From 5f9ea37a3d59f854b0ee8446e51e81a2718b85f8 Mon Sep 17 00:00:00 2001
From: Matthias Schmidt <gravatronics@live.com>
Date: Thu, 15 Apr 2021 14:19:22 +0200
Subject: [PATCH] Include compiled template code in exception logs (#4122)

* Include compiled template code in exception logs

Close #3943

* Highlight error line in exceptions' template context

* Replace `break` with `return` in `getTemplateContextLines()`
---
 .../files/acp/templates/exceptionLogView.tpl  |  2 +-
 wcfsetup/install/files/lib/core.functions.php | 91 ++++++++++++++++++-
 2 files changed, 91 insertions(+), 2 deletions(-)

diff --git a/wcfsetup/install/files/acp/templates/exceptionLogView.tpl b/wcfsetup/install/files/acp/templates/exceptionLogView.tpl
index 7a26735b76..2cf2d8818e 100644
--- a/wcfsetup/install/files/acp/templates/exceptionLogView.tpl
+++ b/wcfsetup/install/files/acp/templates/exceptionLogView.tpl
@@ -133,7 +133,7 @@
 						{foreach from=$chain[information] item=extraInformation}
 							<dl>
 								<dt>{$extraInformation[0]}</dt>
-								<dd>{$extraInformation[1]}</dd>
+								<dd style="white-space: pre-wrap;">{$extraInformation[1]}</dd>
 							</dl>
 						{/foreach}
 					{/if}
diff --git a/wcfsetup/install/files/lib/core.functions.php b/wcfsetup/install/files/lib/core.functions.php
index 4cc97ca124..b414761add 100644
--- a/wcfsetup/install/files/lib/core.functions.php
+++ b/wcfsetup/install/files/lib/core.functions.php
@@ -125,6 +125,62 @@ namespace wcf\functions\exception {
 	use wcf\system\exception\SystemException;
 	use wcf\util\FileUtil;
 	use wcf\util\StringUtil;
+
+	/**
+	 * If the stacktrace contains a compiled template, the context of the relevant template line
+	 * is returned, otherwise an empty array is returned.
+	 */
+	function getTemplateContextLines(\Throwable $e): array {
+		try {
+			$contextLineCount = 5;
+			foreach ($e->getTrace() as $traceEntry) {
+				if (isset($traceEntry['file']) && \preg_match('~/templates/compiled/.+\.php$~',
+					$traceEntry['file'])) {
+					$startLine = $traceEntry['line'] - $contextLineCount;
+					$relativeErrorLine = $contextLineCount;
+					if ($startLine < 0) {
+						$startLine = 0;
+						$relativeErrorLine = $traceEntry['line'] - 1;
+					}
+					
+					$file = \fopen($traceEntry['file'], 'r');
+					if (!$file) {
+						return [];
+					}
+					
+					for ($line = 0; $line < $startLine; $line++) {
+						if (\substr(\fgets($file, 1024), -1) !== "\n") {
+							// We don't want to handle a file where lines exceed 1024 Bytes.
+							return [];
+						}
+					}
+					
+					$maxLineCount = 2 * $contextLineCount + 1;
+					$lines = [];
+					while (!\feof($file) && \count($lines) < $maxLineCount) {
+						$line = \fgets($file, 1024);
+						if (\substr($line, -1) !== "\n" && !\feof($file)) {
+							// We don't want to handle a file where lines exceed 1024 Bytes.
+							return [];
+						}
+						
+						if (count($lines) === $relativeErrorLine - 1) {
+							$line = "====> {$line}";
+						}
+						
+						$lines[] = $line;
+					}
+					
+					return $lines;
+				}
+			}
+		}
+		catch (\Throwable $e) {
+			// Ignore errors while extracting the template context to be saved in the exception log.
+		}
+		
+		return [];
+	}
 	
 	/**
 	 * Logs the given Throwable.
@@ -140,6 +196,24 @@ namespace wcf\functions\exception {
 			return str_replace("\n", ' ', $item);
 		};
 		
+		$getExtraInformation = function (\Throwable $e) {
+			$extraInformation = [];
+			
+			if ($e instanceof IExtraInformationException) {
+				$extraInformation = $e->getExtraInformation();
+			}
+			
+			$templateContextLines = getTemplateContextLines($e);
+			if (!empty($templateContextLines)) {
+				$extraInformation[] = [
+					'Template Context',
+					\implode("", $templateContextLines),
+				];
+			}
+			
+			return !empty($extraInformation) ? base64_encode(serialize($extraInformation)) : "-";
+		};
+		
 		// don't forget to update ExceptionLogUtil / ExceptionLogViewPage, when changing the log file format
 		$message = gmdate('r', TIME_NOW)."\n".
 			'Message: '.$stripNewlines($e->getMessage())."\n".
@@ -156,7 +230,7 @@ namespace wcf\functions\exception {
 			'Error Message: '.$stripNewlines($prev->getMessage())."\n".
 			'Error Code: '.$stripNewlines($prev->getCode())."\n".
 			'File: '.$stripNewlines($prev->getFile()).' ('.$prev->getLine().')'."\n".
-			'Extra Information: '.($prev instanceof IExtraInformationException ? base64_encode(serialize($prev->getExtraInformation())) : '-')."\n".
+			'Extra Information: ' . $getExtraInformation($prev) . "\n".
 			'Stack Trace: '.json_encode(array_map(function ($item) {
 				$item['args'] = array_map(function ($item) {
 					switch (gettype($item)) {
@@ -343,6 +417,11 @@ EXPLANATION;
 					min-height: 1.5em;
 				}
 				
+				pre.exceptionFieldValue {
+					font-size: 14px;
+					white-space: pre-wrap;
+				}
+				
 				.exceptionSystemInformation,
 				.exceptionErrorDetails,
 				.exceptionStacktrace {
@@ -548,6 +627,16 @@ EXPLANATION;
 									<?php
 								}
 							}
+
+							$templateContextLines = getTemplateContextLines($e);
+							if (!empty($templateContextLines)) {
+								?>
+								<li>
+									<p class="exceptionFieldTitle">Template Context<span class="exceptionColon">:</span></p>
+									<pre class="exceptionFieldValue"><?php echo StringUtil::encodeHTML(implode("", $templateContextLines));?></pre>
+								</li>
+								<?php
+							}
 							?>
 							<li>
 								<p class="exceptionFieldTitle">Stack Trace<span class="exceptionColon">:</span></p>
-- 
2.20.1