xref: /dokuwiki/inc/changelog.php (revision 5c2eed9a193e9341fbfee63d4a973898acdc5ee5)
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 PageRevisionLog
338 */
339class PageRevisionLog {
340
341    /** @var string */
342    private $id;
343    /** @var int */
344    private $chunk_size;
345    /** @var array */
346    private $cache;
347
348    /**
349     * Constructor
350     *
351     * @param string $id         page id
352     * @param int    $chunk_size maximum block size read from file
353     */
354    public function __construct($id, $chunk_size = 8192) {
355        global $cache_revinfo;
356
357        $this->cache =& $cache_revinfo;
358        if(!isset($this->cache[$id])) {
359            $this->cache[$id] = array();
360        }
361
362        $this->id = $id;
363        $this->setChunkSize($chunk_size);
364
365    }
366
367    /**
368     * Set chunk size for file reading
369     *
370     * @param int $chunk_size maximum block size read from file
371     */
372    public function setChunkSize($chunk_size) {
373        if(!is_numeric($chunk_size)) $chunk_size = 0;
374
375        $this->chunk_size = (int) max($chunk_size, 0);
376    }
377
378    /**
379     * Get the changelog information for a specific page id and revision (timestamp)
380     *
381     * Adjacent changelog lines are optimistically parsed and cached to speed up
382     * consecutive calls to getRevisionInfo. For large changelog files, only the chunk
383     * containing the requested changelog line is read.
384     *
385     * @param int  $rev        revision timestamp
386     * @param bool $media      look into media log?
387     * @return bool|array false or array with entries:
388     *      - date:  unix timestamp
389     *      - ip:    IPv4 address (127.0.0.1)
390     *      - type:  log line type
391     *      - id:    page id
392     *      - user:  user name
393     *      - sum:   edit summary (or action reason)
394     *      - extra: extra data (varies by line type)
395     *
396     * @author Ben Coburn <btcoburn@silicodon.net>
397     * @author Kate Arzamastseva <pshns@ukr.net>
398     */
399    public function getRevisionInfo($rev, $media = false) {
400        $rev = max($rev, 0);
401
402        // check if it's already in the memory cache
403        if(isset($this->cache[$this->id]) && isset($this->cache[$this->id][$rev])) {
404            return $this->cache[$this->id][$rev];
405        }
406
407        //read lines from changelog
408        list($fp, $lines) = $this->readloglines($media, $rev);
409        if($fp) {
410            fclose($fp);
411        }
412        if(empty($lines)) return false;
413
414        // parse and cache changelog lines
415        foreach($lines as $value) {
416            $tmp = parseChangelogLine($value);
417            if($tmp !== false) {
418                $this->cache[$this->id][$tmp['date']] = $tmp;
419            }
420        }
421        if(!isset($this->cache[$this->id][$rev])) {
422            return false;
423        }
424        return $this->cache[$this->id][$rev];
425    }
426
427    /**
428     * Return a list of page revisions numbers
429     *
430     * Does not guarantee that the revision exists in the attic,
431     * only that a line with the date exists in the changelog.
432     * By default the current revision is skipped.
433     *
434     * The current revision is automatically skipped when the page exists.
435     * See $INFO['meta']['last_change'] for the current revision.
436     * A negative $first let read the current revision too.
437     *
438     * For efficiency, the log lines are parsed and cached for later
439     * calls to getRevisionInfo. Large changelog files are read
440     * backwards in chunks until the requested number of changelog
441     * lines are recieved.
442     *
443     * @param int  $first      skip the first n changelog lines
444     * @param int  $num        number of revisions to return
445     * @param bool $media      look into media log?
