = $this->mFilteredExifData['ComponentsConfiguration'];
 399                         $ccVals = array();
 400                         for ( $i = 0; $i < strlen( $val ); $i++ ) {
 401                                 $ccVals[$i] = ord( substr( $val, $i, 1 ) );
 402                         }
 403                         $ccVals['_type'] = 'ol'; //this is for formatting later.
 404                         $this->mFilteredExifData['ComponentsConfiguration'] = $ccVals;
 405                 }
 406
 407                 //GPSVersion(ID) is treated as the wrong type by php exif support.
 408                 //Go through each byte turning it into a version string.
 409                 //For example: "\x02\x02\x00\x00" -> "2.2.0.0"
 410
 411                 //Also change exif tag name from GPSVersion (what php exif thinks it is)
 412                 //to GPSVersionID (what the exif standard thinks it is).
 413
 414                 if ( isset ( $this->mFilteredExifData['GPSVersion'] ) ) {
 415                         $val = $this->mFilteredExifData['GPSVersion'];
 416                         $newVal = '';
 417                         for ( $i = 0; $i < strlen( $val ); $i++ ) {
 418                                 if ( $i !== 0 ) {
 419                                         $newVal .= '.';
 420                                 }
 421                                 $newVal .= ord( substr( $val, $i, 1 ) );
 422                         }
 423                         if ( $this->byteOrder === 'LE' ) {
 424                                 // Need to reverse the string
 425                                 $newVal2 = '';
 426                                 for ( $i = strlen( $newVal ) - 1; $i >= 0; $i-- ) {
 427                                         $newVal2 .= substr( $newVal, $i, 1 );
 428                                 }
 429                                 $this->mFilteredExifData['GPSVersionID'] = $newVal2;
 430                         } else {
 431                                 $this->mFilteredExifData['GPSVersionID'] = $newVal;
 432                         }
 433                         unset( $this->mFilteredExifData['GPSVersion'] );
 434                 }
 435
 436         }
 437         /**
 438          * Do userComment tags and similar. See pg. 34 of exif standard.
 439          * basically first 8 bytes is charset, rest is value.
 440          * This has not been tested on any shift-JIS strings.
 441          * @param string $prop prop name.
 442          */
 443         private function charCodeString( $prop ) {
 444                 if ( isset( $this->mFilteredExifData[$prop] ) ) {
 445
 446                         if ( strlen( $this->mFilteredExifData[$prop] ) <= 8 ) {
 447                                 //invalid. Must be at least 9 bytes long.
 448
 449                                 $this->debug( $this->mFilteredExifData[$prop], __FUNCTION__, false );
 450                                 unset( $this->mFilteredExifData[$prop] );
 451                                 return;
 452                         }
 453                         $charCode = substr( $this->mFilteredExifData[$prop], 0, 8 );
 454                         $val = substr( $this->mFilteredExifData[$prop], 8 );
 455
 456                         switch ( $charCode ) {
 457                                 case "\x4A\x49\x53\x00\x00\x00\x00\x00":
 458                                         //JIS
 459                                         $charset = "Shift-JIS";
 460                                         break;
 461                                 case "UNICODE\x00":
 462                                         $charset = "UTF-16" . $this->byteOrder;
 463                                         break;
 464                                 default: //ascii or undefined.
 465                                         $charset = "";
 466                                         break;
 467                         }
 468                         // This could possibly check to see if iconv is really installed
 469                         // or if we're using the compatibility wrapper in globalFunctions.php
 470                         if ( $charset ) {
 471                                 wfSuppressWarnings();
 472                                 $val = iconv( $charset, 'UTF-8//IGNORE', $val );
 473                                 wfRestoreWarnings();
 474                         } else {
 475                                 // if valid utf-8, assume that, otherwise assume windows-1252
 476                                 $valCopy = $val;
 477                                 UtfNormal::quickIsNFCVerify( $valCopy ); //validates $valCopy.
 478                                 if ( $valCopy !== $val ) {
 479                                         wfSuppressWarnings();
 480                                         $val = iconv( 'Windows-1252', 'UTF-8//IGNORE', $val );
 481                                         wfRestoreWarnings();
 482                                 }
 483                         }
 484
 485                         //trim and check to make sure not only whitespace.
 486                         $val = trim( $val );
 487                         if ( strlen( $val ) === 0 ) {
 488                                 //only whitespace.
