lbrycrd/src/util.cpp

// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2017 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 <util.h>

#include <chainparamsbase.h>
#include <random.h>
#include <serialize.h>
#include <utilstrencodings.h>

#include <stdarg.h>

#if (defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__DragonFly__))
#include <pthread.h>
#include <pthread_np.h>
#endif

#ifndef WIN32
// for posix_fallocate
#ifdef __linux__

#ifdef _POSIX_C_SOURCE
#undef _POSIX_C_SOURCE
#endif

#define _POSIX_C_SOURCE 200112L

#endif // __linux__

#include <algorithm>
#include <fcntl.h>
#include <sched.h>
#include <sys/resource.h>
#include <sys/stat.h>

#else

#ifdef _MSC_VER
#pragma warning(disable:4786)
#pragma warning(disable:4804)
#pragma warning(disable:4805)
#pragma warning(disable:4717)
#endif

#ifdef _WIN32_WINNT
#undef _WIN32_WINNT
#endif
#define _WIN32_WINNT 0x0501

#ifdef _WIN32_IE
#undef _WIN32_IE
#endif
#define _WIN32_IE 0x0501

#define WIN32_LEAN_AND_MEAN 1
#ifndef NOMINMAX
#define NOMINMAX
#endif

#include <io.h> /* for _commit */
#include <shlobj.h>
#endif

#ifdef HAVE_SYS_PRCTL_H
#include <sys/prctl.h>
#endif

#ifdef HAVE_MALLOPT_ARENA_MAX
#include <malloc.h>
#endif

#include <boost/interprocess/sync/file_lock.hpp>
#include <boost/program_options/detail/config_file.hpp>
#include <boost/thread.hpp>
#include <openssl/crypto.h>
#include <openssl/rand.h>
#include <openssl/conf.h>
#include <thread>

// Application startup time (used for uptime calculation)
const int64_t nStartupTime = GetTime();

const char * const BITCOIN_CONF_FILENAME = "bitcoin.conf";
const char * const BITCOIN_PID_FILENAME = "bitcoind.pid";
const char * const DEFAULT_DEBUGLOGFILE = "debug.log";

ArgsManager gArgs;
bool fPrintToConsole = false;
bool fPrintToDebugLog = true;

bool fLogTimestamps = DEFAULT_LOGTIMESTAMPS;
bool fLogTimeMicros = DEFAULT_LOGTIMEMICROS;
bool fLogIPs = DEFAULT_LOGIPS;
std::atomic<bool> fReopenDebugLog(false);
CTranslationInterface translationInterface;

/** Log categories bitfield. */
std::atomic<uint32_t> logCategories(0);

/** Init OpenSSL library multithreading support */
static std::unique_ptr<CCriticalSection[]> ppmutexOpenSSL;
void locking_callback(int mode, int i, const char* file, int line) NO_THREAD_SAFETY_ANALYSIS
{
    if (mode & CRYPTO_LOCK) {
        ENTER_CRITICAL_SECTION(ppmutexOpenSSL[i]);
    } else {
        LEAVE_CRITICAL_SECTION(ppmutexOpenSSL[i]);
    }
}

// Singleton for wrapping OpenSSL setup/teardown.
class CInit
{
public:
    CInit()
    {
        // Init OpenSSL library multithreading support
        ppmutexOpenSSL.reset(new CCriticalSection[CRYPTO_num_locks()]);
        CRYPTO_set_locking_callback(locking_callback);

        // OpenSSL can optionally load a config file which lists optional loadable modules and engines.
        // We don't use them so we don't require the config. However some of our libs may call functions
        // which attempt to load the config file, possibly resulting in an exit() or crash if it is missing
        // or corrupt. Explicitly tell OpenSSL not to try to load the file. The result for our libs will be
        // that the config appears to have been loaded and there are no modules/engines available.
        OPENSSL_no_config();

#ifdef WIN32
        // Seed OpenSSL PRNG with current contents of the screen
        RAND_screen();
#endif

        // Seed OpenSSL PRNG with performance counter
        RandAddSeed();
    }
    ~CInit()
    {
        // Securely erase the memory used by the PRNG
        RAND_cleanup();
        // Shutdown OpenSSL library multithreading support
        CRYPTO_set_locking_callback(nullptr);
        // Clear the set of locks now to maintain symmetry with the constructor.
        ppmutexOpenSSL.reset();
    }
}
instance_of_cinit;

