<?php
// +----------------------------------------------------------------------+
// | PHP version 5                                                        |
// +----------------------------------------------------------------------+
// | Copyright (c) 2002-2004 James Heinrich                               |
// +----------------------------------------------------------------------+
// | This source file is subject to version 2 of the GPL license,         |
// | that is bundled with this package in the file license.txt and is     |
// | available through the world-wide-web at the following url:           |
// | http://www.gnu.org/copyleft/gpl.html                                 |
// +----------------------------------------------------------------------+
// | getID3() - http://getid3.sourceforge.net or http://www.getid3.org    |
// +----------------------------------------------------------------------+
// | Authors: James Heinrich <infoØgetid3*org>                            |
// |          Allan Hansen <ahØartemis*dk>                                |
// +----------------------------------------------------------------------+
// | module.lib.data-hash.php                                             |
// | getID3() library file.                                               |
// | dependencies: NONE.                                                  |
// +----------------------------------------------------------------------+
//
// $Id: module.lib.data_hash.php,v 1.1 2004/11/17 19:15:08 openface Exp $



class getid3_lib_data_hash
{
    
    private $getid3;
    
    
    // constructer - calculate md5/sha1 data
    public function __construct(getID3 $getid3, $algorithm) {
    
        $this->getid3 = $getid3;
        
        // Check algorithm
        if (!preg_match('/^(md5|sha1)$/', $algorithm)) {
            throw new getid3_exception('Unsupported algorithm, "'.$algorithm.'", in GetHashdata()');
        }
        
        
        //// Handle ogg vorbis files
        
        if ((@$getid3->info['fileformat'] == 'ogg') && (@$getid3->info['audio']['dataformat'] == 'vorbis')) {

            // We cannot get an identical md5_data value for Ogg files where the comments
            // span more than 1 Ogg page (compared to the same audio data with smaller
            // comments) using the normal getID3() method of MD5'ing the data between the
            // end of the comments and the end of the file (minus any trailing tags),
            // because the page sequence numbers of the pages that the audio data is on
            // do not match. Under normal circumstances, where comments are smaller than
            // the nominal 4-8kB page size, then this is not a problem, but if there are
            // very large comments, the only way around it is to strip off the comment
            // tags with vorbiscomment and MD5 that file.
            // This procedure must be applied to ALL Ogg files, not just the ones with
            // comments larger than 1 page, because the below method simply MD5's the
            // whole file with the comments stripped, not just the portion after the
            // comments block (which is the standard getID3() method.

            // The above-mentioned problem of comments spanning multiple pages and changing
            // page sequence numbers likely happens for OggSpeex and OggFLAC as well, but
            // currently vorbiscomment only works on OggVorbis files.

            if ((bool)ini_get('safe_mode')) {
                throw new getid3_exception('PHP running in Safe Mode - cannot make system call to vorbiscomment[.exe]  needed for '.$algorithm.'_data.');
            }
        
            // Prevent user from aborting script
            $old_abort = ignore_user_abort(true);

            // Create empty file
            $empty = tempnam('*', 'getID3');
            touch($empty);

            // Use vorbiscomment to make temp file without comments
            $temp = tempnam('*', 'getID3');
            
            if ($getid3->windowed) {
                
                $vorbiscomment = $getid3->option_helperapps_dir.'\\vorbiscomment.exe';
                if (!is_readable($vorbiscomment)) {
                    throw new getid3_exception($vorbiscomment.' does not exist.');
                }
                
                $command_line = $vorbiscomment.' -w -c "'.$empty.'" "'.realpath($getid3->filename).'" "'.$temp.'"';

            } else {
                
                $command_line = 'vorbiscomment -w -c "'.$empty.'" "'.realpath($getid3->filename).'" "'.$temp.'" 2>&1';
            }

            // Error from vorbiscomment
            if ($vorbis_comment_error = `$command_line`) {
                throw new getid3_exception('System call to vorbiscomment[.exe] needed for '.$algorithm.'_data failed. If vorbiscomment is unavailable, please download from http://www.vorbis.com/download.psp. Error returned: '.$vorbis_comment_error);
            } 

