admin/health.php

   1 <?php
   2
   3     ob_start(); //for whitespace test
   4     require_once('../config.php');
   5
   6     // extra whitespace test - intentionally breaks cookieless mode
   7     $extraws = '';
   8     while (ob_get_level()) {
   9         $extraws .= ob_get_contents();
  10         ob_end_clean();
  11     }
  12
  13     require_once($CFG->libdir.'/adminlib.php');
  14
  15     admin_externalpage_setup('healthcenter');
  16
  17     define('SEVERITY_NOTICE',      'notice');
  18     define('SEVERITY_ANNOYANCE',   'annoyance');
  19     define('SEVERITY_SIGNIFICANT', 'significant');
  20     define('SEVERITY_CRITICAL',    'critical');
  21
  22     $solution = optional_param('solution', 0, PARAM_SAFEDIR); //in fact it is class name alhanumeric and _
  23
  24     require_login();
  25     require_capability('moodle/site:config', get_context_instance(CONTEXT_SYSTEM));
  26
  27     $site = get_site();
  28
  29     echo $OUTPUT->header();
  30
  31 echo <<<STYLES
  32 <style type="text/css">
  33 div#healthnoproblemsfound {
  34     width: 60%;
  35     margin: auto;
  36     padding: 1em;
  37     border: 1px black solid;
  38     -moz-border-radius: 6px;
  39 }
  40 dl.healthissues {
  41     width: 60%;
  42     margin: auto;
  43 }
  44 dl.critical dt, dl.critical dd {
  45     background-color: #a71501;
  46 }
  47 dl.significant dt, dl.significant dd {
  48     background-color: #d36707;
  49 }
  50 dl.annoyance dt, dl.annoyance dd {
  51     background-color: #dba707;
  52 }
  53 dl.notice dt, dl.notice dd {
  54     background-color: #e5db36;
  55 }
  56 dt.solution, dd.solution, div#healthnoproblemsfound {
  57     background-color: #5BB83E !important;
  58 }
  59 dl.healthissues dt, dl.healthissues dd {
  60     margin: 0px;
  61     padding: 1em;
  62     border: 1px black solid;
  63 }
  64 dl.healthissues dt {
  65     font-weight: bold;
  66     border-bottom: none;
  67     padding-bottom: 0.5em;
  68 }
  69 dl.healthissues dd {
  70     border-top: none;
  71     padding-top: 0.5em;
  72     margin-bottom: 10px;
  73 }
  74 dl.healthissues dd form {
  75     margin-top: 0.5em;
  76     text-align: right;
  77 }
  78 form#healthformreturn {
  79     text-align: center;
  80     margin: 2em;
  81 }
  82 dd.solution p {
  83     padding: 0px;
  84     margin: 1em 0px;
  85 }
  86 dd.solution li {
  87     margin-top: 1em;
  88 }
  89
  90 </style>
  91 STYLES;
  92
  93     if(strpos($solution, 'problem_') === 0 && class_exists($solution)) {
  94         health_print_solution($solution);
  95     }
  96     else {
  97         health_find_problems();
  98     }
  99
 100
 101     echo $OUTPUT->footer();
 102
 103
 104 function health_find_problems() {
 105     global $OUTPUT;
 106
 107     echo $OUTPUT->heading(get_string('healthcenter'));
 108
 109     $issues   = array(
 110         SEVERITY_CRITICAL    => array(),
 111         SEVERITY_SIGNIFICANT => array(),
 112         SEVERITY_ANNOYANCE   => array(),
 113         SEVERITY_NOTICE      => array(),
 114     );
 115     $problems = 0;
 116
 117     for($i = 1; $i < 1000000; ++$i) {
 118         $classname = sprintf('problem_%06d', $i);
 119         if(!class_exists($classname)) {
 120             break;
 121         }
 122         $problem = new $classname;
 123         if($problem->exists()) {
 124             $severity = $problem->severity();
 125             $issues[$severity][$classname] = array(
 126                 'severity'    => $severity,
 127                 'description' => $problem->description(),
 128                 'title'       => $problem->title()
 129             );
 130             ++$problems;
 131         }
 132         unset($problem);
 133     }
 134
 135     if($problems == 0) {
 136         echo '<div id="healthnoproblemsfound">';
 137         echo get_string('healthnoproblemsfound');
 138         echo '</div>';
 139     }
 140     else {
 141         echo $OUTPUT->heading(get_string('healthproblemsdetected'));
 142         $severities = array(SEVERITY_CRITICAL, SEVERITY_SIGNIFICANT, SEVERITY_ANNOYANCE, SEVERITY_NOTICE);
 143         foreach($severities as $severity) {
 144             if(!empty($issues[$severity])) {
 145                 echo '<dl class="healthissues '.$severity.'">';
 146                 foreach($issues[$severity] as $classname => $data) {
 147                     echo '<dt id="'.$classname.'">'.$data['title'].'</dt>';
 148                     echo '<dd>'.$data['description'];
 149                     echo '<form action="health.php#solution" method="get">';
 150                     echo '<input type="hidden" name="solution" value="'.$classname.'" /><input type="submit" value="'.get_string('viewsolution').'" />';
 151                     echo '</form></dd>';
 152                 }
 153                 echo '</dl>';
 154             }
 155         }
 156     }
 157 }
