xref: /dokuwiki/inc/changelog.php (revision 3213bf4e5dd55220bd7614bf0030e6e680b4c227)
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 *
22 * @param string $line changelog line
23 * @return array|bool parsed line or false
24 */
25function parseChangelogLine($line) {
26    $line = rtrim($line, "\n");
27    $tmp = explode("\t", $line);
28    if ($tmp!==false && count($tmp)>1) {
29        $info = array();
30        $info['date']  = (int)$tmp[0]; // unix timestamp
31        $info['ip']    = $tmp[1]; // IPv4 address (127.0.0.1)
32        $info['type']  = $tmp[2]; // log line type
33        $info['id']    = $tmp[3]; // page id
34        $info['user']  = $tmp[4]; // user name
35        $info['sum']   = $tmp[5]; // edit summary (or action reason)
36        $info['extra'] = $tmp[6]; // extra data (varies by line type)
37        if(isset($tmp[7]) && $tmp[7] !== '') { //last item has line-end||
38            $info['sizechange'] = (int) $tmp[7];
39        } else {
40            $info['sizechange'] = null;
41        }
42        return $info;
43    } else {
44        return false;
45    }
46}
47
48/**
49 * Add's an entry to the changelog and saves the metadata for the page
50 *
51 * @param int    $date      Timestamp of the change
52 * @param String $id        Name of the affected page
53 * @param String $type      Type of the change see DOKU_CHANGE_TYPE_*
54 * @param String $summary   Summary of the change
55 * @param mixed  $extra     In case of a revert the revision (timestmp) of the reverted page
56 * @param array  $flags     Additional flags in a key value array.
57 *                             Available flags:
58 *                             - ExternalEdit - mark as an external edit.
59 * @param null|int $sizechange Change of filesize
60 *
61 * @author Andreas Gohr <andi@splitbrain.org>
62 * @author Esther Brunner <wikidesign@gmail.com>
63 * @author Ben Coburn <btcoburn@silicodon.net>
64 */
65function addLogEntry($date, $id, $type=DOKU_CHANGE_TYPE_EDIT, $summary='', $extra='', $flags=null, $sizechange = null){
66    global $conf, $INFO;
67    /** @var Input $INPUT */
68    global $INPUT;
69
70    // check for special flags as keys
71    if (!is_array($flags)) { $flags = array(); }
72    $flagExternalEdit = isset($flags['ExternalEdit']);
73
74    $id = cleanid($id);
75    $file = wikiFN($id);
76    $created = @filectime($file);
77    $minor = ($type===DOKU_CHANGE_TYPE_MINOR_EDIT);
78    $wasRemoved = ($type===DOKU_CHANGE_TYPE_DELETE);
79
80    if(!$date) $date = time(); //use current time if none supplied
81    $remote = (!$flagExternalEdit)?clientIP(true):'127.0.0.1';
82    $user   = (!$flagExternalEdit)?$INPUT->server->str('REMOTE_USER'):'';
83    if($sizechange === null) {
84        $sizechange = '';
85    } else {
86        $sizechange = (int) $sizechange;
87    }
88
89    $strip = array("\t", "\n");
90    $logline = array(
91        'date'       => $date,
92        'ip'         => $remote,
93        'type'       => str_replace($strip, '', $type),
94        'id'         => $id,
95        'user'       => $user,
96        'sum'        => utf8_substr(str_replace($strip, '', $summary), 0, 255),
97        'extra'      => str_replace($strip, '', $extra),
98        'sizechange' => $sizechange
99    );
100
101    $wasCreated = ($type===DOKU_CHANGE_TYPE_CREATE);
102    $wasReverted = ($type===DOKU_CHANGE_TYPE_REVERT);
103    // update metadata
104    if (!$wasRemoved) {
105        $oldmeta = p_read_metadata($id);
106        $meta    = array();
107        if ($wasCreated && empty($oldmeta['persistent']['date']['created'])){
108            // newly created
109            $meta['date']['created'] = $created;
110            if ($user){
111                $meta['creator'] = $INFO['userinfo']['name'];
112                $meta['user']    = $user;
113            }
114        } elseif (($wasCreated || $wasReverted) && !empty($oldmeta['persistent']['date']['created'])) {
115            // re-created / restored
116            $meta['date']['created']  = $oldmeta['persistent']['date']['created'];
117            $meta['date']['modified'] = $created; // use the files ctime here
118            $meta['creator'] = $oldmeta['persistent']['creator'];
119            if ($user) $meta['contributor'][$user] = $INFO['userinfo']['name'];
120        } elseif (!$minor) {   // non-minor modification
121            $meta['date']['modified'] = $date;
122            if ($user) $meta['contributor'][$user] = $INFO['userinfo']['name'];
123        }
124        $meta['last_change'] = $logline;
125        p_set_metadata($id, $meta);
126    }
127
128    // add changelog lines
129    $logline = implode("\t", $logline)."\n";
130    io_saveFile(metaFN($id,'.changes'),$logline,true); //page changelog
131    io_saveFile($conf['changelog'],$logline,true); //global changelog cache
132}
133
134/**
135 * Add's an entry to the media changelog
136 *
137 * @author Michael Hamann <michael@content-space.de>
138 * @author Andreas Gohr <andi@splitbrain.org>
139 * @author Esther Brunner <wikidesign@gmail.com>
140 * @author Ben Coburn <btcoburn@silicodon.net>
141 *
142 * @param int    $date      Timestamp of the change
143 * @param String $id        Name of the affected page
144 * @param String $type      Type of the change see DOKU_CHANGE_TYPE_*
145 * @param String $summary   Summary of the change
146 * @param mixed  $extra     In case of a revert the revision (timestmp) of the reverted page
147 * @param array  $flags     Additional flags in a key value array.