 489                                 $this->debug( $this->mFilteredExifData[$prop], __FUNCTION__, "$prop: Is only whitespace" );
 490                                 unset( $this->mFilteredExifData[$prop] );
 491                                 return;
 492                         }
 493
 494                         //all's good.
 495                         $this->mFilteredExifData[$prop] = $val;
 496                 }
 497         }
 498         /**
 499          * Convert an Exif::UNDEFINED from a raw binary string
 500          * to its value. This is sometimes needed depending on
 501          * the type of UNDEFINED field
 502          * @param string $prop name of property
 503          */
 504         private function exifPropToOrd( $prop ) {
 505                 if ( isset( $this->mFilteredExifData[$prop] ) ) {
 506                         $this->mFilteredExifData[$prop] = ord( $this->mFilteredExifData[$prop] );
 507                 }
 508         }
 509         /**
 510          * Convert gps in exif form to a single floating point number
 511          * for example 10 degress 20`40`` S -> -10.34444
 512          * @param string $prop a gps coordinate exif tag name (like GPSLongitude)
 513          */
 514         private function exifGPStoNumber( $prop ) {
 515                 $loc =& $this->mFilteredExifData[$prop];
 516                 $dir =& $this->mFilteredExifData[$prop . 'Ref'];
 517                 $res = false;
 518
 519                 if ( isset( $loc ) && isset( $dir ) && ( $dir === 'N' || $dir === 'S' || $dir === 'E' || $dir === 'W' ) ) {
 520                         list( $num, $denom ) = explode( '/', $loc[0] );
 521                         $res = $num / $denom;
 522                         list( $num, $denom ) = explode( '/', $loc[1] );
 523                         $res += ( $num / $denom ) * ( 1 / 60 );
 524                         list( $num, $denom ) = explode( '/', $loc[2] );
 525                         $res += ( $num / $denom ) * ( 1 / 3600 );
 526
 527                         if ( $dir === 'S' || $dir === 'W' ) {
 528                                 $res *= - 1; // make negative
 529                         }
 530                 }
 531
 532                 // update the exif records.
 533
 534                 if ( $res !== false ) { // using !== as $res could potentially be 0
 535                         $this->mFilteredExifData[$prop] = $res;
 536                         unset( $this->mFilteredExifData[$prop . 'Ref'] );
 537                 } else { // if invalid
 538                         unset( $this->mFilteredExifData[$prop] );
 539                         unset( $this->mFilteredExifData[$prop . 'Ref'] );
 540                 }
 541         }
 542
 543         /**
 544          * Use FormatMetadata to create formatted values for display to user
 545          * (is this ever used?)
 546          *
 547          * @deprecated since 1.18
 548          */
 549         function makeFormattedData() {
 550                 wfDeprecated( __METHOD__, '1.18' );
 551                 $this->mFormattedExifData = FormatMetadata::getFormattedData(
 552                         $this->mFilteredExifData );
 553         }
 554         /**#@-*/
 555
 556         /**#@+
 557          * @return array
 558          */
 559         /**
 560          * Get $this->mRawExifData
 561          * @return array
 562          */
 563         function getData() {
 564                 return $this->mRawExifData;
 565         }
 566
 567         /**
 568          * Get $this->mFilteredExifData
 569          */
 570         function getFilteredData() {
 571                 return $this->mFilteredExifData;
 572         }
 573
 574         /**
 575          * Get $this->mFormattedExifData
 576          *
 577          * This returns the data for display to user.
 578          * Its unclear if this is ever used.
 579          *
 580          * @deprecated since 1.18
 581          */
 582         function getFormattedData() {
 583                 wfDeprecated( __METHOD__, '1.18' );
 584                 if ( !$this->mFormattedExifData ) {
 585                         $this->makeFormattedData();
 586                 }
 587                 return $this->mFormattedExifData;
 588         }
 589         /**#@-*/
 590
 591         /**
 592          * The version of the output format
 593          *
 594          * Before the actual metadata information is saved in the database we
 595          * strip some of it since we don't want to save things like thumbnails
 596          * which usually accompany Exif data. This value gets saved in the
 597          * database along with the actual Exif data, and if the version in the
 598          * database doesn't equal the value returned by this function the Exif
 599          * data is regenerated.
 600          *
 601          * @return int
 602          */
 603         public static function version() {
 604                 return 2; // We don't need no bloddy constants!
