Add support for Snap Steam installations

Add support for Steam installations using Snap.

The Snap Steam is packaged by Canonical and Valve developers recommend
Steam's own `.deb` instead of the Snap. In any case, we should support
this though we should be wary in case some issues are caused by the Snap
version.

CHANGELOG.md

@@ -7,6 +7,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ## [Unreleased]
 ### Added
  - `--cwd-app` flag to set working directory to the game's installation directory
+ - Add support Snap Steam installations
 
 ### Changed
  - `protontricks -c` and `protontricks-launch` now use the current working directory instead of the game's installation directory. `--cwd-app` can be used to restore old behavior. Scripts can also `$STEAM_APP_PATH` environment variable to determine the game's installation directory; this has been supported (albeit undocumented) since 1.8.0.

src/protontricks/gui.py

@@ -15,6 +15,7 @@
 from .config import get_config
 from .flatpak import get_inaccessible_paths
 from .util import get_cache_dir
+from .steam import SNAP_STEAM_DIRS
 
 APP_ICON_SIZE = (32, 32)
 
@@ -251,7 +252,17 @@ def _get_zenity_args():
                 "/com.valvesoftware.Steam/.local/share/Steam"
             )
         )
-        install_type = "Flatpak" if is_flatpak else "Native"
+        is_snap = any(
+            str(steam_path).endswith(snap_dir)
+            for snap_dir in SNAP_STEAM_DIRS
+        )
+
+        if is_flatpak:
+            install_type = "Flatpak"
+        elif is_snap:
+            install_type = "Snap"
+        else:
+            install_type = "Native"
 
         cmd_input.append(f"{i+1}: {install_type} - {steam_path}")
 

src/protontricks/steam.py

@@ -27,6 +27,11 @@
     ".local/share/Steam",
 ]
 
+SNAP_STEAM_DIRS = [
+    "snap/steam",
+    ".snap/data/steam"
+]
+
 OS_RELEASE_PATHS = [
     "/run/host/os-release",  # The host file if we're inside a Flatpak sandbox
     "/etc/os-release"
@@ -388,14 +393,19 @@ def has_runtime_dir(path):
 
             candidates[(str(steam_path), str(steam_root_))] = True
 
-    # Check for Flatpak Steam separately and ensure we don't mix steam_root
-    # and steam_path from Flatpak and non-Flatpak installations of Steam.
+    # Check for Flatpak and Snap Steam separately and ensure we don't mix steam_root
+    # and steam_path from Flatpak/Snap and native installations of Steam.
     steam_path = \
         Path.home() / ".var/app/com.valvesoftware.Steam/data/Steam"
     steam_path = steam_path.resolve()
     if has_steamapps_dir(steam_path):
         candidates[(str(steam_path), str(steam_path))] = True
 
+    for steam_dir in SNAP_STEAM_DIRS:
+        steam_path = (Path.home() / steam_dir).resolve()
+        if has_steamapps_dir(steam_path):
+            candidates[(str(steam_path), str(steam_path))] = True
+
     for steam_path, _ in candidates.keys():
         logger.info("Found Steam directory at %s", steam_path)