xref: /dokuwiki/inc/changelog.php (revision 4c3263af6652b0a479e2c742914eb67a7929b9b9)
1<?php
2/**
3 * Changelog handling functions
4 *
5 * @license    GPL 2 (http://www.gnu.org/licenses/gpl.html)
6 * @author     Andreas Gohr <andi@splitbrain.org>
7 */
8
9// Constants for known core changelog line types.
10// Use these in place of string literals for more readable code.
11define('DOKU_CHANGE_TYPE_CREATE',       'C');
12define('DOKU_CHANGE_TYPE_EDIT',         'E');
13define('DOKU_CHANGE_TYPE_MINOR_EDIT',   'e');
14define('DOKU_CHANGE_TYPE_DELETE',       'D');
15define('DOKU_CHANGE_TYPE_REVERT',       'R');
16
17/**
18 * parses a changelog line into it's components
19 *
20 * @author Ben Coburn <btcoburn@silicodon.net>
21 */
22function parseChangelogLine($line) {
23    $tmp = explode("\t", $line);
24    if ($tmp!==false && count($tmp)>1) {
25        $info = array();
26        $info['date']  = (int)$tmp[0]; // unix timestamp
27        $info['ip']    = $tmp[1]; // IPv4 address (127.0.0.1)
28        $info['type']  = $tmp[2]; // log line type
29        $info['id']    = $tmp[3]; // page id
30        $info['user']  = $tmp[4]; // user name
31        $info['sum']   = $tmp[5]; // edit summary (or action reason)
32        $info['extra'] = rtrim($tmp[6], "\n"); // extra data (varies by line type)
33        return $info;
34    } else { return false; }
35}
36
37/**
38 * Add's an entry to the changelog and saves the metadata for the page
39 *
40 * @param int    $date      Timestamp of the change
41 * @param String $id        Name of the affected page
42 * @param String $type      Type of the change see DOKU_CHANGE_TYPE_*
43 * @param String $summary   Summary of the change
44 * @param mixed  $extra     In case of a revert the revision (timestmp) of the reverted page
45 * @param array  $flags     Additional flags in a key value array.
46 *                             Availible flags:
47 *                             - ExternalEdit - mark as an external edit.
48 *
49 * @author Andreas Gohr <andi@splitbrain.org>
50 * @author Esther Brunner <wikidesign@gmail.com>
51 * @author Ben Coburn <btcoburn@silicodon.net>
52 */
53function addLogEntry($date, $id, $type=DOKU_CHANGE_TYPE_EDIT, $summary='', $extra='', $flags=null){
54    global $conf, $INFO;
55
56    // check for special flags as keys
57    if (!is_array($flags)) { $flags = array(); }
58    $flagExternalEdit = isset($flags['ExternalEdit']);
59
60    $id = cleanid($id);
61    $file = wikiFN($id);
62    $created = @filectime($file);
63    $minor = ($type===DOKU_CHANGE_TYPE_MINOR_EDIT);
64    $wasRemoved = ($type===DOKU_CHANGE_TYPE_DELETE);
65
66    if(!$date) $date = time(); //use current time if none supplied
67    $remote = (!$flagExternalEdit)?clientIP(true):'127.0.0.1';
68    $user   = (!$flagExternalEdit)?$_SERVER['REMOTE_USER']:'';
69
70    $strip = array("\t", "\n");
71    $logline = array(
72            'date'  => $date,
73            'ip'    => $remote,
74            'type'  => str_replace($strip, '', $type),
75            'id'    => $id,
76            'user'  => $user,
77            'sum'   => utf8_substr(str_replace($strip, '', $summary),0,255),
78            'extra' => str_replace($strip, '', $extra)
79            );
80
81    // update metadata
82    if (!$wasRemoved) {
83        $oldmeta = p_read_metadata($id);
84        $meta    = array();
85        if (!$INFO['exists'] && empty($oldmeta['persistent']['date']['created'])){ // newly created
86            $meta['date']['created'] = $created;
87            if ($user){
88                $meta['creator'] = $INFO['userinfo']['name'];
89                $meta['user']    = $user;