 605         }
 606
 607         /**#@+
 608          * Validates if a tag value is of the type it should be according to the Exif spec
 609          *
 610          * @private
 611          *
 612          * @param $in Mixed: the input value to check
 613          * @return bool
 614          */
 615         private function isByte( $in ) {
 616                 if ( !is_array( $in ) && sprintf( '%d', $in ) == $in && $in >= 0 && $in <= 255 ) {
 617                         $this->debug( $in, __FUNCTION__, true );
 618                         return true;
 619                 } else {
 620                         $this->debug( $in, __FUNCTION__, false );
 621                         return false;
 622                 }
 623         }
 624
 625         /**
 626          * @param $in
 627          * @return bool
 628          */
 629         private function isASCII( $in ) {
 630                 if ( is_array( $in ) ) {
 631                         return false;
 632                 }
 633
 634                 if ( preg_match( "/[^\x0a\x20-\x7e]/", $in ) ) {
 635                         $this->debug( $in, __FUNCTION__, 'found a character not in our whitelist' );
 636                         return false;
 637                 }
 638
 639                 if ( preg_match( '/^\s*$/', $in ) ) {
 640                         $this->debug( $in, __FUNCTION__, 'input consisted solely of whitespace' );
 641                         return false;
 642                 }
 643
 644                 return true;
 645         }
 646
 647         /**
 648          * @param $in
 649          * @return bool
 650          */
 651         private function isShort( $in ) {
 652                 if ( !is_array( $in ) && sprintf( '%d', $in ) == $in && $in >= 0 && $in <= 65536 ) {
 653                         $this->debug( $in, __FUNCTION__, true );
 654                         return true;
 655                 } else {
 656                         $this->debug( $in, __FUNCTION__, false );
 657                         return false;
 658                 }
 659         }
 660
 661         /**
 662          * @param $in
 663          * @return bool
 664          */
 665         private function isLong( $in ) {
 666                 if ( !is_array( $in ) && sprintf( '%d', $in ) == $in && $in >= 0 && $in <= 4294967296 ) {
 667                         $this->debug( $in, __FUNCTION__, true );
 668                         return true;
 669                 } else {
 670                         $this->debug( $in, __FUNCTION__, false );
 671                         return false;
 672                 }
 673         }
 674
 675         /**
 676          * @param $in
 677          * @return bool
 678          */
 679         private function isRational( $in ) {
 680                 $m = array();
 681                 if ( !is_array( $in ) && preg_match( '/^(\d+)\/(\d+[1-9]|[1-9]\d*)$/', $in, $m ) ) { # Avoid division by zero
 682                         return $this->isLong( $m[1] ) && $this->isLong( $m[2] );
 683                 } else {
 684                         $this->debug( $in, __FUNCTION__, 'fed a non-fraction value' );
 685                         return false;
 686                 }
 687         }
 688
 689         /**
 690          * @param $in
 691          * @return bool
 692          */
 693         private function isUndefined( $in ) {
 694                 $this->debug( $in, __FUNCTION__, true );
 695                 return true;
 696         }
 697
 698         /**
 699          * @param $in
 700          * @return bool
 701          */
 702         private function isSlong( $in ) {
 703                 if ( $this->isLong( abs( $in ) ) ) {
 704                         $this->debug( $in, __FUNCTION__, true );
 705                         return true;
 706                 } else {
 707                         $this->debug( $in, __FUNCTION__, false );
 708                         return false;
 709                 }
 710         }
 711
 712         /**
 713          * @param $in
 714          * @return bool
 715          */
 716         private function isSrational( $in ) {
 717                 $m = array();
 718                 if ( !is_array( $in ) && preg_match( '/^(-?\d+)\/(\d+[1-9]|[1-9]\d*)$/', $in, $m ) ) { # Avoid division by zero
 719                         return $this->isSlong( $m[0] ) && $this->isSlong( $m[1] );
 720                 } else {
 721                         $this->debug( $in, __FUNCTION__, 'fed a non-fraction value' );
 722                         return false;
 723                 }
 724         }
 725         /**#@-*/
 726
 727         /**
 728          * Validates if a tag has a legal value according to the Exif spec
 729          *
 730          * @private
 731          * @param string $section section where tag is located.
 732          * @param string $tag the tag to check.
 733          * @param $val Mixed: the value of the tag.
 734          * @param $recursive Boolean: true if called recursively for array types.