 158
 159 function health_print_solution($classname) {
 160     global $OUTPUT;
 161     $problem = new $classname;
 162     $data = array(
 163         'title'       => $problem->title(),
 164         'severity'    => $problem->severity(),
 165         'description' => $problem->description(),
 166         'solution'    => $problem->solution()
 167     );
 168
 169     echo $OUTPUT->heading(get_string('healthcenter'));
 170     echo $OUTPUT->heading(get_string('healthproblemsolution'));
 171     echo '<dl class="healthissues '.$data['severity'].'">';
 172     echo '<dt>'.$data['title'].'</dt>';
 173     echo '<dd>'.$data['description'].'</dd>';
 174     echo '<dt id="solution" class="solution">'.get_string('healthsolution').'</dt>';
 175     echo '<dd class="solution">'.$data['solution'].'</dd></dl>';
 176     echo '<form id="healthformreturn" action="health.php#'.$classname.'" method="get">';
 177     echo '<input type="submit" value="'.get_string('healthreturntomain').'" />';
 178     echo '</form>';
 179 }
 180
 181 class problem_base {
 182     function exists() {
 183         return false;
 184     }
 185     function title() {
 186         return '???';
 187     }
 188     function severity() {
 189         return SEVERITY_NOTICE;
 190     }
 191     function description() {
 192         return '';
 193     }
 194     function solution() {
 195         return '';
 196     }
 197 }
 198
 199 class problem_000002 extends problem_base {
 200     function title() {
 201         return 'Extra characters at the end of config.php or other library function';
 202     }
 203     function exists() {
 204         global $extraws;
 205
 206         if($extraws === '') {
 207             return false;
 208         }
 209         return true;
 210     }
 211     function severity() {
 212         return SEVERITY_SIGNIFICANT;
 213     }
 214     function description() {
 215         return 'Your Moodle configuration file config.php or another library file, contains some characters after the closing PHP tag (?>). This causes Moodle to exhibit several kinds of problems (such as broken downloaded files) and must be fixed.';
 216     }
 217     function solution() {
 218         global $CFG;
 219         return 'You need to edit <strong>'.$CFG->dirroot.'/config.php</strong> and remove all characters (including spaces and returns) after the ending ?> tag. These two characters should be the very last in that file. The extra trailing whitespace may be also present in other PHP files that are included from lib/setup.php.';
 220     }
 221 }
 222
 223 class problem_000003 extends problem_base {
 224     function title() {
 225         return '$CFG->dataroot does not exist or does not have write permissions';
 226     }
 227     function exists() {
 228         global $CFG;
 229         if(!is_dir($CFG->dataroot) || !is_writable($CFG->dataroot)) {
 230             return true;
 231         }
 232         return false;
 233     }
 234     function severity() {
 235         return SEVERITY_SIGNIFICANT;
 236     }
 237     function description() {
 238         global $CFG;
 239         return 'Your <strong>config.php</strong> says that your "data root" directory is <strong>'.$CFG->dataroot.'</strong>. However, this directory either does not exist or cannot be written to by Moodle. This means that a variety of problems will be present, such as users not being able to log in and not being able to upload any files. It is imperative that you address this problem for Moodle to work correctly.';
 240     }
 241     function solution() {
 242         global $CFG;
 243         return 'First of all, make sure that the directory <strong>'.$CFG->dataroot.'</strong> exists. If the directory does exist, then you must make sure that Moodle is able to write to it. Contact your web server administrator and request that he gives write permissions for that directory to the user that the web server process is running as.';
 244     }
 245 }
 246
 247 class problem_000004 extends problem_base {
 248     function title() {
 249         return 'cron.php is not set up to run automatically';
 250     }
 251     function exists() {
 252         global $DB;
 253         $lastcron = $DB->get_field_sql('SELECT max(lastcron) FROM {modules}');
 254         return (time() - $lastcron > 3600 * 24);
 255     }
 256     function severity() {
 257         return SEVERITY_SIGNIFICANT;
 258     }
 259     function description() {
 260         return 'The cron.php mainenance script has not been run in the past 24 hours. This probably means that your server is not configured to automatically run this script in regular time intervals. If this is the case, then Moodle will mostly work as it should but some operations (notably sending email to users) will not be carried out at all.';
 261     }
 262     function solution() {
 263         global $CFG;