446     * @return array with the revision timestamps
447     *
448     * @author Ben Coburn <btcoburn@silicodon.net>
449     * @author Kate Arzamastseva <pshns@ukr.net>
450     */
451    public function getRevisions($first, $num, $media = false) {
452        $revs = array();
453        $lines = array();
454        $count  = 0;
455        if ($media) {
456            $file = mediaMetaFN($this->id, '.changes');
457        } else {
458            $file = metaFN($this->id, '.changes');
459        }
460        $num = max($num, 0);
461        if ($num == 0) { return $revs; }
462
463        $this->chunk_size = max($this->chunk_size, 0);
464        if ($first<0) {
465            $first = 0;
466        } else if (!$media && @file_exists(wikiFN($this->id)) || $media && @file_exists(mediaFN($this->id))) {
467            // skip current revision if the page exists
468            $first = max($first+1, 0);
469        }
470
471        if (!@file_exists($file)) { return $revs; }
472        if (filesize($file)<$this->chunk_size || $this->chunk_size==0) {
473            // read whole file
474            $lines = file($file);
475            if ($lines===false) { return $revs; }
476        } else {
477            // read chunks backwards
478            $fp = fopen($file, 'rb'); // "file pointer"
479            if ($fp===false) { return $revs; }
480            fseek($fp, 0, SEEK_END);
481            $tail = ftell($fp);
482
483            // chunk backwards
484            $finger = max($tail-$this->chunk_size, 0);
485            while ($count<$num+$first) {
486                fseek($fp, $finger);
487                $nl = $finger;
488                if ($finger>0) {
489                    fgets($fp); // slip the finger forward to a new line
490                    $nl = ftell($fp);
491                }
492
493                // was the chunk big enough? if not, take another bite
494                if($nl > 0 && $tail <= $nl){
495                    $finger = max($finger-$this->chunk_size, 0);
496                    continue;
497                }else{
498                    $finger = $nl;
499                }
500
501                // read chunk
502                $chunk = '';
503                $read_size = max($tail-$finger, 0); // found chunk size
504                $got = 0;
505                while ($got<$read_size && !feof($fp)) {
506                    $tmp = @fread($fp, max($read_size-$got, 0));
507                    if ($tmp===false) { break; } //error state
508                    $got += strlen($tmp);
509                    $chunk .= $tmp;
510                }
511                $tmp = explode("\n", $chunk);
512                array_pop($tmp); // remove trailing newline
513
514                // combine with previous chunk
515                $count += count($tmp);
516                $lines = array_merge($tmp, $lines);
517
518                // next chunk
519                if ($finger==0) { break; } // already read all the lines
520                else {
521                    $tail = $finger;
522                    $finger = max($tail-$this->chunk_size, 0);
523                }
524            }
525            fclose($fp);
526        }
527
528        // skip parsing extra lines
529        $num = max(min(count($lines)-$first, $num), 0);
530        if      ($first>0 && $num>0)  { $lines = array_slice($lines, max(count($lines)-$first-$num, 0), $num); }
531        else if ($first>0 && $num==0) { $lines = array_slice($lines, 0, max(count($lines)-$first, 0)); }
532        else if ($first==0 && $num>0) { $lines = array_slice($lines, max(count($lines)-$num, 0)); }
533
534        // handle lines in reverse order
535        for ($i = count($lines)-1; $i >= 0; $i--) {
536            $tmp = parseChangelogLine($lines[$i]);
537            if ($tmp!==false) {
538                $this->cache[$this->id][$tmp['date']] = $tmp;
539                $revs[] = $tmp['date'];
540            }
541        }
542
543        return $revs;
544    }
545
546    /**
547     * Get the nth revision left or right handside  for a specific page id and revision (timestamp)
548     *
549     * For large changelog files, only the chunk containing the
550     * reference revision $rev is read and sometimes a next chunck.
551     *
552     * Adjacent changelog lines are optimistically parsed and cached to speed up
553     * consecutive calls to getRevisionInfo.
554     *
555     * @param int  $rev        revision timestamp used as startdate (doesn't need to be revisionnumber)
556     * @param int  $direction  give position of returned revision with respect to $rev; positive=next, negative=prev
557     * @param bool $media      look into media log?
558     * @return bool|int
559     *      timestamp of the requested revision
560     *      otherwise false
561     */
562    public function getRelativeRevision($rev, $direction, $media = false) {
563        $rev = max($rev, 0);
564        $direction = (int) $direction;
565
566        //no direction given or last rev, so no follow-up
567        if(!$direction || ($direction > 0 && $this->isCurrentRevision($rev)) ) {
568            return false;
569        }
570
571        //get lines from changelog
572        list($fp, $lines, $head, $tail, $eof) = $this->readloglines($media, $rev);
573        if(empty($lines)) return false;
574
575        // look for revisions later/earlier then $rev, when founded count till the wanted revision is reached
576        // also parse and cache changelog lines for getRevisionInfo().
