exif.php

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                        // Check if the data is over 4 bytes long
                        if ( strlen( $data ) > 4 )
                        {
                                // Data is longer than 4 bytes - it needs to be offset
                                // Check if this entry is the Maker Note
                                if ( ( $Tag_Definitions_Name == "EXIF" ) && ( $tag[ 'Tag Number' ] == 37500 ) )
                                {
                                        // This is the makernote - It will have already been stored
                                        // at its original offset to help preserve it
                                        // all we need to do is add the Offset to the IFD packed data
                                        $data_offset = $tag[ 'Offset' ];

                                        $ifd_body_str .= put_IFD_Data_Type( $data_offset, 4, $Byte_Align );
                                }
                                else
                                {
                                        // This is NOT the makernote
                                        // Calculate the data offset
                                        $data_offset = $IFD_offset + $IFD_len + strlen($ifd_data_str);

                                        // Add the offset to the IFD packed data
                                        $ifd_body_str .= put_IFD_Data_Type( $data_offset, 4, $Byte_Align );

                                        // Add the data to the offset packed data
                                        $ifd_data_str .= $data;
                                }
                        }
                        else
                        {
                                // Data is less than or equal to 4 bytes - Add it to the packed IFD data as is
                                $ifd_body_str .= $data;
                        }

                }
        }

        // Assemble the IFD body onto the packed data
        $packed_data .= $ifd_body_str;

        // Check if there is another IFD after this one
        if( $Another_IFD === TRUE )
        {
                // There is another IFD after this
                // Calculate the Next-IFD offset so that it goes immediately after this IFD
                $next_ifd_offset = $IFD_offset + $IFD_len + strlen($ifd_data_str);
        }
        else
        {
                // There is NO IFD after this - indicate with offset=0
                $next_ifd_offset = 0;
        }

        // Add the Next-IFD offset to the packed data
        $packed_data .= put_IFD_Data_Type( $next_ifd_offset, 4, $Byte_Align );

        // Add the offset data to the packed data
        $packed_data .= $ifd_data_str;

        // Return the resulting packed data
        return $packed_data;
}

/******************************************************************************
* End of Function:     get_IFD_Packed_Data
******************************************************************************/





/******************************************************************************
*
* Internal Function:     process_TIFF_Header
*
* Description:  Decodes the information stored in a TIFF header and it's
*               Image File Directories (IFD's). This information is returned
*               in an array
*
* Parameters:   filehnd - The handle of a open image file, positioned at the
*                          start of the TIFF header
*               Tag_Definitions_Name - The name of the Tag Definitions group
*                                      within the global array IFD_Tag_Definitions
*
*
* Returns:      OutputArray - Array of IFD records
*               FALSE - If an error occured in decoding
*
******************************************************************************/

function process_TIFF_Header( $filehnd, $Tag_Definitions_Name )
{


        // Save the file position where the TIFF header starts, as offsets are relative to this position
        $Tiff_start_pos = ftell( $filehnd );



        // Read the eight bytes of the TIFF header
        $DataStr = network_safe_fread( $filehnd, 8 );

        // Check that we did get all eight bytes
        if ( strlen( $DataStr ) != 8 )
        {
                return FALSE;   // Couldn't read the TIFF header properly
        }

        $pos = 0;
        // First two bytes indicate the byte alignment - should be 'II' or 'MM'
        // II = Intel (LSB first, MSB last - Little Endian)
        // MM = Motorola (MSB first, LSB last - Big Endian)
        $Byte_Align = substr( $DataStr, $pos, 2 );



        // Check the Byte Align Characters for validity
        if ( ( $Byte_Align != "II" ) && ( $Byte_Align != "MM" ) )
        {
                // Byte align field is invalid - we won't be able to decode file
                return FALSE;
        }

        // Skip over the Byte Align field which was just read
        $pos += 2;

        // Next two bytes are TIFF ID - should be value 42 with the appropriate byte alignment
        $TIFF_ID = substr( $DataStr, $pos, 2 );

        if ( get_IFD_Data_Type( $TIFF_ID, 3, $Byte_Align ) != 42 )
        {
                // TIFF header ID not found
                return FALSE;
        }

        // Skip over the TIFF ID field which was just read
        $pos += 2;


        // Next four bytes are the offset to the first IFD
        $offset_str = substr( $DataStr, $pos, 4 );
        $offset = get_IFD_Data_Type( $offset_str, 4, $Byte_Align );

        // Done reading TIFF Header


        // Move to first IFD

        if ( fseek( $filehnd, $Tiff_start_pos + $offset ) !== 0 )
        {
                // Error seeking to position of first IFD
                return FALSE;
        }



        // Flag that a makernote has not been found yet
        $GLOBALS[ "Maker_Note_Tag" ] = FALSE;

        // Read the IFD chain into an array
        $Output_Array = read_Multiple_IFDs( $filehnd, $Tiff_start_pos, $Byte_Align, $Tag_Definitions_Name );

