fix: Reuse the prefix the client made for a shortcut id (#1107)

* fix: Reuse the prefix the client made for a shortcut id

droiddeck-proton-run builds the prefix path as steamapps/compatdata/<appid>,
but the client names that folder with the signed 32-bit form of the shortcut
id. A shortcut whose id has the top bit set therefore got a second, empty
prefix, and the first launch after that ran wineboot from scratch: the
session sat on a black screen for the length of a full prefix init, and the
old prefix was never reused.

Match the folder by its unsigned value instead, the way the client does:
int(name) % 2 ** 32 == appid % 2 ** 32. prefix_of() also accepts a negative
folder name now, and reports its unsigned id so the Steam environment it sets
up stays valid.

* fix: Reject folder names int() cannot read, and skip files

lstrip("-").isdigit() accepts "--1" and superscript digits, which int() then
raises on, and one such entry in compatdata would stop shortcut resolution.
Match r"-?[0-9]+" instead. A matching name is also only used when it is a
directory, so a stray file cannot take STEAM_COMPAT_DATA_PATH.

* fix: reuse signed shortcut compatdata prefix

* fix: prefer initialized Proton shortcut prefixes

---------

Co-authored-by: xXJsonDeruloXx <danielhimebauch@gmail.com>
Co-authored-by: Kurt Himebauch <136133082+xXJSONDeruloXx@users.noreply.github.com>

tools/linuxfs/overlay/usr/local/bin/droiddeck-proton-run

@@ -193,9 +193,9 @@ def steam_game(program, libs):
 def prefix_of(program):
     for folder, below in ancestors(program):
         parent = os.path.dirname(folder)
-        if below == "pfx" and os.path.basename(parent) == "compatdata" and os.path.basename(folder).isdigit():
+        if below == "pfx" and os.path.basename(parent) == "compatdata" and re.fullmatch(r"-?[0-9]+", os.path.basename(folder)):
             library = os.path.dirname(os.path.dirname(parent))
-            return Target(os.path.basename(folder), folder, os.path.dirname(program), library, "prefix")
+            return Target(str(int(os.path.basename(folder)) % 2 ** 32), folder, os.path.dirname(program), library, "prefix")
     return None
 
 
@@ -238,6 +238,30 @@ def shortcut_entries(root):
     return entries
 
 
+def prefix_folder(root, appid):
+    """The prefix folder the client made for [appid], under either spelling of the id."""
+    folder = os.path.join(root, "steamapps", "compatdata")
+    try:
+        names = sorted(os.listdir(folder))
+    except OSError:
+        names = []
+    candidates = []
+    for name in names:
+        if not re.fullmatch(r"-?[0-9]+", name):
+            continue
+        try:
+            matches = int(name) % 2 ** 32 == appid % 2 ** 32
+        except ValueError:
+            continue
+        match = os.path.join(folder, name)
+        if matches and os.path.isdir(match):
+            candidates.append((os.path.isdir(os.path.join(match, "pfx")),
+                               name == str(appid % 2 ** 32), name, match))
+    if candidates:
+        return min(candidates, key=lambda item: (not item[0], not item[1], item[2]))[3]
+    return os.path.join(folder, str(appid % 2 ** 32))
+
+
 def vdf_string(token):
     return re.sub(r'\\(.)', r'\1', token[1:-1]) if token.startswith('"') else ""
 
@@ -275,7 +299,7 @@ def steam_options(app, root):
 def shortcut(program, root):
     for appid, exe, start in shortcut_entries(root):
         if same_file(program, exe):
-            return Target(appid, os.path.join(root, "steamapps", "compatdata", str(appid)),
+            return Target(appid, prefix_folder(root, appid),
                           os.path.dirname(program), root, "shortcut", start if os.path.isdir(start) else None)
     return None
 
@@ -292,7 +316,7 @@ def locate(program, root):
     if found:
         return found
     appid = own_id(program)
-    return Target(appid, os.path.join(root, "steamapps", "compatdata", str(appid)),
+    return Target(appid, prefix_folder(root, appid),
                   os.path.dirname(program), root, "own")
 
 
@@ -376,7 +400,8 @@ def steam_launch(appid, root):
 
 
 def shortcut_target(appid, program, start, root):
-    return Target(appid, os.path.join(root, "steamapps", "compatdata", str(appid)), os.path.dirname(program), root,
+    appid = int(appid) % 2 ** 32
+    return Target(str(appid), prefix_folder(root, appid), os.path.dirname(program), root,
                   "shortcut", start if start and os.path.isdir(start) else None)
 
 

tools/tests/test_desktop_open.py

@@ -570,6 +570,50 @@ class ProtonRunTest(Temp):
         self.game("70", "Linux Game", "run.sh")
         self.assertEqual(self.run_main(["--app", "70"])[0], 2)
 
+    def test_without_steam_a_shortcut_reuses_a_signed_prefix_folder(self):
+        bat = self.write("Games/Epic/Game/.droiddeck-launch.bat", b"@echo off")
+        start = self.tmp / "Games/Epic/Game/Binaries"
+        start.mkdir()
+        signed = self.root / "steamapps/compatdata/-1561598272"
+        signed.mkdir(parents=True)
+        code, calls, dirs = self.run_main(["--app", "2733369024", "--dir", str(start), "--", str(bat)])
+        self.assertIsNone(code)
+        env = calls[0][2]
+        self.assertEqual(env["STEAM_COMPAT_DATA_PATH"], str(signed))
+        self.assertFalse((self.root / "steamapps/compatdata/2733369024").exists())
+
+    def test_prefix_folder_prefers_initialized_unsigned_over_empty_signed(self):
+        signed = self.root / "steamapps/compatdata/-1561598272"
+        signed.mkdir(parents=True)
+        initialized = self.root / "steamapps/compatdata/2733369024/pfx"
+        initialized.mkdir(parents=True)
+
+        self.assertEqual(RUN["prefix_folder"](str(self.root), 2733369024), str(initialized.parent))
+
+    def test_prefix_folder_prefers_initialized_signed_over_empty_unsigned(self):
+        unsigned = self.root / "steamapps/compatdata/2733369024"
+        unsigned.mkdir(parents=True)
+        initialized = self.root / "steamapps/compatdata/-1561598272/pfx"
+        initialized.mkdir(parents=True)
+
+        self.assertEqual(RUN["prefix_folder"](str(self.root), 2733369024), str(initialized.parent))
+
+    def test_prefix_folder_prefers_unsigned_when_initialization_ties(self):
+        unsigned = self.root / "steamapps/compatdata/2733369024/pfx"
+        unsigned.mkdir(parents=True)
+        signed = self.root / "steamapps/compatdata/-1561598272/pfx"
+        signed.mkdir(parents=True)
+
+        self.assertEqual(RUN["prefix_folder"](str(self.root), 2733369024), str(unsigned.parent))
+
+    def test_prefix_folder_skips_numeric_names_too_long_to_convert(self):
+        from unittest.mock import patch
+        folder = self.root / "steamapps/compatdata"
+        folder.mkdir(parents=True)
+        with patch.object(RUN["os"], "listdir", return_value=["9" * 5000]):
+            self.assertEqual(RUN["prefix_folder"](str(self.root), 2733369024),
+                             str(folder / "2733369024"))
+
     def test_without_steam_a_shortcut_keeps_its_prefix_folder_and_launch_options(self):
         bat = self.write("Games/Epic/Game/.droiddeck-launch.bat", b"@echo off")
         start = self.tmp / "Games/Epic/Game/Binaries"