577        $revcounter       = 0;
578        $relativerev      = false;
579        $checkotherchunck = true; //always runs once
580        while(!$relativerev && $checkotherchunck) {
581            $tmp = array();
582            //parse in normal or reverse order
583            $count = count($lines);
584            if($direction > 0) {
585                $start = 0;
586                $step  = 1;
587            } else {
588                $start = $count - 1;
589                $step  = -1;
590            }
591            for($i = $start; $i >= 0 && $i < $count; $i = $i + $step) {
592                $tmp = parseChangelogLine($lines[$i]);
593                if($tmp !== false) {
594                    $this->cache[$this->id][$tmp['date']] = $tmp;
595                    //look for revs older/earlier then reference $rev and select $direction-th one
596                    if(($direction > 0 && $tmp['date'] > $rev) || ($direction < 0 && $tmp['date'] < $rev)) {
597                        $revcounter++;
598                        if($revcounter == abs($direction)) {
599                            $relativerev = $tmp['date'];
600                        }
601                    }
602                }
603            }
604
605            //true when $rev is found, but not the wanted follow-up.
606            $checkotherchunck = $fp
607                && ($tmp['date'] == $rev || ($revcounter > 0 && !$relativerev))
608                && !(($tail == $eof && $direction > 0) || ($head == 0 && $direction < 0));
609
610            if($checkotherchunck) {
611                //search bounds of chunck, rounded on new line, but smaller than $chunck_size
612                if($direction > 0) {
613                    $head        = $tail;
614                    $lookpointer = true;
615                    $tail        = $head + floor($this->chunk_size * (2 / 3));
616                    while($lookpointer) {
617                        $tail        = min($tail, $eof);
618                        $tail        = $this->getNewlinepointer($fp, $tail);
619                        $lookpointer = $tail - $head > $this->chunk_size;
620                        if($lookpointer) {
621                            $tail = $head + floor(($tail - $head) / 2);
622                        }
623                        if($tail == $head) break;
624                    }
625                } else {
626                    $tail = $head;
627                    $head = max($tail - $this->chunk_size, 0);
628                    $head = $this->getNewlinepointer($fp, $head);
629                }
630
631                //load next chunck
632                $lines = $this->readChunk($fp, $head, $tail);
633                if(empty($lines)) break;
634            }
635        }
636        if($fp) {
637            fclose($fp);
638        }
639
640        return $relativerev;
641    }
642
643
644    /**
645     * Returns lines from changelog.
646     * If file larger than $chuncksize, only chunck is read that could contain $rev.
647     *
648     * @param bool $media look into media log?
649     * @param int  $rev   revision timestamp
650     * @return array(fp, array(changeloglines), $head, $tail, $eof)|bool
651     *     returns false when not succeed. fp only defined for chuck reading, needs closing.
652     */
653    protected function readloglines($media, $rev) {
654        if($media) {
655            $file = mediaMetaFN($this->id, '.changes');
656        } else {
657            $file = metaFN($this->id, '.changes');
658        }
659
660        if(!@file_exists($file)) {
661            return false;
662        }
663
664        $fp    = null;
665        $head  = 0;
666        $tail  = 0;
667        $eof   = 0;
668
669        if(filesize($file) < $this->chunk_size || $this->chunk_size == 0) {
670            // read whole file
671            $lines = file($file);
672            if($lines === false) {
673                return false;
674            }
675        } else {
676            // read by chunk
677            $fp = fopen($file, 'rb'); // "file pointer"
678            if($fp === false) {
679                return false;
680            }
681            $head = 0;
682            fseek($fp, 0, SEEK_END);
683            $eof        = ftell($fp);
684            $tail       = $eof;
685
686            // find chunk
687            while($tail - $head > $this->chunk_size) {
688                $finger     = $head + floor(($tail - $head) / 2.0);
689                $finger     = $this->getNewlinepointer($fp, $finger);
690                $tmp        = fgets($fp);
691                $tmp        = parseChangelogLine($tmp);
692                $finger_rev = $tmp['date'];
693                if($finger == $head || $finger == $tail) {
694                    break;
695                }
696                if($finger_rev > $rev) {
697                    $tail = $finger;
698                } else {
699                    $head = $finger;
700                }
701            }
702
703            if($tail - $head < 1) {
704                // cound not find chunk, assume requested rev is missing
705                fclose($fp);
706                return false;
707            }
708
709            $lines = $this->readChunk($fp, $head, $tail);
710        }
711        return array(
712            $fp,
713            $lines,
714            $head,
715            $tail,
716            $eof
717        );
718    }
719
720    /**
721     * Read chunk and return array with lines of given chunck.
