Fix: add immutable=1 flag for read-only SQLite access to avoid WAL/SHM errors on readonly DB

Author: GeneralK1ng

Lib/dbm/sqlite3.py

@@ -59,19 +59,24 @@ def __init__(self, path, /, *, flag, mode):
 
         # We use the URI format when opening the database.
         uri = _normalize_uri(path)
-        uri = f"{uri}?mode={flag}"
+        if flag == "ro":
+            # Add immutable=1 to allow read-only SQLite access even if wal/shm missing
+            uri = f"{uri}?mode={flag}&immutable=1"
+        else:
+            uri = f"{uri}?mode={flag}"
 
         try:
             self._cx = sqlite3.connect(uri, autocommit=True, uri=True)
         except sqlite3.Error as exc:
             raise error(str(exc))
-
+        self._readonly = (flag == "ro")
         # This is an optimization only; it's ok if it fails.
-        with suppress(sqlite3.OperationalError):
-            self._cx.execute("PRAGMA journal_mode = wal")
+        if not self._readonly:
+            with suppress(sqlite3.OperationalError):
+                self._cx.execute("PRAGMA journal_mode = OFF")
 
-        if flag == "rwc":
-            self._execute(BUILD_TABLE)
+            if flag == "rwc":
+                self._execute(BUILD_TABLE)
 
     def _execute(self, *args, **kwargs):
         if not self._cx: