Exif.php

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<?php
class Exif {
    const BYTE = 1;
 
    const ASCII = 2;
 
    const SHORT = 3;
 
    const LONG = 4;
 
    const RATIONAL = 5;
 
    const SHORT_OR_LONG = 6;
 
    const UNDEFINED = 7;
 
    const SLONG = 9;
 
    const SRATIONAL = 10;
 
    const IGNORE = -1;
 
    private $mExifTags;
 
    private $mRawExifData;
 
    private $mFilteredExifData;
 
    private $file;
 
    private $basename;
 
    private $log = false;
 
    private $byteOrder;
 
    function __construct( $file, $byteOrder = '' ) {
        $this->mExifTags = array(
            # TIFF Rev. 6.0 Attribute Information (p22)
            'IFD0' => array(
                # Tags relating to image structure
                'ImageWidth' => Exif::SHORT_OR_LONG, # Image width
                'ImageLength' => Exif::SHORT_OR_LONG, # Image height
                'BitsPerSample' => array( Exif::SHORT, 3 ), # Number of bits per component
                # "When a primary image is JPEG compressed, this designation is not"
                # "necessary and is omitted." (p23)
                'Compression' => Exif::SHORT, # Compression scheme #p23
                'PhotometricInterpretation' => Exif::SHORT, # Pixel composition #p23
                'Orientation' => Exif::SHORT, # Orientation of image #p24
                'SamplesPerPixel' => Exif::SHORT, # Number of components
                'PlanarConfiguration' => Exif::SHORT, # Image data arrangement #p24
                'YCbCrSubSampling' => array( Exif::SHORT, 2 ), # Subsampling ratio of Y to C #p24
                'YCbCrPositioning' => Exif::SHORT, # Y and C positioning #p24-25
                'XResolution' => Exif::RATIONAL, # Image resolution in width direction
                'YResolution' => Exif::RATIONAL, # Image resolution in height direction
                'ResolutionUnit' => Exif::SHORT, # Unit of X and Y resolution #(p26)
 
                # Tags relating to recording offset
                'StripOffsets' => Exif::SHORT_OR_LONG, # Image data location
                'RowsPerStrip' => Exif::SHORT_OR_LONG, # Number of rows per strip
                'StripByteCounts' => Exif::SHORT_OR_LONG, # Bytes per compressed strip
                'JPEGInterchangeFormat' => Exif::SHORT_OR_LONG, # Offset to JPEG SOI
                'JPEGInterchangeFormatLength' => Exif::SHORT_OR_LONG, # Bytes of JPEG data
 
                # Tags relating to image data characteristics
                'TransferFunction' => Exif::IGNORE, # Transfer function
                'WhitePoint' => array( Exif::RATIONAL, 2 ), # White point chromaticity
                'PrimaryChromaticities' => array( Exif::RATIONAL, 6 ), # Chromaticities of primarities
                # Color space transformation matrix coefficients #p27
                'YCbCrCoefficients' => array( Exif::RATIONAL, 3 ),
                'ReferenceBlackWhite' => array( Exif::RATIONAL, 6 ), # Pair of black and white reference values
 
                # Other tags
                'DateTime' => Exif::ASCII, # File change date and time
                'ImageDescription' => Exif::ASCII, # Image title
                'Make' => Exif::ASCII, # Image input equipment manufacturer
                'Model' => Exif::ASCII, # Image input equipment model
                'Software' => Exif::ASCII, # Software used
                'Artist' => Exif::ASCII, # Person who created the image
                'Copyright' => Exif::ASCII, # Copyright holder
            ),
 
            # Exif IFD Attribute Information (p30-31)
            'EXIF' => array(
                # @todo NOTE: Nonexistence of this field is taken to mean nonconformance
                # to the Exif 2.1 AND 2.2 standards
                'ExifVersion' => Exif::UNDEFINED, # Exif version
                'FlashPixVersion' => Exif::UNDEFINED, # Supported Flashpix version #p32
 