148 *                             Available flags:
149 *                             - (none, so far)
150 * @param null|int $sizechange Change of filesize
151 */
152function addMediaLogEntry(
153    $date,
154    $id,
155    $type=DOKU_CHANGE_TYPE_EDIT,
156    $summary='',
157    $extra='',
158    $flags=null,
159    $sizechange = null)
160{
161    global $conf;
162    /** @var Input $INPUT */
163    global $INPUT;
164
165    $id = cleanid($id);
166
167    if(!$date) $date = time(); //use current time if none supplied
168    $remote = clientIP(true);
169    $user   = $INPUT->server->str('REMOTE_USER');
170    if($sizechange === null) {
171        $sizechange = '';
172    } else {
173        $sizechange = (int) $sizechange;
174    }
175
176    $strip = array("\t", "\n");
177    $logline = array(
178        'date'       => $date,
179        'ip'         => $remote,
180        'type'       => str_replace($strip, '', $type),
181        'id'         => $id,
182        'user'       => $user,
183        'sum'        => utf8_substr(str_replace($strip, '', $summary), 0, 255),
184        'extra'      => str_replace($strip, '', $extra),
185        'sizechange' => $sizechange
186    );
187
188    // add changelog lines
189    $logline = implode("\t", $logline)."\n";
190    io_saveFile($conf['media_changelog'],$logline,true); //global media changelog cache
191    io_saveFile(mediaMetaFN($id,'.changes'),$logline,true); //media file's changelog
192}
193
194/**
195 * returns an array of recently changed files using the
196 * changelog
197 *
198 * The following constants can be used to control which changes are
199 * included. Add them together as needed.
200 *
201 * RECENTS_SKIP_DELETED   - don't include deleted pages
202 * RECENTS_SKIP_MINORS    - don't include minor changes
203 * RECENTS_SKIP_SUBSPACES - don't include subspaces
204 * RECENTS_MEDIA_CHANGES  - return media changes instead of page changes
205 * RECENTS_MEDIA_PAGES_MIXED  - return both media changes and page changes
206 *
207 * @param int    $first   number of first entry returned (for paginating
208 * @param int    $num     return $num entries
209 * @param string $ns      restrict to given namespace
210 * @param int    $flags   see above
211 * @return array recently changed files
212 *
213 * @author Ben Coburn <btcoburn@silicodon.net>
214 * @author Kate Arzamastseva <pshns@ukr.net>
215 */
216function getRecents($first,$num,$ns='',$flags=0){
217    global $conf;
218    $recent = array();
219    $count  = 0;
220
221    if(!$num)
222        return $recent;
223
224    // read all recent changes. (kept short)
225    if ($flags & RECENTS_MEDIA_CHANGES) {
226        $lines = @file($conf['media_changelog']);
227    } else {
228        $lines = @file($conf['changelog']);
229    }
230    $lines_position = count($lines)-1;
231    $media_lines_position = 0;
232    $media_lines = array();
233
234    if ($flags & RECENTS_MEDIA_PAGES_MIXED) {
235        $media_lines = @file($conf['media_changelog']);
236        $media_lines_position = count($media_lines)-1;
237    }
238
239    $seen = array(); // caches seen lines, _handleRecent() skips them
240
241    // handle lines
242    while ($lines_position >= 0 || (($flags & RECENTS_MEDIA_PAGES_MIXED) && $media_lines_position >=0)) {
243        if (empty($rec) && $lines_position >= 0) {
244            $rec = _handleRecent(@$lines[$lines_position], $ns, $flags, $seen);
245            if (!$rec) {
246                $lines_position --;
247                continue;
248            }
249        }
250        if (($flags & RECENTS_MEDIA_PAGES_MIXED) && empty($media_rec) && $media_lines_position >= 0) {
251            $media_rec = _handleRecent(
252                @$media_lines[$media_lines_position],
253                $ns,
254                $flags | RECENTS_MEDIA_CHANGES,
255                $seen
256            );
257            if (!$media_rec) {
258                $media_lines_position --;
259                continue;
260            }
261        }
262        if (($flags & RECENTS_MEDIA_PAGES_MIXED) && @$media_rec['date'] >= @$rec['date']) {
263            $media_lines_position--;
264            $x = $media_rec;
265            $x['media'] = true;
