Fix the follow-up review's findings

- APK reader: read members with a bounded read, since ZipFile.read inflates
  a member fully before trimming it to a forged declared size; the reference
  walk counts every entry it examines, dead ends and cycles included.
- Titles: a path that exists under the root wins over stripping the archive
  prefix; the prefix is taken before a linked folder is staged elsewhere
  (another drive on Windows); the install dialog loads a fresh title list
  first and says so if it couldn't check.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

tests/test_frame_apk.py

@@ -4,6 +4,7 @@ import os
 import struct
 import sys
 import tempfile
+import tracemalloc
 import unittest
 import zipfile
 
@@ -144,6 +145,26 @@ class ApkInfo(unittest.TestCase):
         finally:
             frame_apk.MAX_MANIFEST = limit
 
+    def test_forged_sizes_dont_inflate_everything(self):
+        # The central directory claims 1 byte; the deflated data holds 16 MB of zeros.
+        buf = io.BytesIO()
+        with zipfile.ZipFile(buf, 'w', zipfile.ZIP_DEFLATED) as z:
+            z.writestr('AndroidManifest.xml', bytes(16 * 1024**2))
+        data = bytearray(buf.getvalue())
+        for sig, field in ((b'PK\x01\x02', 24), (b'PK\x03\x04', 22)):
+            at = data.index(sig)
+            data[at + field:at + field + 4] = struct.pack('<I', 1)
+        limit, frame_apk.MAX_MANIFEST = frame_apk.MAX_MANIFEST, 1024**2
+        tracemalloc.start()
+        try:
+            with self.assertRaises(frame_apk.ApkError):
+                self.read(bytes(data))
+            peak = tracemalloc.get_traced_memory()[1]
+        finally:
+            tracemalloc.stop()
+            frame_apk.MAX_MANIFEST = limit
+        self.assertLess(peak, 8 * 1024**2)
+
     def test_reference_cycles_and_fan_out_are_bounded(self):
         res = frame_apk.Resources(b'')
         ref = frame_apk.T_REF
@@ -153,6 +174,16 @@ class ApkInfo(unittest.TestCase):
         res.entries = {i: [('', 0, ref, i + 1)] * 5 for i in range(1, 6)}
         res.entries[6] = [('', 0, frame_apk.T_STRING, 0)]
         self.assertEqual(len(res.values(1)), frame_apk.MAX_VALUES)
+        # Forty references at each hop round a four-id cycle: millions of dead ends.
+        looked = []
+
+        class Counting(dict):
+            def get(self, key, default=None):
+                looked.append(key)
+                return dict.get(self, key, default)
+        res.entries = Counting({i: [('', 0, ref, i % 4 + 1)] * 40 for i in range(1, 5)})
+        self.assertEqual(res.values(1), [])
+        self.assertLess(len(looked), frame_apk.MAX_STEPS + 10)
 
 
 if __name__ == '__main__':

tests/test_frame_titles.py

@@ -153,6 +153,26 @@ class Targets(unittest.TestCase):
         with self.assertRaises(FrameError):
             frame_titles._choose(p, 'Game/../../outside.exe')
 
+    def test_root_relative_path_wins_over_archive_prefix(self):
+        # Game/Game/A.exe and Game/A.exe: 'Game/A.exe' is a real path under the root Game/.
+        p = self.plan({'Game/Game/A.exe': pe(0x8664), 'Game/A.exe': pe(0x8664)}, 'Game')
+        self.assertEqual(p['unwrapped'], 'Game')
+        frame_titles._choose(p, 'Game/A.exe')
+        self.assertEqual(p['target'], 'Game/A.exe')
+
+    @unittest.skipIf(os.name == 'nt', 'needs symlinks')
+    def test_prefix_is_taken_before_staging(self):
+        # A folder with a link is staged into a temporary copy; the prefix still names
+        # the folders stepped into in the original.
+        d = self.tree({'Game/A.exe': pe(0x8664)})
+        os.symlink('A.exe', os.path.join(d, 'Game', 'link.exe'))
+        p = frame_titles.inspect(d, 'Game')
+        try:
+            self.assertEqual(p['unwrapped'], 'Game')
+            self.assertTrue(p['work'])
+        finally:
+            frame_titles.discard(p)
+
 
