test: Add test for file system permissions

test/functional/feature_posix_fs_permissions.py

@@ -0,0 +1,43 @@
+#!/usr/bin/env python3
+# Copyright (c) 2022 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Test file system permissions for POSIX platforms.
+"""
+
+import os
+import stat
+
+from test_framework.test_framework import BitcoinTestFramework
+
+
+class PosixFsPermissionsTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.setup_clean_chain = True
+        self.num_nodes = 1
+
+    def skip_test_if_missing_module(self):
+        self.skip_if_platform_not_posix()
+
+    def check_directory_permissions(self, dir):
+        mode = os.lstat(dir).st_mode
+        self.log.info(f"{stat.filemode(mode)} {dir}")
+        assert mode == (stat.S_IFDIR | stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR)
+
+    def check_file_permissions(self, file):
+        mode = os.lstat(file).st_mode
+        self.log.info(f"{stat.filemode(mode)} {file}")
+        assert mode == (stat.S_IFREG | stat.S_IRUSR | stat.S_IWUSR)
+
+    def run_test(self):
+        self.stop_node(0)
+        datadir = os.path.join(self.nodes[0].datadir, self.chain)
+        self.check_directory_permissions(datadir)
+        walletsdir = os.path.join(datadir, "wallets")
+        self.check_directory_permissions(walletsdir)
+        debuglog = os.path.join(datadir, "debug.log")
+        self.check_file_permissions(debuglog)
+
+
+if __name__ == '__main__':
+    PosixFsPermissionsTest().main()

test/functional/test_framework/test_framework.py

@@ -880,6 +880,11 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
         if platform.system() != "Linux":
             raise SkipTest("not on a Linux system")
 
+    def skip_if_platform_not_posix(self):
+        """Skip the running test if we are not on a POSIX platform"""
+        if os.name != 'posix':
+            raise SkipTest("not on a POSIX system")
+
     def skip_if_no_bitcoind_zmq(self):
         """Skip the running test if bitcoind has not been compiled with zmq support."""
         if not self.is_zmq_compiled():

test/functional/test_runner.py

@@ -211,6 +211,7 @@ BASE_SCRIPTS = [
     'p2p_addrv2_relay.py',
     'p2p_compactblocks_hb.py',
     'p2p_disconnect_ban.py',
+    'feature_posix_fs_permissions.py',
     'rpc_decodescript.py',
     'rpc_blockchain.py',
     'rpc_deprecated.py',