includes/Exception.php

   1 <?php
   2 /**
   3  * Exception class and handler
   4  *
   5  * @file
   6  */
   7
   8 /**
   9  * @defgroup Exception Exception
  10  */
  11
  12 /**
  13  * MediaWiki exception
  14  *
  15  * @ingroup Exception
  16  */
  17 class MWException extends Exception {
  18         /**
  19          * Should the exception use $wgOut to output the error ?
  20          * @return bool
  21          */
  22         function useOutputPage() {
  23                 return $this->useMessageCache() &&
  24                         !empty( $GLOBALS['wgFullyInitialised'] ) &&
  25                         ( !empty( $GLOBALS['wgArticle'] ) || ( !empty( $GLOBALS['wgOut'] ) && !$GLOBALS['wgOut']->isArticleRelated() ) ) &&
  26                         !empty( $GLOBALS['wgTitle'] );
  27         }
  28
  29         /**
  30          * Can the extension use wfMsg() to get i18n messages ?
  31          * @return bool
  32          */
  33         function useMessageCache() {
  34                 global $wgLang;
  35
  36                 foreach ( $this->getTrace() as $frame ) {
  37                         if ( isset( $frame['class'] ) && $frame['class'] === 'LocalisationCache' ) {
  38                                 return false;
  39                         }
  40                 }
  41
  42                 return is_object( $wgLang );
  43         }
  44
  45         /**
  46          * Run hook to allow extensions to modify the text of the exception
  47          *
  48          * @param $name String: class name of the exception
  49          * @param $args Array: arguments to pass to the callback functions
  50          * @return Mixed: string to output or null if any hook has been called
  51          */
  52         function runHooks( $name, $args = array() ) {
  53                 global $wgExceptionHooks;
  54
  55                 if ( !isset( $wgExceptionHooks ) || !is_array( $wgExceptionHooks ) ) {
  56                         return; // Just silently ignore
  57                 }
  58
  59                 if ( !array_key_exists( $name, $wgExceptionHooks ) || !is_array( $wgExceptionHooks[ $name ] ) ) {
  60                         return;
  61                 }
  62
  63                 $hooks = $wgExceptionHooks[ $name ];
  64                 $callargs = array_merge( array( $this ), $args );
  65
  66                 foreach ( $hooks as $hook ) {
  67                         if ( is_string( $hook ) || ( is_array( $hook ) && count( $hook ) >= 2 && is_string( $hook[0] ) ) ) {    // 'function' or array( 'class', hook' )
  68                                 $result = call_user_func_array( $hook, $callargs );
  69                         } else {
  70                                 $result = null;
  71                         }
  72
  73                         if ( is_string( $result ) )
  74                                 return $result;
  75                 }
  76         }
  77
  78         /**
  79          * Get a message from i18n
  80          *
  81          * @param $key String: message name
  82          * @param $fallback String: default message if the message cache can't be
  83          *                  called by the exception
  84          * The function also has other parameters that are arguments for the message
  85          * @return String message with arguments replaced
  86          */
  87         function msg( $key, $fallback /*[, params...] */ ) {
  88                 $args = array_slice( func_get_args(), 2 );
  89
  90                 if ( $this->useMessageCache() ) {
  91                         return wfMsgReal( $key, $args );
  92                 } else {
  93                         return wfMsgReplaceArgs( $fallback, $args );
  94                 }
  95         }
  96
  97         /**
  98          * If $wgShowExceptionDetails is true, return a HTML message with a
  99          * backtrace to the error, otherwise show a message to ask to set it to true
 100          * to show that information.
 101          *
 102          * @return String html to output
 103          */
 104         function getHTML() {
 105                 global $wgShowExceptionDetails;
 106
 107                 if ( $wgShowExceptionDetails ) {
 108                         return '<p>' . nl2br( htmlspecialchars( $this->getMessage() ) ) .
 109                                 '</p><p>Backtrace:</p><p>' . nl2br( htmlspecialchars( $this->getTraceAsString() ) ) .
 110                                 "</p>\n";
 111                 } else {
 112                         return "<p>Set <b><tt>\$wgShowExceptionDetails = true;</tt></b> " .
 113                                 "at the bottom of LocalSettings.php to show detailed " .
 114                                 "debugging information.</p>";
 115                 }
 116         }
 117
 118         /**
 119          * If $wgShowExceptionDetails is true, return a text message with a
 120          * backtrace to the error.
 121          */
 122         function getText() {
 123                 global $wgShowExceptionDetails;
 124
 125                 if ( $wgShowExceptionDetails ) {
 126                         return $this->getMessage() .
 127                                 "\nBacktrace:\n" . $this->getTraceAsString() . "\n";
 128                 } else {
 129                         return "Set \$wgShowExceptionDetails = true; " .
