Remove MAX_PATH limit from:

- GetTempFilenameForAtomicWrite
- SetUserDirectory

Source/Core/Common/FileUtil.cpp

@@ -639,19 +639,21 @@ std::string CreateTempDir()
 #endif
 }
 
-std::string GetTempFilenameForAtomicWrite(const std::string& path)
+std::string GetTempFilenameForAtomicWrite(std::string path)
 {
-  std::string abs = path;
 #ifdef _WIN32
-  TCHAR absbuf[MAX_PATH];
-  if (_tfullpath(absbuf, UTF8ToTStr(path).c_str(), MAX_PATH) != nullptr)
-    abs = TStrToUTF8(absbuf);
+  std::unique_ptr<TCHAR[], decltype(&std::free)> absbuf{
+      _tfullpath(nullptr, UTF8ToTStr(path).c_str(), 0), std::free};
+  if (absbuf != nullptr)
+  {
+    path = TStrToUTF8(absbuf.get());
+  }
 #else
   char absbuf[PATH_MAX];
   if (realpath(path.c_str(), absbuf) != nullptr)
-    abs = absbuf;
+    path = absbuf;
 #endif
-  return abs + ".xxx";
+  return std::move(path) + ".xxx";
 }
 
 #if defined(__APPLE__)

Source/Core/Common/FileUtil.h

@@ -172,7 +172,7 @@ bool SetCurrentDir(const std::string& directory);
 std::string CreateTempDir();
 
 // Get a filename that can hopefully be atomically renamed to the given path.
-std::string GetTempFilenameForAtomicWrite(const std::string& path);
+std::string GetTempFilenameForAtomicWrite(std::string path);
 
 // Gets a set user directory path
 // Don't call prior to setting the base user directory

Source/Core/UICommon/UICommon.cpp

@@ -211,46 +211,57 @@ void SetUserDirectory(const std::string& custom_path)
   //    -> Use GetExeDirectory()\User
 
   // Check our registry keys
+  // TODO: Maybe use WIL when it's available?
   HKEY hkey;
   DWORD local = 0;
-  TCHAR configPath[MAX_PATH] = {0};
+  std::unique_ptr<TCHAR[]> configPath;
   if (RegOpenKeyEx(HKEY_CURRENT_USER, TEXT("Software\\Dolphin Emulator"), 0, KEY_QUERY_VALUE,
                    &hkey) == ERROR_SUCCESS)
   {
     DWORD size = 4;
     if (RegQueryValueEx(hkey, TEXT("LocalUserConfig"), nullptr, nullptr,
                         reinterpret_cast<LPBYTE>(&local), &size) != ERROR_SUCCESS)
+    {
       local = 0;
+    }
+
+    size = 0;
+    RegQueryValueEx(hkey, TEXT("UserConfigPath"), nullptr, nullptr, nullptr, &size);
+    configPath = std::make_unique<TCHAR[]>(size / sizeof(TCHAR));
+    if (RegQueryValueEx(hkey, TEXT("UserConfigPath"), nullptr, nullptr,
+                        reinterpret_cast<LPBYTE>(configPath.get()), &size) != ERROR_SUCCESS)
+    {
+      configPath.reset();
+    }
 
-    size = MAX_PATH;
-    if (RegQueryValueEx(hkey, TEXT("UserConfigPath"), nullptr, nullptr, (LPBYTE)configPath,
-                        &size) != ERROR_SUCCESS)
-      configPath[0] = 0;
     RegCloseKey(hkey);
   }
 
-  local = local || File::Exists(File::GetExeDirectory() + DIR_SEP "portable.txt");
+  local = local != 0 || File::Exists(File::GetExeDirectory() + DIR_SEP "portable.txt");
 
-  // Get Program Files path in case we need it.
-  TCHAR my_documents[MAX_PATH];
-  bool my_documents_found = SUCCEEDED(
-      SHGetFolderPath(nullptr, CSIDL_MYDOCUMENTS, nullptr, SHGFP_TYPE_CURRENT, my_documents));
+  // Get Documents path in case we need it.
+  // TODO: Maybe use WIL when it's available?
+  PWSTR my_documents = nullptr;
+  bool my_documents_found =
+      SUCCEEDED(SHGetKnownFolderPath(FOLDERID_Documents, KF_FLAG_DEFAULT, nullptr, &my_documents));
 
   if (local)  // Case 1-2
     user_path = File::GetExeDirectory() + DIR_SEP USERDATA_DIR DIR_SEP;
-  else if (configPath[0])  // Case 3
-    user_path = TStrToUTF8(configPath);
+  else if (configPath)  // Case 3
+    user_path = TStrToUTF8(configPath.get());
   else if (my_documents_found)  // Case 4
     user_path = TStrToUTF8(my_documents) + DIR_SEP "Dolphin Emulator" DIR_SEP;
   else  // Case 5
     user_path = File::GetExeDirectory() + DIR_SEP USERDATA_DIR DIR_SEP;
 
+  CoTaskMemFree(my_documents);
+
   // Prettify the path: it will be displayed in some places, we don't want a mix
   // of \ and /.
-  user_path = ReplaceAll(user_path, "\\", DIR_SEP);
+  user_path = ReplaceAll(std::move(user_path), "\\", DIR_SEP);
 
   // Make sure it ends in DIR_SEP.
-  if (*user_path.rbegin() != DIR_SEP_CHR)
+  if (user_path.back() != DIR_SEP_CHR)
     user_path += DIR_SEP;
 
 #else
@@ -325,7 +336,7 @@ void SetUserDirectory(const std::string& custom_path)
 #endif
   }
 #endif
-  File::SetUserPath(D_USER_IDX, user_path);
+  File::SetUserPath(D_USER_IDX, std::move(user_path));
 }
 
 void SaveWiimoteSources()