 264         return 'For detailed instructions on how to enable cron, see <a href="'.$CFG->wwwroot.'/doc/?file=install.html#cron">this section</a> of the installation manual.';
 265     }
 266 }
 267
 268 class problem_000005 extends problem_base {
 269     function title() {
 270         return 'PHP: session.auto_start is enabled';
 271     }
 272     function exists() {
 273         return ini_get_bool('session.auto_start');
 274     }
 275     function severity() {
 276         return SEVERITY_CRITICAL;
 277     }
 278     function description() {
 279         return 'Your PHP configuration includes an enabled setting, session.auto_start, that <strong>must be disabled</strong> in order for Moodle to work correctly. Notable symptoms arising from this misconfiguration include fatal errors and/or blank pages when trying to log in.';
 280     }
 281     function solution() {
 282         global $CFG;
 283         return '<p>There are two ways you can solve this problem:</p><ol><li>If you have access to your main <strong>php.ini</strong> file, then find the line that looks like this: <pre>session.auto_start = 1</pre> and change it to <pre>session.auto_start = 0</pre> and then restart your web server. Be warned that this, as any other PHP setting change, might affect other web applications running on the server.</li><li>Finally, you may be able to change this setting just for your site by creating or editing the file <strong>'.$CFG->dirroot.'/.htaccess</strong> to contain this line: <pre>php_value session.auto_start "0"</pre></li></ol>';
 284     }
 285 }
 286
 287 class problem_000006 extends problem_base {
 288     function title() {
 289         return 'PHP: magic_quotes_runtime is enabled';
 290     }
 291     function exists() {
 292         return (ini_get_bool('magic_quotes_runtime'));
 293     }
 294     function severity() {
 295         return SEVERITY_SIGNIFICANT;
 296     }
 297     function description() {
 298         return 'Your PHP configuration includes an enabled setting, magic_quotes_runtime, that <strong>must be disabled</strong> in order for Moodle to work correctly. Notable symptoms arising from this misconfiguration include strange display errors whenever a text field that includes single or double quotes is processed.';
 299     }
 300     function solution() {
 301         global $CFG;
 302         return '<p>There are two ways you can solve this problem:</p><ol><li>If you have access to your main <strong>php.ini</strong> file, then find the line that looks like this: <pre>magic_quotes_runtime = On</pre> and change it to <pre>magic_quotes_runtime = Off</pre> and then restart your web server. Be warned that this, as any other PHP setting change, might affect other web applications running on the server.</li><li>Finally, you may be able to change this setting just for your site by creating or editing the file <strong>'.$CFG->dirroot.'/.htaccess</strong> to contain this line: <pre>php_value magic_quotes_runtime "Off"</pre></li></ol>';
 303     }
 304 }
 305
 306 class problem_000007 extends problem_base {
 307     function title() {
 308         return 'PHP: file_uploads is disabled';
 309     }
 310     function exists() {
 311         return !ini_get_bool('file_uploads');
 312     }
 313     function severity() {
 314         return SEVERITY_SIGNIFICANT;
 315     }
 316     function description() {
 317         return 'Your PHP configuration includes a disabled setting, file_uploads, that <strong>must be enabled</strong> to let Moodle offer its full functionality. Until this setting is enabled, it will not be possible to upload any files into Moodle. This includes, for example, course content and user pictures.';
 318     }
 319     function solution() {
 320         global $CFG;
 321         return '<p>There are two ways you can solve this problem:</p><ol><li>If you have access to your main <strong>php.ini</strong> file, then find the line that looks like this: <pre>file_uploads = Off</pre> and change it to <pre>file_uploads = On</pre> and then restart your web server. Be warned that this, as any other PHP setting change, might affect other web applications running on the server.</li><li>Finally, you may be able to change this setting just for your site by creating or editing the file <strong>'.$CFG->dirroot.'/.htaccess</strong> to contain this line: <pre>php_value file_uploads "On"</pre></li></ol>';
 322     }
 323 }
 324
 325 class problem_000008 extends problem_base {
 326     function title() {
 327         return 'PHP: memory_limit cannot be controlled by Moodle';
 328     }
 329     function exists() {
 330         global $CFG;
 331
 332         $oldmemlimit = @ini_get('memory_limit');
 333         if (empty($oldmemlimit)) {
 334             // PHP not compiled with memory limits, this means that it's
 335             // probably limited to 8M or in case of Windows not at all.