 130                                 "in LocalSettings.php to show detailed debugging information.\n";
 131                 }
 132         }
 133
 134         /* Return titles of this error page */
 135         function getPageTitle() {
 136                 if ( $this->useMessageCache() ) {
 137                         return wfMsg( 'internalerror' );
 138                 } else {
 139                         global $wgSitename;
 140
 141                         return "$wgSitename error";
 142                 }
 143         }
 144
 145         /**
 146          * Return the requested URL and point to file and line number from which the
 147          * exception occured
 148          *
 149          * @return String
 150          */
 151         function getLogMessage() {
 152                 global $wgRequest;
 153
 154                 $file = $this->getFile();
 155                 $line = $this->getLine();
 156                 $message = $this->getMessage();
 157
 158                 if ( isset( $wgRequest ) ) {
 159                         $url = $wgRequest->getRequestURL();
 160                         if ( !$url ) {
 161                                 $url = '[no URL]';
 162                         }
 163                 } else {
 164                         $url = '[no req]';
 165                 }
 166
 167                 return "$url   Exception from line $line of $file: $message";
 168         }
 169
 170         /** Output the exception report using HTML */
 171         function reportHTML() {
 172                 global $wgOut;
 173
 174                 if ( $this->useOutputPage() ) {
 175                         $wgOut->setPageTitle( $this->getPageTitle() );
 176                         $wgOut->setRobotPolicy( "noindex,nofollow" );
 177                         $wgOut->setArticleRelated( false );
 178                         $wgOut->enableClientCache( false );
 179                         $wgOut->redirect( '' );
 180                         $wgOut->clearHTML();
 181
 182                         $hookResult = $this->runHooks( get_class( $this ) );
 183                         if ( $hookResult ) {
 184                                 $wgOut->addHTML( $hookResult );
 185                         } else {
 186                                 $wgOut->addHTML( $this->getHTML() );
 187                         }
 188
 189                         $wgOut->output();
 190                 } else {
 191                         $hookResult = $this->runHooks( get_class( $this ) . "Raw" );
 192                         if ( $hookResult ) {
 193                                 die( $hookResult );
 194                         }
 195
 196                         if ( defined( 'MEDIAWIKI_INSTALL' ) || $this->htmlBodyOnly() ) {
 197                                 echo $this->getHTML();
 198                         } else {
 199                                 echo $this->htmlHeader();
 200                                 echo $this->getHTML();
 201                                 echo $this->htmlFooter();
 202                         }
 203                 }
 204         }
 205
 206         /**
 207          * Output a report about the exception and takes care of formatting.
 208          * It will be either HTML or plain text based on isCommandLine().
 209          */
 210         function report() {
 211                 $log = $this->getLogMessage();
 212
 213                 if ( $log ) {
 214                         wfDebugLog( 'exception', $log );
 215                 }
 216
 217                 if ( self::isCommandLine() ) {
 218                         wfPrintError( $this->getText() );
 219                 } else {
 220                         $this->reportHTML();
 221                 }
 222         }
 223
 224         /**
 225          * Send headers and output the beginning of the html page if not using
 226          * $wgOut to output the exception.
 227          */
 228         function htmlHeader() {
 229                 global $wgLogo, $wgOutputEncoding, $wgLang;
 230
 231                 if ( !headers_sent() ) {
 232                         header( 'HTTP/1.0 500 Internal Server Error' );
 233                         header( 'Content-type: text/html; charset=' . $wgOutputEncoding );
 234                         /* Don't cache error pages!  They cause no end of trouble... */
 235                         header( 'Cache-control: none' );
 236                         header( 'Pragma: nocache' );
 237                 }
 238
 239                 $title = Html::element( 'title', null, $this->getPageTitle() );
 240
 241                 $left = $wgLang->alignStart();
 242                 $right = $wgLang->alignEnd();
 243                 $header = Html::element( 'img', array(
 244                         'src' => $wgLogo,
 245                         'style' => "float: $left; margin-$right: 1em;",
 246                         'alt' => '' ), $this->getPageTitle() );
 247
 248                 $attribs = array( 'dir' => $wgLang->getDir(), 'lang' => $wgLang->getCode() );
 249
 250                 return
 251                         Html::htmlHeader( $attribs ) .
 252                         Html::rawElement( 'head', null, $title ) . "\n".
 253                         Html::openElement( 'body' ) . "\n" .
 254                         Html::rawElement( 'h1', null, $header ) . "\n";
 255         }
 256
 257         /**
 258          * print the end of the html page if not using $wgOut.
 259          */
 260         function htmlFooter() {
 261                 return Html::closeElement( 'body' ) . Html::closeElement( 'html' );
 262         }
 263
 264         /**
 265          * headers handled by subclass?