 class Zips(unittest.TestCase):
     def setUp(self):

ui/frame_apk.py

@@ -18,6 +18,7 @@ MAX_MANIFEST = 16 * 1024**2
 MAX_ARSC = 128 * 1024**2      # real ones are a few MB; the largest apps' tens of MB
 MAX_ICON = 8 * 1024**2
 MAX_VALUES = 256              # resolved values per reference, across all its hops
+MAX_STEPS = 4096              # entries examined per reference, dead ends and cycles included
 
 
 class ApkError(Exception):
@@ -135,18 +136,20 @@ class Resources:
                 resid = (pid << 24) | (tid << 16) | index
                 self.entries.setdefault(resid, []).append((language, density, dtype, value))
 
-    def values(self, resid, depth=0, seen=frozenset()):
-        """[(language, density, type, data)] with references followed, at most
-        MAX_VALUES of them and never round a cycle."""
+    def values(self, resid, depth=0, seen=frozenset(), steps=None):
+        """[(language, density, type, data)] with references followed: never round a
+        cycle, at most MAX_VALUES results and MAX_STEPS entries examined in all."""
+        steps = steps if steps is not None else [MAX_STEPS]
         out = []
         seen = seen | {resid}
         for lang, dens, dtype, value in self.entries.get(resid, []):
-            if len(out) >= MAX_VALUES:
+            steps[0] -= 1
+            if steps[0] < 0 or len(out) >= MAX_VALUES:
                 break
             if dtype == T_REF and depth < 5:
                 if value not in seen:
                     out += [(lang or l2, dens or d2, t2, v2)
-                            for l2, d2, t2, v2 in self.values(value, depth + 1, seen)]
+                            for l2, d2, t2, v2 in self.values(value, depth + 1, seen, steps)]
             else:
                 out.append((lang, dens, dtype, value))
         return out[:MAX_VALUES]
@@ -184,10 +187,16 @@ def _icons(attr, res):
 
 
 def _read(z, name, limit):
+    """A member's bytes, inflating at most limit + 1 of them whatever its header claims
+    (ZipFile.read inflates everything first, then trims to the declared size)."""
     size = z.getinfo(name).file_size
     if size > limit:
         raise ApkError(f'{name} in the APK is {size / 1024**2:.0f} MB, more than a real one ({limit // 1024**2} MB)')
-    return z.read(name)
+    with z.open(name) as f:
+        data = f.read(limit + 1)
+    if len(data) > limit:
+        raise ApkError(f'{name} in the APK is larger than a real one ({limit // 1024**2} MB)')
+    return data
 
 
 def apk_info(path):

ui/frame_titles.py

@@ -321,6 +321,13 @@ def _stage_folder(src, dest):
     return dest
 
 
+def _below(top, root):
+    """The folders _unwrap stepped through from top to root, as 'a/b', or ''. Taken
+    before staging moves root elsewhere (possibly another drive on Windows)."""
+    rel = os.path.relpath(root, os.path.realpath(top)).replace(os.sep, '/')
+    return '' if rel == '.' else rel
+
+
 def _unwrap(root):
     """Step into a single top-level folder, the usual shape of a zipped build.
 
