Merge bitcoin/bitcoin#26606: wallet: Implement independent BDB parser

d51fbab4b3 wallet, test: Be able to always swap BDB endianness (Ava Chow)
0b753156ce test: Test bdb_ro dump of wallet without reset LSNs (Ava Chow)
c1984f1282 test: Test dumping dbs with overflow pages (Ava Chow)
fd7b16e391 test: Test dumps of other endian BDB files (Ava Chow)
6ace3e953f bdb: Be able to make byteswapped databases (Ava Chow)
d9878903fb Error if LSNs are not reset (Ava Chow)
4d7a3ae78e Berkeley RO Database fuzz test (TheCharlatan)
3568dce9e9 tests: Add BerkeleyRO to db prefix tests (Ava Chow)
70cfbfdadf wallettool: Optionally use BERKELEY_RO as format when dumping BDB wallets (Ava Chow)
dd57713f6e Add MakeBerkeleyRODatabase (Ava Chow)
6e50bee67d Implement handling of other endianness in BerkeleyRODatabase (Ava Chow)
cdd61c9cc1 wallet: implement independent BDB deserializer in BerkeleyRODatabase (Ava Chow)
ecba230979 wallet: implement BerkeleyRODatabase::Backup (Ava Chow)
0c8e728476 wallet: implement BerkeleyROBatch (Ava Chow)
756ff9b478 wallet: add dummy BerkeleyRODatabase and BerkeleyROBatch classes (Ava Chow)
ca18aea5c4 Add AutoFile::seek and tell (Ava Chow)

Pull request description:

  Split from #26596

  This PR adds `BerkeleyRODatabase` which is an independent implementation of a BDB file parser. It provides read only access to a BDB file, and can therefore be used as a read only database backend for wallets. This will be used for dumping legacy wallet records and migrating legacy wallets without the need for BDB itself.

  Wallettool's `dump` command is changed to use `BerkeleyRODatabase` instead of `BerkeleyDatabase` (and `CWallet` itself) to demonstrate that this parser works and to test it against the existing wallettool functional tests.

ACKs for top commit:
  josibake:
    reACK d51fbab4b3
  TheCharlatan:
    Re-ACK d51fbab4b3
  furszy:
    reACK d51fbab4b3
  laanwj:
    re-ACK d51fbab4b3
  theStack:
    ACK d51fbab4b3

Tree-SHA512: 1e7b97edf223b2974eed2e9eac1179fc82bb6359e0a66b7d2a0c8b9fa515eae9ea036f1edf7c76cdab2e75ad994962b134b41056ccfbc33b8d54f0859e86657b

