Merge bitcoin/bitcoin#32736: wallet: Correct dir iteration error handling

272cd09b79 log: Use warning level while scanning wallet dir (MarcoFalke)
1777644367 qa, wallet: Verify warning when failing to scan (Hodlinator)
893e51ffeb wallet: Correct dir iteration error handling (Hodlinator)

Pull request description:

  Make wallet DB properly detect and report failure to scan wallet directory. Seems to have been broken since moving from Boost to `std::filesystem`.

  Found while reviewing: https://github.com/bitcoin/bitcoin/pull/31410#pullrequestreview-2604068753

ACKs for top commit:
  achow101:
    ACK 272cd09b79
  maflcko:
    re-ACK 272cd09b79 🍽
  rkrux:
    tACK 272cd09b79

Tree-SHA512: 969afde2e37f885ed0c823dc36d2dbeaa0378639849c6a26f8ac67b4f1997eea95bbcae6d58aef5b716807210f37eb166c0cda7ba1d6caffd34249970833af3a

test/functional/wallet_multiwallet.py

@@ -78,6 +78,24 @@ class MultiWalletTest(BitcoinTestFramework):
         self.stop_nodes()
         assert_equal(os.path.isfile(wallet_dir(self.default_wallet_name, self.wallet_data_filename)), True)
 
+        self.log.info("Verify warning is emitted when failing to scan the wallets directory")
+        if platform.system() == 'Windows':
+            self.log.warning('Skipping test involving chmod as Windows does not support it.')
+        elif os.geteuid() == 0:
+            self.log.warning('Skipping test involving chmod as it requires a non-root user.')
+        else:
+            self.start_node(0)
+            with self.nodes[0].assert_debug_log(unexpected_msgs=['Error scanning directory entries under'], expected_msgs=[]):
+                result = self.nodes[0].listwalletdir()
+                assert_equal(result, {'wallets': [{'name': 'default_wallet', 'warnings': []}]})
+            os.chmod(data_dir('wallets'), 0)
+            with self.nodes[0].assert_debug_log(expected_msgs=['Error scanning directory entries under']):
+                result = self.nodes[0].listwalletdir()
+                assert_equal(result, {'wallets': []})
+            self.stop_node(0)
+            # Restore permissions
+            os.chmod(data_dir('wallets'), stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR)
+
         # create symlink to verify wallet directory path can be referenced
         # through symlink
         os.mkdir(wallet_dir('w7'))
@@ -129,7 +147,7 @@ class MultiWalletTest(BitcoinTestFramework):
         os.mkdir(wallet_dir('no_access'))
         os.chmod(wallet_dir('no_access'), 0)
         try:
-            with self.nodes[0].assert_debug_log(expected_msgs=['Error scanning']):
+            with self.nodes[0].assert_debug_log(expected_msgs=["Error while scanning wallet dir"]):
                 walletlist = self.nodes[0].listwalletdir()['wallets']
         finally:
             # Need to ensure access is restored for cleanup