722     * Has no check if $head and $tail are really at a new line
723     *
724     * @param $fp resource filepointer
725     * @param $head int start point chunck
726     * @param $tail int end point chunck
727     * @return array lines read from chunck
728     */
729    protected function readChunk($fp, $head, $tail) {
730        $chunk      = '';
731        $chunk_size = max($tail - $head, 0); // found chunk size
732        $got        = 0;
733        fseek($fp, $head);
734        while($got < $chunk_size && !feof($fp)) {
735            $tmp = @fread($fp, max($chunk_size - $got, 0));
736            if($tmp === false) { //error state
737                break;
738            }
739            $got += strlen($tmp);
740            $chunk .= $tmp;
741        }
742        $lines = explode("\n", $chunk);
743        array_pop($lines); // remove trailing newline
744        return $lines;
745    }
746
747    /**
748     * Set pointer to first new line after $finger and return its position
749     *
750     * @param $fp resource filepointer
751     * @param $finger int a pointer
752     * @return int pointer
753     */
754    protected function getNewlinepointer($fp, $finger) {
755        fseek($fp, $finger);
756        fgets($fp); // slip the finger forward to a new line
757        return ftell($fp);
758    }
759
760    /**
761     * Check whether given revision is the current page
762     *
763     * @param int $rev timestamp of current page
764     * @return bool true if $rev is current revision, otherwise false
765     */
766    public function isCurrentRevision($rev){
767        return isset($INFO['meta']['last_change']) && $rev == $INFO['meta']['last_change']['date'];
768    }
769}
770
771/**
772 * Get the changelog information for a specific page id
773 * and revision (timestamp). Adjacent changelog lines
774 * are optimistically parsed and cached to speed up
775 * consecutive calls to getRevisionInfo. For large
776 * changelog files, only the chunk containing the
777 * requested changelog line is read.
778 *
779 * @deprecated 20-11-2013
780 *
781 * @author Ben Coburn <btcoburn@silicodon.net>
782 * @author Kate Arzamastseva <pshns@ukr.net>
783 */
784function getRevisionInfo($id, $rev, $chunk_size=8192, $media=false) {
785
786    $log = new PageRevisionLog($id, $chunk_size);
787    return $log->getRevisionInfo($rev, $media);
788}
789
790/**
791 * Return a list of page revisions numbers
792 * Does not guarantee that the revision exists in the attic,
793 * only that a line with the date exists in the changelog.
794 * By default the current revision is skipped.
795 *
796 * id:    the page of interest
797 * first: skip the first n changelog lines
798 * num:   number of revisions to return
799 *
800 * The current revision is automatically skipped when the page exists.
801 * See $INFO['meta']['last_change'] for the current revision.
802 *
803 * For efficiency, the log lines are parsed and cached for later
804 * calls to getRevisionInfo. Large changelog files are read
805 * backwards in chunks until the requested number of changelog
806 * lines are recieved.
807 *
808 * @deprecated 20-11-2013
809 *
810 * @author Ben Coburn <btcoburn@silicodon.net>
811 * @author Kate Arzamastseva <pshns@ukr.net>
812 */
813function getRevisions($id, $first, $num, $chunk_size=8192, $media=false) {
814    $log = new PageRevisionLog($id, $chunk_size);
815    return $log->getRevisions($first, $num, $media);
816}
817
818/**
819* Return an existing revision for a specific date which is
820* the current one or less or equal then the date
821*
822* @param string $id
823* @param number $date_at
824* @param boolean $media
825* @return string revision ('' for current)
826*/
827function getProperRevision($id,$date_at,$media = false){
828    $create_time = @filemtime($media?mediaFN($id):wikiFN($id));
829    if(((int)$date_at) >= $create_time) { //requestet REV older then time($id) => load current
830        return '';
831    } else {
832        $log = new PageRevisionLog($id);
833        if($rev = $log->getRelativeRevision($date_at+1, -1,$media)) {
834            return $rev;
835        } else {
836            return false;
837        }
838    }
839}