wallettool: Add dump command

Adds a new dump command to bitcoin-wallet which prints out all of the
wallet's records in hex.

src/Makefile.am

@@ -249,6 +249,7 @@ BITCOIN_CORE_H = \
   wallet/context.h \
   wallet/crypter.h \
   wallet/db.h \
+  wallet/dump.h \
   wallet/feebumper.h \
   wallet/fees.h \
   wallet/ismine.h \
@@ -361,6 +362,7 @@ libbitcoin_wallet_a_SOURCES = \
   wallet/context.cpp \
   wallet/crypter.cpp \
   wallet/db.cpp \
+  wallet/dump.cpp \
   wallet/feebumper.cpp \
   wallet/fees.cpp \
   wallet/interfaces.cpp \

src/bitcoin-wallet.cpp

@@ -27,6 +27,7 @@ static void SetupWalletToolArgs(ArgsManager& argsman)
     argsman.AddArg("-version", "Print version and exit", ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     argsman.AddArg("-datadir=<dir>", "Specify data directory", ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     argsman.AddArg("-wallet=<wallet-name>", "Specify wallet name", ArgsManager::ALLOW_ANY | ArgsManager::NETWORK_ONLY, OptionsCategory::OPTIONS);
+    argsman.AddArg("-dumpfile=<file name>", "When used with 'dump', writes out the records to this file.", ArgsManager::ALLOW_STRING, OptionsCategory::OPTIONS);
     argsman.AddArg("-debug=<category>", "Output debugging information (default: 0).", ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-descriptors", "Create descriptors wallet. Only for create", ArgsManager::ALLOW_BOOL, OptionsCategory::OPTIONS);
     argsman.AddArg("-printtoconsole", "Send trace/debug info to console (default: 1 when no -debug is true, 0 otherwise).", ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
@@ -34,6 +35,7 @@ static void SetupWalletToolArgs(ArgsManager& argsman)
     argsman.AddArg("info", "Get wallet info", ArgsManager::ALLOW_ANY, OptionsCategory::COMMANDS);
     argsman.AddArg("create", "Create new wallet file", ArgsManager::ALLOW_ANY, OptionsCategory::COMMANDS);
     argsman.AddArg("salvage", "Attempt to recover private keys from a corrupt wallet. Warning: 'salvage' is experimental.", ArgsManager::ALLOW_ANY, OptionsCategory::COMMANDS);
+    argsman.AddArg("dump", "Print out all of the wallet key-value records", ArgsManager::ALLOW_ANY, OptionsCategory::COMMANDS);
 }
 
 static bool WalletAppInit(int argc, char* argv[])

src/wallet/dump.cpp

@@ -0,0 +1,96 @@
+// Copyright (c) 2020 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 <wallet/dump.h>
+
+#include <util/translation.h>
+#include <wallet/wallet.h>
+
+static const std::string DUMP_MAGIC = "BITCOIN_CORE_WALLET_DUMP";
+uint32_t DUMP_VERSION = 1;
+
+bool DumpWallet(CWallet& wallet, bilingual_str& error)
+{
+    // Get the dumpfile
+    std::string dump_filename = gArgs.GetArg("-dumpfile", "");
+    if (dump_filename.empty()) {
+        error = _("No dump file provided. To use dump, -dumpfile=<filename> must be provided.");
+        return false;
+    }
+
+    fs::path path = dump_filename;
+    path = fs::absolute(path);
+    if (fs::exists(path)) {
+        error = strprintf(_("File %s already exists. If you are sure this is what you want, move it out of the way first."), path.string());
+        return false;
+    }
+    fsbridge::ofstream dump_file;
+    dump_file.open(path);
+    if (dump_file.fail()) {
+        error = strprintf(_("Unable to open %s for writing"), path.string());
+        return false;
+    }
+
+    CHashWriter hasher(0, 0);
+
+    WalletDatabase& db = wallet.GetDatabase();
+    std::unique_ptr<DatabaseBatch> batch = db.MakeBatch();
+
+    bool ret = true;
+    if (!batch->StartCursor()) {
+        error = _("Error: Couldn't create cursor into database");
+        ret = false;
+    }
+
+    // Write out a magic string with version
+    std::string line = strprintf("%s,%u\n", DUMP_MAGIC, DUMP_VERSION);
+    dump_file.write(line.data(), line.size());
+    hasher.write(line.data(), line.size());
+
+    // Write out the file format
+    line = strprintf("%s,%s\n", "format", db.Format());
+    dump_file.write(line.data(), line.size());
+    hasher.write(line.data(), line.size());
+
+    if (ret) {
+
+        // Read the records
+        while (true) {
+            CDataStream ss_key(SER_DISK, CLIENT_VERSION);
+            CDataStream ss_value(SER_DISK, CLIENT_VERSION);
+            bool complete;
+            ret = batch->ReadAtCursor(ss_key, ss_value, complete);
+            if (complete) {
+                ret = true;
+                break;
+            } else if (!ret) {
+                error = _("Error reading next record from wallet database");
+                break;
+            }
+            std::string key_str = HexStr(ss_key);
+            std::string value_str = HexStr(ss_value);
+            line = strprintf("%s,%s\n", key_str, value_str);
+            dump_file.write(line.data(), line.size());
+            hasher.write(line.data(), line.size());
+        }
+    }
+
+    batch->CloseCursor();
+    batch.reset();
+
+    // Close the wallet after we're done with it. The caller won't be doing this
+    wallet.Close();
+
+    if (ret) {
+        // Write the hash
+        tfm::format(dump_file, "checksum,%s\n", HexStr(hasher.GetHash()));
+        dump_file.close();
+    } else {
+        // Remove the dumpfile on failure
+        dump_file.close();
+        fs::remove(path);
+    }
+
+    return ret;
+}

