[build] Move wallet load functions to wallet/load unit

Moves the following wallet load functions to a new wallet/load unit in
the libbitcoin_wallet library. All other functions in wallet/init remain
in libbitcoin_server:

- `VerifyWallets`
- `LoadWallets`
- `StartWallets`
- `FlushWallets`
- `StopWallets`
- `UnloadWallets`

6 files changed, 156 insertions, 122 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 21fd365d38..7849e4740b 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -222,6 +222,7 @@ BITCOIN_CORE_H = \
   wallet/db.h \
   wallet/feebumper.h \
   wallet/fees.h \
+  wallet/load.h \
   wallet/psbtwallet.h \
   wallet/rpcwallet.h \
   wallet/wallet.h \
@@ -293,6 +294,9 @@ libbitcoin_server_a_SOURCES = \
   versionbits.cpp \
   $(BITCOIN_CORE_H)
 
+if ENABLE_WALLET
+libbitcoin_server_a_SOURCES += wallet/init.cpp
+endif
 if !ENABLE_WALLET
 libbitcoin_server_a_SOURCES += dummywallet.cpp
 endif
@@ -319,7 +323,7 @@ libbitcoin_wallet_a_SOURCES = \
   wallet/db.cpp \
   wallet/feebumper.cpp \
   wallet/fees.cpp \
-  wallet/init.cpp \
+  wallet/load.cpp \
   wallet/psbtwallet.cpp \
   wallet/rpcdump.cpp \
   wallet/rpcwallet.cpp \
diff --git a/src/interfaces/wallet.cpp b/src/interfaces/wallet.cpp
index 0bb9739c9c..f98a49f9b1 100644
--- a/src/interfaces/wallet.cpp
+++ b/src/interfaces/wallet.cpp
@@ -29,6 +29,7 @@
 #include <wallet/feebumper.h>
 #include <wallet/fees.h>
 #include <wallet/rpcwallet.h>
+#include <wallet/load.h>
 #include <wallet/wallet.h>
 #include <wallet/walletutil.h>
 
diff --git a/src/wallet/init.cpp b/src/wallet/init.cpp
index 1b4d69bc37..e7eea94e06 100644
--- a/src/wallet/init.cpp
+++ b/src/wallet/init.cpp
@@ -131,58 +131,6 @@ bool WalletInit::ParameterInteraction() const
     return true;
 }
 
