Merge #14453: rpc: Fix wallet unload during walletpassphrase timeout

8907df9 qa: Ensure wallet unload during walletpassphrase timeout (João Barbosa)
321decf rpc: Fix wallet unload during walletpassphrase timeout (João Barbosa)

Pull request description:

  Replaces the raw wallet pointer in the `RPCRunLater` callback with a `std::weak_ptr` to check if the wallet is not expired.

  To test:
  ```
  bitcoind -regtest
  bitcoin-cli -regtest encryptwallet foobar
  bitcoin-cli -regtest walletpassphrase foobar 5 && bitcoin-cli -regtest unloadwallet ""
  ```

  Fixes #14452.

Tree-SHA512: 311e839234f5fb7955ab5412a2cfc1903ee7132ea56a8ab992ede3614586834886bd65192b76531ae0aa3a526b38e70ca2e1cdbabe52995906ff97b49d93c268

Author: laanwj

src/wallet/rpcwallet.cpp

@@ -1803,13 +1803,6 @@ static UniValue keypoolrefill(const JSONRPCRequest& request)
 }
 
 
-static void LockWallet(CWallet* pWallet)
-{
-    LOCK(pWallet->cs_wallet);
-    pWallet->nRelockTime = 0;
-    pWallet->Lock();
-}
-
 static UniValue walletpassphrase(const JSONRPCRequest& request)
 {
     std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
@@ -1879,7 +1872,18 @@ static UniValue walletpassphrase(const JSONRPCRequest& request)
     pwallet->TopUpKeyPool();
 
     pwallet->nRelockTime = GetTime() + nSleepTime;
-    RPCRunLater(strprintf("lockwallet(%s)", pwallet->GetName()), std::bind(LockWallet, pwallet), nSleepTime);
+
+    // Keep a weak pointer to the wallet so that it is possible to unload the
+    // wallet before the following callback is called. If a valid shared pointer
+    // is acquired in the callback then the wallet is still loaded.
+    std::weak_ptr<CWallet> weak_wallet = wallet;
+    RPCRunLater(strprintf("lockwallet(%s)", pwallet->GetName()), [weak_wallet] {
+        if (auto shared_wallet = weak_wallet.lock()) {
+            LOCK(shared_wallet->cs_wallet);
+            shared_wallet->Lock();
+            shared_wallet->nRelockTime = 0;
+        }
+    }, nSleepTime);
 
     return NullUniValue;
 }

test/functional/wallet_multiwallet.py

@@ -8,6 +8,7 @@
 """
 import os
 import shutil
+import time
 
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.test_node import ErrorMatch
@@ -273,7 +274,11 @@ def wallet_file(name):
         assert 'w1' not in self.nodes[0].listwallets()
 
         # Successfully unload the wallet referenced by the request endpoint
+        # Also ensure unload works during walletpassphrase timeout
+        w2.encryptwallet('test')
+        w2.walletpassphrase('test', 1)
         w2.unloadwallet()
+        time.sleep(1.1)
         assert 'w2' not in self.nodes[0].listwallets()
 
         # Successfully unload all wallets