        // Check if a makernote was found
        if ( $GLOBALS[ "Maker_Note_Tag" ] != FALSE )
        {
                // Makernote was found - Process it
                // The makernote needs to be processed after all other
                // tags as it may require some of the other tags in order
                // to be processed properly
                $GLOBALS[ "Maker_Note_Tag" ] = Read_Makernote_Tag( $GLOBALS[ "Maker_Note_Tag" ], $Output_Array, $filehnd );

        }

        $Output_Array[ 'Makernote_Tag' ] = $GLOBALS[ "Maker_Note_Tag" ];

        // Save the Name of the Tags used in the output array
        $Output_Array[ 'Tags Name' ] = $Tag_Definitions_Name;



        // Save the Byte alignment
        $Output_Array['Byte_Align'] = $Byte_Align;


        // Return the output array
        return $Output_Array ;
}

/******************************************************************************
* End of Function:     process_TIFF_Header
******************************************************************************/






/******************************************************************************
*
* Internal Function:     read_Multiple_IFDs
*
* Description:  Reads and interprets a chain of standard Image File Directories (IFD's),
*               and returns the entries in an array. This chain is made up from IFD's
*               which have a pointer to the next IFD. IFD's are read until the next
*               pointer indicates there are no more
*
* Parameters:   filehnd - a handle for the image file being read, positioned at the
*                         start of the IFD chain
*               Tiff_offset - The offset of the TIFF header from the start of the file
*               Byte_Align - either "MM" or "II" indicating Motorola or Intel Byte alignment
*               Tag_Definitions_Name - The name of the Tag Definitions group within the global array IFD_Tag_Definitions
*               local_offsets - True indicates that offset data should be interpreted as being relative to the start of the currrent entry
*                               False (normal) indicates offests are relative to start of Tiff header as per IFD standard
*               read_next_ptr - True (normal) indicates that a pointer to the next IFD should be read at the end of the IFD
*                               False indicates that no pointer follows the IFD
*
*
* Returns:      OutputArray - Array of IFD entries
*
******************************************************************************/

function read_Multiple_IFDs( $filehnd, $Tiff_offset, $Byte_Align, $Tag_Definitions_Name, $local_offsets = FALSE, $read_next_ptr = TRUE )
{
        // Start at the offset of the first IFD
        $Next_Offset = 0;

        do
        {
                // Read an IFD
                list($IFD_Array , $Next_Offset) = read_IFD_universal( $filehnd, $Tiff_offset, $Byte_Align, $Tag_Definitions_Name, $local_offsets, $read_next_ptr );

                // Move to the position of the next IFD
                if ( fseek( $filehnd, $Tiff_offset + $Next_Offset ) !== 0 )
                {
                        // Error seeking to position of next IFD
                        echo "<p>Error: Corrupted EXIF</p>\n";
                        return FALSE;
                }

                $Output_Array[] = $IFD_Array;


        } while ( $Next_Offset != 0 );      // Until the Next IFD Offset is zero


        // return resulting array

        return $Output_Array ;
}

/******************************************************************************
* End of Function:     read_Multiple_IFDs
******************************************************************************/







/******************************************************************************
*
* Internal Function:     read_IFD_universal
*
* Description:  Reads and interprets a standard or Non-standard Image File
*               Directory (IFD), and returns the entries in an array
*
* Parameters:   filehnd - a handle for the image file being read, positioned at the start
*                         of the IFD
*               Tiff_offset - The offset of the TIFF header from the start of the file
*               Byte_Align - either "MM" or "II" indicating Motorola or Intel Byte alignment
*               Tag_Definitions_Name - The name of the Tag Definitions group within the global array IFD_Tag_Definitions
*               local_offsets - True indicates that offset data should be interpreted as being relative to the start of the currrent entry
*                               False (normal) indicates offests are relative to start of Tiff header as per IFD standard
*               read_next_ptr - True (normal) indicates that a pointer to the next IFD should be read at the end of the IFD
*                               False indicates that no pointer follows the IFD
*
* Returns:      OutputArray - Array of IFD entries
*               Next_Offset - Offset to next IFD (zero = no next IFD)
*
******************************************************************************/

function read_IFD_universal( $filehnd, $Tiff_offset, $Byte_Align, $Tag_Definitions_Name, $local_offsets = FALSE, $read_next_ptr = TRUE )
{
        if ( ( $filehnd == NULL ) || ( feof( $filehnd ) ) )
        {
                return array (FALSE , 0);
        }

        // Record the Name of the Tag Group used for this IFD in the output array
        $OutputArray[ 'Tags Name' ] = $Tag_Definitions_Name;

        // Record the offset of the TIFF header in the output array
        $OutputArray[ 'Tiff Offset' ] = $Tiff_offset;

        // First 2 bytes of IFD are number of entries in the IFD
        $No_Entries_str = network_safe_fread( $filehnd, 2 );
        $No_Entries = get_IFD_Data_Type( $No_Entries_str, 3, $Byte_Align );


        // If the data is corrupt, the number of entries may be huge, which will cause errors
        // This is often caused by a lack of a Next-IFD pointer
        if ( $No_Entries> 10000 )