                # Tags relating to Image Data Characteristics
                'ColorSpace' => Exif::SHORT, # Color space information #p32
 
                # Tags relating to image configuration
                'ComponentsConfiguration' => Exif::UNDEFINED, # Meaning of each component #p33
                'CompressedBitsPerPixel' => Exif::RATIONAL, # Image compression mode
                'PixelYDimension' => Exif::SHORT_OR_LONG, # Valid image width
                'PixelXDimension' => Exif::SHORT_OR_LONG, # Valid image height
 
                # Tags relating to related user information
                'MakerNote' => Exif::IGNORE, # Manufacturer notes
                'UserComment' => Exif::UNDEFINED, # User comments #p34
 
                # Tags relating to related file information
                'RelatedSoundFile' => Exif::ASCII, # Related audio file
 
                # Tags relating to date and time
                'DateTimeOriginal' => Exif::ASCII, # Date and time of original data generation #p36
                'DateTimeDigitized' => Exif::ASCII, # Date and time of original data generation
                'SubSecTime' => Exif::ASCII, # DateTime subseconds
                'SubSecTimeOriginal' => Exif::ASCII, # DateTimeOriginal subseconds
                'SubSecTimeDigitized' => Exif::ASCII, # DateTimeDigitized subseconds
 
                # Tags relating to picture-taking conditions (p31)
                'ExposureTime' => Exif::RATIONAL, # Exposure time
                'FNumber' => Exif::RATIONAL, # F Number
                'ExposureProgram' => Exif::SHORT, # Exposure Program #p38
                'SpectralSensitivity' => Exif::ASCII, # Spectral sensitivity
                'ISOSpeedRatings' => Exif::SHORT, # ISO speed rating
                'OECF' => Exif::IGNORE,
                # Optoelectronic conversion factor. Note: We don't have support for this atm.
                'ShutterSpeedValue' => Exif::SRATIONAL, # Shutter speed
                'ApertureValue' => Exif::RATIONAL, # Aperture
                'BrightnessValue' => Exif::SRATIONAL, # Brightness
                'ExposureBiasValue' => Exif::SRATIONAL, # Exposure bias
                'MaxApertureValue' => Exif::RATIONAL, # Maximum land aperture
                'SubjectDistance' => Exif::RATIONAL, # Subject distance
                'MeteringMode' => Exif::SHORT, # Metering mode #p40
                'LightSource' => Exif::SHORT, # Light source #p40-41
                'Flash' => Exif::SHORT, # Flash #p41-42
                'FocalLength' => Exif::RATIONAL, # Lens focal length
                'SubjectArea' => array( Exif::SHORT, 4 ), # Subject area
                'FlashEnergy' => Exif::RATIONAL, # Flash energy
                'SpatialFrequencyResponse' => Exif::IGNORE, # Spatial frequency response. Not supported atm.
                'FocalPlaneXResolution' => Exif::RATIONAL, # Focal plane X resolution
                'FocalPlaneYResolution' => Exif::RATIONAL, # Focal plane Y resolution
                'FocalPlaneResolutionUnit' => Exif::SHORT, # Focal plane resolution unit #p46
                'SubjectLocation' => array( Exif::SHORT, 2 ), # Subject location
                'ExposureIndex' => Exif::RATIONAL, # Exposure index
                'SensingMethod' => Exif::SHORT, # Sensing method #p46
                'FileSource' => Exif::UNDEFINED, # File source #p47
                'SceneType' => Exif::UNDEFINED, # Scene type #p47
                'CFAPattern' => Exif::IGNORE, # CFA pattern. not supported atm.
                'CustomRendered' => Exif::SHORT, # Custom image processing #p48
                'ExposureMode' => Exif::SHORT, # Exposure mode #p48
                'WhiteBalance' => Exif::SHORT, # White Balance #p49
                'DigitalZoomRatio' => Exif::RATIONAL, # Digital zoom ration
                'FocalLengthIn35mmFilm' => Exif::SHORT, # Focal length in 35 mm film
                'SceneCaptureType' => Exif::SHORT, # Scene capture type #p49
                'GainControl' => Exif::SHORT, # Scene control #p49-50
                'Contrast' => Exif::SHORT, # Contrast #p50
                'Saturation' => Exif::SHORT, # Saturation #p50
                'Sharpness' => Exif::SHORT, # Sharpness #p50
                'DeviceSettingDescription' => Exif::IGNORE,
                # Device settings description. This could maybe be supported. Need to find an
                # example file that uses this to see if it has stuff of interest in it.
                'SubjectDistanceRange' => Exif::SHORT, # Subject distance range #p51
 