-bool VerifyWallets(interfaces::Chain& chain, const std::vector<std::string>& wallet_files)
-{
-    if (gArgs.IsArgSet("-walletdir")) {
-        fs::path wallet_dir = gArgs.GetArg("-walletdir", "");
-        boost::system::error_code error;
-        // The canonical path cleans the path, preventing >1 Berkeley environment instances for the same directory
-        fs::path canonical_wallet_dir = fs::canonical(wallet_dir, error);
-        if (error || !fs::exists(wallet_dir)) {
-            chain.initError(strprintf(_("Specified -walletdir \"%s\" does not exist"), wallet_dir.string()));
-            return false;
-        } else if (!fs::is_directory(wallet_dir)) {
-            chain.initError(strprintf(_("Specified -walletdir \"%s\" is not a directory"), wallet_dir.string()));
-            return false;
-        // The canonical path transforms relative paths into absolute ones, so we check the non-canonical version
-        } else if (!wallet_dir.is_absolute()) {
-            chain.initError(strprintf(_("Specified -walletdir \"%s\" is a relative path"), wallet_dir.string()));
-            return false;
-        }
-        gArgs.ForceSetArg("-walletdir", canonical_wallet_dir.string());
-    }
-
-    LogPrintf("Using wallet directory %s\n", GetWalletDir().string());
-
-    chain.initMessage(_("Verifying wallet(s)..."));
-
-    // Parameter interaction code should have thrown an error if -salvagewallet
-    // was enabled with more than wallet file, so the wallet_files size check
-    // here should have no effect.
-    bool salvage_wallet = gArgs.GetBoolArg("-salvagewallet", false) && wallet_files.size() <= 1;
-
-    // Keep track of each wallet absolute path to detect duplicates.
-    std::set<fs::path> wallet_paths;
-
-    for (const auto& wallet_file : wallet_files) {
-        WalletLocation location(wallet_file);
-
-        if (!wallet_paths.insert(location.GetPath()).second) {
-            chain.initError(strprintf(_("Error loading wallet %s. Duplicate -wallet filename specified."), wallet_file));
-            return false;
-        }
-
-        std::string error_string;
-        std::string warning_string;
-        bool verify_success = CWallet::Verify(chain, location, salvage_wallet, error_string, warning_string);
-        if (!error_string.empty()) chain.initError(error_string);
-        if (!warning_string.empty()) chain.initWarning(warning_string);
-        if (!verify_success) return false;
-    }
-
-    return true;
-}
-
 void WalletInit::Construct(InitInterfaces& interfaces) const
 {
     if (gArgs.GetBoolArg("-disablewallet", DEFAULT_DISABLE_WALLET)) {
@@ -192,52 +140,3 @@ void WalletInit::Construct(InitInterfaces& interfaces) const
     gArgs.SoftSetArg("-wallet", "");
     interfaces.chain_clients.emplace_back(interfaces::MakeWalletClient(*interfaces.chain, gArgs.GetArgs("-wallet")));
 }
-
-bool LoadWallets(interfaces::Chain& chain, const std::vector<std::string>& wallet_files)
-{
-    for (const std::string& walletFile : wallet_files) {
-        std::shared_ptr<CWallet> pwallet = CWallet::CreateWalletFromFile(chain, WalletLocation(walletFile));
-        if (!pwallet) {
-            return false;
-        }
-        AddWallet(pwallet);
-    }
-
-    return true;
-}
-
-void StartWallets(CScheduler& scheduler)
-{
-    for (const std::shared_ptr<CWallet>& pwallet : GetWallets()) {
-        pwallet->postInitProcess();
-    }
-
-    // Schedule periodic wallet flushes and tx rebroadcasts
-    scheduler.scheduleEvery(MaybeCompactWalletDB, 500);
-    scheduler.scheduleEvery(MaybeResendWalletTxs, 1000);
-}
-
-void FlushWallets()
-{
-    for (const std::shared_ptr<CWallet>& pwallet : GetWallets()) {
-        pwallet->Flush(false);
-    }
-}
-
-void StopWallets()
-{
-    for (const std::shared_ptr<CWallet>& pwallet : GetWallets()) {
-        pwallet->Flush(true);
-    }
-}
-
-void UnloadWallets()
-{
-    auto wallets = GetWallets();
-    while (!wallets.empty()) {
-        auto wallet = wallets.back();
-        wallets.pop_back();
-        RemoveWallet(wallet);
-        UnloadWallet(std::move(wallet));
-    }
-}
diff --git a/src/wallet/load.cpp b/src/wallet/load.cpp
new file mode 100644
index 0000000000..79c5f439df
--- /dev/null
+++ b/src/wallet/load.cpp
@@ -0,0 +1,112 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2018 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/load.h>
+
+#include <interfaces/chain.h>
+#include <scheduler.h>
+#include <util/system.h>
+#include <wallet/wallet.h>
+
+bool VerifyWallets(interfaces::Chain& chain, const std::vector<std::string>& wallet_files)
+{
+    if (gArgs.IsArgSet("-walletdir")) {
+        fs::path wallet_dir = gArgs.GetArg("-walletdir", "");
+        boost::system::error_code error;
+        // The canonical path cleans the path, preventing >1 Berkeley environment instances for the same directory
+        fs::path canonical_wallet_dir = fs::canonical(wallet_dir, error);
+        if (error || !fs::exists(wallet_dir)) {
+            chain.initError(strprintf(_("Specified -walletdir \"%s\" does not exist"), wallet_dir.string()));
+            return false;
+        } else if (!fs::is_directory(wallet_dir)) {
+            chain.initError(strprintf(_("Specified -walletdir \"%s\" is not a directory"), wallet_dir.string()));
+            return false;
