Merge bitcoin/bitcoin#21732: MOVEONLY: Move common init code to init/common

615965cfd1ef1e0627d69970d99bdfedb9176833 Move common package version code to init/common (Russell Yanofsky)
5bed2ab42c4f1a820468f7005ce62e39001f6611 Move common logging start code to init/common (Russell Yanofsky)
1fb7fcfa52569a652d3ea55c210b725e60b7d86f Move common logging GetArgs code to init/common (Russell Yanofsky)
90469c16906ab451bb1250df5e51563870a7ef3b Move common logging AddArg code to init/common (Russell Yanofsky)
387c4cf5887bfdaf1606e1b287d901e4c449514f Move common sanity check code to init/common (Russell Yanofsky)
a67b54855b294802d52f09fa60d3f63550cbada7 Move common global init code to init/common (Russell Yanofsky)

Pull request description:

  This PR is part of the [process separation project](https://github.com/bitcoin/bitcoin/projects/10).

  ---

  This change is move-only and can be easily reviewed with `--color-moved=dimmed_zebra`. The moves are needed to avoid duplicating common init code between different binaries (`bitcoin-node`, `bitcoin-wallet`, etc) in #10102. In #10102, each binary has it's own init file (`src/init/bitcoin-node.cpp`, `src/init/bitcoin-wallet.cpp`) so this PR moves the common code to `src/init/common.cpp`.

ACKs for top commit:
  MarcoFalke:
    review ACK 615965cfd1ef1e0627d69970d99bdfedb9176833 🖱
  practicalswift:
    cr ACK 615965cfd1ef1e0627d69970d99bdfedb9176833: dimmed zebra looks correct

Tree-SHA512: 859e1d86aee17eb50a49d806cf62d30d12f6b15018e41c096da41d7e535a9d2d088481cb340fee59e6c68e512a74b61c7146f2683465f553dc4953bf32f2a7b4

4 files changed, 210 insertions, 122 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index e25e210e1e..d5190206c0 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -156,6 +156,7 @@ BITCOIN_CORE_H = \
   index/txindex.h \
   indirectmap.h \
   init.h \
+  init/common.h \
   interfaces/chain.h \
   interfaces/handler.h \
   interfaces/node.h \
@@ -521,6 +522,7 @@ libbitcoin_common_a_SOURCES = \
   core_read.cpp \
   core_write.cpp \
   external_signer.cpp \
+  init/common.cpp \
   key.cpp \
   key_io.cpp \
   merkleblock.cpp \
diff --git a/src/init.cpp b/src/init.cpp
index 741e70f748..cb056c85eb 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -22,9 +22,9 @@
 #include <httpserver.h>
 #include <index/blockfilterindex.h>
 #include <index/txindex.h>
+#include <init/common.h>
 #include <interfaces/chain.h>
 #include <interfaces/node.h>
-#include <key.h>
 #include <mapport.h>
 #include <miner.h>
 #include <net.h>
@@ -151,8 +151,6 @@ static fs::path GetPidFile(const ArgsManager& args)
 // shutdown thing.
 //
 
-static std::unique_ptr<ECCVerifyHandle> globalVerifyHandle;
-
 void Interrupt(NodeContext& node)
 {
     InterruptHTTPServer();
@@ -286,8 +284,7 @@ void Shutdown(NodeContext& node)
     node.chain_clients.clear();
     UnregisterAllValidationInterfaces();
     GetMainSignals().UnregisterBackgroundSignalScheduler();
-    globalVerifyHandle.reset();
-    ECC_Stop();
+    init::UnsetGlobals();
     node.mempool.reset();
     node.fee_estimator.reset();
     node.chainman = nullptr;
@@ -363,6 +360,8 @@ void SetupServerArgs(NodeContext& node)
     SetupHelpOptions(argsman);
     argsman.AddArg("-help-debug", "Print help message with debugging options and exit", ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST); // server-only for now
 
