From f9c7383de9e19c95e41fa4e136fd8c02c29781a7 Mon Sep 17 00:00:00 2001
From: Brad Jorsch <bjorsch@wikimedia.org>
Date: Mon, 20 Apr 2015 12:09:24 -0400
Subject: [PATCH] API: Better handle UsageException from the printer itself

Try falling back to use the printer without any of its parameters in
case one of them is what's failing.

Change-Id: I2611550109de4219bf1cc43333d038753e9eb87c
---
 includes/api/ApiFormatBase.php | 29 ++++++++++++++++++++++++
 includes/api/ApiMain.php       | 41 ++++++++++++++++++++++------------
 2 files changed, 56 insertions(+), 14 deletions(-)

diff --git a/includes/api/ApiFormatBase.php b/includes/api/ApiFormatBase.php
index 26eac082fa..d078dc453f 100644
--- a/includes/api/ApiFormatBase.php
+++ b/includes/api/ApiFormatBase.php
@@ -32,6 +32,7 @@
 abstract class ApiFormatBase extends ApiBase {
 	private $mIsHtml, $mFormat, $mUnescapeAmps, $mHelp;
 	private $mBuffer, $mDisabled = false;
+	protected $mForceDefaultParams = false;
 
 	/**
 	 * If $format ends with 'fm', pretty-print the output in HTML.
@@ -107,6 +108,34 @@ abstract class ApiFormatBase extends ApiBase {
 		return true;
 	}
 
+	/**
+	 * Ignore request parameters, force a default.
+	 *
+	 * Used as a fallback if errors are being thrown.
+	 * @since 1.26
+	 */
+	public function forceDefaultParams() {
+		$this->mForceDefaultParams = true;
+	}
+
+	/**
+	 * Overridden to honor $this->forceDefaultParams(), if applicable
+	 * @since 1.26
+	 */
+	protected function getParameterFromSettings( $paramName, $paramSettings, $parseLimit ) {
+		if ( !$this->mForceDefaultParams ) {
+			return parent::getParameterFromSettings( $paramName, $paramSettings, $parseLimit );
+		}
+
+		if ( !is_array( $paramSettings ) ) {
+			return $paramSettings;
+		} elseif ( isset( $paramSettings[self::PARAM_DFLT] ) ) {
+			return $paramSettings[self::PARAM_DFLT];
+		} else {
+			return null;
+		}
+	}
+
 	/**
 	 * Initialize the printer function and prepare the output headers.
 	 * @param bool $unused Always false since 1.25
diff --git a/includes/api/ApiMain.php b/includes/api/ApiMain.php
index 7e3dcff2ee..2ec3aa8675 100644
--- a/includes/api/ApiMain.php
+++ b/includes/api/ApiMain.php
@@ -495,7 +495,22 @@ class ApiMain extends ApiBase {
 		// Reset and print just the error message
 		ob_clean();
 
-		$this->printResult( true );
+		// Printer may not be initialized if the extractRequestParams() fails for the main module
+		$this->createErrorPrinter();
+
+		try {
+			$this->printResult( true );
+		} catch ( UsageException $ex ) {
+			// The error printer itself is failing. Try suppressing its request
+			// parameters and redo.
+			$this->setWarning(
+				'Error printer failed (will retry without params): ' . $ex->getMessage()
+			);
+			$this->mPrinter = null;
+			$this->createErrorPrinter();
+			$this->mPrinter->forceDefaultParams();
+			$this->printResult( true );
+		}
 	}
 
 	/**
@@ -792,22 +807,14 @@ class ApiMain extends ApiBase {
 	}
 
 	/**
-	 * Replace the result data with the information about an exception.
-	 * Returns the error code
-	 * @param Exception $e
-	 * @return string
+	 * Create the printer for error output
 	 */
-	protected function substituteResultWithError( $e ) {
-		$result = $this->getResult();
-
-		// Printer may not be initialized if the extractRequestParams() fails for the main module
+	private function createErrorPrinter() {
 		if ( !isset( $this->mPrinter ) ) {
-			// The printer has not been created yet. Try to manually get formatter value.
 			$value = $this->getRequest()->getVal( 'format', self::API_DEFAULT_FORMAT );
 			if ( !$this->mModuleMgr->isDefined( $value, 'format' ) ) {
 				$value = self::API_DEFAULT_FORMAT;
 			}
-
 			$this->mPrinter = $this->createPrinterByName( $value );
 		}
 
@@ -816,10 +823,16 @@ class ApiMain extends ApiBase {
 		if ( !$this->mPrinter->canPrintErrors() ) {
 			$this->mPrinter = $this->createPrinterByName( self::API_DEFAULT_FORMAT );
 		}
+	}
 
-		// Update raw mode flag for the selected printer.
-		$result->setRawMode( $this->mPrinter->getNeedsRawData() );
-
+	/**
+	 * Replace the result data with the information about an exception.
+	 * Returns the error code
+	 * @param Exception $e
+	 * @return string
+	 */
+	protected function substituteResultWithError( $e ) {
+		$result = $this->getResult();
 		$config = $this->getConfig();
 
 		if ( $e instanceof UsageException ) {
-- 
2.20.1