 336             // We can ignore it for now - there is not much to test anyway
 337             // TODO: add manual test that fills memory??
 338             return false;
 339         }
 340         $oldmemlimit = get_real_size($oldmemlimit);
 341         //now lets change the memory limit to something higher
 342         $newmemlimit = ($oldmemlimit + 1024*1024*5);
 343         raise_memory_limit($newmemlimit);
 344         $testmemlimit = get_real_size(@ini_get('memory_limit'));
 345         //verify the change had any effect at all
 346         if ($oldmemlimit == $testmemlimit) {
 347             //memory limit can not be changed - is it big enough then?
 348             if ($oldmemlimit < get_real_size('128M')) {
 349                 return true;
 350             } else {
 351                 return false;
 352             }
 353         }
 354         reduce_memory_limit($oldmemlimit);
 355         return false;
 356     }
 357     function severity() {
 358         return SEVERITY_NOTICE;
 359     }
 360     function description() {
 361         return 'The settings for PHP on your server do not allow a script to request more memory during its execution. '.
 362                'This means that there is a hard limit of '.@ini_get('memory_limit').' for each script. '.
 363                'It is possible that certain operations within Moodle will require more than this amount in order '.
 364                'to complete successfully, especially if there are lots of data to be processed.';
 365     }
 366     function solution() {
 367         return 'It is recommended that you contact your web server administrator to address this issue.';
 368     }
 369 }
 370
 371 class problem_000009 extends problem_base {
 372     function title() {
 373         return 'SQL: using account without password';
 374     }
 375     function exists() {
 376         global $CFG;
 377         return empty($CFG->dbpass);
 378     }
 379     function severity() {
 380         return SEVERITY_CRITICAL;
 381     }
 382     function description() {
 383         global $CFG;
 384         return 'The user account your are connecting to the database server with is set up without a password. This is a very big security risk and is only somewhat lessened if your database is configured to not accept connections from any hosts other than the server Moodle is running on. Unless you use a strong password to connect to the database, you risk unauthorized access to and manipulation of your data.'.($CFG->dbuser != 'root'?'':' <strong>This is especially alarming because such access to the database would be as the superuser (root)!</strong>');
 385     }
 386     function solution() {
 387         global $CFG;
 388         return 'You should change the password of the user <strong>'.$CFG->dbuser.'</strong> both in your database and in your Moodle <strong>config.php</strong> immediately!'.($CFG->dbuser != 'root'?'':' It would also be a good idea to change the user account from root to something else, because this would lessen the impact in the event that your database is compromised anyway.');
 389     }
 390 }
 391 /* // not implemented in 2.0 yet
 392 class problem_000010 extends problem_base {
 393     function title() {
 394         return 'Uploaded files: slasharguments disabled or not working';
 395     }
 396     function exists() {
 397         if (!$this->is_enabled()) {
 398             return true;
 399         }
 400         if ($this->status() < 1) {
 401             return true;
 402         }
 403         return false;
 404     }
 405     function severity() {
 406         if ($this->is_enabled() and $this->status() == 0) {
 407             return SEVERITY_SIGNIFICANT;
 408         } else {
 409             return SEVERITY_ANNOYANCE;
 410         }
 411     }
 412     function description() {
 413         global $CFG;
 414         $desc = 'Slasharguments are needed for relative linking in uploaded resources:<ul>';
 415         if (!$this->is_enabled()) {
 416             $desc .= '<li>slasharguments are <strong>disabled</strong> in Moodle configuration</li>';