            // Get hash of newly created file
            $hash_function = $algorithm . '_file';
            $getid3->info[$algorithm.'_data'] = $hash_function($temp);

            // Clean up
            unlink($empty);
            unlink($temp);

            // Reset abort setting
            ignore_user_abort($old_abort);
            
            // Return success
            return true;
        }

        //// Handle other file formats
        
        // Get hash from part of file
        if (@$getid3->info['avdataoffset'] || (@$getid3->info['avdataend']  &&  @$getid3->info['avdataend'] < $getid3->info['filesize'])) {
            
            if ((bool)ini_get('safe_mode')) {
                $getid3->warning('PHP running in Safe Mode - backtick operator not available, using slower non-system-call '.$algorithm.' algorithm.');
                $hash_function = 'hash_file_partial_safe_mode';
            }
            else {
                $hash_function = $getid3->windowed ? 'hash_file_partial_windows' : 'hash_file_partial_unix';
            }
            
            $getid3->info[$algorithm.'_data'] = $this->$hash_function($getid3->filename, $getid3->info['avdataoffset'], $getid3->info['avdataend'], $algorithm);
        } 
    
        // Get hash from whole file - use built-in md5_file() and sha1_file()
        else {
            $hash_function = $algorithm . '_file';
            $getid3->info[$algorithm.'_data'] = $hash_function($getid3->filename);
        }
    }
    
    
    
    // Return md5/sha1sum for a file from starting position to absolute end position
    // Using windows system call
    private function hash_file_partial_windows($file, $offset, $end, $algorithm) {
        
        $size = $end - $offset;
        
        // It seems that sha1sum.exe for Windows only works on physical files, does not accept piped data
        // Fall back to create-temp-file method:
        if ($algorithm == 'sha1') {
            return $this->hash_file_partial_safe_mode($file, $offset, $end, $algorithm);
        }
        
        foreach (array ('alg_sum' => $algorithm.'sum.exe', 'cygwin' => 'cygwin1.dll', 'head' => 'head.exe', 'tail' => 'tail.exe') as $name => $req_filename) {
                
            $$name = $this->getid3->option_helperapps_dir.'\\'.$req_filename;
            
            // helper apps not available - fall back to old method
            if (!is_readable($$name)) {
                return $this->hash_file_partial_safe_mode($file, $offset, $end, $algorithm);
            }
        }

        $command_line  = $head.' -c '.$end.' "'.realpath($file).'" | '.$tail.' -c '.$size.' | '.$alg_sum;

        return substr(`$command_line`, 0, $algorithm == 'md5' ? 32 : 40);
    }
    
    
    
    // Return md5/sha1sum for a file from starting position to absolute end position
    // Using unix system call
    private function hash_file_partial_unix($file, $offset, $end, $algorithm) {

        $size = $end - $offset;

        $command_line = "head -c $end \"$file\" | tail -c $size | ${algorithm}sum"; 
        
        return substr(`$command_line`, 0, $algorithm == 'md5' ? 32 : 40);
    }
        


    // Return md5/sha1sum for a file from starting position to absolute end position
    // Using slow safe_mode temp file
    private function hash_file_partial_safe_mode($file, $offset, $end, $algorithm) {        

        // Attempt to create a temporary file in the system temp directory - invalid dirname should force to system temp dir
        if (($data_filename = tempnam('*', 'getID3')) === false) {
            throw new getid3_exception('Unable to create temporary file.');
        }

        // Init
        $result = false;

        // Copy parts of file
        if ($fp = @fopen($file, 'rb')) {

            if ($fp_data = @fopen($data_filename, 'wb')) {

                fseek($fp, $offset, SEEK_SET);
                $bytes_left_to_write = $end - $offset;
                while (($bytes_left_to_write > 0) && ($buffer = fread($fp, getid3::FREAD_BUFFER_SIZE))) {
                    $bytes_written = fwrite($fp_data, $buffer, $bytes_left_to_write);
                    $bytes_left_to_write -= $bytes_written;
                }
                fclose($fp_data);
                $hash_function = $algorithm . '_file';
                $result = $hash_function($data_filename);

            }
            fclose($fp);
        }
        unlink($data_filename);
        return $result;
    }

}

?>