90            }
91        } elseif (!$INFO['exists'] && !empty($oldmeta['persistent']['date']['created'])) { // re-created / restored
92            $meta['date']['created']  = $oldmeta['persistent']['date']['created'];
93            $meta['date']['modified'] = $created; // use the files ctime here
94            $meta['creator'] = $oldmeta['persistent']['creator'];
95            if ($user) $meta['contributor'][$user] = $INFO['userinfo']['name'];
96        } elseif (!$minor) {   // non-minor modification
97            $meta['date']['modified'] = $date;
98            if ($user) $meta['contributor'][$user] = $INFO['userinfo']['name'];
99        }
100        $meta['last_change'] = $logline;
101        p_set_metadata($id, $meta);
102    }
103
104    // add changelog lines
105    $logline = implode("\t", $logline)."\n";
106    io_saveFile(metaFN($id,'.changes'),$logline,true); //page changelog
107    io_saveFile($conf['changelog'],$logline,true); //global changelog cache
108}
109
110/**
111 * Add's an entry to the media changelog
112 *
113 * @author Michael Hamann <michael@content-space.de>
114 * @author Andreas Gohr <andi@splitbrain.org>
115 * @author Esther Brunner <wikidesign@gmail.com>
116 * @author Ben Coburn <btcoburn@silicodon.net>
117 */
118function addMediaLogEntry($date, $id, $type=DOKU_CHANGE_TYPE_EDIT, $summary='', $extra='', $flags=null){
119    global $conf;
120
121    $id = cleanid($id);
122
123    if(!$date) $date = time(); //use current time if none supplied
124    $remote = clientIP(true);
125    $user   = $_SERVER['REMOTE_USER'];
126
127    $strip = array("\t", "\n");
128    $logline = array(
129            'date'  => $date,
130            'ip'    => $remote,
131            'type'  => str_replace($strip, '', $type),
132            'id'    => $id,
133            'user'  => $user,
134            'sum'   => utf8_substr(str_replace($strip, '', $summary),0,255),
135            'extra' => str_replace($strip, '', $extra)
136            );
137
138    // add changelog lines
139    $logline = implode("\t", $logline)."\n";
140    io_saveFile($conf['media_changelog'],$logline,true); //global media changelog cache
141    io_saveFile(mediaMetaFN($id,'.changes'),$logline,true); //media file's changelog
142}
143
144/**
145 * returns an array of recently changed files using the
146 * changelog
147 *
148 * The following constants can be used to control which changes are
149 * included. Add them together as needed.
150 *
151 * RECENTS_SKIP_DELETED   - don't include deleted pages
152 * RECENTS_SKIP_MINORS    - don't include minor changes
153 * RECENTS_SKIP_SUBSPACES - don't include subspaces
154 * RECENTS_MEDIA_CHANGES  - return media changes instead of page changes
155 * RECENTS_MEDIA_PAGES_MIXED  - return both media changes and page changes
156 *
157 * @param int    $first   number of first entry returned (for paginating
158 * @param int    $num     return $num entries
159 * @param string $ns      restrict to given namespace
160 * @param int    $flags   see above
161 * @return array recently changed files
162 *
163 * @author Ben Coburn <btcoburn@silicodon.net>
164 * @author Kate Arzamastseva <pshns@ukr.net>
165 */
166function getRecents($first,$num,$ns='',$flags=0){
167    global $conf;
168    $recent = array();
169    $count  = 0;
170
171    if(!$num)
172        return $recent;
173
174    // read all recent changes. (kept short)
175    if ($flags & RECENTS_MEDIA_CHANGES) {
176        $lines = @file($conf['media_changelog']);
177    } else {
178        $lines = @file($conf['changelog']);
179    }
180    $lines_position = count($lines)-1;
