admin/health.php

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