From 4eadc0762906136bc2f73d1f7e675b6d3b82cf63 Mon Sep 17 00:00:00 2001
From: Connor McLaughlin <stenzek@gmail.com>
Date: Mon, 3 Feb 2020 13:53:08 +1000
Subject: [PATCH] Common/StringUtil: Fix more incorrect usage of va_list

---
 src/common/string.cpp      | 5 ++++-
 src/common/string_util.cpp | 8 ++++++--
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/common/string.cpp b/src/common/string.cpp
index 2b9682585..8d32c8b73 100644
--- a/src/common/string.cpp
+++ b/src/common/string.cpp
@@ -328,7 +328,10 @@ void String::AppendFormattedStringVA(const char* FormatString, va_list ArgPtr)
 
   for (;;)
   {
-    int ret = std::vsnprintf(pBuffer, currentBufferSize, FormatString, ArgPtr);
+    va_list ArgPtrCopy;
+    va_copy(ArgPtrCopy, ArgPtr);
+    int ret = std::vsnprintf(pBuffer, currentBufferSize, FormatString, ArgPtrCopy);
+    va_end(ArgPtrCopy);
     if (ret < 0 || ((u32)ret >= (currentBufferSize - 1)))
     {
       currentBufferSize *= 2;
diff --git a/src/common/string_util.cpp b/src/common/string_util.cpp
index 401007007..38f6ad7d5 100644
--- a/src/common/string_util.cpp
+++ b/src/common/string_util.cpp
@@ -14,11 +14,15 @@ std::string StdStringFromFormat(const char* format, ...)
 
 std::string StdStringFromFormatV(const char* format, std::va_list ap)
 {
+  std::va_list ap_copy;
+  va_copy(ap_copy, ap);
+
 #ifdef WIN32
-  int len = _vscprintf(format, ap);
+  int len = _vscprintf(format, ap_copy);
 #else
-  int len = std::vsnprintf(nullptr, 0, format, ap);
+  int len = std::vsnprintf(nullptr, 0, format, ap_copy);
 #endif
+  va_end(ap_copy);
 
   std::string ret;
   ret.resize(len);