 417         } else {
 418             $desc .= '<li>slasharguments are enabled in Moodle configuration</li>';
 419         }
 420         if ($this->status() == -1) {
 421             $desc .= '<li>can not run automatic test, you can verify it <a href="'.$CFG->wwwroot.'/file.php/testslasharguments" target="_blank">here</a> manually</li>';
 422         } else if ($this->status() == 0) {
 423             $desc .= '<li>slashargument test <strong>failed</strong>, please check server configuration</li>';
 424         } else {
 425             $desc .= '<li>slashargument test passed</li>';
 426         }
 427         $desc .= '</ul>';
 428         return $desc;
 429     }
 430     function solution() {
 431         global $CFG;
 432         $enabled = $this->is_enabled();
 433         $status = $this->status();
 434         $solution = '';
 435         if ($enabled and ($status == 0)) {
 436             $solution .= 'Slasharguments are enabled, but the test failed. Please disable slasharguments in Moodle configuration or fix the server configuration.<hr />';
 437         } else if ((!$enabled) and ($status == 0)) {
 438             $solution .= 'Slasharguments are disabled and the test failed. You may try to fix the server configuration.<hr />';
 439         } else if ($enabled and ($status == -1)) {
 440             $solution .= 'Slasharguments are enabled, <a href="'.$CFG->wwwroot.'/file.php/testslasharguments">automatic testing</a> not possible.<hr />';
 441         } else if ((!$enabled) and ($status == -1)) {
 442             $solution .= 'Slasharguments are disabled, <a href="'.$CFG->wwwroot.'/file.php/testslasharguments">automatic testing</a> not possible.<hr />';
 443         } else if ((!$enabled) and ($status > 0)) {
 444             $solution .= 'Slasharguments are disabled though the iternal test is OK. You should enable slasharguments in Moodle configuration.';
 445         } else if ($enabled and ($status > 0)) {
 446             $solution .= 'Congratulations - everything seems OK now :-D';
 447         }
 448         if ($status < 1) {
 449             $solution .= '<p>IIS:<ul><li>try to add <code>cgi.fix_pathinfo=1</code> to php.ini</li><li>do NOT enable AllowPathInfoForScriptMappings !!!</li><li>slasharguments may not work when using ISAPI and PHP 4.3.10 and older</li></ul></p>';
 450             $solution .= '<p>Apache 1:<ul><li>try to add <code>cgi.fix_pathinfo=1</code> to php.ini</li></ul></p>';
 451             $solution .= '<p>Apache 2:<ul><li>you must add <code>AcceptPathInfo on</code> to php.ini or .htaccess</li><li>try to add <code>cgi.fix_pathinfo=1</code> to php.ini</li></ul></p>';
 452         }
 453         return $solution;
 454     }
 455     function is_enabled() {
 456         global $CFG;
 457         return !empty($CFG->slasharguments);
 458     }
 459     function status() {
 460         global $CFG;
 461         $handle = @fopen($CFG->wwwroot.'/file.php?file=/testslasharguments', "r");
 462         $contents = @trim(fread($handle, 10));
 463         @fclose($handle);
 464         if ($contents != 'test -1') {
 465             return -1;
 466         }
 467         $handle = @fopen($CFG->wwwroot.'/file.php/testslasharguments', "r");
 468         $contents = trim(@fread($handle, 10));
 469         @fclose($handle);
 470         switch ($contents) {
 471             case 'test 1': return 1;
 472             case 'test 2': return 2;
 473             default:  return 0;
 474         }
 475     }
 476 }*/
 477
 478 class problem_000012 extends problem_base {
 479     function title() {
 480         return 'Random questions data consistency';
 481     }
 482     function exists() {
 483         global $DB;
 484         return $DB->record_exists_select('question', "qtype = 'random' AND parent <> id", array());
 485     }
 486     function severity() {
 487         return SEVERITY_ANNOYANCE;
 488     }
 489     function description() {
 490         return '<p>For random questions, question.parent should equal question.id. ' .
 491         'There are some questions in your database for which this is not true. ' .