266            $media_rec = false;
267        } else {
268            $lines_position--;
269            $x = $rec;
270            if ($flags & RECENTS_MEDIA_CHANGES) $x['media'] = true;
271            $rec = false;
272        }
273        if(--$first >= 0) continue; // skip first entries
274        $recent[] = $x;
275        $count++;
276        // break when we have enough entries
277        if($count >= $num){ break; }
278    }
279    return $recent;
280}
281
282/**
283 * returns an array of files changed since a given time using the
284 * changelog
285 *
286 * The following constants can be used to control which changes are
287 * included. Add them together as needed.
288 *
289 * RECENTS_SKIP_DELETED   - don't include deleted pages
290 * RECENTS_SKIP_MINORS    - don't include minor changes
291 * RECENTS_SKIP_SUBSPACES - don't include subspaces
292 * RECENTS_MEDIA_CHANGES  - return media changes instead of page changes
293 *
294 * @param int    $from    date of the oldest entry to return
295 * @param int    $to      date of the newest entry to return (for pagination, optional)
296 * @param string $ns      restrict to given namespace (optional)
297 * @param int    $flags   see above (optional)
298 * @return array of files
299 *
300 * @author Michael Hamann <michael@content-space.de>
301 * @author Ben Coburn <btcoburn@silicodon.net>
302 */
303function getRecentsSince($from,$to=null,$ns='',$flags=0){
304    global $conf;
305    $recent = array();
306
307    if($to && $to < $from)
308        return $recent;
309
310    // read all recent changes. (kept short)
311    if ($flags & RECENTS_MEDIA_CHANGES) {
312        $lines = @file($conf['media_changelog']);
313    } else {
314        $lines = @file($conf['changelog']);
315    }
316    if(!$lines) return $recent;
317
318    // we start searching at the end of the list
319    $lines = array_reverse($lines);
320
321    // handle lines
322    $seen = array(); // caches seen lines, _handleRecent() skips them
323
324    foreach($lines as $line){
325        $rec = _handleRecent($line, $ns, $flags, $seen);
326        if($rec !== false) {
327            if ($rec['date'] >= $from) {
328                if (!$to || $rec['date'] <= $to) {
329                    $recent[] = $rec;
330                }
331            } else {
332                break;
333            }
334        }
335    }
336
337    return array_reverse($recent);
338}
339
340/**
341 * Internal function used by getRecents
342 *
343 * don't call directly
344 *
345 * @see getRecents()
346 * @author Andreas Gohr <andi@splitbrain.org>
347 * @author Ben Coburn <btcoburn@silicodon.net>
348 *
349 * @param string $line   changelog line
350 * @param string $ns     restrict to given namespace
351 * @param int    $flags  flags to control which changes are included
352 * @param array  $seen   listing of seen pages
353 * @return array|bool    false or array with info about a change
354 */
355function _handleRecent($line,$ns,$flags,&$seen){
356    if(empty($line)) return false;   //skip empty lines
357
358    // split the line into parts
359    $recent = parseChangelogLine($line);
360    if ($recent===false) { return false; }
361
362    // skip seen ones
363    if(isset($seen[$recent['id']])) return false;
364
365    // skip minors
366    if($recent['type']===DOKU_CHANGE_TYPE_MINOR_EDIT && ($flags & RECENTS_SKIP_MINORS)) return false;
367
368    // remember in seen to skip additional sights
369    $seen[$recent['id']] = 1;
370
371    // check if it's a hidden page
372    if(isHiddenPage($recent['id'])) return false;
373
374    // filter namespace
375    if (($ns) && (strpos($recent['id'],$ns.':') !== 0)) return false;
376
377    // exclude subnamespaces
378    if (($flags & RECENTS_SKIP_SUBSPACES) && (getNS($recent['id']) != $ns)) return false;
379
380    // check ACL
381    if ($flags & RECENTS_MEDIA_CHANGES) {
382        $recent['perms'] = auth_quickaclcheck(getNS($recent['id']).':*');
383    } else {
384        $recent['perms'] = auth_quickaclcheck($recent['id']);
385    }
386    if ($recent['perms'] < AUTH_READ) return false;
387
388    // check existance
389    if($flags & RECENTS_SKIP_DELETED){
