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