From d2c39767e3620ff088844ae00dbee28337175d9e Mon Sep 17 00:00:00 2001
From: Gleb Mazovetskiy <glex.spb@gmail.com>
Date: Sun, 26 Jan 2020 23:29:21 +0000
Subject: [PATCH] mpqapi: Fix open MPQs getting cleared on exit

---
 Source/mpqapi.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/Source/mpqapi.cpp b/Source/mpqapi.cpp
index c26a488ec..ef381ba07 100644
--- a/Source/mpqapi.cpp
+++ b/Source/mpqapi.cpp
@@ -366,8 +366,11 @@ BOOL OpenMPQ(const char *pszArchive, DWORD dwChar)
 			key = Hash("(hash table)", 3);
 			Decrypt(sgpHashTbl, 0x8000, key);
 		}
-		return TRUE;
 	}
+	// Set output position to the end to ensure the file is not cleared if the MPQ
+	// is closed without having anything written to it.
+	if (exists)
+		GOTO_IF_FAIL(on_error, archive, seekp, 0, std::ios::end);
 	return TRUE;
 on_error:
 	CloseMPQ(pszArchive, TRUE, dwChar);