+    init::AddLoggingArgs(argsman);
+
     const auto defaultBaseParams = CreateBaseChainParams(CBaseChainParams::MAIN);
     const auto testnetBaseParams = CreateBaseChainParams(CBaseChainParams::TESTNET);
     const auto signetBaseParams = CreateBaseChainParams(CBaseChainParams::SIGNET);
@@ -394,7 +393,6 @@ void SetupServerArgs(NodeContext& node)
     argsman.AddArg("-datadir=<dir>", "Specify data directory", ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     argsman.AddArg("-dbbatchsize", strprintf("Maximum database write batch size in bytes (default: %u)", nDefaultDbBatchSize), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::OPTIONS);
     argsman.AddArg("-dbcache=<n>", strprintf("Maximum database cache size <n> MiB (%d to %d, default: %d). In addition, unused mempool memory is shared for this cache (see -maxmempool).", nMinDbCache, nMaxDbCache, nDefaultDbCache), ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
-    argsman.AddArg("-debuglogfile=<file>", strprintf("Specify location of debug log file. Relative paths will be prefixed by a net-specific datadir location. (-nodebuglogfile to disable; default: %s)", DEFAULT_DEBUGLOGFILE), ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     argsman.AddArg("-feefilter", strprintf("Tell other nodes to filter invs to us by our mempool min fee (default: %u)", DEFAULT_FEEFILTER), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::OPTIONS);
     argsman.AddArg("-includeconf=<file>", "Specify additional configuration file, relative to the -datadir path (only useable from configuration file, not command line)", ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     argsman.AddArg("-loadblock=<file>", "Imports blocks from external file on startup", ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
@@ -522,25 +520,10 @@ void SetupServerArgs(NodeContext& node)
     argsman.AddArg("-limitdescendantsize=<n>", strprintf("Do not accept transactions if any ancestor would have more than <n> kilobytes of in-mempool descendants (default: %u).", DEFAULT_DESCENDANT_SIZE_LIMIT), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-addrmantest", "Allows to test address relay on localhost", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-capturemessages", "Capture all P2P messages to disk", ArgsManager::ALLOW_BOOL | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
-    argsman.AddArg("-debug=<category>", "Output debugging information (default: -nodebug, supplying <category> is optional). "
-        "If <category> is not supplied or if <category> = 1, output all debugging information. <category> can be: " + LogInstance().LogCategoriesString() + ". This option can be specified multiple times to output multiple categories.",
-        ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
-    argsman.AddArg("-debugexclude=<category>", strprintf("Exclude debugging information for a category. Can be used in conjunction with -debug=1 to output debug logs for all categories except the specified category. This option can be specified multiple times to exclude multiple categories."), ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
-    argsman.AddArg("-logips", strprintf("Include IP addresses in debug output (default: %u)", DEFAULT_LOGIPS), ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
-    argsman.AddArg("-logtimestamps", strprintf("Prepend debug output with timestamp (default: %u)", DEFAULT_LOGTIMESTAMPS), ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
-#ifdef HAVE_THREAD_LOCAL
-    argsman.AddArg("-logthreadnames", strprintf("Prepend debug output with name of the originating thread (only available on platforms supporting thread_local) (default: %u)", DEFAULT_LOGTHREADNAMES), ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
-#else
-    hidden_args.emplace_back("-logthreadnames");
-#endif
-    argsman.AddArg("-logsourcelocations", strprintf("Prepend debug output with name of the originating source location (source file, line number and function name) (default: %u)", DEFAULT_LOGSOURCELOCATIONS), ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
-    argsman.AddArg("-logtimemicros", strprintf("Add microsecond precision to debug timestamps (default: %u)", DEFAULT_LOGTIMEMICROS), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-mocktime=<n>", "Replace actual time with " + UNIX_EPOCH_TIME + " (default: 0)", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-maxsigcachesize=<n>", strprintf("Limit sum of signature cache and script execution cache sizes to <n> MiB (default: %u)", DEFAULT_MAX_SIG_CACHE_SIZE), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-maxtipage=<n>", strprintf("Maximum tip age in seconds to consider node in initial block download (default: %u)", DEFAULT_MAX_TIP_AGE), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-printpriority", strprintf("Log transaction fee per kB when mining blocks (default: %u)", DEFAULT_PRINTPRIORITY), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
-    argsman.AddArg("-printtoconsole", "Send trace/debug info to console (default: 1 when no -daemon. To disable logging to file, set -nodebuglogfile)", ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
-    argsman.AddArg("-shrinkdebugfile", "Shrink debug.log file on client startup (default: 1 when no -debug)", ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-uacomment=<cmt>", "Append comment to the user agent string", ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
 