/**
 * LogPrintf() has been broken a couple of times now
 * by well-meaning people adding mutexes in the most straightforward way.
 * It breaks because it may be called by global destructors during shutdown.
 * Since the order of destruction of static/global objects is undefined,
 * defining a mutex as a global object doesn't work (the mutex gets
 * destroyed, and then some later destructor calls OutputDebugStringF,
 * maybe indirectly, and you get a core dump at shutdown trying to lock
 * the mutex).
 */

static std::once_flag debugPrintInitFlag;

/**
 * We use std::call_once() to make sure mutexDebugLog and
 * vMsgsBeforeOpenLog are initialized in a thread-safe manner.
 *
 * NOTE: fileout, mutexDebugLog and sometimes vMsgsBeforeOpenLog
 * are leaked on exit. This is ugly, but will be cleaned up by
 * the OS/libc. When the shutdown sequence is fully audited and
 * tested, explicit destruction of these objects can be implemented.
 */
static FILE* fileout = nullptr;
static std::mutex* mutexDebugLog = nullptr;
static std::list<std::string>* vMsgsBeforeOpenLog;

static int FileWriteStr(const std::string &str, FILE *fp)
{
    return fwrite(str.data(), 1, str.size(), fp);
}

static void DebugPrintInit()
{
    assert(mutexDebugLog == nullptr);
    mutexDebugLog = new std::mutex();
    vMsgsBeforeOpenLog = new std::list<std::string>;
}

fs::path GetDebugLogPath()
{
    fs::path logfile(gArgs.GetArg("-debuglogfile", DEFAULT_DEBUGLOGFILE));
    return AbsPathForConfigVal(logfile);
}

bool OpenDebugLog()
{
    std::call_once(debugPrintInitFlag, &DebugPrintInit);
    std::lock_guard<std::mutex> scoped_lock(*mutexDebugLog);

    assert(fileout == nullptr);
    assert(vMsgsBeforeOpenLog);
    fs::path pathDebug = GetDebugLogPath();

    fileout = fsbridge::fopen(pathDebug, "a");
    if (!fileout) {
        return false;
    }

    setbuf(fileout, nullptr); // unbuffered
    // dump buffered messages from before we opened the log
    while (!vMsgsBeforeOpenLog->empty()) {
        FileWriteStr(vMsgsBeforeOpenLog->front(), fileout);
        vMsgsBeforeOpenLog->pop_front();
    }

    delete vMsgsBeforeOpenLog;
    vMsgsBeforeOpenLog = nullptr;
    return true;
}

struct CLogCategoryDesc
{
    uint32_t flag;
    std::string category;
};

const CLogCategoryDesc LogCategories[] =
{
    {BCLog::NONE, "0"},
    {BCLog::NONE, "none"},
    {BCLog::NET, "net"},
    {BCLog::TOR, "tor"},
    {BCLog::MEMPOOL, "mempool"},
    {BCLog::HTTP, "http"},
    {BCLog::BENCH, "bench"},
    {BCLog::ZMQ, "zmq"},
    {BCLog::DB, "db"},
    {BCLog::RPC, "rpc"},
    {BCLog::ESTIMATEFEE, "estimatefee"},
    {BCLog::ADDRMAN, "addrman"},
    {BCLog::SELECTCOINS, "selectcoins"},
    {BCLog::REINDEX, "reindex"},
    {BCLog::CMPCTBLOCK, "cmpctblock"},
    {BCLog::RAND, "rand"},
    {BCLog::PRUNE, "prune"},
    {BCLog::PROXY, "proxy"},
    {BCLog::MEMPOOLREJ, "mempoolrej"},
    {BCLog::LIBEVENT, "libevent"},
    {BCLog::COINDB, "coindb"},
    {BCLog::QT, "qt"},
    {BCLog::LEVELDB, "leveldb"},
    {BCLog::ALL, "1"},
    {BCLog::ALL, "all"},
};