+        // The canonical path transforms relative paths into absolute ones, so we check the non-canonical version
+        } else if (!wallet_dir.is_absolute()) {
+            chain.initError(strprintf(_("Specified -walletdir \"%s\" is a relative path"), wallet_dir.string()));
+            return false;
+        }
+        gArgs.ForceSetArg("-walletdir", canonical_wallet_dir.string());
+    }
+
+    LogPrintf("Using wallet directory %s\n", GetWalletDir().string());
+
+    chain.initMessage(_("Verifying wallet(s)..."));
+
+    // Parameter interaction code should have thrown an error if -salvagewallet
+    // was enabled with more than wallet file, so the wallet_files size check
+    // here should have no effect.
+    bool salvage_wallet = gArgs.GetBoolArg("-salvagewallet", false) && wallet_files.size() <= 1;
+
+    // Keep track of each wallet absolute path to detect duplicates.
+    std::set<fs::path> wallet_paths;
+
+    for (const auto& wallet_file : wallet_files) {
+        WalletLocation location(wallet_file);
+
+        if (!wallet_paths.insert(location.GetPath()).second) {
+            chain.initError(strprintf(_("Error loading wallet %s. Duplicate -wallet filename specified."), wallet_file));
+            return false;
+        }
+
+        std::string error_string;
+        std::string warning_string;
+        bool verify_success = CWallet::Verify(chain, location, salvage_wallet, error_string, warning_string);
+        if (!error_string.empty()) chain.initError(error_string);
+        if (!warning_string.empty()) chain.initWarning(warning_string);
+        if (!verify_success) return false;
+    }
+
+    return true;
+}
+
+bool LoadWallets(interfaces::Chain& chain, const std::vector<std::string>& wallet_files)
+{
+    for (const std::string& walletFile : wallet_files) {
+        std::shared_ptr<CWallet> pwallet = CWallet::CreateWalletFromFile(chain, WalletLocation(walletFile));
+        if (!pwallet) {
+            return false;
+        }
+        AddWallet(pwallet);
+    }
+
+    return true;
+}
+
+void StartWallets(CScheduler& scheduler)
+{
+    for (const std::shared_ptr<CWallet>& pwallet : GetWallets()) {
+        pwallet->postInitProcess();
+    }
+
+    // Schedule periodic wallet flushes and tx rebroadcasts
+    scheduler.scheduleEvery(MaybeCompactWalletDB, 500);
+    scheduler.scheduleEvery(MaybeResendWalletTxs, 1000);
+}
+
+void FlushWallets()
+{
+    for (const std::shared_ptr<CWallet>& pwallet : GetWallets()) {
+        pwallet->Flush(false);
+    }
+}
+
+void StopWallets()
+{
+    for (const std::shared_ptr<CWallet>& pwallet : GetWallets()) {
+        pwallet->Flush(true);
+    }
+}
+
+void UnloadWallets()
+{
+    auto wallets = GetWallets();
+    while (!wallets.empty()) {
+        auto wallet = wallets.back();
+        wallets.pop_back();
+        RemoveWallet(wallet);
+        UnloadWallet(std::move(wallet));
+    }
+}
diff --git a/src/wallet/load.h b/src/wallet/load.h
new file mode 100644
index 0000000000..9bb6f2166e
--- /dev/null
+++ b/src/wallet/load.h
@@ -0,0 +1,38 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2018 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_LOAD_H
+#define BITCOIN_WALLET_LOAD_H
+
+#include <string>
+#include <vector>
+
+class CScheduler;
+
+namespace interfaces {
+class Chain;
+} // namespace interfaces
+
+//! Responsible for reading and validating the -wallet arguments and verifying the wallet database.
+//! This function will perform salvage on the wallet if requested, as long as only one wallet is
+//! being loaded (WalletParameterInteraction forbids -salvagewallet, -zapwallettxes or -upgradewallet with multiwallet).
+bool VerifyWallets(interfaces::Chain& chain, const std::vector<std::string>& wallet_files);
+
+//! Load wallet databases.
+bool LoadWallets(interfaces::Chain& chain, const std::vector<std::string>& wallet_files);
+
+//! Complete startup of wallets.
+void StartWallets(CScheduler& scheduler);
+
+//! Flush all wallets in preparation for shutdown.
+void FlushWallets();
+
+//! Stop all wallets. Wallets will be flushed first.
+void StopWallets();
+
+//! Close all wallets.
+void UnloadWallets();
+
+#endif // BITCOIN_WALLET_LOAD_H
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 587b2814c0..cefdf479c6 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -35,26 +35,6 @@
 #include <utility>
 #include <vector>
 
-//! Responsible for reading and validating the -wallet arguments and verifying the wallet database.
-//! This function will perform salvage on the wallet if requested, as long as only one wallet is
-//! being loaded (WalletParameterInteraction forbids -salvagewallet, -zapwallettxes or -upgradewallet with multiwallet).
-bool VerifyWallets(interfaces::Chain& chain, const std::vector<std::string>& wallet_files);
-
-//! Load wallet databases.
-bool LoadWallets(interfaces::Chain& chain, const std::vector<std::string>& wallet_files);
-
-//! Complete startup of wallets.
-void StartWallets(CScheduler& scheduler);
-
-//! Flush all wallets in preparation for shutdown.
-void FlushWallets();
-
-//! Stop all wallets. Wallets will be flushed first.
-void StopWallets();
-
-//! Close all wallets.
-void UnloadWallets();
-
 //! Explicitly unload and delete the wallet.
 //! Blocks the current thread after signaling the unload intent so that all
 //! wallet clients release the wallet.