181    $media_lines_position = 0;
182    $media_lines = array();
183
184    if ($flags & RECENTS_MEDIA_PAGES_MIXED) {
185        $media_lines = @file($conf['media_changelog']);
186        $media_lines_position = count($media_lines)-1;
187    }
188
189    $seen = array(); // caches seen lines, _handleRecent() skips them
190
191    // handle lines
192    while ($lines_position >= 0 || (($flags & RECENTS_MEDIA_PAGES_MIXED) && $media_lines_position >=0)) {
193        if (empty($rec) && $lines_position >= 0) {
194            $rec = _handleRecent(@$lines[$lines_position], $ns, $flags, $seen);
195            if (!$rec) {
196                $lines_position --;
197                continue;
198            }
199        }
200        if (($flags & RECENTS_MEDIA_PAGES_MIXED) && empty($media_rec) && $media_lines_position >= 0) {
201            $media_rec = _handleRecent(@$media_lines[$media_lines_position], $ns, $flags | RECENTS_MEDIA_CHANGES, $seen);
202            if (!$media_rec) {
203                $media_lines_position --;
204                continue;
205            }
206        }
207        if (($flags & RECENTS_MEDIA_PAGES_MIXED) && @$media_rec['date'] >= @$rec['date']) {
208            $media_lines_position--;
209            $x = $media_rec;
210            $x['media'] = true;
211            $media_rec = false;
212        } else {
213            $lines_position--;
214            $x = $rec;
215            if ($flags & RECENTS_MEDIA_CHANGES) $x['media'] = true;
216            $rec = false;
217        }
218        if(--$first >= 0) continue; // skip first entries
219        $recent[] = $x;
220        $count++;
221        // break when we have enough entries
222        if($count >= $num){ break; }
223    }
224    return $recent;
225}
226
227/**
228 * returns an array of files changed since a given time using the
229 * changelog
230 *
231 * The following constants can be used to control which changes are
232 * included. Add them together as needed.
233 *
234 * RECENTS_SKIP_DELETED   - don't include deleted pages
235 * RECENTS_SKIP_MINORS    - don't include minor changes
236 * RECENTS_SKIP_SUBSPACES - don't include subspaces
237 * RECENTS_MEDIA_CHANGES  - return media changes instead of page changes
238 *
239 * @param int    $from    date of the oldest entry to return
240 * @param int    $to      date of the newest entry to return (for pagination, optional)
241 * @param string $ns      restrict to given namespace (optional)
242 * @param int    $flags   see above (optional)
243 * @return array of files
244 *
245 * @author Michael Hamann <michael@content-space.de>
246 * @author Ben Coburn <btcoburn@silicodon.net>
247 */
248function getRecentsSince($from,$to=null,$ns='',$flags=0){
249    global $conf;
250    $recent = array();
251
252    if($to && $to < $from)
253        return $recent;
254
255    // read all recent changes. (kept short)
256    if ($flags & RECENTS_MEDIA_CHANGES) {
257        $lines = @file($conf['media_changelog']);
258    } else {
259        $lines = @file($conf['changelog']);
260    }
261    if(!$lines) return $recent;
262
263    // we start searching at the end of the list
264    $lines = array_reverse($lines);
265
266    // handle lines
267    $seen = array(); // caches seen lines, _handleRecent() skips them
268
269    foreach($lines as $line){
270        $rec = _handleRecent($line, $ns, $flags, $seen);
271        if($rec !== false) {
272            if ($rec['date'] >= $from) {
273                if (!$to || $rec['date'] <= $to) {
274                    $recent[] = $rec;
275                }
276            } else {