bool GetLogCategory(uint32_t *f, const std::string *str)
{
    if (f && str) {
        if (*str == "") {
            *f = BCLog::ALL;
            return true;
        }
        for (unsigned int i = 0; i < ARRAYLEN(LogCategories); i++) {
            if (LogCategories[i].category == *str) {
                *f = LogCategories[i].flag;
                return true;
            }
        }
    }
    return false;
}

std::string ListLogCategories()
{
    std::string ret;
    int outcount = 0;
    for (unsigned int i = 0; i < ARRAYLEN(LogCategories); i++) {
        // Omit the special cases.
        if (LogCategories[i].flag != BCLog::NONE && LogCategories[i].flag != BCLog::ALL) {
            if (outcount != 0) ret += ", ";
            ret += LogCategories[i].category;
            outcount++;
        }
    }
    return ret;
}

std::vector<CLogCategoryActive> ListActiveLogCategories()
{
    std::vector<CLogCategoryActive> ret;
    for (unsigned int i = 0; i < ARRAYLEN(LogCategories); i++) {
        // Omit the special cases.
        if (LogCategories[i].flag != BCLog::NONE && LogCategories[i].flag != BCLog::ALL) {
            CLogCategoryActive catActive;
            catActive.category = LogCategories[i].category;
            catActive.active = LogAcceptCategory(LogCategories[i].flag);
            ret.push_back(catActive);
        }
    }
    return ret;
}

/**
 * fStartedNewLine is a state variable held by the calling context that will
 * suppress printing of the timestamp when multiple calls are made that don't
 * end in a newline. Initialize it to true, and hold it, in the calling context.
 */
static std::string LogTimestampStr(const std::string &str, std::atomic_bool *fStartedNewLine)
{
    std::string strStamped;

    if (!fLogTimestamps)
        return str;

    if (*fStartedNewLine) {
        int64_t nTimeMicros = GetTimeMicros();
        strStamped = FormatISO8601DateTime(nTimeMicros/1000000);
        if (fLogTimeMicros) {
            strStamped.pop_back();
            strStamped += strprintf(".%06dZ", nTimeMicros%1000000);
        }
        int64_t mocktime = GetMockTime();
        if (mocktime) {
            strStamped += " (mocktime: " + FormatISO8601DateTime(mocktime) + ")";
        }
        strStamped += ' ' + str;
    } else
        strStamped = str;

    if (!str.empty() && str[str.size()-1] == '\n')
        *fStartedNewLine = true;
    else
        *fStartedNewLine = false;

    return strStamped;
}

int LogPrintStr(const std::string &str)
{
    int ret = 0; // Returns total number of characters written
    static std::atomic_bool fStartedNewLine(true);

    std::string strTimestamped = LogTimestampStr(str, &fStartedNewLine);

    if (fPrintToConsole)
    {
        // print to console
        ret = fwrite(strTimestamped.data(), 1, strTimestamped.size(), stdout);
        fflush(stdout);
    }
    else if (fPrintToDebugLog)
    {
        std::call_once(debugPrintInitFlag, &DebugPrintInit);
        std::lock_guard<std::mutex> scoped_lock(*mutexDebugLog);

        // buffer if we haven't opened the log yet
        if (fileout == nullptr) {
            assert(vMsgsBeforeOpenLog);
            ret = strTimestamped.length();
            vMsgsBeforeOpenLog->push_back(strTimestamped);
        }
        else
        {
            // reopen the log file, if requested
            if (fReopenDebugLog) {
                fReopenDebugLog = false;
                fs::path pathDebug = GetDebugLogPath();
                if (fsbridge::freopen(pathDebug,"a",fileout) != nullptr)
                    setbuf(fileout, nullptr); // unbuffered
            }

            ret = FileWriteStr(strTimestamped, fileout);
        }
    }
    return ret;
}

/** A map that contains all the currently held directory locks. After
 * successful locking, these will be held here until the global destructor
 * cleans them up and thus automatically unlocks them, or ReleaseDirectoryLocks
 * is called.
 */
static std::map<std::string, std::unique_ptr<boost::interprocess::file_lock>> dir_locks;
/** Mutex to protect dir_locks. */
static std::mutex cs_dir_locks;

bool LockDirectory(const fs::path& directory, const std::string lockfile_name, bool probe_only)
{
    std::lock_guard<std::mutex> ulock(cs_dir_locks);
    fs::path pathLockFile = directory / lockfile_name;