390        $fn = (($flags & RECENTS_MEDIA_CHANGES) ? mediaFN($recent['id']) : wikiFN($recent['id']));
391        if(!file_exists($fn)) return false;
392    }
393
394    return $recent;
395}
396
397/**
398 * Class ChangeLog
399 * methods for handling of changelog of pages or media files
400 */
401abstract class ChangeLog {
402
403    /** @var string */
404    protected $id;
405    /** @var int */
406    protected $chunk_size;
407    /** @var array */
408    protected $cache;
409
410    /**
411     * Constructor
412     *
413     * @param string $id         page id
414     * @param int $chunk_size maximum block size read from file
415     */
416    public function __construct($id, $chunk_size = 8192) {
417        global $cache_revinfo;
418
419        $this->cache =& $cache_revinfo;
420        if(!isset($this->cache[$id])) {
421            $this->cache[$id] = array();
422        }
423
424        $this->id = $id;
425        $this->setChunkSize($chunk_size);
426
427    }
428
429    /**
430     * Set chunk size for file reading
431     * Chunk size zero let read whole file at once
432     *
433     * @param int $chunk_size maximum block size read from file
434     */
435    public function setChunkSize($chunk_size) {
436        if(!is_numeric($chunk_size)) $chunk_size = 0;
437
438        $this->chunk_size = (int) max($chunk_size, 0);
439    }
440
441    /**
442     * Returns path to changelog
443     *
444     * @return string path to file
445     */
446    abstract protected function getChangelogFilename();
447
448    /**
449     * Returns path to current page/media
450     *
451     * @return string path to file
452     */
453    abstract protected function getFilename();
454
455    /**
456     * Get the changelog information for a specific page id and revision (timestamp)
457     *
458     * Adjacent changelog lines are optimistically parsed and cached to speed up
459     * consecutive calls to getRevisionInfo. For large changelog files, only the chunk
460     * containing the requested changelog line is read.
461     *
462     * @param int $rev        revision timestamp
463     * @return bool|array false or array with entries:
464     *      - date:  unix timestamp
465     *      - ip:    IPv4 address (127.0.0.1)
466     *      - type:  log line type
467     *      - id:    page id
468     *      - user:  user name
469     *      - sum:   edit summary (or action reason)
470     *      - extra: extra data (varies by line type)
471     *
472     * @author Ben Coburn <btcoburn@silicodon.net>
473     * @author Kate Arzamastseva <pshns@ukr.net>
474     */
475    public function getRevisionInfo($rev) {
476        $rev = max($rev, 0);
477
478        // check if it's already in the memory cache
479        if(isset($this->cache[$this->id]) && isset($this->cache[$this->id][$rev])) {
480            return $this->cache[$this->id][$rev];
481        }
482
483        //read lines from changelog
484        list($fp, $lines) = $this->readloglines($rev);
485        if($fp) {
486            fclose($fp);
487        }
488        if(empty($lines)) return false;
489
490        // parse and cache changelog lines
491        foreach($lines as $value) {
492            $tmp = parseChangelogLine($value);
493            if($tmp !== false) {
494                $this->cache[$this->id][$tmp['date']] = $tmp;
495            }
496        }
497        if(!isset($this->cache[$this->id][$rev])) {
498            return false;
499        }
500        return $this->cache[$this->id][$rev];
501    }
502
503    /**
504     * Return a list of page revisions numbers
505     *
506     * Does not guarantee that the revision exists in the attic,
507     * only that a line with the date exists in the changelog.
508     * By default the current revision is skipped.
509     *
510     * The current revision is automatically skipped when the page exists.
511     * See $INFO['meta']['last_change'] for the current revision.
512     * A negative $first let read the current revision too.
513     *
514     * For efficiency, the log lines are parsed and cached for later
515     * calls to getRevisionInfo. Large changelog files are read
516     * backwards in chunks until the requested number of changelog
517     * lines are recieved.