     SetupChainParamsBaseOptions(argsman);
@@ -675,30 +658,6 @@ static void StartupNotify(const ArgsManager& args)
 }
 #endif
 
-/** Sanity checks
- *  Ensure that Bitcoin is running in a usable environment with all
- *  necessary library support.
- */
-static bool InitSanityCheck()
-{
-    if (!ECC_InitSanityCheck()) {
-        return InitError(Untranslated("Elliptic curve cryptography sanity check failure. Aborting."));
-    }
-
-    if (!glibcxx_sanity_test())
-        return false;
-
-    if (!Random_SanityCheck()) {
-        return InitError(Untranslated("OS cryptographic RNG sanity check failure. Aborting."));
-    }
-
-    if (!ChronoSanityCheck()) {
-        return InitError(Untranslated("Clock epoch mismatch. Aborting."));
-    }
-
-    return true;
-}
-
 static bool AppInitServers(NodeContext& node)
 {
     const ArgsManager& args = *Assert(node.args);
@@ -796,25 +755,8 @@ void InitParameterInteraction(ArgsManager& args)
  */
 void InitLogging(const ArgsManager& args)
 {
-    LogInstance().m_print_to_file = !args.IsArgNegated("-debuglogfile");
-    LogInstance().m_file_path = AbsPathForConfigVal(args.GetArg("-debuglogfile", DEFAULT_DEBUGLOGFILE));
-    LogInstance().m_print_to_console = args.GetBoolArg("-printtoconsole", !args.GetBoolArg("-daemon", false));
-    LogInstance().m_log_timestamps = args.GetBoolArg("-logtimestamps", DEFAULT_LOGTIMESTAMPS);
-    LogInstance().m_log_time_micros = args.GetBoolArg("-logtimemicros", DEFAULT_LOGTIMEMICROS);
-#ifdef HAVE_THREAD_LOCAL
-    LogInstance().m_log_threadnames = args.GetBoolArg("-logthreadnames", DEFAULT_LOGTHREADNAMES);
-#endif
-    LogInstance().m_log_sourcelocations = args.GetBoolArg("-logsourcelocations", DEFAULT_LOGSOURCELOCATIONS);
-
-    fLogIPs = args.GetBoolArg("-logips", DEFAULT_LOGIPS);
-
-    std::string version_string = FormatFullVersion();
-#ifdef DEBUG
-    version_string += " (debug build)";
-#else
-    version_string += " (release build)";
-#endif
-    LogPrintf(PACKAGE_NAME " version %s\n", version_string);
+    init::SetLoggingOptions(args);
+    init::LogPackageVersion();
 }
 
 namespace { // Variables internal to initialization process only
@@ -982,26 +924,7 @@ bool AppInitParameterInteraction(const ArgsManager& args)
         InitWarning(strprintf(_("Reducing -maxconnections from %d to %d, because of system limitations."), nUserMaxConnections, nMaxConnections));
 
     // ********************************************************* Step 3: parameter-to-internal-flags
-    if (args.IsArgSet("-debug")) {
-        // Special-case: if -debug=0/-nodebug is set, turn off debugging messages
-        const std::vector<std::string> categories = args.GetArgs("-debug");
-
-        if (std::none_of(categories.begin(), categories.end(),
-            [](std::string cat){return cat == "0" || cat == "none";})) {
-            for (const auto& cat : categories) {
-                if (!LogInstance().EnableCategory(cat)) {
-                    InitWarning(strprintf(_("Unsupported logging category %s=%s."), "-debug", cat));
-                }
-            }
-        }
-    }
-
-    // Now remove the logging categories which were explicitly excluded
-    for (const std::string& cat : args.GetArgs("-debugexclude")) {
-        if (!LogInstance().DisableCategory(cat)) {
-            InitWarning(strprintf(_("Unsupported logging category %s=%s."), "-debugexclude", cat));
-        }
-    }
+    init::SetLoggingCategories(args);
 
     fCheckBlockIndex = args.GetBoolArg("-checkblockindex", chainparams.DefaultConsistencyChecks());
     fCheckpointsEnabled = args.GetBoolArg("-checkpoints", DEFAULT_CHECKPOINTS_ENABLED);
@@ -1148,16 +1071,11 @@ bool AppInitSanityChecks()
 {
     // ********************************************************* Step 4: sanity checks
 