    // If a lock for this directory already exists in the map, don't try to re-lock it
    if (dir_locks.count(pathLockFile.string())) {
        return true;
    }

    // Create empty lock file if it doesn't exist.
    FILE* file = fsbridge::fopen(pathLockFile, "a");
    if (file) fclose(file);

    try {
        auto lock = MakeUnique<boost::interprocess::file_lock>(pathLockFile.string().c_str());
        if (!lock->try_lock()) {
            return false;
        }
        if (!probe_only) {
            // Lock successful and we're not just probing, put it into the map
            dir_locks.emplace(pathLockFile.string(), std::move(lock));
        }
    } catch (const boost::interprocess::interprocess_exception& e) {
        return error("Error while attempting to lock directory %s: %s", directory.string(), e.what());
    }
    return true;
}

void ReleaseDirectoryLocks()
{
    std::lock_guard<std::mutex> ulock(cs_dir_locks);
    dir_locks.clear();
}

bool DirIsWritable(const fs::path& directory)
{
    fs::path tmpFile = directory / fs::unique_path();

    FILE* file = fsbridge::fopen(tmpFile, "a");
    if (!file) return false;

    fclose(file);
    remove(tmpFile);

    return true;
}

/**
 * Interpret a string argument as a boolean.
 *
 * The definition of atoi() requires that non-numeric string values like "foo",
 * return 0. This means that if a user unintentionally supplies a non-integer
 * argument here, the return value is always false. This means that -foo=false
 * does what the user probably expects, but -foo=true is well defined but does
 * not do what they probably expected.
 *
 * The return value of atoi() is undefined when given input not representable as
 * an int. On most systems this means string value between "-2147483648" and
 * "2147483647" are well defined (this method will return true). Setting
 * -txindex=2147483648 on most systems, however, is probably undefined.
 *
 * For a more extensive discussion of this topic (and a wide range of opinions
 * on the Right Way to change this code), see PR12713.
 */
static bool InterpretBool(const std::string& strValue)
{
    if (strValue.empty())
        return true;
    return (atoi(strValue) != 0);
}

/** Internal helper functions for ArgsManager */
class ArgsManagerHelper {
public:
    typedef std::map<std::string, std::vector<std::string>> MapArgs;

    /** Find arguments in a map and add them to a vector */
    static inline void AddArgs(std::vector<std::string>& res, const MapArgs& map_args, const std::string& arg)
    {
        auto it = map_args.find(arg);
        if (it != map_args.end()) {
            res.insert(res.end(), it->second.begin(), it->second.end());
        }
    }

    /** Return true/false if an argument is set in a map, and also
     *  return the first (or last) of the possibly multiple values it has
     */
    static inline std::pair<bool,std::string> GetArgHelper(const MapArgs& map_args, const std::string& arg, bool getLast = false)
    {
        auto it = map_args.find(arg);

        if (it == map_args.end() || it->second.empty()) {
            return std::make_pair(false, std::string());
        }

        if (getLast) {
            return std::make_pair(true, it->second.back());
        } else {
            return std::make_pair(true, it->second.front());
        }
    }

    /* Get the string value of an argument, returning a pair of a boolean
     * indicating the argument was found, and the value for the argument
     * if it was found (or the empty string if not found).
     */
    static inline std::pair<bool,std::string> GetArg(const ArgsManager &am, const std::string& arg)
    {
        LOCK(am.cs_args);
        std::pair<bool,std::string> found_result(false, std::string());

        // We pass "true" to GetArgHelper in order to return the last
        // argument value seen from the command line (so "bitcoind -foo=bar
        // -foo=baz" gives GetArg(am,"foo")=={true,"baz"}
        found_result = GetArgHelper(am.m_override_args, arg, true);
        if (found_result.first) {
            return found_result;
        }

        // But in contrast we return the first argument seen in a config file,
        // so "foo=bar \n foo=baz" in the config file gives
        // GetArg(am,"foo")={true,"bar"}
        found_result = GetArgHelper(am.m_config_args, arg);
        if (found_result.first) {
            return found_result;
        }

        return found_result;
    }
};