518     *
519     * @param int $first      skip the first n changelog lines
520     * @param int $num        number of revisions to return
521     * @return array with the revision timestamps
522     *
523     * @author Ben Coburn <btcoburn@silicodon.net>
524     * @author Kate Arzamastseva <pshns@ukr.net>
525     */
526    public function getRevisions($first, $num) {
527        $revs = array();
528        $lines = array();
529        $count = 0;
530
531        $num = max($num, 0);
532        if($num == 0) {
533            return $revs;
534        }
535
536        if($first < 0) {
537            $first = 0;
538        } else if(file_exists($this->getFilename())) {
539            // skip current revision if the page exists
540            $first = max($first + 1, 0);
541        }
542
543        $file = $this->getChangelogFilename();
544
545        if(!file_exists($file)) {
546            return $revs;
547        }
548        if(filesize($file) < $this->chunk_size || $this->chunk_size == 0) {
549            // read whole file
550            $lines = file($file);
551            if($lines === false) {
552                return $revs;
553            }
554        } else {
555            // read chunks backwards
556            $fp = fopen($file, 'rb'); // "file pointer"
557            if($fp === false) {
558                return $revs;
559            }
560            fseek($fp, 0, SEEK_END);
561            $tail = ftell($fp);
562
563            // chunk backwards
564            $finger = max($tail - $this->chunk_size, 0);
565            while($count < $num + $first) {
566                $nl = $this->getNewlinepointer($fp, $finger);
567
568                // was the chunk big enough? if not, take another bite
569                if($nl > 0 && $tail <= $nl) {
570                    $finger = max($finger - $this->chunk_size, 0);
571                    continue;
572                } else {
573                    $finger = $nl;
574                }
575
576                // read chunk
577                $chunk = '';
578                $read_size = max($tail - $finger, 0); // found chunk size
579                $got = 0;
580                while($got < $read_size && !feof($fp)) {
581                    $tmp = @fread($fp, max(min($this->chunk_size, $read_size - $got), 0));
582                    if($tmp === false) {
583                        break;
584                    } //error state
585                    $got += strlen($tmp);
586                    $chunk .= $tmp;
587                }
588                $tmp = explode("\n", $chunk);
589                array_pop($tmp); // remove trailing newline
590
591                // combine with previous chunk
592                $count += count($tmp);
593                $lines = array_merge($tmp, $lines);
594
595                // next chunk
596                if($finger == 0) {
597                    break;
598                } // already read all the lines
599                else {
600                    $tail = $finger;
601                    $finger = max($tail - $this->chunk_size, 0);
602                }
603            }
604            fclose($fp);
605        }
606
607        // skip parsing extra lines
608        $num = max(min(count($lines) - $first, $num), 0);
609        if     ($first > 0 && $num > 0)  { $lines = array_slice($lines, max(count($lines) - $first - $num, 0), $num); }
610        else if($first > 0 && $num == 0) { $lines = array_slice($lines, 0, max(count($lines) - $first, 0)); }
611        else if($first == 0 && $num > 0) { $lines = array_slice($lines, max(count($lines) - $num, 0)); }
612
613        // handle lines in reverse order
614        for($i = count($lines) - 1; $i >= 0; $i--) {
615            $tmp = parseChangelogLine($lines[$i]);
616            if($tmp !== false) {
617                $this->cache[$this->id][$tmp['date']] = $tmp;
618                $revs[] = $tmp['date'];
619            }
620        }
621
622        return $revs;
623    }
624
625    /**
626     * Get the nth revision left or right handside  for a specific page id and revision (timestamp)
627     *
628     * For large changelog files, only the chunk containing the
629     * reference revision $rev is read and sometimes a next chunck.
630     *
631     * Adjacent changelog lines are optimistically parsed and cached to speed up
632     * consecutive calls to getRevisionInfo.
633     *
634     * @param int $rev        revision timestamp used as startdate (doesn't need to be revisionnumber)
635     * @param int $direction  give position of returned revision with respect to $rev; positive=next, negative=prev
636     * @return bool|int
637     *      timestamp of the requested revision
638     *      otherwise false
639     */
640    public function getRelativeRevision($rev, $direction) {
641        $rev = max($rev, 0);
642        $direction = (int) $direction;
643
644        //no direction given or last rev, so no follow-up
645        if(!$direction || ($direction > 0 && $this->isCurrentRevision($rev))) {
646            return false;
647        }
648
649        //get lines from changelog
650        list($fp, $lines, $head, $tail, $eof) = $this->readloglines($rev);
651        if(empty($lines)) return false;
652
653        // look for revisions later/earlier then $rev, when founded count till the wanted revision is reached
654        // also parse and cache changelog lines for getRevisionInfo().