277                break;
278            }
279        }
280    }
281
282    return array_reverse($recent);
283}
284
285/**
286 * Internal function used by getRecents
287 *
288 * don't call directly
289 *
290 * @see getRecents()
291 * @author Andreas Gohr <andi@splitbrain.org>
292 * @author Ben Coburn <btcoburn@silicodon.net>
293 */
294function _handleRecent($line,$ns,$flags,&$seen){
295    if(empty($line)) return false;   //skip empty lines
296
297    // split the line into parts
298    $recent = parseChangelogLine($line);
299    if ($recent===false) { return false; }
300
301    // skip seen ones
302    if(isset($seen[$recent['id']])) return false;
303
304    // skip minors
305    if($recent['type']===DOKU_CHANGE_TYPE_MINOR_EDIT && ($flags & RECENTS_SKIP_MINORS)) return false;
306
307    // remember in seen to skip additional sights
308    $seen[$recent['id']] = 1;
309
310    // check if it's a hidden page
311    if(isHiddenPage($recent['id'])) return false;
312
313    // filter namespace
314    if (($ns) && (strpos($recent['id'],$ns.':') !== 0)) return false;
315
316    // exclude subnamespaces
317    if (($flags & RECENTS_SKIP_SUBSPACES) && (getNS($recent['id']) != $ns)) return false;
318
319    // check ACL
320    if ($flags & RECENTS_MEDIA_CHANGES) {
321        $recent['perms'] = auth_quickaclcheck(getNS($recent['id']).':*');
322    } else {
323        $recent['perms'] = auth_quickaclcheck($recent['id']);
324    }
325    if ($recent['perms'] < AUTH_READ) return false;
326
327    // check existance
328    if($flags & RECENTS_SKIP_DELETED){
329        $fn = (($flags & RECENTS_MEDIA_CHANGES) ? mediaFN($recent['id']) : wikiFN($recent['id']));
330        if(!@file_exists($fn)) return false;
331    }
332
333    return $recent;
334}
335
336/**
337 * Class ChangeLog
338 * methods for handling of changelog of pages or media files
339 */
340abstract class ChangeLog {
341
342    /** @var string */
343    protected $id;
344    /** @var int */
345    protected $chunk_size;
346    /** @var array */
347    protected $cache;
348
349    /**
350     * Constructor
351     *
352     * @param string $id         page id
353     * @param int    $chunk_size maximum block size read from file
354     */
355    public function __construct($id, $chunk_size = 8192) {
356        global $cache_revinfo;
357
358        $this->cache =& $cache_revinfo;
359        if(!isset($this->cache[$id])) {
360            $this->cache[$id] = array();
361        }
362
363        $this->id = $id;
364        $this->setChunkSize($chunk_size);
365
366    }
367
368    /**
369     * Set chunk size for file reading
370     * Chunk size zero let read whole file at once
371     *
372     * @param int $chunk_size maximum block size read from file
373     */
374    public function setChunkSize($chunk_size) {
375        if(!is_numeric($chunk_size)) $chunk_size = 0;
376
377        $this->chunk_size = (int) max($chunk_size, 0);
378    }
379
380    /**
381     * Returns path to changelog
382     *
383     * @return string path to file
384     */
385    abstract protected function getChangelogFilename();
386
387    /**
388     * Returns path to current page/media
389     *
390     * @return string path to file
391     */
392    abstract protected function getFilename();
393
394    /**
395     * Get the changelog information for a specific page id and revision (timestamp)
396     *
397     * Adjacent changelog lines are optimistically parsed and cached to speed up
398     * consecutive calls to getRevisionInfo. For large changelog files, only the chunk
399     * containing the requested changelog line is read.