/**
 * Interpret -nofoo as if the user supplied -foo=0.
 *
 * This method also tracks when the -no form was supplied, and if so,
 * checks whether there was a double-negative (-nofoo=0 -> -foo=1).
 *
 * If there was not a double negative, it removes the "no" from the key,
 * and returns true, indicating the caller should clear the args vector
 * to indicate a negated option.
 *
 * If there was a double negative, it removes "no" from the key, sets the
 * value to "1" and returns false.
 *
 * If there was no "no", it leaves key and value untouched and returns
 * false.
 *
 * Where an option was negated can be later checked using the
 * IsArgNegated() method. One use case for this is to have a way to disable
 * options that are not normally boolean (e.g. using -nodebuglogfile to request
 * that debug log output is not sent to any file at all).
 */
static bool InterpretNegatedOption(std::string& key, std::string& val)
{
    if (key.substr(0, 3) == "-no") {
        bool bool_val = InterpretBool(val);
        key.erase(1, 2);
        if (!bool_val ) {
            // Double negatives like -nofoo=0 are supported (but discouraged)
            LogPrintf("Warning: parsed potentially confusing double-negative %s=%s\n", key, val);
            val = "1";
        } else {
            return true;
        }
    }
    return false;
}

void ArgsManager::ParseParameters(int argc, const char* const argv[])
{
    LOCK(cs_args);
    m_override_args.clear();

    for (int i = 1; i < argc; i++) {
        std::string key(argv[i]);
        std::string val;
        size_t is_index = key.find('=');
        if (is_index != std::string::npos) {
            val = key.substr(is_index + 1);
            key.erase(is_index);
        }
#ifdef WIN32
        std::transform(key.begin(), key.end(), key.begin(), ::tolower);
        if (key[0] == '/')
            key[0] = '-';
#endif

        if (key[0] != '-')
            break;

        // Transform --foo to -foo
        if (key.length() > 1 && key[1] == '-')
            key.erase(0, 1);

        // Check for -nofoo
        if (InterpretNegatedOption(key, val)) {
            m_override_args[key].clear();
        } else {
            m_override_args[key].push_back(val);
        }
    }
}

std::vector<std::string> ArgsManager::GetArgs(const std::string& strArg) const
{
    std::vector<std::string> result = {};
    if (IsArgNegated(strArg)) return result; // special case

    LOCK(cs_args);
    ArgsManagerHelper::AddArgs(result, m_override_args, strArg);
    ArgsManagerHelper::AddArgs(result, m_config_args, strArg);
    return result;
}

bool ArgsManager::IsArgSet(const std::string& strArg) const
{
    if (IsArgNegated(strArg)) return true; // special case
    return ArgsManagerHelper::GetArg(*this, strArg).first;
}

bool ArgsManager::IsArgNegated(const std::string& strArg) const
{
    LOCK(cs_args);

    const auto& ov = m_override_args.find(strArg);
    if (ov != m_override_args.end()) return ov->second.empty();

    const auto& cf = m_config_args.find(strArg);
    if (cf != m_config_args.end()) return cf->second.empty();

    return false;
}

std::string ArgsManager::GetArg(const std::string& strArg, const std::string& strDefault) const
{
    if (IsArgNegated(strArg)) return "0";
    std::pair<bool,std::string> found_res = ArgsManagerHelper::GetArg(*this, strArg);
    if (found_res.first) return found_res.second;
    return strDefault;
}

int64_t ArgsManager::GetArg(const std::string& strArg, int64_t nDefault) const
{
    if (IsArgNegated(strArg)) return 0;
    std::pair<bool,std::string> found_res = ArgsManagerHelper::GetArg(*this, strArg);
    if (found_res.first) return atoi64(found_res.second);
    return nDefault;
}

bool ArgsManager::GetBoolArg(const std::string& strArg, bool fDefault) const
{
    if (IsArgNegated(strArg)) return false;
    std::pair<bool,std::string> found_res = ArgsManagerHelper::GetArg(*this, strArg);
    if (found_res.first) return InterpretBool(found_res.second);
    return fDefault;
}

bool ArgsManager::SoftSetArg(const std::string& strArg, const std::string& strValue)
{
    LOCK(cs_args);
    if (IsArgSet(strArg)) return false;
    ForceSetArg(strArg, strValue);
    return true;
}

