From a3fd33f8a1725a035f5e7b7c73a1f4e199fcf690 Mon Sep 17 00:00:00 2001
From: Gunnar Beutner <gunnar@beutner.name>
Date: Wed, 4 Nov 2015 19:05:47 +0100
Subject: [PATCH] Fix race condition in ConfigWriter::EmitIdentifier

fixes #10538
---
 lib/base/configwriter.cpp | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/lib/base/configwriter.cpp b/lib/base/configwriter.cpp
index eac3ca7b9..f43e68da3 100644
--- a/lib/base/configwriter.cpp
+++ b/lib/base/configwriter.cpp
@@ -146,9 +146,14 @@ void ConfigWriter::EmitIndent(std::ostream& fp, int indentLevel)
 void ConfigWriter::EmitIdentifier(std::ostream& fp, const String& identifier, bool inAssignment)
 {
 	static std::set<String> keywords;
-	if (keywords.empty()) {
-		const std::vector<String>& vkeywords = GetKeywords();
-		std::copy(vkeywords.begin(), vkeywords.end(), std::inserter(keywords, keywords.begin()));
+	static boost::mutex mutex;
+
+	{
+		boost::mutex::scoped_lock lock(mutex);
+		if (keywords.empty()) {
+			const std::vector<String>& vkeywords = GetKeywords();
+			std::copy(vkeywords.begin(), vkeywords.end(), std::inserter(keywords, keywords.begin()));
+		}
 	}
 
 	if (keywords.find(identifier) != keywords.end()) {