 735          * @return bool
 736          */
 737         private function validate( $section, $tag, $val, $recursive = false ) {
 738                 $debug = "tag is '$tag'";
 739                 $etype = $this->mExifTags[$section][$tag];
 740                 $ecount = 1;
 741                 if( is_array( $etype ) ) {
 742                         list( $etype, $ecount ) = $etype;
 743                         if ( $recursive )
 744                                 $ecount = 1; // checking individual elements
 745                 }
 746                 $count = count( $val );
 747                 if( $ecount != $count ) {
 748                         $this->debug( $val, __FUNCTION__, "Expected $ecount elements for $tag but got $count" );
 749                         return false;
 750                 }
 751                 if( $count > 1 ) {
 752                         foreach( $val as $v ) {
 753                                 if( !$this->validate( $section, $tag, $v, true ) ) {
 754                                         return false;
 755                                 }
 756                         }
 757                         return true;
 758                 }
 759                 // Does not work if not typecast
 760                 switch( (string)$etype ) {
 761                         case (string)Exif::BYTE:
 762                                 $this->debug( $val, __FUNCTION__, $debug );
 763                                 return $this->isByte( $val );
 764                         case (string)Exif::ASCII:
 765                                 $this->debug( $val, __FUNCTION__, $debug );
 766                                 return $this->isASCII( $val );
 767                         case (string)Exif::SHORT:
 768                                 $this->debug( $val, __FUNCTION__, $debug );
 769                                 return $this->isShort( $val );
 770                         case (string)Exif::LONG:
 771                                 $this->debug( $val, __FUNCTION__, $debug );
 772                                 return $this->isLong( $val );
 773                         case (string)Exif::RATIONAL:
 774                                 $this->debug( $val, __FUNCTION__, $debug );
 775                                 return $this->isRational( $val );
 776                         case (string)Exif::SHORT_OR_LONG:
 777                                 $this->debug( $val, __FUNCTION__, $debug );
 778                                 return $this->isShort( $val ) || $this->isLong( $val );
 779                         case (string)Exif::UNDEFINED:
 780                                 $this->debug( $val, __FUNCTION__, $debug );
 781                                 return $this->isUndefined( $val );
 782                         case (string)Exif::SLONG:
 783                                 $this->debug( $val, __FUNCTION__, $debug );
 784                                 return $this->isSlong( $val );
 785                         case (string)Exif::SRATIONAL:
 786                                 $this->debug( $val, __FUNCTION__, $debug );
 787                                 return $this->isSrational( $val );
 788                         case (string)Exif::IGNORE:
 789                                 $this->debug( $val, __FUNCTION__, $debug );
 790                                 return false;
 791                         default:
 792                                 $this->debug( $val, __FUNCTION__, "The tag '$tag' is unknown" );
 793                                 return false;
 794                 }
 795         }
 796
 797         /**
 798          * Convenience function for debugging output
 799          *
 800          * @private
 801          *
 802          * @param $in Mixed:
 803          * @param $fname String:
 804          * @param $action Mixed: , default NULL.
 805          */
 806         private function debug( $in, $fname, $action = null ) {
 807                 if ( !$this->log ) {
 808                         return;
 809                 }
 810                 $type = gettype( $in );
 811                 $class = ucfirst( __CLASS__ );
 812                 if ( is_array( $in ) ) {
 813                         $in = print_r( $in, true );
 814                 }
 815
 816                 if ( $action === true ) {
 817                         wfDebugLog( $this->log, "$class::$fname: accepted: '$in' (type: $type)\n" );
 818                 } elseif ( $action === false ) {
 819                         wfDebugLog( $this->log, "$class::$fname: rejected: '$in' (type: $type)\n" );
 820                 } elseif ( $action === null ) {
 821                         wfDebugLog( $this->log, "$class::$fname: input was: '$in' (type: $type)\n" );
 822                 } else {
 823                         wfDebugLog( $this->log, "$class::$fname: $action (type: $type; content: '$in')\n" );
 824                 }
 825         }
 826
 827         /**
 828          * Convenience function for debugging output
 829          *
 830          * @private
 831          *
 832          * @param string $fname the name of the function calling this function
 833          * @param $io Boolean: Specify whether we're beginning or ending
 834          */
 835         private function debugFile( $fname, $io ) {
 836                 if ( !$this->log ) {
 837                         return;
 838                 }
 839                 $class = ucfirst( __CLASS__ );
 840                 if ( $io ) {
 841                         wfDebugLog( $this->log, "$class::$fname: begin processing: '{$this->basename}'\n" );
 842                 } else {
 843                         wfDebugLog( $this->log, "$class::$fname: end processing: '{$this->basename}'\n" );
 844                 }
 845         }
 846 }