From 761f178651b032de505ca4ccc8d012c38beeab25 Mon Sep 17 00:00:00 2001
From: General_K1ng <generak1ng0@gmail.com>
Date: Mon, 16 Jun 2025 22:39:22 +0800
Subject: [PATCH 1/3] Fix: add immutable=1 flag for read-only SQLite access to
 avoid WAL/SHM errors on readonly DB

---
 Lib/dbm/sqlite3.py | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/Lib/dbm/sqlite3.py b/Lib/dbm/sqlite3.py
index b296a1bcd1bbfa..7ee35d04399420 100644
--- a/Lib/dbm/sqlite3.py
+++ b/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:

From 3e3a3ba6c6f1a8ea747e08b3d1ad6b098366d4b6 Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <43283697+blurb-it[bot]@users.noreply.github.com>
Date: Mon, 16 Jun 2025 15:00:14 +0000
Subject: [PATCH 2/3] gh-135386: Fix dbm.sqlite3 readonly open error by using
 immutable=1

---
 Lib/dbm/sqlite3.py                              |  1 +
 Lib/test/test_dbm_sqlite3.py                    | 17 +++++++++++++++++
 ...25-06-16-15-00-13.gh-issue-135386.lNrxLc.rst |  1 +
 3 files changed, 19 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2025-06-16-15-00-13.gh-issue-135386.lNrxLc.rst

diff --git a/Lib/dbm/sqlite3.py b/Lib/dbm/sqlite3.py
index 7ee35d04399420..9ca9f8f999e207 100644
--- a/Lib/dbm/sqlite3.py
+++ b/Lib/dbm/sqlite3.py
@@ -69,6 +69,7 @@ def __init__(self, path, /, *, flag, mode):
             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.
         if not self._readonly:
diff --git a/Lib/test/test_dbm_sqlite3.py b/Lib/test/test_dbm_sqlite3.py
index 9216da8a63f957..1553e28cfee197 100644
--- a/Lib/test/test_dbm_sqlite3.py
+++ b/Lib/test/test_dbm_sqlite3.py
@@ -1,3 +1,4 @@
+import os
 import sys
 import unittest
 from contextlib import closing
@@ -89,6 +90,22 @@ def test_readonly_keys(self):
     def test_readonly_iter(self):
         self.assertEqual([k for k in self.db], [b"key1", b"key2"])
 
+    def test_readonly_open_without_wal_shm(self):
+        wal_path = self.filename + "-wal"
+        shm_path = self.filename + "-shm"
+
+        for suffix in wal_path, shm_path:
+            try:
+                os.remove(suffix)
+            except FileNotFoundError:
+                pass
+
+        os.chmod(self.filename, 0o444)
+
+        with dbm_sqlite3.open(self.filename, "r") as db:
+            self.assertEqual(db[b"key1"], b"value1")
+            self.assertEqual(db[b"key2"], b"value2")
+
 
 class ReadWrite(_SQLiteDbmTests):
 
diff --git a/Misc/NEWS.d/next/Library/2025-06-16-15-00-13.gh-issue-135386.lNrxLc.rst b/Misc/NEWS.d/next/Library/2025-06-16-15-00-13.gh-issue-135386.lNrxLc.rst
new file mode 100644
index 00000000000000..d3f81cb9201aaf
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-06-16-15-00-13.gh-issue-135386.lNrxLc.rst
@@ -0,0 +1 @@
+Fix :exc:`sqlite3.OperationalError` error when using :func:`dbm.open` with a read-only file object.

From 7f988ddabc6df30213af62294b26fbbe57c9c0a7 Mon Sep 17 00:00:00 2001
From: General_K1ng <generak1ng0@gmail.com>
Date: Tue, 17 Jun 2025 21:56:37 +0800
Subject: [PATCH 3/3] Add test: readonly sqlite db without wal/shm (skip on
 Windows)

---
 Lib/test/test_dbm_sqlite3.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Lib/test/test_dbm_sqlite3.py b/Lib/test/test_dbm_sqlite3.py
index 1553e28cfee197..467ada060cfe77 100644
--- a/Lib/test/test_dbm_sqlite3.py
+++ b/Lib/test/test_dbm_sqlite3.py
@@ -90,6 +90,7 @@ def test_readonly_keys(self):
     def test_readonly_iter(self):
         self.assertEqual([k for k in self.db], [b"key1", b"key2"])
 
+    @unittest.skipIf(sys.platform.startswith("win"), "incompatible with Windows file locking")
     def test_readonly_open_without_wal_shm(self):
         wal_path = self.filename + "-wal"
         shm_path = self.filename + "-shm"