src/wallet/dump.h

@@ -0,0 +1,14 @@
+// Copyright (c) 2020 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_WALLET_DUMP_H
+#define BITCOIN_WALLET_DUMP_H
+
+class CWallet;
+
+struct bilingual_str;
+
+bool DumpWallet(CWallet& wallet, bilingual_str& error);
+
+#endif // BITCOIN_WALLET_DUMP_H

src/wallet/wallettool.cpp

@@ -5,6 +5,7 @@
 #include <fs.h>
 #include <util/system.h>
 #include <util/translation.h>
+#include <wallet/dump.h>
 #include <wallet/salvage.h>
 #include <wallet/wallet.h>
 #include <wallet/walletutil.h>
@@ -106,6 +107,12 @@ bool ExecuteWalletToolFunc(const std::string& command, const std::string& name)
 {
     fs::path path = fs::absolute(name, GetWalletDir());
 
+    // -dumpfile is only allowed with dump and createfromdump. Disallow it for all other commands.
+    if (gArgs.IsArgSet("-dumpfile") && command != "dump" && command != "createfromdump") {
+        tfm::format(std::cerr, "The -dumpfile option can only be used with the \"dump\" and \"createfromdump\" commands.\n");
+        return false;
+    }
+
     if (command == "create") {
         DatabaseOptions options;
         options.require_create = true;
@@ -119,8 +126,7 @@ bool ExecuteWalletToolFunc(const std::string& command, const std::string& name)
             WalletShowInfo(wallet_instance.get());
             wallet_instance->Close();
         }
-    } else if (command == "info" || command == "salvage") {
+    } else if (command == "info") {
-        if (command == "info") {
         DatabaseOptions options;
         options.require_existing = true;
         std::shared_ptr<CWallet> wallet_instance = MakeWallet(name, path, options);
@@ -145,7 +151,19 @@ bool ExecuteWalletToolFunc(const std::string& command, const std::string& name)
         tfm::format(std::cerr, "Salvage command is not available as BDB support is not compiled");
         return false;
 #endif
+    } else if (command == "dump") {
+        DatabaseOptions options;
+        options.require_existing = true;
+        std::shared_ptr<CWallet> wallet_instance = MakeWallet(name, path, options);
+        if (!wallet_instance) return false;
+        bilingual_str error;
+        bool ret = DumpWallet(*wallet_instance, error);
+        if (!ret && !error.empty()) {
+            tfm::format(std::cerr, "%s\n", error.original);
+            return ret;
         }
+        tfm::format(std::cout, "The dumpfile may contain private keys. To ensure the safety of your Bitcoin, do not share the dumpfile.\n");
+        return ret;
     } else {
         tfm::format(std::cerr, "Invalid command: %s\n", command);
         return false;