400     *
401     * @param int  $rev        revision timestamp
402     * @return bool|array false or array with entries:
403     *      - date:  unix timestamp
404     *      - ip:    IPv4 address (127.0.0.1)
405     *      - type:  log line type
406     *      - id:    page id
407     *      - user:  user name
408     *      - sum:   edit summary (or action reason)
409     *      - extra: extra data (varies by line type)
410     *
411     * @author Ben Coburn <btcoburn@silicodon.net>
412     * @author Kate Arzamastseva <pshns@ukr.net>
413     */
414    public function getRevisionInfo($rev) {
415        $rev = max($rev, 0);
416
417        // check if it's already in the memory cache
418        if(isset($this->cache[$this->id]) && isset($this->cache[$this->id][$rev])) {
419            return $this->cache[$this->id][$rev];
420        }
421
422        //read lines from changelog
423        list($fp, $lines) = $this->readloglines($rev);
424        if($fp) {
425            fclose($fp);
426        }
427        if(empty($lines)) return false;
428
429        // parse and cache changelog lines
430        foreach($lines as $value) {
431            $tmp = parseChangelogLine($value);
432            if($tmp !== false) {
433                $this->cache[$this->id][$tmp['date']] = $tmp;
434            }
435        }
436        if(!isset($this->cache[$this->id][$rev])) {
437            return false;
438        }
439        return $this->cache[$this->id][$rev];
440    }
441
442    /**
443     * Return a list of page revisions numbers
444     *
445     * Does not guarantee that the revision exists in the attic,
446     * only that a line with the date exists in the changelog.
447     * By default the current revision is skipped.
448     *
449     * The current revision is automatically skipped when the page exists.
450     * See $INFO['meta']['last_change'] for the current revision.
451     * A negative $first let read the current revision too.
452     *
453     * For efficiency, the log lines are parsed and cached for later
454     * calls to getRevisionInfo. Large changelog files are read
455     * backwards in chunks until the requested number of changelog
456     * lines are recieved.
457     *
458     * @param int  $first      skip the first n changelog lines
459     * @param int  $num        number of revisions to return
460     * @return array with the revision timestamps
461     *
462     * @author Ben Coburn <btcoburn@silicodon.net>
463     * @author Kate Arzamastseva <pshns@ukr.net>
464     */
465    public function getRevisions($first, $num) {
466        $revs = array();
467        $lines = array();
468        $count  = 0;
469
470        $num = max($num, 0);
471        if ($num == 0) { return $revs; }
472
473        if ($first<0) {
474            $first = 0;
475        } else if (@file_exists($this->getFilename())) {
476            // skip current revision if the page exists
477            $first = max($first+1, 0);
478        }
479
480        $file = $this->getChangelogFilename();
481
482        if (!@file_exists($file)) { return $revs; }
483        if (filesize($file)<$this->chunk_size || $this->chunk_size==0) {
484            // read whole file
485            $lines = file($file);
486            if ($lines===false) { return $revs; }
487        } else {
488            // read chunks backwards
489            $fp = fopen($file, 'rb'); // "file pointer"
490            if ($fp===false) { return $revs; }
491            fseek($fp, 0, SEEK_END);
492            $tail = ftell($fp);
493
494            // chunk backwards
495            $finger = max($tail-$this->chunk_size, 0);
496            while ($count<$num+$first) {
497                fseek($fp, $finger);
498                $nl = $finger;
499                if ($finger>0) {
500                    fgets($fp); // slip the finger forward to a new line
501                    $nl = ftell($fp);
502                }
503
504                // was the chunk big enough? if not, take another bite
505                if($nl > 0 && $tail <= $nl){
506                    $finger = max($finger-$this->chunk_size, 0);
507                    continue;
508                }else{
509                    $finger = $nl;
510                }
511
512                // read chunk
513                $chunk = '';
514                $read_size = max($tail-$finger, 0); // found chunk size
515                $got = 0;