bool ArgsManager::SoftSetBoolArg(const std::string& strArg, bool fValue)
{
    if (fValue)
        return SoftSetArg(strArg, std::string("1"));
    else
        return SoftSetArg(strArg, std::string("0"));
}

void ArgsManager::ForceSetArg(const std::string& strArg, const std::string& strValue)
{
    LOCK(cs_args);
    m_override_args[strArg] = {strValue};
}

bool HelpRequested(const ArgsManager& args)
{
    return args.IsArgSet("-?") || args.IsArgSet("-h") || args.IsArgSet("-help");
}

static const int screenWidth = 79;
static const int optIndent = 2;
static const int msgIndent = 7;

std::string HelpMessageGroup(const std::string &message) {
    return std::string(message) + std::string("\n\n");
}

std::string HelpMessageOpt(const std::string &option, const std::string &message) {
    return std::string(optIndent,' ') + std::string(option) +
           std::string("\n") + std::string(msgIndent,' ') +
           FormatParagraph(message, screenWidth - msgIndent, msgIndent) +
           std::string("\n\n");
}

static std::string FormatException(const std::exception* pex, const char* pszThread)
{
#ifdef WIN32
    char pszModule[MAX_PATH] = "";
    GetModuleFileNameA(nullptr, pszModule, sizeof(pszModule));
#else
    const char* pszModule = "bitcoin";
#endif
    if (pex)
        return strprintf(
            "EXCEPTION: %s       \n%s       \n%s in %s       \n", typeid(*pex).name(), pex->what(), pszModule, pszThread);
    else
        return strprintf(
            "UNKNOWN EXCEPTION       \n%s in %s       \n", pszModule, pszThread);
}

void PrintExceptionContinue(const std::exception* pex, const char* pszThread)
{
    std::string message = FormatException(pex, pszThread);
    LogPrintf("\n\n************************\n%s\n", message);
    fprintf(stderr, "\n\n************************\n%s\n", message.c_str());
}

fs::path GetDefaultDataDir()
{
    // Windows < Vista: C:\Documents and Settings\Username\Application Data\Bitcoin
    // Windows >= Vista: C:\Users\Username\AppData\Roaming\Bitcoin
    // Mac: ~/Library/Application Support/Bitcoin
    // Unix: ~/.bitcoin
#ifdef WIN32
    // Windows
    return GetSpecialFolderPath(CSIDL_APPDATA) / "Bitcoin";
#else
    fs::path pathRet;
    char* pszHome = getenv("HOME");
    if (pszHome == nullptr || strlen(pszHome) == 0)
        pathRet = fs::path("/");
    else
        pathRet = fs::path(pszHome);
#ifdef MAC_OSX
    // Mac
    return pathRet / "Library/Application Support/Bitcoin";
#else
    // Unix
    return pathRet / ".bitcoin";
#endif
#endif
}

static fs::path g_blocks_path_cached;
static fs::path g_blocks_path_cache_net_specific;
static fs::path pathCached;
static fs::path pathCachedNetSpecific;
static CCriticalSection csPathCached;

const fs::path &GetBlocksDir(bool fNetSpecific)
{

    LOCK(csPathCached);

    fs::path &path = fNetSpecific ? g_blocks_path_cache_net_specific : g_blocks_path_cached;

    // This can be called during exceptions by LogPrintf(), so we cache the
    // value so we don't have to do memory allocations after that.
    if (!path.empty())
        return path;

    if (gArgs.IsArgSet("-blocksdir")) {
        path = fs::system_complete(gArgs.GetArg("-blocksdir", ""));
        if (!fs::is_directory(path)) {
            path = "";
            return path;
        }
    } else {
        path = GetDataDir(false);
    }
    if (fNetSpecific)
        path /= BaseParams().DataDir();

    path /= "blocks";
    fs::create_directories(path);
    return path;
}

const fs::path &GetDataDir(bool fNetSpecific)
{

    LOCK(csPathCached);

    fs::path &path = fNetSpecific ? pathCachedNetSpecific : pathCached;

