From bf957a575c9134732718906b9271a9d87972a561 Mon Sep 17 00:00:00 2001
From: Nekotekina <nekotekina@gmail.com>
Date: Sat, 14 Mar 2020 12:59:09 +0300
Subject: [PATCH] VFS: fix out of range problem in vfs::unescape
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Also improve unescape with "！" allowing any character
---
 rpcs3/Emu/VFS.cpp | 39 +++++++++++++++++++++++++++++++++------
 1 file changed, 33 insertions(+), 6 deletions(-)

diff --git a/rpcs3/Emu/VFS.cpp b/rpcs3/Emu/VFS.cpp
index 974952c9ab..c9da2758be 100644
--- a/rpcs3/Emu/VFS.cpp
+++ b/rpcs3/Emu/VFS.cpp
@@ -438,17 +438,30 @@ std::string vfs::unescape(std::string_view path)
 	std::string result;
 	result.reserve(path.size());
 
+	// Emulate NTS
+	auto get_char = [&](std::size_t pos) -> char2
+	{
+		if (pos < path.size())
+		{
+			return path[pos];
+		}
+		else
+		{
+			return '\0';
+		}
+	};
+
 	for (std::size_t i = 0, s = path.size(); i < s; i++)
 	{
 		switch (char2 c = path[i])
 		{
 		case char2{u8"！"[0]}:
 		{
-			switch (char2 c2 = path[i + 1])
+			switch (char2 c2 = get_char(i + 1))
 			{
 			case char2{u8"！"[1]}:
 			{
-				const uchar c3 = path[i + 2];
+				const uchar c3 = get_char(i + 2);
 
 				if (c3 >= 0x81 && c3 <= 0xbf)
 				{
@@ -465,7 +478,7 @@ std::string vfs::unescape(std::string_view path)
 					case char2{u8"８"[2]}:
 					case char2{u8"９"[2]}:
 					{
-						result += path[i + 2];
+						result += static_cast<char>(c3);
 						result.back() -= u8"０"[2];
 						continue;
 					}
@@ -492,15 +505,24 @@ std::string vfs::unescape(std::string_view path)
 					case char2{u8"Ｕ"[2]}:
 					case char2{u8"Ｖ"[2]}:
 					{
-						result += path[i + 2];
+						result += static_cast<char>(c3);
 						result.back() -= u8"Ａ"[2];
 						result.back() += 10;
 						continue;
 					}
 					case char2{u8"！"[2]}:
 					{
+						if (const char2 c4 = get_char(i + 3))
+						{
+							// Escape anything but null character
+							result += c4;
+						}
+						else
+						{
+							return result;
+						}
+
 						i += 3;
-						result += c;
 						continue;
 					}
 					case char2{u8"．"[2]}:
@@ -572,7 +594,7 @@ std::string vfs::unescape(std::string_view path)
 			}
 			case char2{u8"｀"[1]}:
 			{
-				const uchar c3 = path[i + 2];
+				const uchar c3 = get_char(i + 2);
 
 				if (c3 >= 0x80 && c3 <= 0x9e)
 				{
@@ -607,6 +629,11 @@ std::string vfs::unescape(std::string_view path)
 			}
 			break;
 		}
+		case 0:
+		{
+			// NTS detected
+			return result;
+		}
 		default:
 		{
 			result += c;