655        $revcounter = 0;
656        $relativerev = false;
657        $checkotherchunck = true; //always runs once
658        while(!$relativerev && $checkotherchunck) {
659            $tmp = array();
660            //parse in normal or reverse order
661            $count = count($lines);
662            if($direction > 0) {
663                $start = 0;
664                $step = 1;
665            } else {
666                $start = $count - 1;
667                $step = -1;
668            }
669            for($i = $start; $i >= 0 && $i < $count; $i = $i + $step) {
670                $tmp = parseChangelogLine($lines[$i]);
671                if($tmp !== false) {
672                    $this->cache[$this->id][$tmp['date']] = $tmp;
673                    //look for revs older/earlier then reference $rev and select $direction-th one
674                    if(($direction > 0 && $tmp['date'] > $rev) || ($direction < 0 && $tmp['date'] < $rev)) {
675                        $revcounter++;
676                        if($revcounter == abs($direction)) {
677                            $relativerev = $tmp['date'];
678                        }
679                    }
680                }
681            }
682
683            //true when $rev is found, but not the wanted follow-up.
684            $checkotherchunck = $fp
685                && ($tmp['date'] == $rev || ($revcounter > 0 && !$relativerev))
686                && !(($tail == $eof && $direction > 0) || ($head == 0 && $direction < 0));
687
688            if($checkotherchunck) {
689                list($lines, $head, $tail) = $this->readAdjacentChunk($fp, $head, $tail, $direction);
690
691                if(empty($lines)) break;
692            }
693        }
694        if($fp) {
695            fclose($fp);
696        }
697
698        return $relativerev;
699    }
700
701    /**
702     * Returns revisions around rev1 and rev2
703     * When available it returns $max entries for each revision
704     *
705     * @param int $rev1 oldest revision timestamp
706     * @param int $rev2 newest revision timestamp (0 looks up last revision)
707     * @param int $max maximum number of revisions returned
708     * @return array with two arrays with revisions surrounding rev1 respectively rev2
709     */
710    public function getRevisionsAround($rev1, $rev2, $max = 50) {
711        $max = floor(abs($max) / 2)*2 + 1;
712        $rev1 = max($rev1, 0);
713        $rev2 = max($rev2, 0);
714
715        if($rev2) {
716            if($rev2 < $rev1) {
717                $rev = $rev2;
718                $rev2 = $rev1;
719                $rev1 = $rev;
720            }
721        } else {
722            //empty right side means a removed page. Look up last revision.
723            $revs = $this->getRevisions(-1, 1);
724            $rev2 = $revs[0];
725        }
726        //collect revisions around rev2
727        list($revs2, $allrevs, $fp, $lines, $head, $tail) = $this->retrieveRevisionsAround($rev2, $max);
728
729        if(empty($revs2)) return array(array(), array());
730
731        //collect revisions around rev1
732        $index = array_search($rev1, $allrevs);
733        if($index === false) {
734            //no overlapping revisions
735            list($revs1,,,,,) = $this->retrieveRevisionsAround($rev1, $max);
736            if(empty($revs1)) $revs1 = array();
737        } else {
738            //revisions overlaps, reuse revisions around rev2
739            $revs1 = $allrevs;
740            while($head > 0) {
741                for($i = count($lines) - 1; $i >= 0; $i--) {
742                    $tmp = parseChangelogLine($lines[$i]);
743                    if($tmp !== false) {
744                        $this->cache[$this->id][$tmp['date']] = $tmp;
745                        $revs1[] = $tmp['date'];
746                        $index++;
747
748                        if($index > floor($max / 2)) break 2;
749                    }
750                }
751
752                list($lines, $head, $tail) = $this->readAdjacentChunk($fp, $head, $tail, -1);
753            }
754            sort($revs1);
755            //return wanted selection
756            $revs1 = array_slice($revs1, max($index - floor($max/2), 0), $max);
757        }
758
759        return array(array_reverse($revs1), array_reverse($revs2));
760    }
761
762    /**
763     * Returns lines from changelog.
764     * If file larger than $chuncksize, only chunck is read that could contain $rev.
765     *
766     * @param int $rev   revision timestamp
767     * @return array|false
768     *     if success returns array(fp, array(changeloglines), $head, $tail, $eof)
769     *     where fp only defined for chuck reading, needs closing.
