Check for result size failure in ApiQuery

If someone sets $wgAPIMaxResultSize crazily small and then queries a
large number of pages, it can cause ApiQuery to fail to populate the
'pages' node. Then submodules might add data to the node, leading to
errors from the XML formatter (or bogus output from other formatters).

While that particular failure mode is probably going away soon, it's
still good to catch the error situation.

Bug: 68989
Change-Id: If0b2eda421fd86dd7acc4fe48cec47741e214221

diff --git a/includes/api/ApiQuery.php b/includes/api/ApiQuery.php
index 94727cb..606012c 100644 (file)
--- a/includes/api/ApiQuery.php
+++ b/includes/api/ApiQuery.php
@@ -348,29 +348,29 @@ class ApiQuery extends ApiBase {
                $pageSet = $this->getPageSet();
                $result = $this->getResult();
 
-               // We don't check for a full result set here because we can't be adding
-               // more than 380K. The maximum revision size is in the megabyte range,
-               // and the maximum result size must be even higher than that.
+               // We can't really handle max-result-size failure here, but we need to
+               // check anyway in case someone set the limit stupidly low.
+               $fit = true;
 
                $values = $pageSet->getNormalizedTitlesAsResult( $result );
                if ( $values ) {
-                       $result->addValue( 'query', 'normalized', $values );
+                       $fit = $fit && $result->addValue( 'query', 'normalized', $values );
                }
                $values = $pageSet->getConvertedTitlesAsResult( $result );
                if ( $values ) {
-                       $result->addValue( 'query', 'converted', $values );
+                       $fit = $fit && $result->addValue( 'query', 'converted', $values );
                }
                $values = $pageSet->getInterwikiTitlesAsResult( $result, $this->mParams['iwurl'] );
                if ( $values ) {
-                       $result->addValue( 'query', 'interwiki', $values );
+                       $fit = $fit && $result->addValue( 'query', 'interwiki', $values );
                }
                $values = $pageSet->getRedirectTitlesAsResult( $result );
                if ( $values ) {
-                       $result->addValue( 'query', 'redirects', $values );
+                       $fit = $fit && $result->addValue( 'query', 'redirects', $values );
                }
                $values = $pageSet->getMissingRevisionIDsAsResult( $result );
                if ( $values ) {
-                       $result->addValue( 'query', 'badrevids', $values );
+                       $fit = $fit && $result->addValue( 'query', 'badrevids', $values );
                }
 
                // Page elements
@@ -426,12 +426,21 @@ class ApiQuery extends ApiBase {
                                // json treats all map keys as strings - converting to match
                                $pageIDs = array_map( 'strval', $pageIDs );
                                $result->setIndexedTagName( $pageIDs, 'id' );
-                               $result->addValue( 'query', 'pageids', $pageIDs );
+                               $fit = $fit && $result->addValue( 'query', 'pageids', $pageIDs );
                        }
 
                        $result->setIndexedTagName( $pages, 'page' );
-                       $result->addValue( 'query', 'pages', $pages );
+                       $fit = $fit && $result->addValue( 'query', 'pages', $pages );
                }
+
+               if ( !$fit ) {
+                       $this->dieUsage(
+                               'The value of $wgAPIMaxResultSize on this wiki is ' .
+                                       'too small to hold basic result information',
+                               'badconfig'
+                       );
+               }
+
                if ( $this->mParams['export'] ) {
                        $this->doExport( $pageSet, $result );
                }