 266          */
 267         function htmlBodyOnly() {
 268                 return false;
 269         }
 270
 271         static function isCommandLine() {
 272                 return !empty( $GLOBALS['wgCommandLineMode'] ) && !defined( 'MEDIAWIKI_INSTALL' );
 273         }
 274 }
 275
 276 /**
 277  * Exception class which takes an HTML error message, and does not
 278  * produce a backtrace. Replacement for OutputPage::fatalError().
 279  * @ingroup Exception
 280  */
 281 class FatalError extends MWException {
 282         function getHTML() {
 283                 return $this->getMessage();
 284         }
 285
 286         function getText() {
 287                 return $this->getMessage();
 288         }
 289 }
 290
 291 /**
 292  * @ingroup Exception
 293  */
 294 class ErrorPageError extends MWException {
 295         public $title, $msg;
 296
 297         /**
 298          * Note: these arguments are keys into wfMsg(), not text!
 299          */
 300         function __construct( $title, $msg ) {
 301                 $this->title = $title;
 302                 $this->msg = $msg;
 303                 parent::__construct( wfMsg( $msg ) );
 304         }
 305
 306         function report() {
 307                 global $wgOut;
 308
 309                 $wgOut->showErrorPage( $this->title, $this->msg );
 310                 $wgOut->output();
 311         }
 312 }
 313
 314 /**
 315  * Install an exception handler for MediaWiki exception types.
 316  */
 317 function wfInstallExceptionHandler() {
 318         set_exception_handler( 'wfExceptionHandler' );
 319 }
 320
 321 /**
 322  * Report an exception to the user
 323  */
 324 function wfReportException( Exception $e ) {
 325         global $wgShowExceptionDetails;
 326
 327         $cmdLine = MWException::isCommandLine();
 328
 329         if ( $e instanceof MWException ) {
 330                 try {
 331                         $e->report();
 332                 } catch ( Exception $e2 ) {
 333                         // Exception occurred from within exception handler
 334                         // Show a simpler error message for the original exception,
 335                         // don't try to invoke report()
 336                         $message = "MediaWiki internal error.\n\n";
 337
 338                         if ( $wgShowExceptionDetails ) {
 339                                 $message .= 'Original exception: ' . $e->__toString() . "\n\n" .
 340                                         'Exception caught inside exception handler: ' . $e2->__toString();
 341                         } else {
 342                                 $message .= "Exception caught inside exception handler.\n\n" .
 343                                         "Set \$wgShowExceptionDetails = true; at the bottom of LocalSettings.php " .
 344                                         "to show detailed debugging information.";
 345                         }
 346
 347                         $message .= "\n";
 348
 349                         if ( $cmdLine ) {
 350                                 wfPrintError( $message );
 351                         } else {
 352                                 echo nl2br( htmlspecialchars( $message ) ) . "\n";
 353                         }
 354                 }
 355         } else {
 356                 $message = "Unexpected non-MediaWiki exception encountered, of type \"" . get_class( $e ) . "\"\n" .
 357                         $e->__toString() . "\n";
 358
 359                 if ( $wgShowExceptionDetails ) {
 360                         $message .= "\n" . $e->getTraceAsString() . "\n";
 361                 }
 362
 363                 if ( $cmdLine ) {
 364                         wfPrintError( $message );
 365                 } else {
 366                         echo nl2br( htmlspecialchars( $message ) ) . "\n";
 367                 }
 368         }
 369 }
 370
 371 /**
 372  * Print a message, if possible to STDERR.
 373  * Use this in command line mode only (see isCommandLine)
 374  */
 375 function wfPrintError( $message ) {
 376         # NOTE: STDERR may not be available, especially if php-cgi is used from the command line (bug #15602).
 377         #      Try to produce meaningful output anyway. Using echo may corrupt output to STDOUT though.
 378         if ( defined( 'STDERR' ) ) {
 379                 fwrite( STDERR, $message );
 380         } else {
 381                 echo( $message );
 382         }
 383 }
 384
 385 /**
 386  * Exception handler which simulates the appropriate catch() handling:
 387  *
 388  *   try {
 389  *       ...
 390  *   } catch ( MWException $e ) {
 391  *       $e->report();
 392  *   } catch ( Exception $e ) {
 393  *       echo $e->__toString();
 394  *   }
 395  */
 396 function wfExceptionHandler( $e ) {
 397         global $wgFullyInitialised;
 398
 399         wfReportException( $e );
 400
 401         // Final cleanup
 402         if ( $wgFullyInitialised ) {
 403                 try {
 404                         wfLogProfilingData(); // uses $wgRequest, hence the $wgFullyInitialised condition
 405                 } catch ( Exception $e ) {}
 406         }
 407
 408         // Exit value should be nonzero for the benefit of shell jobs
 409         exit( 1 );
 410 }