770     *     otherwise false
771     */
772    protected function readloglines($rev) {
773        $file = $this->getChangelogFilename();
774
775        if(!file_exists($file)) {
776            return false;
777        }
778
779        $fp = null;
780        $head = 0;
781        $tail = 0;
782        $eof = 0;
783
784        if(filesize($file) < $this->chunk_size || $this->chunk_size == 0) {
785            // read whole file
786            $lines = file($file);
787            if($lines === false) {
788                return false;
789            }
790        } else {
791            // read by chunk
792            $fp = fopen($file, 'rb'); // "file pointer"
793            if($fp === false) {
794                return false;
795            }
796            $head = 0;
797            fseek($fp, 0, SEEK_END);
798            $eof = ftell($fp);
799            $tail = $eof;
800
801            // find chunk
802            while($tail - $head > $this->chunk_size) {
803                $finger = $head + floor(($tail - $head) / 2.0);
804                $finger = $this->getNewlinepointer($fp, $finger);
805                $tmp = fgets($fp);
806                if($finger == $head || $finger == $tail) {
807                    break;
808                }
809                $tmp = parseChangelogLine($tmp);
810                $finger_rev = $tmp['date'];
811
812                if($finger_rev > $rev) {
813                    $tail = $finger;
814                } else {
815                    $head = $finger;
816                }
817            }
818
819            if($tail - $head < 1) {
820                // cound not find chunk, assume requested rev is missing
821                fclose($fp);
822                return false;
823            }
824
825            $lines = $this->readChunk($fp, $head, $tail);
826        }
827        return array(
828            $fp,
829            $lines,
830            $head,
831            $tail,
832            $eof
833        );
834    }
835
836    /**
837     * Read chunk and return array with lines of given chunck.
838     * Has no check if $head and $tail are really at a new line
839     *
840     * @param resource $fp    resource filepointer
841     * @param int      $head  start point chunck
842     * @param int      $tail  end point chunck
843     * @return array lines read from chunck
844     */
845    protected function readChunk($fp, $head, $tail) {
846        $chunk = '';
847        $chunk_size = max($tail - $head, 0); // found chunk size
848        $got = 0;
849        fseek($fp, $head);
850        while($got < $chunk_size && !feof($fp)) {
851            $tmp = @fread($fp, max(min($this->chunk_size, $chunk_size - $got), 0));
852            if($tmp === false) { //error state
853                break;
854            }
855            $got += strlen($tmp);
856            $chunk .= $tmp;
857        }
858        $lines = explode("\n", $chunk);
859        array_pop($lines); // remove trailing newline
860        return $lines;
861    }
862
863    /**
864     * Set pointer to first new line after $finger and return its position
865     *
866     * @param resource $fp      filepointer
867     * @param int      $finger  a pointer
868     * @return int pointer
869     */
870    protected function getNewlinepointer($fp, $finger) {
871        fseek($fp, $finger);
872        $nl = $finger;
873        if($finger > 0) {
874            fgets($fp); // slip the finger forward to a new line
875            $nl = ftell($fp);
876        }
877        return $nl;
878    }
879
880    /**
881     * Check whether given revision is the current page
882     *
883     * @param int $rev   timestamp of current page
884     * @return bool true if $rev is current revision, otherwise false
885     */
886    public function isCurrentRevision($rev) {
887        return $rev == @filemtime($this->getFilename());
888    }
889
890    /**
891    * Return an existing revision for a specific date which is
892    * the current one or younger or equal then the date
893    *
894    * @param number $date_at timestamp
895    * @return string revision ('' for current)
896    */
897    public function getLastRevisionAt($date_at){
898        //requested date_at(timestamp) younger or equal then modified_time($this->id) => load current
899        if(file_exists($this->getFilename()) && $date_at >= @filemtime($this->getFilename())) {
900            return '';
901        } else if ($rev = $this->getRelativeRevision($date_at+1, -1)) { //+1 to get also the requested date revision
902            return $rev;
903        } else {
904            return false;
905        }
906    }
907
908    /**
909     * Returns the next lines of the changelog  of the chunck before head or after tail
910     *
911     * @param resource $fp filepointer
912     * @param int $head position head of last chunk
913     * @param int $tail position tail of last chunk
914     * @param int $direction positive forward, negative backward
915     * @return array with entries:
916     *    - $lines: changelog lines of readed chunk
917     *    - $head: head of chunk
918     *    - $tail: tail of chunk
919     */
920    protected function readAdjacentChunk($fp, $head, $tail, $direction) {
921        if(!$fp) return array(array(), $head, $tail);
922
923        if($direction > 0) {
924            //read forward
925            $head = $tail;
926            $tail = $head + floor($this->chunk_size * (2 / 3));
927            $tail = $this->getNewlinepointer($fp, $tail);
928        } else {
929            //read backward
930            $tail = $head;
931            $head = max($tail - $this->chunk_size, 0);
932            while(true) {
933                $nl = $this->getNewlinepointer($fp, $head);
934                // was the chunk big enough? if not, take another bite
935                if($nl > 0 && $tail <= $nl) {
936                    $head = max($head - $this->chunk_size, 0);
937                } else {
938                    $head = $nl;
939                    break;
940                }
941            }
942        }
943
944        //load next chunck
945        $lines = $this->readChunk($fp, $head, $tail);
946        return array($lines, $head, $tail);
947    }
948
949    /**
950     * Collect the $max revisions near to the timestamp $rev
951     *
952     * @param int $rev revision timestamp
953     * @param int $max maximum number of revisions to be returned
954     * @return bool|array
955     *     return array with entries:
956     *       - $requestedrevs: array of with $max revision timestamps
957     *       - $revs: all parsed revision timestamps
958     *       - $fp: filepointer only defined for chuck reading, needs closing.