    // This can be called during exceptions by LogPrintf(), so we cache the
    // value so we don't have to do memory allocations after that.
    if (!path.empty())
        return path;

    if (gArgs.IsArgSet("-datadir")) {
        path = fs::system_complete(gArgs.GetArg("-datadir", ""));
        if (!fs::is_directory(path)) {
            path = "";
            return path;
        }
    } else {
        path = GetDefaultDataDir();
    }
    if (fNetSpecific)
        path /= BaseParams().DataDir();

    if (fs::create_directories(path)) {
        // This is the first run, create wallets subdirectory too
        fs::create_directories(path / "wallets");
    }

    return path;
}

void ClearDatadirCache()
{
    LOCK(csPathCached);

    pathCached = fs::path();
    pathCachedNetSpecific = fs::path();
    g_blocks_path_cached = fs::path();
    g_blocks_path_cache_net_specific = fs::path();
}

fs::path GetConfigFile(const std::string& confPath)
{
    return AbsPathForConfigVal(fs::path(confPath), false);
}

void ArgsManager::ReadConfigStream(std::istream& stream)
{
    LOCK(cs_args);

    std::set<std::string> setOptions;
    setOptions.insert("*");

    for (boost::program_options::detail::config_file_iterator it(stream, setOptions), end; it != end; ++it)
    {
        std::string strKey = std::string("-") + it->string_key;
        std::string strValue = it->value[0];
        if (InterpretNegatedOption(strKey, strValue)) {
            m_config_args[strKey].clear();
        } else {
            m_config_args[strKey].push_back(strValue);
        }
    }
}

void ArgsManager::ReadConfigFile(const std::string& confPath)
{
    {
        LOCK(cs_args);
        m_config_args.clear();
    }

    fs::ifstream stream(GetConfigFile(confPath));

    // ok to not have a config file
    if (stream.good()) {
        ReadConfigStream(stream);
    }

    // If datadir is changed in .conf file:
    ClearDatadirCache();
    if (!fs::is_directory(GetDataDir(false))) {
        throw std::runtime_error(strprintf("specified data directory \"%s\" does not exist.", gArgs.GetArg("-datadir", "").c_str()));
    }
}

std::string ArgsManager::GetChainName() const
{
    bool fRegTest = GetBoolArg("-regtest", false);
    bool fTestNet = GetBoolArg("-testnet", false);

    if (fTestNet && fRegTest)
        throw std::runtime_error("Invalid combination of -regtest and -testnet.");
    if (fRegTest)
        return CBaseChainParams::REGTEST;
    if (fTestNet)
        return CBaseChainParams::TESTNET;
    return CBaseChainParams::MAIN;
}

#ifndef WIN32
fs::path GetPidFile()
{
    return AbsPathForConfigVal(fs::path(gArgs.GetArg("-pid", BITCOIN_PID_FILENAME)));
}

void CreatePidFile(const fs::path &path, pid_t pid)
{
    FILE* file = fsbridge::fopen(path, "w");
    if (file)
    {
        fprintf(file, "%d\n", pid);
        fclose(file);
    }
}
#endif

bool RenameOver(fs::path src, fs::path dest)
{
#ifdef WIN32
    return MoveFileExA(src.string().c_str(), dest.string().c_str(),
                       MOVEFILE_REPLACE_EXISTING) != 0;
#else
    int rc = std::rename(src.string().c_str(), dest.string().c_str());
    return (rc == 0);
#endif /* WIN32 */
}

/**
 * Ignores exceptions thrown by Boost's create_directories if the requested directory exists.
 * Specifically handles case where path p exists, but it wasn't possible for the user to
 * write to the parent directory.
 */
bool TryCreateDirectories(const fs::path& p)
{
    try
    {
        return fs::create_directories(p);
    } catch (const fs::filesystem_error&) {
        if (!fs::exists(p) || !fs::is_directory(p))
            throw;
    }

    // create_directories didn't create the directory, it had to have existed already
    return false;
}

void FileCommit(FILE *file)
{
    fflush(file); // harmless if redundantly called
#ifdef WIN32
    HANDLE hFile = (HANDLE)_get_osfhandle(_fileno(file));
    FlushFileBuffers(hFile);
#else
    #if defined(__linux__) || defined(__NetBSD__)
    fdatasync(fileno(file));
    #elif defined(__APPLE__) && defined(F_FULLFSYNC)
    fcntl(fileno(file), F_FULLFSYNC, 0);
    #else
    fsync(fileno(file));
    #endif
#endif
}

bool TruncateFile(FILE *file, unsigned int length) {
#if defined(WIN32)
    return _chsize(_fileno(file), length) == 0;
#else
    return ftruncate(fileno(file), length) == 0;
#endif
}