516                while ($got<$read_size && !feof($fp)) {
517                    $tmp = @fread($fp, max($read_size-$got, 0));
518                    if ($tmp===false) { break; } //error state
519                    $got += strlen($tmp);
520                    $chunk .= $tmp;
521                }
522                $tmp = explode("\n", $chunk);
523                array_pop($tmp); // remove trailing newline
524
525                // combine with previous chunk
526                $count += count($tmp);
527                $lines = array_merge($tmp, $lines);
528
529                // next chunk
530                if ($finger==0) { break; } // already read all the lines
531                else {
532                    $tail = $finger;
533                    $finger = max($tail-$this->chunk_size, 0);
534                }
535            }
536            fclose($fp);
537        }
538
539        // skip parsing extra lines
540        $num = max(min(count($lines)-$first, $num), 0);
541        if      ($first>0 && $num>0)  { $lines = array_slice($lines, max(count($lines)-$first-$num, 0), $num); }
542        else if ($first>0 && $num==0) { $lines = array_slice($lines, 0, max(count($lines)-$first, 0)); }
543        else if ($first==0 && $num>0) { $lines = array_slice($lines, max(count($lines)-$num, 0)); }
544
545        // handle lines in reverse order
546        for ($i = count($lines)-1; $i >= 0; $i--) {
547            $tmp = parseChangelogLine($lines[$i]);
548            if ($tmp!==false) {
549                $this->cache[$this->id][$tmp['date']] = $tmp;
550                $revs[] = $tmp['date'];
551            }
552        }
553
554        return $revs;
555    }
556
557    /**
558     * Get the nth revision left or right handside  for a specific page id and revision (timestamp)
559     *
560     * For large changelog files, only the chunk containing the
561     * reference revision $rev is read and sometimes a next chunck.
562     *
563     * Adjacent changelog lines are optimistically parsed and cached to speed up
564     * consecutive calls to getRevisionInfo.
565     *
566     * @param int  $rev        revision timestamp used as startdate (doesn't need to be revisionnumber)
567     * @param int  $direction  give position of returned revision with respect to $rev; positive=next, negative=prev
568     * @return bool|int
569     *      timestamp of the requested revision
570     *      otherwise false
571     */
572    public function getRelativeRevision($rev, $direction) {
573        $rev = max($rev, 0);
574        $direction = (int) $direction;
575
576        //no direction given or last rev, so no follow-up
577        if(!$direction || ($direction > 0 && $this->isCurrentRevision($rev)) ) {
578            return false;
579        }
580
581        //get lines from changelog
582        list($fp, $lines, $head, $tail, $eof) = $this->readloglines($rev);
583        if(empty($lines)) return false;
584
585        // look for revisions later/earlier then $rev, when founded count till the wanted revision is reached
586        // also parse and cache changelog lines for getRevisionInfo().
587        $revcounter       = 0;
588        $relativerev      = false;
589        $checkotherchunck = true; //always runs once
590        while(!$relativerev && $checkotherchunck) {
591            $tmp = array();
592            //parse in normal or reverse order
593            $count = count($lines);
594            if($direction > 0) {
595                $start = 0;
596                $step  = 1;
597            } else {
598                $start = $count - 1;
599                $step  = -1;
600            }
601            for($i = $start; $i >= 0 && $i < $count; $i = $i + $step) {
602                $tmp = parseChangelogLine($lines[$i]);
603                if($tmp !== false) {
604                    $this->cache[$this->id][$tmp['date']] = $tmp;
605                    //look for revs older/earlier then reference $rev and select $direction-th one
606                    if(($direction > 0 && $tmp['date'] > $rev) || ($direction < 0 && $tmp['date'] < $rev)) {
607                        $revcounter++;
608                        if($revcounter == abs($direction)) {
609                            $relativerev = $tmp['date'];
610                        }
611                    }
612                }
613            }
614
615            //true when $rev is found, but not the wanted follow-up.