 492         'One way that this could have happened is for random questions restored from backup before ' .
 493         '<a href="http://tracker.moodle.org/browse/MDL-5482">MDL-5482</a> was fixed.</p>';
 494     }
 495     function solution() {
 496         global $CFG;
 497         return '<p>Upgrade to Moodle 1.9.1 or later, or manually execute the SQL</p>' .
 498         '<pre>UPDATE ' . $CFG->prefix . 'question SET parent = id WHERE qtype = \'random\' and parent &lt;> id;</pre>';
 499     }
 500 }
 501
 502 class problem_000013 extends problem_base {
 503     function title() {
 504         return 'Multi-answer questions data consistency';
 505     }
 506     function exists() {
 507         global $DB;
 508         $positionexpr = $DB->sql_position($DB->sql_concat("','", "q.id", "','"),
 509                 $DB->sql_concat("','", "qma.sequence", "','"));
 510         return $DB->record_exists_sql("
 511                 SELECT * FROM {question} q
 512                     JOIN {question_multianswer} qma ON $positionexpr > 0
 513                 WHERE qma.question <> q.parent") ||
 514             $DB->record_exists_sql("
 515                 SELECT * FROM {question} q
 516                     JOIN {question} parent_q ON parent_q.id = q.parent
 517                 WHERE q.category <> parent_q.category");
 518     }
 519     function severity() {
 520         return SEVERITY_ANNOYANCE;
 521     }
 522     function description() {
 523         return '<p>For each sub-question whose id is listed in ' .
 524         'question_multianswer.sequence, its question.parent field should equal ' .
 525         'question_multianswer.question; and each sub-question should be in the same ' .
 526         'category as its parent. There are questions in your database for ' .
 527         'which this is not the case. One way that this could have happened is ' .
 528         'for multi-answer questions restored from backup before ' .
 529         '<a href="http://tracker.moodle.org/browse/MDL-14750">MDL-14750</a> was fixed.</p>';
 530     }
 531     function solution() {
 532         return '<p>Upgrade to Moodle 1.9.1 or later, or manually execute the ' .
 533         'code in question_multianswer_fix_subquestion_parents_and_categories in ' .
 534         '<a href="http://cvs.moodle.org/moodle/question/type/multianswer/db/upgrade.php?revision=1.1.10.2&amp;view=markup">/question/type/multianswer/db/upgrade.php' .
 535         'from the 1.9 stable branch</a>.</p>';
 536     }
 537 }
 538
 539 class problem_000014 extends problem_base {
 540     function title() {
 541         return 'Only multianswer and random questions should be the parent of another question';
 542     }
 543     function exists() {
 544         global $DB;
 545         return $DB->record_exists_sql("
 546                 SELECT * FROM {question} q
 547                     JOIN {question} parent_q ON parent_q.id = q.parent
 548                 WHERE parent_q.qtype NOT IN ('random', 'multianswer')");
 549     }
 550     function severity() {
 551         return SEVERITY_ANNOYANCE;
 552     }
 553     function description() {
 554         return '<p>You have questions that violate this in your databse. ' .
 555         'You will need to investigate to determine how this happened.</p>';
 556     }
 557     function solution() {
 558         return '<p>It is impossible to give a solution without knowing more about ' .
 559         ' how the problem was caused. You may be able to get help from the ' .
 560         '<a href="http://moodle.org/mod/forum/view.php?f=121">Quiz forum</a>.</p>';
 561     }
 562 }
 563
 564 class problem_000015 extends problem_base {
 565     function title() {
 566         return 'Question categories should belong to a valid context';
 567     }
 568     function exists() {
 569         global $DB;
 570         return $DB->record_exists_sql("
 571             SELECT qc.*, (SELECT COUNT(1) FROM {question} q WHERE q.category = qc.id) AS numquestions
 572             FROM {question_categories} qc
 573                 LEFT JOIN {context} con ON qc.contextid = con.id
 574             WHERE con.id IS NULL");
 575     }
 576     function severity() {
 577         return SEVERITY_ANNOYANCE;
 578     }
 579     function description() {
 580         global $DB;
 581         $problemcategories = $DB->get_records_sql("
 582             SELECT qc.id, qc.name, qc.contextid, (SELECT COUNT(1) FROM {question} q WHERE q.category = qc.id) AS numquestions
 583             FROM {question_categories} qc
 584                 LEFT JOIN {context} con ON qc.contextid = con.id
 585             WHERE con.id IS NULL
 586             ORDER BY numquestions DESC, qc.name");
 587         $table = '<table><thead><tr><th>Cat id</th><th>Category name</th>' .