src/wallet/test/fuzz/wallet_bdb_parser.cpp

@@ -0,0 +1,133 @@
+// Copyright (c) 2023 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 <config/bitcoin-config.h> // IWYU pragma: keep
+#include <test/fuzz/FuzzedDataProvider.h>
+#include <test/fuzz/fuzz.h>
+#include <test/fuzz/util.h>
+#include <test/util/setup_common.h>
+#include <util/fs.h>
+#include <util/time.h>
+#include <util/translation.h>
+#include <wallet/bdb.h>
+#include <wallet/db.h>
+#include <wallet/dump.h>
+#include <wallet/migrate.h>
+
+#include <fstream>
+#include <iostream>
+
+using wallet::DatabaseOptions;
+using wallet::DatabaseStatus;
+
+namespace {
+TestingSetup* g_setup;
+} // namespace
+
+void initialize_wallet_bdb_parser()
+{
+    static auto testing_setup = MakeNoLogFileContext<TestingSetup>();
+    g_setup = testing_setup.get();
+}
+
+FUZZ_TARGET(wallet_bdb_parser, .init = initialize_wallet_bdb_parser)
+{
+    const auto wallet_path = g_setup->m_args.GetDataDirNet() / "fuzzed_wallet.dat";
+
+    {
+        AutoFile outfile{fsbridge::fopen(wallet_path, "wb")};
+        outfile << Span{buffer};
+    }
+
+    const DatabaseOptions options{};
+    DatabaseStatus status;
+    bilingual_str error;
+
+    fs::path bdb_ro_dumpfile{g_setup->m_args.GetDataDirNet() / "fuzzed_dumpfile_bdb_ro.dump"};
+    if (fs::exists(bdb_ro_dumpfile)) { // Writing into an existing dump file will throw an exception
+        remove(bdb_ro_dumpfile);
+    }
+    g_setup->m_args.ForceSetArg("-dumpfile", fs::PathToString(bdb_ro_dumpfile));
+
+#ifdef USE_BDB
+    bool bdb_ro_err = false;
+    bool bdb_ro_pgno_err = false;
+#endif
+    auto db{MakeBerkeleyRODatabase(wallet_path, options, status, error)};
+    if (db) {
+        assert(DumpWallet(g_setup->m_args, *db, error));
+    } else {
+#ifdef USE_BDB
+        bdb_ro_err = true;
+#endif
+        if (error.original == "AutoFile::ignore: end of file: iostream error" ||
+            error.original == "AutoFile::read: end of file: iostream error" ||
+            error.original == "Not a BDB file" ||
+            error.original == "Unsupported BDB data file version number" ||
+            error.original == "Unexpected page type, should be 9 (BTree Metadata)" ||
+            error.original == "Unexpected database flags, should only be 0x20 (subdatabases)" ||
+            error.original == "Unexpected outer database root page type" ||
+            error.original == "Unexpected number of entries in outer database root page" ||
+            error.original == "Subdatabase has an unexpected name" ||
+            error.original == "Subdatabase page number has unexpected length" ||
+            error.original == "Unexpected inner database page type" ||
+            error.original == "Unknown record type in records page" ||
+            error.original == "Unknown record type in internal page" ||
+            error.original == "Unexpected page size" ||
+            error.original == "Unexpected page type" ||
+            error.original == "Page number mismatch" ||
+            error.original == "Bad btree level" ||
+            error.original == "Bad page size" ||
+            error.original == "File size is not a multiple of page size" ||
+            error.original == "Meta page number mismatch") {
+            // Do nothing
+        } else if (error.original == "Subdatabase last page is greater than database last page" ||
+                   error.original == "Page number is greater than database last page" ||
+                   error.original == "Page number is greater than subdatabase last page" ||
+                   error.original == "Last page number could not fit in file") {
+#ifdef USE_BDB
+            bdb_ro_pgno_err = true;
+#endif
+        } else {
+            throw std::runtime_error(error.original);
+        }
+    }
+
+#ifdef USE_BDB
+    // Try opening with BDB
+    fs::path bdb_dumpfile{g_setup->m_args.GetDataDirNet() / "fuzzed_dumpfile_bdb.dump"};
+    if (fs::exists(bdb_dumpfile)) { // Writing into an existing dump file will throw an exception
+        remove(bdb_dumpfile);
+    }
+    g_setup->m_args.ForceSetArg("-dumpfile", fs::PathToString(bdb_dumpfile));
+
+    try {
+        auto db{MakeBerkeleyDatabase(wallet_path, options, status, error)};
+        if (bdb_ro_err && !db) {
+            return;
+        }
+        assert(db);
+        if (bdb_ro_pgno_err) {
+            // BerkeleyRO will throw on opening for errors involving bad page numbers, but BDB does not.
+            // Ignore those.
+            return;
+        }
+        assert(!bdb_ro_err);
+        assert(DumpWallet(g_setup->m_args, *db, error));
+    } catch (const std::runtime_error& e) {
+        if (bdb_ro_err) return;
+        throw e;
+    }
+
+    // Make sure the dumpfiles match
+    if (fs::exists(bdb_ro_dumpfile) && fs::exists(bdb_dumpfile)) {
+        std::ifstream bdb_ro_dump(bdb_ro_dumpfile, std::ios_base::binary | std::ios_base::in);
+        std::ifstream bdb_dump(bdb_dumpfile, std::ios_base::binary | std::ios_base::in);
+        assert(std::equal(
+            std::istreambuf_iterator<char>(bdb_ro_dump.rdbuf()),
+            std::istreambuf_iterator<char>(),
+            std::istreambuf_iterator<char>(bdb_dump.rdbuf())));
+    }
+#endif
+}