Merge bitcoin#15710: wallet: Catch ios_base::failure specifically

7486e27 Tests: Unit test related to WalletDB ReadKeyValue (Bushstar)
32def8d Catch ios_base::failure specifically (Peter Bushnell)

Pull request description:

  In bitcoin#2950 a hash of the pubkey and private was added to speed up key import, this was made backwards compatible by reading the hash in a try block with an ellipses catch all in case the hash was not present.

  CDataStream::read() specifically throws std::ios_base::failure, backwards compatibility expects only that error to be thrown, if something else gets thrown we should not be catching it. The change in this commit is to catch that exception only. If any other exception is thrown other than std::ios_base::failure it will be caught by the wider try block and an error written to the log and/or console.

  CDataStream::read() throwing std::ios_base::failure.
  https://github.com/bitcoin/bitcoin/blob/2c364fde423e74b4e03ebcff4582a9db7a6c4e4b/src/streams.h#L191

  Wider catch statements that pick up all others exceptions other than ios_base::failure.
  https://github.com/bitcoin/bitcoin/blob/2c364fde423e74b4e03ebcff4582a9db7a6c4e4b/src/wallet/walletdb.cpp#L425

  https://github.com/bitcoin/bitcoin/blob/2c364fde423e74b4e03ebcff4582a9db7a6c4e4b/src/wallet/walletdb.cpp#L430

ACKs for top commit:
  laanwj:
    Code review ACK 7486e27

Tree-SHA512: 5364bf935af8ec603bf5b8fef8c23b5cdaa4fe3506090cff988413221f2eaa99f7a91929afb42a35f8881ce2328744a0d32052da51ca0a5b2e65b6809e97f604

src/Makefile.test.include

@@ -182,6 +182,7 @@ BITCOIN_TESTS += \
   wallet/test/coinjoin_tests.cpp \
   wallet/test/psbt_wallet_tests.cpp \
   wallet/test/wallet_tests.cpp \
+  wallet/test/walletdb_tests.cpp \
   wallet/test/wallet_crypto_tests.cpp \
   wallet/test/coinselector_tests.cpp \
   wallet/test/init_tests.cpp \

src/wallet/test/walletdb_tests.cpp

@@ -0,0 +1,29 @@
+// Copyright (c) 2012-2019 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <test/util/setup_common.h>
+#include <clientversion.h>
+#include <streams.h>
+#include <uint256.h>
+
+#include <boost/test/unit_test.hpp>
+
+BOOST_FIXTURE_TEST_SUITE(walletdb_tests, BasicTestingSetup)
+
+BOOST_AUTO_TEST_CASE(walletdb_readkeyvalue)
+{
+    /**
+     * When ReadKeyValue() reads from either a "key" or "wkey" it first reads the CDataStream steam into a
+     * CPrivKey or CWalletKey respectively and then reads a hash of the pubkey and privkey into a uint256.
+     * Wallets from 0.8 or before do not store the pubkey/privkey hash, trying to read the hash from old
+     * wallets throws an exception, for backwards compatibility this read is wrapped in a try block to
+     * silently fail. The test here makes sure the type of exception thrown from CDataStream::read()
+     * matches the type we expect, otherwise we need to update the "key"/"wkey" exception type caught.
+     */
+    CDataStream ssValue(SER_DISK, CLIENT_VERSION);
+    uint256 dummy;
+    BOOST_CHECK_THROW(ssValue >> dummy, std::ios_base::failure);
+}
+
+BOOST_AUTO_TEST_SUITE_END()

src/wallet/walletdb.cpp

@@ -327,7 +327,7 @@ ReadKeyValue(CWallet* pwallet, CDataStream& ssKey, CDataStream& ssValue,
             {
                 ssValue >> hash;
             }
-            catch (...) {}
+            catch (const std::ios_base::failure&) {}
 
             bool fSkipCheck = false;