do not migrate legacy homepath when using -homepath arg

Author: illwieckz

src/common/FileSystem.cpp

@@ -2069,7 +2069,6 @@ std::string DefaultHomePath()
 #else
 	struct stat stl, stx;
 
-	std::string legacyHomePath = Path::Build(std::string(home), "." PRODUCT_NAME_LOWER);
 	const char* _xdgDataHome = getenv("XDG_DATA_HOME");
 	std::string xdgDataHome = _xdgDataHome == NULL ? "" : std::string(_xdgDataHome);
 	std::string xdgHomePath;
@@ -2080,6 +2079,31 @@ std::string DefaultHomePath()
 
 	xdgHomePath = Path::Build(xdgDataHome, PRODUCT_NAME_LOWER);
 
+	return xdgHomePath;
+#endif
+#endif
+}
+
+void MigrateHomePath(std::StringRef cmdlineHomePath)
+{
+#if defined(__linux__)
+	std::string xdgHomePath = DefaultHomePath();
+
+	// if user set custom home path using -homepath arg, do nothing
+	if (! xdgHomePath.compare(cmdlineHomePath)) {
+		return;
+	}
+
+	const char* home = getenv("HOME");
+	if (!home) {
+		// in this case DefaultHomePath() returned "" earlier,
+		// hence homePath is neither the legacy one neither the
+		// xdg one, hence there is nothing to do.
+		return
+	}
+
+	std::string legacyHomePath = Path::Build(std::string(home), "." PRODUCT_NAME_LOWER);
+
 	if (lstat(legacyHomePath.c_str(), &stl) == 0) {
 		if (S_ISDIR(stl.st_mode) || S_ISLNK(stl.st_mode)) {
 			if (stat(xdgHomePath.c_str(), &stx) != 0) {
@@ -2118,9 +2142,6 @@ std::string DefaultHomePath()
 			}
 		}
 	}
-
-	return xdgHomePath;
-#endif
 #endif
 }
 #endif // BUILD_VM
@@ -2176,6 +2197,8 @@ static Util::optional<std::string> GetRealPath(Str::StringRef path, std::string&
 
 void Initialize(Str::StringRef homePath, Str::StringRef libPath, const std::vector<std::string>& paths)
 {
+	MigrateHomePath(homePath);
+
 	// Create the homepath and its pkg directory to avoid any issues later on
 	std::error_code err;
 	RawPath::CreatePathTo(FS::Path::Build(homePath, "pkg") + "/", err);