                'ImageUniqueID' => Exif::ASCII, # Unique image ID
            ),
 
            # GPS Attribute Information (p52)
            'GPS' => array(
                'GPSVersion' => Exif::UNDEFINED,
                # Should be an array of 4 Exif::BYTE's. However php treats it as an undefined
                # Note exif standard calls this GPSVersionID, but php doesn't like the id suffix
                'GPSLatitudeRef' => Exif::ASCII, # North or South Latitude #p52-53
                'GPSLatitude' => array( Exif::RATIONAL, 3 ), # Latitude
                'GPSLongitudeRef' => Exif::ASCII, # East or West Longitude #p53
                'GPSLongitude' => array( Exif::RATIONAL, 3 ), # Longitude
                'GPSAltitudeRef' => Exif::UNDEFINED,
                # Altitude reference. Note, the exif standard says this should be an EXIF::Byte,
                # but php seems to disagree.
                'GPSAltitude' => Exif::RATIONAL, # Altitude
                'GPSTimeStamp' => array( Exif::RATIONAL, 3 ), # GPS time (atomic clock)
                'GPSSatellites' => Exif::ASCII, # Satellites used for measurement
                'GPSStatus' => Exif::ASCII, # Receiver status #p54
                'GPSMeasureMode' => Exif::ASCII, # Measurement mode #p54-55
                'GPSDOP' => Exif::RATIONAL, # Measurement precision
                'GPSSpeedRef' => Exif::ASCII, # Speed unit #p55
                'GPSSpeed' => Exif::RATIONAL, # Speed of GPS receiver
                'GPSTrackRef' => Exif::ASCII, # Reference for direction of movement #p55
                'GPSTrack' => Exif::RATIONAL, # Direction of movement
                'GPSImgDirectionRef' => Exif::ASCII, # Reference for direction of image #p56
                'GPSImgDirection' => Exif::RATIONAL, # Direction of image
                'GPSMapDatum' => Exif::ASCII, # Geodetic survey data used
                'GPSDestLatitudeRef' => Exif::ASCII, # Reference for latitude of destination #p56
                'GPSDestLatitude' => array( Exif::RATIONAL, 3 ), # Latitude destination
                'GPSDestLongitudeRef' => Exif::ASCII, # Reference for longitude of destination #p57
                'GPSDestLongitude' => array( Exif::RATIONAL, 3 ), # Longitude of destination
                'GPSDestBearingRef' => Exif::ASCII, # Reference for bearing of destination #p57
                'GPSDestBearing' => Exif::RATIONAL, # Bearing of destination
                'GPSDestDistanceRef' => Exif::ASCII, # Reference for distance to destination #p57-58
                'GPSDestDistance' => Exif::RATIONAL, # Distance to destination
                'GPSProcessingMethod' => Exif::UNDEFINED, # Name of GPS processing method
                'GPSAreaInformation' => Exif::UNDEFINED, # Name of GPS area
                'GPSDateStamp' => Exif::ASCII, # GPS date
                'GPSDifferential' => Exif::SHORT, # GPS differential correction
            ),
        );
 