-    // Initialize elliptic curve code
-    std::string sha256_algo = SHA256AutoDetect();
-    LogPrintf("Using the '%s' SHA256 implementation\n", sha256_algo);
-    RandomInit();
-    ECC_Start();
-    globalVerifyHandle.reset(new ECCVerifyHandle());
+    init::SetGlobals();
 
-    // Sanity check
-    if (!InitSanityCheck())
+    if (!init::SanityChecks()) {
         return InitError(strprintf(_("Initialization sanity check failed. %s is shutting down."), PACKAGE_NAME));
+    }
 
     // Probe the data directory lock to give an early error message, if possible
     // We cannot hold the data directory lock here, as the forking for daemon() hasn't yet happened,
@@ -1197,38 +1115,11 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
         // Detailed error printed inside CreatePidFile().
         return false;
     }
-    if (LogInstance().m_print_to_file) {
-        if (args.GetBoolArg("-shrinkdebugfile", LogInstance().DefaultShrinkDebugFile())) {
-            // Do this first since it both loads a bunch of debug.log into memory,
-            // and because this needs to happen before any other debug.log printing
-            LogInstance().ShrinkDebugFile();
-        }
-    }
-    if (!LogInstance().StartLogging()) {
-            return InitError(strprintf(Untranslated("Could not open debug log file %s"),
-                LogInstance().m_file_path.string()));
-    }
-
-    if (!LogInstance().m_log_timestamps)
-        LogPrintf("Startup time: %s\n", FormatISO8601DateTime(GetTime()));
-    LogPrintf("Default data directory %s\n", GetDefaultDataDir().string());
-    LogPrintf("Using data directory %s\n", GetDataDir().string());
-
-    // Only log conf file usage message if conf file actually exists.
-    fs::path config_file_path = GetConfigFile(args.GetArg("-conf", BITCOIN_CONF_FILENAME));
-    if (fs::exists(config_file_path)) {
-        LogPrintf("Config file: %s\n", config_file_path.string());
-    } else if (args.IsArgSet("-conf")) {
-        // Warn if no conf file exists at path provided by user
-        InitWarning(strprintf(_("The specified config file %s does not exist"), config_file_path.string()));
-    } else {
-        // Not categorizing as "Warning" because it's the default behavior
-        LogPrintf("Config file: %s (not found, skipping)\n", config_file_path.string());
+    if (!init::StartLogging(args)) {
+        // Detailed error printed inside StartLogging().
+        return false;
     }
 
-    // Log the config arguments to debug.log
-    args.LogArgs();
-
     LogPrintf("Using at most %i automatic connections (%i file descriptors available)\n", nMaxConnections, nFD);
 
