Fix duplicate app entries

Steam now lists the main installation path itself in the
`libraryfolders.vdf`. This path can also have a different path but
resolve to one of the existing paths due to one of them being a symlink.
This results in Protontricks finding duplicate appmanifest files unless
the duplicate library paths are removed.

Fixes #118

CHANGELOG.md

@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
+## [Unreleased]
+### Fixed
+ - Fix duplicate Steam application entries
+
 ## [1.6.0] - 2021-08-08
 ### Added
  - Add `protontricks-launch` script to launch Windows executables using Proton app specific Wine prefixes

src/protontricks/steam.py

@@ -686,7 +686,14 @@ def parse_library_folders(data):
             )
         ) from exc
 
-    return [steam_path] + library_folders
+    paths = [steam_path] + library_folders
+
+    # Get rid of duplicate paths by fully resolving them and turning them into
+    # a set and back
+    paths = [path.resolve() for path in paths]
+    paths = list(set(paths))
+
+    return paths
 
 
 def get_compat_tool_dirs(steam_root):

tests/test_steam.py

@@ -257,6 +257,38 @@ def test_get_steam_lib_paths_corrupted_libraryfolders(
 
         assert "Library folder configuration file" in str(exc.value)
 
+    def test_get_steam_lib_paths_duplicate_paths(
+            self, steam_dir, steam_library_factory):
+        """
+        Retrive Steam library folders and ensure duplicate paths (eg.
+        an existing path OR a symlink that resolves to an existing path)
+        are removed from the returned list.
+
+        Regression test for #118
+        """
+        library_dir = steam_library_factory("TestLibrary_A")
+
+        # Create a symlink from TestLibrary_B to TestLibrary_A
+        (library_dir.parent / "TestLibrary_B").symlink_to(library_dir)
+
+        # Add the duplicate library folder
+        vdf_data = vdf.loads(
+            (steam_dir / "steamapps" / "libraryfolders.vdf").read_text()
+        )
+        vdf_data["LibraryFolders"]["2"] = str(
+            library_dir.parent / "TestLibrary_B"
+        )
+        (steam_dir / "steamapps" / "libraryfolders.vdf").write_text(
+            vdf.dumps(vdf_data)
+        )
+
+        library_paths = get_steam_lib_paths(steam_dir)
+
+        # Only two paths should be returned
+        assert len(library_paths) == 2
+        assert steam_dir in library_paths
+        assert library_dir in library_paths
+
 
 class TestFindAppidProtonPrefix:
     def test_find_appid_proton_prefix_steamapps_case(