        $this->file = $file;
        $this->basename = wfBaseName( $this->file );
        if ( $byteOrder === 'BE' || $byteOrder === 'LE' ) {
            $this->byteOrder = $byteOrder;
        } else {
            // Only give a warning for b/c, since originally we didn't
            // require this. The number of things affected by this is
            // rather small.
            wfWarn( 'Exif class did not have byte order specified. ' .
                'Some properties may be decoded incorrectly.' );
            $this->byteOrder = 'BE'; // BE seems about twice as popular as LE in jpg's.
        }
 
        $this->debugFile( $this->basename, __FUNCTION__, true );
        if ( function_exists( 'exif_read_data' ) ) {
            wfSuppressWarnings();
            $data = exif_read_data( $this->file, 0, true );
            wfRestoreWarnings();
        } else {
            throw new MWException( "Internal error: exif_read_data not present. " .
                "\$wgShowEXIF may be incorrectly set or not checked by an extension." );
        }
        $this->mRawExifData = $data ?: array();
        $this->makeFilteredData();
        $this->collapseData();
        $this->debugFile( __FUNCTION__, false );
    }
 
    function makeFilteredData() {
        $this->mFilteredExifData = array();
 
        foreach ( array_keys( $this->mRawExifData ) as $section ) {
            if ( !array_key_exists( $section, $this->mExifTags ) ) {
                $this->debug( $section, __FUNCTION__, "'$section' is not a valid Exif section" );
                continue;
            }
 
            foreach ( array_keys( $this->mRawExifData[$section] ) as $tag ) {
                if ( !array_key_exists( $tag, $this->mExifTags[$section] ) ) {
                    $this->debug( $tag, __FUNCTION__, "'$tag' is not a valid tag in '$section'" );
                    continue;
                }
 
                $this->mFilteredExifData[$tag] = $this->mRawExifData[$section][$tag];
                // This is ok, as the tags in the different sections do not conflict.
                // except in computed and thumbnail section, which we don't use.
 
                $value = $this->mRawExifData[$section][$tag];
                if ( !$this->validate( $section, $tag, $value ) ) {
                    $this->debug( $value, __FUNCTION__, "'$tag' contained invalid data" );
                    unset( $this->mFilteredExifData[$tag] );
                }
            }
        }
    }
 
    function collapseData() {
 
        $this->exifGPStoNumber( 'GPSLatitude' );
        $this->exifGPStoNumber( 'GPSDestLatitude' );
        $this->exifGPStoNumber( 'GPSLongitude' );
        $this->exifGPStoNumber( 'GPSDestLongitude' );
 
        if ( isset( $this->mFilteredExifData['GPSAltitude'] )
            && isset( $this->mFilteredExifData['GPSAltitudeRef'] )
        ) {
            // We know altitude data is a <num>/<denom> from the validation
            // functions ran earlier. But multiplying such a string by -1
            // doesn't work well, so convert.
            list( $num, $denom ) = explode( '/', $this->mFilteredExifData['GPSAltitude'] );
            $this->mFilteredExifData['GPSAltitude'] = $num / $denom;
 
            if ( $this->mFilteredExifData['GPSAltitudeRef'] === "\1" ) {
                $this->mFilteredExifData['GPSAltitude'] *= -1;
            }
            unset( $this->mFilteredExifData['GPSAltitudeRef'] );
        }
 
        $this->exifPropToOrd( 'FileSource' );
        $this->exifPropToOrd( 'SceneType' );
 
        $this->charCodeString( 'UserComment' );
        $this->charCodeString( 'GPSProcessingMethod' );
        $this->charCodeString( 'GPSAreaInformation' );
 
        //ComponentsConfiguration should really be an array instead of a string...
        //This turns a string of binary numbers into an array of numbers.
 
        if ( isset( $this->mFilteredExifData['ComponentsConfiguration'] ) ) {
            $val = $this->mFilteredExifData['ComponentsConfiguration'];
            $ccVals = array();
 