     // Warn about relative -datadir path.
diff --git a/src/init/common.cpp b/src/init/common.cpp
new file mode 100644
index 0000000000..79e0c9da78
--- /dev/null
+++ b/src/init/common.cpp
@@ -0,0 +1,167 @@
+// Copyright (c) 2021 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#if defined(HAVE_CONFIG_H)
+#include <config/bitcoin-config.h>
+#endif
+
+#include <clientversion.h>
+#include <compat/sanity.h>
+#include <crypto/sha256.h>
+#include <key.h>
+#include <logging.h>
+#include <node/ui_interface.h>
+#include <pubkey.h>
+#include <random.h>
+#include <util/system.h>
+#include <util/time.h>
+#include <util/translation.h>
+
+#include <memory>
+
+static std::unique_ptr<ECCVerifyHandle> globalVerifyHandle;
+
+namespace init {
+void SetGlobals()
+{
+    std::string sha256_algo = SHA256AutoDetect();
+    LogPrintf("Using the '%s' SHA256 implementation\n", sha256_algo);
+    RandomInit();
+    ECC_Start();
+    globalVerifyHandle.reset(new ECCVerifyHandle());
+}
+
+void UnsetGlobals()
+{
+    globalVerifyHandle.reset();
+    ECC_Stop();
+}
+
+bool SanityChecks()
+{
+    if (!ECC_InitSanityCheck()) {
+        return InitError(Untranslated("Elliptic curve cryptography sanity check failure. Aborting."));
+    }
+
+    if (!glibcxx_sanity_test())
+        return false;
+
+    if (!Random_SanityCheck()) {
+        return InitError(Untranslated("OS cryptographic RNG sanity check failure. Aborting."));
+    }
+
+    if (!ChronoSanityCheck()) {
+        return InitError(Untranslated("Clock epoch mismatch. Aborting."));
+    }
+
+    return true;
+}
+
+void AddLoggingArgs(ArgsManager& argsman)
+{
+    argsman.AddArg("-debuglogfile=<file>", strprintf("Specify location of debug log file. Relative paths will be prefixed by a net-specific datadir location. (-nodebuglogfile to disable; default: %s)", DEFAULT_DEBUGLOGFILE), ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
+    argsman.AddArg("-debug=<category>", "Output debugging information (default: -nodebug, supplying <category> is optional). "
+        "If <category> is not supplied or if <category> = 1, output all debugging information. <category> can be: " + LogInstance().LogCategoriesString() + ". This option can be specified multiple times to output multiple categories.",
+        ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
+    argsman.AddArg("-debugexclude=<category>", strprintf("Exclude debugging information for a category. Can be used in conjunction with -debug=1 to output debug logs for all categories except the specified category. This option can be specified multiple times to exclude multiple categories."), ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
+    argsman.AddArg("-logips", strprintf("Include IP addresses in debug output (default: %u)", DEFAULT_LOGIPS), ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
+    argsman.AddArg("-logtimestamps", strprintf("Prepend debug output with timestamp (default: %u)", DEFAULT_LOGTIMESTAMPS), ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
+#ifdef HAVE_THREAD_LOCAL
+    argsman.AddArg("-logthreadnames", strprintf("Prepend debug output with name of the originating thread (only available on platforms supporting thread_local) (default: %u)", DEFAULT_LOGTHREADNAMES), ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
+#else
+    argsman.AddHiddenArgs({"-logthreadnames"});
+#endif
+    argsman.AddArg("-logsourcelocations", strprintf("Prepend debug output with name of the originating source location (source file, line number and function name) (default: %u)", DEFAULT_LOGSOURCELOCATIONS), ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
+    argsman.AddArg("-logtimemicros", strprintf("Add microsecond precision to debug timestamps (default: %u)", DEFAULT_LOGTIMEMICROS), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
+    argsman.AddArg("-printtoconsole", "Send trace/debug info to console (default: 1 when no -daemon. To disable logging to file, set -nodebuglogfile)", ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
+    argsman.AddArg("-shrinkdebugfile", "Shrink debug.log file on client startup (default: 1 when no -debug)", ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
+}
+
+void SetLoggingOptions(const ArgsManager& args)
+{
+    LogInstance().m_print_to_file = !args.IsArgNegated("-debuglogfile");
+    LogInstance().m_file_path = AbsPathForConfigVal(args.GetArg("-debuglogfile", DEFAULT_DEBUGLOGFILE));