@@ -424,8 +431,8 @@ def inspect(path, name=None):
     work = None
     try:
         if os.path.isdir(path):
-            base = path
             root = _unwrap(path)
+            unwrapped = _below(path, root)
             if _has_links(root):
                 # scp -r follows links, so a link out of the folder could upload
                 # anything; copy the folder with its links made safe first.
@@ -434,24 +441,22 @@ def inspect(path, name=None):
         elif path.lower().endswith('.zip'):
             work = tempfile.mkdtemp(prefix=f'{TMP_PREFIX}{os.getpid()}-')
             extract_zip(path, work)
-            base = work
             root = _unwrap(work)
+            unwrapped = _below(work, root)
         elif classify(path):
             # A single executable is uploaded on its own; don't copy a whole Downloads folder.
             work = tempfile.mkdtemp(prefix=f'{TMP_PREFIX}{os.getpid()}-')
             shutil.copy2(path, os.path.join(work, os.path.basename(path)))
-            base = root = work
+            root, unwrapped = work, ''
         else:
             raise FrameError(f'{os.path.basename(path)} is not a .zip, a folder or a program')
         title = name or display_name(os.path.basename(path.rstrip('/\\')))
         found = candidates(root, title)
         if not found:
             raise FrameError(f'no Linux or Windows program found in {os.path.basename(path)}')
-        # An exe path may be given as it is in the archive, above the folder _unwrap stepped into.
-        unwrapped = os.path.relpath(root, os.path.realpath(base)).replace(os.sep, '/')
         plan = {'source': os.path.basename(path.rstrip('/\\')), 'name': title, 'id': title_id(title),
                 'root': root, 'work': work, 'candidates': found,
-                'unwrapped': '' if unwrapped == '.' else unwrapped,
+                'unwrapped': unwrapped,
                 'size': _tree_size(root), 'warnings': []}
         _choose(plan, found[0]['path'])
         return plan
@@ -474,8 +479,11 @@ def _tree_size(root):
 def _choose(plan, rel, runtime=None):
     """Set plan's launch target (a path relative to root) and its runtime."""
     rel = rel.replace('\\', '/')
+    # A manifest may name the program as it is in the archive, above the folder
+    # _unwrap stepped into. A path that works as it is always wins.
     prefix = plan.get('unwrapped') and plan['unwrapped'] + '/'
-    if prefix and rel.startswith(prefix):
+    if (prefix and rel.startswith(prefix) and not any(c['path'] == rel for c in plan['candidates'])
+            and not os.path.isfile(os.path.join(plan['root'], *rel.split('/')))):
         rel = rel[len(prefix):]
     target = next((c for c in plan['candidates'] if c['path'] == rel), None)
     if target is None:

ui/index.html

@@ -1200,6 +1200,7 @@ async function sideloadOne(file, path, isDir = false) {
       await act(`Copy ${file.name} to ~/Downloads`, () => upload(file, "push"));
     return;
   }
+  await loadTitles();  // fresh, so the dialog can say whether this replaces an installed title
   const choice = await confirmTitle(r.plan, canPush);
   if (choice === "push") {
     api("/api/titles", { action: "discard", token: r.token }).catch(() => {});
@@ -1217,6 +1218,7 @@ function confirmTitle(plan, canPush) {
     $("titleName").value = plan.name;
     const idNote = () => { const id = titleId($("titleName").value);
       $("titleIdNote").textContent = !id ? "Needs some letters or digits"
+        : !installedTitles ? `Shows in Steam as ${id}. Couldn't check whether it's installed already; if it is, this replaces it`
         : installedTitles.has(id.toLowerCase()) ? `Replaces the installed ${id}, and everything in its folder on the Frame`
         : `Shows in Steam as ${id}`; };
     $("titleName").oninput = idNote; idNote();
@@ -1274,11 +1276,11 @@ async function installTitle(token, choice) {
     }
   } finally { $("prog").style.display = "none"; loadTitles(); }
 }
-let installedTitles = new Set();  // lower-case ids, so the install dialog can warn before replacing one
+let installedTitles = null;  // lower-case ids, so the install dialog can warn before replacing one; null: unknown
 async function loadTitles() {
   let list;
   try { list = (await api("/api/titles")).titles; }
-  catch (e) { $("titleList").innerHTML = `<div class="sub">${esc(e.message)}</div>`; return; }
+  catch (e) { installedTitles = null; $("titleList").innerHTML = `<div class="sub">${esc(e.message)}</div>`; return; }
   installedTitles = new Set(list.map(t => String(t.id).toLowerCase()));
   $("titleCount").textContent = list.length ? `${list.length}` : "";
   $("titleList").innerHTML = list.length ? list.map(t => `