 588         "<th>Context id</th><th>Num Questions</th></tr></thead><tbody>\n";
 589         foreach ($problemcategories as $cat) {
 590             $table .= "<tr><td>$cat->id</td><td>" . s($cat->name) . "</td><td>" .
 591             $cat->contextid ."</td><td>$cat->numquestions</td></tr>\n";
 592         }
 593         $table .= '</tbody></table>';
 594         return '<p>All question categories are linked to a context id, and, ' .
 595         'the context they are linked to must exist. The following categories ' .
 596         'belong to a non-existant category:</p>' . $table . '<p>Any of these ' .
 597         'categories that contain no questions can just be deleted form the database. ' .
 598         'Other categories will require more thought.</p>';
 599     }
 600     function solution() {
 601         global $CFG;
 602         return '<p>You can delete the empty categories by executing the following SQL:</p><pre>
 603 DELETE FROM ' . $CFG->prefix . 'question_categories
 604 WHERE
 605     NOT EXISTS (SELECT * FROM ' . $CFG->prefix . 'question q WHERE q.category = ' . $CFG->prefix . 'question_categories.id)
 606 AND NOT EXISTS (SELECT * FROM ' . $CFG->prefix . 'context con WHERE contextid = con.id)
 607         </pre><p>Any remaining categories that contain questions will require more thought. ' .
 608         'People in the <a href="http://moodle.org/mod/forum/view.php?f=121">Quiz forum</a> may be able to help.</p>';
 609     }
 610 }
 611
 612 class problem_000016 extends problem_base {
 613     function title() {
 614         return 'Question categories should belong to the same context as their parent';
 615     }
 616     function exists() {
 617         global $DB;
 618         return $DB->record_exists_sql("
 619             SELECT parent_qc.id AS parent, child_qc.id AS child, child_qc.contextid
 620             FROM {question_categories} child_qc
 621                 JOIN {question_categories} parent_qc ON child_qc.parent = parent_qc.id
 622             WHERE child_qc.contextid <> parent_qc.contextid");
 623     }
 624     function severity() {
 625         return SEVERITY_ANNOYANCE;
 626     }
 627     function description() {
 628         global $DB;
 629         $problemcategories = $DB->get_records_sql("
 630             SELECT
 631                 parent_qc.id AS parentid, parent_qc.name AS parentname, parent_qc.contextid AS parentcon,
 632                 child_qc.id AS childid, child_qc.name AS childname, child_qc.contextid AS childcon
 633             FROM {question_categories} child_qc
 634                 JOIN {question_categories} parent_qc ON child_qc.parent = parent_qc.id
 635             WHERE child_qc.contextid <> parent_qc.contextid");
 636         $table = '<table><thead><tr><th colspan="3">Child category</th><th colspan="3">Parent category</th></tr><tr>' .
 637         '<th>Id</th><th>Name</th><th>Context id</th>' .
 638         '<th>Id</th><th>Name</th><th>Context id</th>' .
 639         "</tr></thead><tbody>\n";
 640         foreach ($problemcategories as $cat) {
 641             $table .= "<tr><td>$cat->childid</td><td>" . s($cat->childname) .
 642             "</td><td>$cat->childcon</td><td>$cat->parentid</td><td>" . s($cat->parentname) .
 643             "</td><td>$cat->parentcon</td></tr>\n";
 644         }
 645         $table .= '</tbody></table>';
 646         return '<p>When one question category is the parent of another, then they ' .
 647         'should both belong to the same context. This is not true for the following categories:</p>' .
 648         $table;
 649     }
 650     function solution() {
 651         return '<p>An automated solution is difficult. It depends whether the ' .
 652         'parent or child category is in the wrong pace.' .
 653         'People in the <a href="http://moodle.org/mod/forum/view.php?f=121">Quiz forum</a> may be able to help.</p>';
 654     }
 655 }
 656
 657 class problem_000017 extends problem_base {
 658     function title() {
 659         return 'Question categories tree structure';
 660     }
 661     function find_problems() {
 662         global $DB;
 663         static $answer = null;
 664
 665         if (is_null($answer)) {
 666             $categories = $DB->get_records('question_categories', array(), 'id');
 667
 668             // Look for missing parents.
