From 80be14530c7e0748fa9b6a01ad045f5d37b48cc3 Mon Sep 17 00:00:00 2001
From: Tim Starling <tstarling@users.mediawiki.org>
Date: Fri, 4 Sep 2009 01:49:34 +0000
Subject: [PATCH] Added $wgShowDBErrorBacktrace, to allow users to easily
 gather backtraces for database connection and query errors. We've had a few
 LocalisationCache bugs that required backtraces to track down.

---
 RELEASE-NOTES                |  2 ++
 includes/DefaultSettings.php |  5 ++++
 includes/db/Database.php     | 44 +++++++++++++++++++++++-------------
 3 files changed, 35 insertions(+), 16 deletions(-)

diff --git a/RELEASE-NOTES b/RELEASE-NOTES
index 8a20f61b05..83fd27da7c 100644
--- a/RELEASE-NOTES
+++ b/RELEASE-NOTES
@@ -201,6 +201,8 @@ this. Was used when mwEmbed was going to be an extension.
   display-in-limit-form.
 * (bug 18880) LogEventsList::showLogExtract() can now take a string-by-reference
   and add its HTML to it, rather than having to go straight to $wgOut.
+* Added $wgShowDBErrorBacktrace, to allow users to easily gather backtraces for
+  database connection and query errors.
 
 === Bug fixes in 1.16 ===
 
diff --git a/includes/DefaultSettings.php b/includes/DefaultSettings.php
index d5e0555b28..985a6e4f93 100644
--- a/includes/DefaultSettings.php
+++ b/includes/DefaultSettings.php
@@ -1172,6 +1172,11 @@ $wgColorErrors          = true;
  */
 $wgShowExceptionDetails = false;
 
+/**
+ * If true, show a backtrace for database errors
+ */
+$wgShowDBErrorBacktrace = false;
+
 /**
  * Expose backend server host names through the API and various HTML comments
  */
diff --git a/includes/db/Database.php b/includes/db/Database.php
index a8659b68bc..34e33dbb61 100644
--- a/includes/db/Database.php
+++ b/includes/db/Database.php
@@ -2420,6 +2420,15 @@ class DBError extends MWException {
 		$this->db =& $db;
 		parent::__construct( $error );
 	}
+
+	function getText() {
+		global $wgShowDBErrorBacktrace;
+		$s = $this->getMessage() . "\n";
+		if ( $wgShowDBErrorBacktrace ) {
+			$s .= "Backtrace:\n" . $this->getTraceAsString() . "\n";
+		}
+		return $s;
+	}
 }
 
 /**
@@ -2447,10 +2456,6 @@ class DBConnectionError extends DBError {
 		return false;
 	}
 	
-	function getText() {
-		return $this->getMessage() . "\n";
-	}
-
 	function getLogMessage() {
 		# Don't send to the exception log
 		return false;
@@ -2467,7 +2472,7 @@ class DBConnectionError extends DBError {
 	}
 
 	function getHTML() {
-		global $wgLang, $wgMessageCache, $wgUseFileCache;
+		global $wgLang, $wgMessageCache, $wgUseFileCache, $wgShowDBErrorBacktrace;
 
 		$sorry = 'Sorry! This site is experiencing technical difficulties.';
 		$again = 'Try waiting a few minutes and reloading.';
@@ -2491,12 +2496,9 @@ class DBConnectionError extends DBError {
 		$noconnect = "<p><strong>$sorry</strong><br />$again</p><p><small>$info</small></p>";
 		$text = str_replace( '$1', $this->error, $noconnect );
 
-		/*
-		if ( $GLOBALS['wgShowExceptionDetails'] ) {
-			$text .= '</p><p>Backtrace:</p><p>' . 
-				nl2br( htmlspecialchars( $this->getTraceAsString() ) ) . 
-				"</p>\n";
-		}*/
+		if ( $wgShowDBErrorBacktrace ) {
+			$text .= '<p>Backtrace:</p><p>' . nl2br( htmlspecialchars( $this->getTraceAsString() ) );
+		}
 
 		$extra = $this->searchForm();
 
@@ -2613,11 +2615,16 @@ class DBQueryError extends DBError {
 	}
 
 	function getText() {
+		global $wgShowDBErrorBacktrace;
 		if ( $this->useMessageCache() ) {
-			return wfMsg( 'dberrortextcl', htmlspecialchars( $this->getSQL() ),
-			  htmlspecialchars( $this->fname ), $this->errno, htmlspecialchars( $this->error ) ) . "\n";
+			$s = wfMsg( 'dberrortextcl', htmlspecialchars( $this->getSQL() ),
+				htmlspecialchars( $this->fname ), $this->errno, htmlspecialchars( $this->error ) ) . "\n";
+			if ( $wgShowDBErrorBacktrace ) {
+				$s .= "Backtrace:\n" . $this->getTraceAsString() . "\n";
+			}
+			return $s;
 		} else {
-			return $this->getMessage();
+			return parent::getText();
 		}
 	}
 	
@@ -2640,12 +2647,17 @@ class DBQueryError extends DBError {
 	}
 
 	function getHTML() {
+		global $wgShowDBErrorBacktrace;
 		if ( $this->useMessageCache() ) {
-			return wfMsgNoDB( 'dberrortext', htmlspecialchars( $this->getSQL() ),
+			$s = wfMsgNoDB( 'dberrortext', htmlspecialchars( $this->getSQL() ),
 			  htmlspecialchars( $this->fname ), $this->errno, htmlspecialchars( $this->error ) );
 		} else {
-			return nl2br( htmlspecialchars( $this->getMessage() ) );
+			$s = nl2br( htmlspecialchars( $this->getMessage() ) );
+		}
+		if ( $wgShowDBErrorBacktrace ) {
+			$s .= '<p>Backtrace:</p><p>' . nl2br( htmlspecialchars( $this->getTraceAsString() ) );
 		}
+		return $s;
 	}
 }
 
-- 
2.20.1