            $strLen = strlen( $val );
            for ( $i = 0; $i < $strLen; $i++ ) {
                $ccVals[$i] = ord( substr( $val, $i, 1 ) );
            }
            $ccVals['_type'] = 'ol'; //this is for formatting later.
            $this->mFilteredExifData['ComponentsConfiguration'] = $ccVals;
        }
 
        //GPSVersion(ID) is treated as the wrong type by php exif support.
        //Go through each byte turning it into a version string.
        //For example: "\x02\x02\x00\x00" -> "2.2.0.0"
 
        //Also change exif tag name from GPSVersion (what php exif thinks it is)
        //to GPSVersionID (what the exif standard thinks it is).
 
        if ( isset( $this->mFilteredExifData['GPSVersion'] ) ) {
            $val = $this->mFilteredExifData['GPSVersion'];
            $newVal = '';
 
            $strLen = strlen( $val );
            for ( $i = 0; $i < $strLen; $i++ ) {
                if ( $i !== 0 ) {
                    $newVal .= '.';
                }
                $newVal .= ord( substr( $val, $i, 1 ) );
            }
 
            if ( $this->byteOrder === 'LE' ) {
                // Need to reverse the string
                $newVal2 = '';
                for ( $i = strlen( $newVal ) - 1; $i >= 0; $i-- ) {
                    $newVal2 .= substr( $newVal, $i, 1 );
                }
                $this->mFilteredExifData['GPSVersionID'] = $newVal2;
            } else {
                $this->mFilteredExifData['GPSVersionID'] = $newVal;
            }
            unset( $this->mFilteredExifData['GPSVersion'] );
        }
    }
 
    private function charCodeString( $prop ) {
        if ( isset( $this->mFilteredExifData[$prop] ) ) {
 
            if ( strlen( $this->mFilteredExifData[$prop] ) <= 8 ) {
                //invalid. Must be at least 9 bytes long.
 
                $this->debug( $this->mFilteredExifData[$prop], __FUNCTION__, false );
                unset( $this->mFilteredExifData[$prop] );
 
                return;
            }
            $charCode = substr( $this->mFilteredExifData[$prop], 0, 8 );
            $val = substr( $this->mFilteredExifData[$prop], 8 );
 
            switch ( $charCode ) {
                case "\x4A\x49\x53\x00\x00\x00\x00\x00":
                    //JIS
                    $charset = "Shift-JIS";
                    break;
                case "UNICODE\x00":
                    $charset = "UTF-16" . $this->byteOrder;
                    break;
                default: //ascii or undefined.
                    $charset = "";
                    break;
            }
            // This could possibly check to see if iconv is really installed
            // or if we're using the compatibility wrapper in globalFunctions.php
            if ( $charset ) {
                wfSuppressWarnings();
                $val = iconv( $charset, 'UTF-8//IGNORE', $val );
                wfRestoreWarnings();
            } else {
                // if valid utf-8, assume that, otherwise assume windows-1252
                $valCopy = $val;
                UtfNormal::quickIsNFCVerify( $valCopy ); //validates $valCopy.
                if ( $valCopy !== $val ) {
                    wfSuppressWarnings();
                    $val = iconv( 'Windows-1252', 'UTF-8//IGNORE', $val );
                    wfRestoreWarnings();
                }
            }
 
            //trim and check to make sure not only whitespace.
            $val = trim( $val );
            if ( strlen( $val ) === 0 ) {
                //only whitespace.
                $this->debug( $this->mFilteredExifData[$prop], __FUNCTION__, "$prop: Is only whitespace" );
                unset( $this->mFilteredExifData[$prop] );
 
                return;
            }
 
            //all's good.
            $this->mFilteredExifData[$prop] = $val;
        }
    }
 
    private function exifPropToOrd( $prop ) {
        if ( isset( $this->mFilteredExifData[$prop] ) ) {
            $this->mFilteredExifData[$prop] = ord( $this->mFilteredExifData[$prop] );
        }
    }
 