616            $checkotherchunck = $fp
617                && ($tmp['date'] == $rev || ($revcounter > 0 && !$relativerev))
618                && !(($tail == $eof && $direction > 0) || ($head == 0 && $direction < 0));
619
620            if($checkotherchunck) {
621                //search bounds of chunck, rounded on new line, but smaller than $chunck_size
622                if($direction > 0) {
623                    $head        = $tail;
624                    $lookpointer = true;
625                    $tail        = $head + floor($this->chunk_size * (2 / 3));
626                    while($lookpointer) {
627                        $tail        = min($tail, $eof);
628                        $tail        = $this->getNewlinepointer($fp, $tail);
629                        $lookpointer = $tail - $head > $this->chunk_size;
630                        if($lookpointer) {
631                            $tail = $head + floor(($tail - $head) / 2);
632                        }
633                        if($tail == $head) break;
634                    }
635                } else {
636                    $tail = $head;
637                    $head = max($tail - $this->chunk_size, 0);
638                    $head = $this->getNewlinepointer($fp, $head);
639                }
640
641                //load next chunck
642                $lines = $this->readChunk($fp, $head, $tail);
643                if(empty($lines)) break;
644            }
645        }
646        if($fp) {
647            fclose($fp);
648        }
649
650        return $relativerev;
651    }
652
653
654    /**
655     * Returns lines from changelog.
656     * If file larger than $chuncksize, only chunck is read that could contain $rev.
657     *
658     * @param int  $rev   revision timestamp
659     * @return array(fp, array(changeloglines), $head, $tail, $eof)|bool
660     *     returns false when not succeed. fp only defined for chuck reading, needs closing.
661     */
662    protected function readloglines($rev) {
663        $file = $this->getChangelogFilename();
664
665        if(!@file_exists($file)) {
666            return false;
667        }
668
669        $fp    = null;
670        $head  = 0;
671        $tail  = 0;
672        $eof   = 0;
673
674        if(filesize($file) < $this->chunk_size || $this->chunk_size == 0) {
675            // read whole file
676            $lines = file($file);
677            if($lines === false) {
678                return false;
679            }
680        } else {
681            // read by chunk
682            $fp = fopen($file, 'rb'); // "file pointer"
683            if($fp === false) {
684                return false;
685            }
686            $head = 0;
687            fseek($fp, 0, SEEK_END);
688            $eof        = ftell($fp);
689            $tail       = $eof;
690
691            // find chunk
692            while($tail - $head > $this->chunk_size) {
693                $finger     = $head + floor(($tail - $head) / 2.0);
694                $finger     = $this->getNewlinepointer($fp, $finger);
695                $tmp        = fgets($fp);
696                $tmp        = parseChangelogLine($tmp);
697                $finger_rev = $tmp['date'];
698                if($finger == $head || $finger == $tail) {
699                    break;
700                }
701                if($finger_rev > $rev) {
702                    $tail = $finger;
703                } else {
704                    $head = $finger;
705                }
706            }
707
708            if($tail - $head < 1) {
709                // cound not find chunk, assume requested rev is missing
710                fclose($fp);
711                return false;
712            }
713
714            $lines = $this->readChunk($fp, $head, $tail);
715        }
716        return array(
717            $fp,
718            $lines,
719            $head,
720            $tail,
721            $eof
722        );
723    }
724
725    /**
726     * Read chunk and return array with lines of given chunck.