959     *       - $lines: non-parsed changelog lines before the parsed revisions
960     *       - $head: position of first readed changelogline
961     *       - $lasttail: position of end of last readed changelogline
962     *     otherwise false
963     */
964    protected function retrieveRevisionsAround($rev, $max) {
965        //get lines from changelog
966        list($fp, $lines, $starthead, $starttail, /* $eof */) = $this->readloglines($rev);
967        if(empty($lines)) return false;
968
969        //parse chunk containing $rev, and read forward more chunks until $max/2 is reached
970        $head = $starthead;
971        $tail = $starttail;
972        $revs = array();
973        $aftercount = $beforecount = 0;
974        while(count($lines) > 0) {
975            foreach($lines as $line) {
976                $tmp = parseChangelogLine($line);
977                if($tmp !== false) {
978                    $this->cache[$this->id][$tmp['date']] = $tmp;
979                    $revs[] = $tmp['date'];
980                    if($tmp['date'] >= $rev) {
981                        //count revs after reference $rev
982                        $aftercount++;
983                        if($aftercount == 1) $beforecount = count($revs);
984                    }
985                    //enough revs after reference $rev?
986                    if($aftercount > floor($max / 2)) break 2;
987                }
988            }
989            //retrieve next chunk
990            list($lines, $head, $tail) = $this->readAdjacentChunk($fp, $head, $tail, 1);
991        }
992        if($aftercount == 0) return false;
993
994        $lasttail = $tail;
995
996        //read additional chuncks backward until $max/2 is reached and total number of revs is equal to $max
997        $lines = array();
998        $i = 0;
999        if($aftercount > 0) {
1000            $head = $starthead;
1001            $tail = $starttail;
1002            while($head > 0) {
1003                list($lines, $head, $tail) = $this->readAdjacentChunk($fp, $head, $tail, -1);
1004
1005                for($i = count($lines) - 1; $i >= 0; $i--) {
1006                    $tmp = parseChangelogLine($lines[$i]);
1007                    if($tmp !== false) {
1008                        $this->cache[$this->id][$tmp['date']] = $tmp;
1009                        $revs[] = $tmp['date'];
1010                        $beforecount++;
1011                        //enough revs before reference $rev?
1012                        if($beforecount > max(floor($max / 2), $max - $aftercount)) break 2;
1013                    }
1014                }
1015            }
1016        }
1017        sort($revs);
1018
1019        //keep only non-parsed lines
1020        $lines = array_slice($lines, 0, $i);
1021        //trunk desired selection
1022        $requestedrevs = array_slice($revs, -$max, $max);
1023
1024        return array($requestedrevs, $revs, $fp, $lines, $head, $lasttail);
1025    }
1026}
1027
1028/**
1029 * Class PageChangelog handles changelog of a wiki page
1030 */
1031class PageChangelog extends ChangeLog {
1032
1033    /**
1034     * Returns path to changelog
1035     *
1036     * @return string path to file
1037     */
1038    protected function getChangelogFilename() {
1039        return metaFN($this->id, '.changes');
1040    }
1041
1042    /**
1043     * Returns path to current page/media
1044     *
1045     * @return string path to file
1046     */
1047    protected function getFilename() {
1048        return wikiFN($this->id);
1049    }
1050}
1051
1052/**
1053 * Class MediaChangelog handles changelog of a media file
1054 */
1055class MediaChangelog extends ChangeLog {
1056
1057    /**
1058     * Returns path to changelog
1059     *
1060     * @return string path to file
1061     */
1062    protected function getChangelogFilename() {
1063        return mediaMetaFN($this->id, '.changes');
1064    }
1065
1066    /**
1067     * Returns path to current page/media
1068     *
1069     * @return string path to file
1070     */
1071    protected function getFilename() {
1072        return mediaFN($this->id);
1073    }
1074}
1075