 669             $missingparent = array();
 670             foreach ($categories as $category) {
 671                 if ($category->parent != 0 && !array_key_exists($category->parent, $categories)) {
 672                     $missingparent[$category->id] = $category;
 673                 }
 674             }
 675
 676             // Look for loops.
 677             $loops = array();
 678             while (!empty($categories)) {
 679                 $current = array_pop($categories);
 680                 $thisloop = array($current->id => $current);
 681                 while (true) {
 682                     if (isset($thisloop[$current->parent])) {
 683                         // Loop detected
 684                         $loops[$current->id] = $thisloop;
 685                         break;
 686                     } else if (!isset($categories[$current->parent])) {
 687                         // Got to the top level, or a category we already know is OK.
 688                         break;
 689                     } else {
 690                         // Continue following the path.
 691                         $current = $categories[$current->parent];
 692                         $thisloop[$current->id] = $current;
 693                         unset($categories[$current->id]);
 694                     }
 695                 }
 696             }
 697
 698             $answer = array($missingparent, $loops);
 699         }
 700
 701         return $answer;
 702     }
 703     function exists() {
 704         list($missingparent, $loops) = $this->find_problems();
 705         return !empty($missingparent) || !empty($loops);
 706     }
 707     function severity() {
 708         return SEVERITY_ANNOYANCE;
 709     }
 710     function description() {
 711         list($missingparent, $loops) = $this->find_problems();
 712
 713         $description = '<p>The question categories should be arranged into tree ' .
 714                 ' structures by the question_categories.parent field. Sometimes ' .
 715                 ' this tree structure gets messed up.</p>';
 716
 717         if (!empty($missingparent)) {
 718             $description .= '<p>The following categories are missing their parents:</p><ul>';
 719             foreach ($missingparent as $cat) {
 720                 $description .= "<li>Category $cat->id: " . s($cat->name) . "</li>\n";
 721             }
 722             $description .= "</ul>\n";
 723         }
 724
 725         if (!empty($loops)) {
 726             $description .= '<p>The following categories form a loop of parents:</p><ul>';
 727             foreach ($loops as $loop) {
 728                 $description .= "<li><ul>\n";
 729                 foreach ($loop as $cat) {
 730                     $description .= "<li>Category $cat->id: " . s($cat->name) . " has parent $cat->parent</li>\n";
 731                 }
 732                 $description .= "</ul></li>\n";
 733             }
 734             $description .= "</ul>\n";
 735         }
 736
 737         return $description;
 738     }
 739     function solution() {
 740         global $CFG;
 741         list($missingparent, $loops) = $this->find_problems();
 742
 743         $solution = '<p>Consider executing the following SQL queries. These fix ' .
 744                 'the problem by moving some categories to the top level.</p>';
 745
 746         if (!empty($missingparent)) {
 747             $solution .= "<pre>UPDATE " . $CFG->prefix . "question_categories\n" .
 748                     "        SET parent = 0\n" .
 749                     "        WHERE id IN (" . implode(',', array_keys($missingparent)) . ");</pre>\n";
 750         }
 751
 752         if (!empty($loops)) {
 753             $solution .= "<pre>UPDATE " . $CFG->prefix . "question_categories\n" .
 754                     "        SET parent = 0\n" .
 755                     "        WHERE id IN (" . implode(',', array_keys($loops)) . ");</pre>\n";
 756         }
 757
 758         return $solution;
 759     }
 760 }
 761
 762 class problem_00000x extends problem_base {
 763     function title() {
 764         return '';
 765     }
 766     function exists() {
 767         return false;
 768     }
 769     function severity() {
 770         return SEVERITY_SIGNIFICANT;
 771     }
 772     function description() {
 773         return '';
 774     }
 775     function solution() {
 776         global $CFG;
 777         return '';
 778     }
 779 }
 780
 781 /*
 782
 783 TODO:
 784
 785     session.save_path -- it doesn't really matter because we are already IN a session, right?
 786     detect unsupported characters in $CFG->wwwroot - see bug Bug #6091 - relative vs absolute path during backup/restore process
 787
 788 */
 789
 790