727     * Has no check if $head and $tail are really at a new line
728     *
729     * @param $fp resource filepointer
730     * @param $head int start point chunck
731     * @param $tail int end point chunck
732     * @return array lines read from chunck
733     */
734    protected function readChunk($fp, $head, $tail) {
735        $chunk      = '';
736        $chunk_size = max($tail - $head, 0); // found chunk size
737        $got        = 0;
738        fseek($fp, $head);
739        while($got < $chunk_size && !feof($fp)) {
740            $tmp = @fread($fp, max($chunk_size - $got, 0));
741            if($tmp === false) { //error state
742                break;
743            }
744            $got += strlen($tmp);
745            $chunk .= $tmp;
746        }
747        $lines = explode("\n", $chunk);
748        array_pop($lines); // remove trailing newline
749        return $lines;
750    }
751
752    /**
753     * Set pointer to first new line after $finger and return its position
754     *
755     * @param $fp resource filepointer
756     * @param $finger int a pointer
757     * @return int pointer
758     */
759    protected function getNewlinepointer($fp, $finger) {
760        fseek($fp, $finger);
761        fgets($fp); // slip the finger forward to a new line
762        return ftell($fp);
763    }
764
765    /**
766     * Check whether given revision is the current page
767     *
768     * @param int  $rev   timestamp of current page
769     * @return bool true if $rev is current revision, otherwise false
770     */
771    public function isCurrentRevision($rev) {
772        return $rev == @filemtime($this->getFilename());
773    }
774
775    /**
776    * Return an existing revision for a specific date which is
777    * the current one or younger or equal then the date
778    *
779    * @param string $id
780    * @param number $date_at timestamp
781    * @return string revision ('' for current)
782    */
783    function getLastRevisionAt($date_at){
784        //requested date_at(timestamp) younger or equal then modified_time($this->id) => load current
785        if($date_at >= @filemtime($this->getFilename())) {
786            return '';
787        } else if ($rev = $this->getRelativeRevision($date_at+1, -1)) { //+1 to get also the requested date revision
788            return $rev;
789        } else {
790            return false;
791        }
792    }
793}
794
795class PageChangelog extends ChangeLog {
796
797    /**
798     * Returns path to changelog
799     *
800     * @return string path to file
801     */
802    protected function getChangelogFilename() {
803        return metaFN($this->id, '.changes');
804    }
805
806    /**
807     * Returns path to current page/media
808     *
809     * @return string path to file
810     */
811    protected function getFilename() {
812        return wikiFN($this->id);
813    }
814}
815
816class MediaChangelog extends ChangeLog {
817
818    /**
819     * Returns path to changelog
820     *
821     * @return string path to file
822     */
823    protected function getChangelogFilename() {
824        return mediaMetaFN($this->id, '.changes');
825    }
826
827    /**
828     * Returns path to current page/media
829     *
830     * @return string path to file
831     */
832    protected function getFilename() {
833        return mediaFN($this->id);
834    }
835}
836
837
838/**
839 * Get the changelog information for a specific page id
840 * and revision (timestamp). Adjacent changelog lines
841 * are optimistically parsed and cached to speed up
842 * consecutive calls to getRevisionInfo. For large
843 * changelog files, only the chunk containing the
844 * requested changelog line is read.
845 *
846 * @deprecated 20-11-2013
847 *
848 * @author Ben Coburn <btcoburn@silicodon.net>
849 * @author Kate Arzamastseva <pshns@ukr.net>
850 */
851function getRevisionInfo($id, $rev, $chunk_size=8192, $media=false) {
852    if($media) {
853        $changelog = new MediaChangeLog($id, $chunk_size);
854    } else {
855        $changelog = new PageChangeLog($id, $chunk_size);
856    }
857    return $changelog->getRevisionInfo($rev);
858}
859
860/**
861 * Return a list of page revisions numbers
862 * Does not guarantee that the revision exists in the attic,
863 * only that a line with the date exists in the changelog.
864 * By default the current revision is skipped.
865 *
866 * id:    the page of interest
867 * first: skip the first n changelog lines
868 * num:   number of revisions to return
869 *
870 * The current revision is automatically skipped when the page exists.
871 * See $INFO['meta']['last_change'] for the current revision.
872 *
873 * For efficiency, the log lines are parsed and cached for later
874 * calls to getRevisionInfo. Large changelog files are read
875 * backwards in chunks until the requested number of changelog
876 * lines are recieved.
877 *
878 * @deprecated 20-11-2013
879 *
880 * @author Ben Coburn <btcoburn@silicodon.net>
881 * @author Kate Arzamastseva <pshns@ukr.net>
882 */
883function getRevisions($id, $first, $num, $chunk_size=8192, $media=false) {
884    if($media) {
885        $changelog = new MediaChangeLog($id, $chunk_size);
886    } else {
887        $changelog = new PageChangeLog($id, $chunk_size);
888    }
889    return $changelog->getRevisions($first, $num);
890}
891
892