    private function exifGPStoNumber( $prop ) {
        $loc =& $this->mFilteredExifData[$prop];
        $dir =& $this->mFilteredExifData[$prop . 'Ref'];
        $res = false;
 
        if ( isset( $loc ) && isset( $dir )
            && ( $dir === 'N' || $dir === 'S' || $dir === 'E' || $dir === 'W' )
        ) {
            list( $num, $denom ) = explode( '/', $loc[0] );
            $res = $num / $denom;
            list( $num, $denom ) = explode( '/', $loc[1] );
            $res += ( $num / $denom ) * ( 1 / 60 );
            list( $num, $denom ) = explode( '/', $loc[2] );
            $res += ( $num / $denom ) * ( 1 / 3600 );
 
            if ( $dir === 'S' || $dir === 'W' ) {
                $res *= -1; // make negative
            }
        }
 
        // update the exif records.
 
        if ( $res !== false ) { // using !== as $res could potentially be 0
            $this->mFilteredExifData[$prop] = $res;
            unset( $this->mFilteredExifData[$prop . 'Ref'] );
        } else { // if invalid
            unset( $this->mFilteredExifData[$prop] );
            unset( $this->mFilteredExifData[$prop . 'Ref'] );
        }
    }
 
    function getData() {
        return $this->mRawExifData;
    }
 
    function getFilteredData() {
        return $this->mFilteredExifData;
    }
 
    public static function version() {
        return 2; // We don't need no bloddy constants!
    }
 
    private function isByte( $in ) {
        if ( !is_array( $in ) && sprintf( '%d', $in ) == $in && $in >= 0 && $in <= 255 ) {
            $this->debug( $in, __FUNCTION__, true );
 
            return true;
        } else {
            $this->debug( $in, __FUNCTION__, false );
 
            return false;
        }
    }
 
    private function isASCII( $in ) {
        if ( is_array( $in ) ) {
            return false;
        }
 
        if ( preg_match( "/[^\x0a\x20-\x7e]/", $in ) ) {
            $this->debug( $in, __FUNCTION__, 'found a character not in our whitelist' );
 
            return false;
        }
 
        if ( preg_match( '/^\s*$/', $in ) ) {
            $this->debug( $in, __FUNCTION__, 'input consisted solely of whitespace' );
 
            return false;
        }
 
        return true;
    }
 
    private function isShort( $in ) {
        if ( !is_array( $in ) && sprintf( '%d', $in ) == $in && $in >= 0 && $in <= 65536 ) {
            $this->debug( $in, __FUNCTION__, true );
 
            return true;
        } else {
            $this->debug( $in, __FUNCTION__, false );
 
            return false;
        }
    }
 
    private function isLong( $in ) {
        if ( !is_array( $in ) && sprintf( '%d', $in ) == $in && $in >= 0 && $in <= 4294967296 ) {
            $this->debug( $in, __FUNCTION__, true );
 
            return true;
        } else {
            $this->debug( $in, __FUNCTION__, false );
 
            return false;
        }
    }
 
    private function isRational( $in ) {
        $m = array();
 
        # Avoid division by zero
        if ( !is_array( $in )
            && preg_match( '/^(\d+)\/(\d+[1-9]|[1-9]\d*)$/', $in, $m )
        ) {
            return $this->isLong( $m[1] ) && $this->isLong( $m[2] );
        } else {
            $this->debug( $in, __FUNCTION__, 'fed a non-fraction value' );
 
            return false;
        }
    }
 
    private function isUndefined( $in ) {
        $this->debug( $in, __FUNCTION__, true );
 
        return true;
    }
 
    private function isSlong( $in ) {
        if ( $this->isLong( abs( $in ) ) ) {
            $this->debug( $in, __FUNCTION__, true );
 
            return true;
        } else {
            $this->debug( $in, __FUNCTION__, false );
 
            return false;
        }
    }
 
    private function isSrational( $in ) {
        $m = array();
 