+    LogInstance().m_print_to_console = args.GetBoolArg("-printtoconsole", !args.GetBoolArg("-daemon", false));
+    LogInstance().m_log_timestamps = args.GetBoolArg("-logtimestamps", DEFAULT_LOGTIMESTAMPS);
+    LogInstance().m_log_time_micros = args.GetBoolArg("-logtimemicros", DEFAULT_LOGTIMEMICROS);
+#ifdef HAVE_THREAD_LOCAL
+    LogInstance().m_log_threadnames = args.GetBoolArg("-logthreadnames", DEFAULT_LOGTHREADNAMES);
+#endif
+    LogInstance().m_log_sourcelocations = args.GetBoolArg("-logsourcelocations", DEFAULT_LOGSOURCELOCATIONS);
+
+    fLogIPs = args.GetBoolArg("-logips", DEFAULT_LOGIPS);
+}
+
+void SetLoggingCategories(const ArgsManager& args)
+{
+    if (args.IsArgSet("-debug")) {
+        // Special-case: if -debug=0/-nodebug is set, turn off debugging messages
+        const std::vector<std::string> categories = args.GetArgs("-debug");
+
+        if (std::none_of(categories.begin(), categories.end(),
+            [](std::string cat){return cat == "0" || cat == "none";})) {
+            for (const auto& cat : categories) {
+                if (!LogInstance().EnableCategory(cat)) {
+                    InitWarning(strprintf(_("Unsupported logging category %s=%s."), "-debug", cat));
+                }
+            }
+        }
+    }
+
+    // Now remove the logging categories which were explicitly excluded
+    for (const std::string& cat : args.GetArgs("-debugexclude")) {
+        if (!LogInstance().DisableCategory(cat)) {
+            InitWarning(strprintf(_("Unsupported logging category %s=%s."), "-debugexclude", cat));
+        }
+    }
+}
+
+bool StartLogging(const ArgsManager& args)
+{
+    if (LogInstance().m_print_to_file) {
+        if (args.GetBoolArg("-shrinkdebugfile", LogInstance().DefaultShrinkDebugFile())) {
+            // Do this first since it both loads a bunch of debug.log into memory,
+            // and because this needs to happen before any other debug.log printing
+            LogInstance().ShrinkDebugFile();
+        }
+    }
+    if (!LogInstance().StartLogging()) {
+            return InitError(strprintf(Untranslated("Could not open debug log file %s"),
+                LogInstance().m_file_path.string()));
+    }
+
+    if (!LogInstance().m_log_timestamps)
+        LogPrintf("Startup time: %s\n", FormatISO8601DateTime(GetTime()));
+    LogPrintf("Default data directory %s\n", GetDefaultDataDir().string());
+    LogPrintf("Using data directory %s\n", GetDataDir().string());
+
+    // Only log conf file usage message if conf file actually exists.
+    fs::path config_file_path = GetConfigFile(args.GetArg("-conf", BITCOIN_CONF_FILENAME));
+    if (fs::exists(config_file_path)) {
+        LogPrintf("Config file: %s\n", config_file_path.string());
+    } else if (args.IsArgSet("-conf")) {
+        // Warn if no conf file exists at path provided by user
+        InitWarning(strprintf(_("The specified config file %s does not exist"), config_file_path.string()));
+    } else {
+        // Not categorizing as "Warning" because it's the default behavior
+        LogPrintf("Config file: %s (not found, skipping)\n", config_file_path.string());
+    }
+
+    // Log the config arguments to debug.log
+    args.LogArgs();
+
+    return true;
+}
+
+void LogPackageVersion()
+{
+    std::string version_string = FormatFullVersion();
+#ifdef DEBUG
+    version_string += " (debug build)";
+#else
+    version_string += " (release build)";
+#endif
+    LogPrintf(PACKAGE_NAME " version %s\n", version_string);
+}
+} // namespace init
diff --git a/src/init/common.h b/src/init/common.h
new file mode 100644
index 0000000000..fc4bc1b280
--- /dev/null
+++ b/src/init/common.h
@@ -0,0 +1,28 @@
+// Copyright (c) 2021 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+//! @file
+//! @brief Common init functions shared by bitcoin-node, bitcoin-wallet, etc.
+
+#ifndef BITCOIN_INIT_COMMON_H
+#define BITCOIN_INIT_COMMON_H
+
+class ArgsManager;
+
+namespace init {
+void SetGlobals();
+void UnsetGlobals();
+/**
+ *  Ensure a usable environment with all
+ *  necessary library support.
+ */
+bool SanityChecks();
+void AddLoggingArgs(ArgsManager& args);
+void SetLoggingOptions(const ArgsManager& args);
+void SetLoggingCategories(const ArgsManager& args);
+bool StartLogging(const ArgsManager& args);
+void LogPackageVersion();
+} // namespace init
+
+#endif // BITCOIN_INIT_COMMON_H