        # Avoid division by zero
        if ( !is_array( $in ) &&
            preg_match( '/^(-?\d+)\/(\d+[1-9]|[1-9]\d*)$/', $in, $m )
        ) {
            return $this->isSlong( $m[0] ) && $this->isSlong( $m[1] );
        } else {
            $this->debug( $in, __FUNCTION__, 'fed a non-fraction value' );
 
            return false;
        }
    }
 
    private function validate( $section, $tag, $val, $recursive = false ) {
        $debug = "tag is '$tag'";
        $etype = $this->mExifTags[$section][$tag];
        $ecount = 1;
        if ( is_array( $etype ) ) {
            list( $etype, $ecount ) = $etype;
            if ( $recursive ) {
                $ecount = 1; // checking individual elements
            }
        }
        $count = count( $val );
        if ( $ecount != $count ) {
            $this->debug( $val, __FUNCTION__, "Expected $ecount elements for $tag but got $count" );
 
            return false;
        }
        if ( $count > 1 ) {
            foreach ( $val as $v ) {
                if ( !$this->validate( $section, $tag, $v, true ) ) {
                    return false;
                }
            }
 
            return true;
        }
        // Does not work if not typecast
        switch ( (string)$etype ) {
            case (string)Exif::BYTE:
                $this->debug( $val, __FUNCTION__, $debug );
 
                return $this->isByte( $val );
            case (string)Exif::ASCII:
                $this->debug( $val, __FUNCTION__, $debug );
 
                return $this->isASCII( $val );
            case (string)Exif::SHORT:
                $this->debug( $val, __FUNCTION__, $debug );
 
                return $this->isShort( $val );
            case (string)Exif::LONG:
                $this->debug( $val, __FUNCTION__, $debug );
 
                return $this->isLong( $val );
            case (string)Exif::RATIONAL:
                $this->debug( $val, __FUNCTION__, $debug );
 
                return $this->isRational( $val );
            case (string)Exif::SHORT_OR_LONG:
                $this->debug( $val, __FUNCTION__, $debug );
 
                return $this->isShort( $val ) || $this->isLong( $val );
            case (string)Exif::UNDEFINED:
                $this->debug( $val, __FUNCTION__, $debug );
 
                return $this->isUndefined( $val );
            case (string)Exif::SLONG:
                $this->debug( $val, __FUNCTION__, $debug );
 
                return $this->isSlong( $val );
            case (string)Exif::SRATIONAL:
                $this->debug( $val, __FUNCTION__, $debug );
 
                return $this->isSrational( $val );
            case (string)Exif::IGNORE:
                $this->debug( $val, __FUNCTION__, $debug );
 
                return false;
            default:
                $this->debug( $val, __FUNCTION__, "The tag '$tag' is unknown" );
 
                return false;
        }
    }
 
    private function debug( $in, $fname, $action = null ) {
        if ( !$this->log ) {
            return;
        }
        $type = gettype( $in );
        $class = ucfirst( __CLASS__ );
        if ( is_array( $in ) ) {
            $in = print_r( $in, true );
        }
 
        if ( $action === true ) {
            wfDebugLog( $this->log, "$class::$fname: accepted: '$in' (type: $type)" );
        } elseif ( $action === false ) {
            wfDebugLog( $this->log, "$class::$fname: rejected: '$in' (type: $type)" );
        } elseif ( $action === null ) {
            wfDebugLog( $this->log, "$class::$fname: input was: '$in' (type: $type)" );
        } else {
            wfDebugLog( $this->log, "$class::$fname: $action (type: $type; content: '$in')" );
        }
    }
 
    private function debugFile( $fname, $io ) {
        if ( !$this->log ) {
            return;
        }
        $class = ucfirst( __CLASS__ );
        if ( $io ) {
            wfDebugLog( $this->log, "$class::$fname: begin processing: '{$this->basename}'" );
        } else {
            wfDebugLog( $this->log, "$class::$fname: end processing: '{$this->basename}'" );
        }
    }
}