/**
 * this function tries to raise the file descriptor limit to the requested number.
 * It returns the actual file descriptor limit (which may be more or less than nMinFD)
 */
int RaiseFileDescriptorLimit(int nMinFD) {
#if defined(WIN32)
    return 2048;
#else
    struct rlimit limitFD;
    if (getrlimit(RLIMIT_NOFILE, &limitFD) != -1) {
        if (limitFD.rlim_cur < (rlim_t)nMinFD) {
            limitFD.rlim_cur = nMinFD;
            if (limitFD.rlim_cur > limitFD.rlim_max)
                limitFD.rlim_cur = limitFD.rlim_max;
            setrlimit(RLIMIT_NOFILE, &limitFD);
            getrlimit(RLIMIT_NOFILE, &limitFD);
        }
        return limitFD.rlim_cur;
    }
    return nMinFD; // getrlimit failed, assume it's fine
#endif
}

/**
 * this function tries to make a particular range of a file allocated (corresponding to disk space)
 * it is advisory, and the range specified in the arguments will never contain live data
 */
void AllocateFileRange(FILE *file, unsigned int offset, unsigned int length) {
#if defined(WIN32)
    // Windows-specific version
    HANDLE hFile = (HANDLE)_get_osfhandle(_fileno(file));
    LARGE_INTEGER nFileSize;
    int64_t nEndPos = (int64_t)offset + length;
    nFileSize.u.LowPart = nEndPos & 0xFFFFFFFF;
    nFileSize.u.HighPart = nEndPos >> 32;
    SetFilePointerEx(hFile, nFileSize, 0, FILE_BEGIN);
    SetEndOfFile(hFile);
#elif defined(MAC_OSX)
    // OSX specific version
    fstore_t fst;
    fst.fst_flags = F_ALLOCATECONTIG;
    fst.fst_posmode = F_PEOFPOSMODE;
    fst.fst_offset = 0;
    fst.fst_length = (off_t)offset + length;
    fst.fst_bytesalloc = 0;
    if (fcntl(fileno(file), F_PREALLOCATE, &fst) == -1) {
        fst.fst_flags = F_ALLOCATEALL;
        fcntl(fileno(file), F_PREALLOCATE, &fst);
    }
    ftruncate(fileno(file), fst.fst_length);
#elif defined(__linux__)
    // Version using posix_fallocate
    off_t nEndPos = (off_t)offset + length;
    posix_fallocate(fileno(file), 0, nEndPos);
#else
    // Fallback version
    // TODO: just write one byte per block
    static const char buf[65536] = {};
    fseek(file, offset, SEEK_SET);
    while (length > 0) {
        unsigned int now = 65536;
        if (length < now)
            now = length;
        fwrite(buf, 1, now, file); // allowed to fail; this function is advisory anyway
        length -= now;
    }
#endif
}

void ShrinkDebugFile()
{
    // Amount of debug.log to save at end when shrinking (must fit in memory)
    constexpr size_t RECENT_DEBUG_HISTORY_SIZE = 10 * 1000000;
    // Scroll debug.log if it's getting too big
    fs::path pathLog = GetDebugLogPath();
    FILE* file = fsbridge::fopen(pathLog, "r");
    // If debug.log file is more than 10% bigger the RECENT_DEBUG_HISTORY_SIZE
    // trim it down by saving only the last RECENT_DEBUG_HISTORY_SIZE bytes
    if (file && fs::file_size(pathLog) > 11 * (RECENT_DEBUG_HISTORY_SIZE / 10))
    {
        // Restart the file with some of the end
        std::vector<char> vch(RECENT_DEBUG_HISTORY_SIZE, 0);
        fseek(file, -((long)vch.size()), SEEK_END);
        int nBytes = fread(vch.data(), 1, vch.size(), file);
        fclose(file);

        file = fsbridge::fopen(pathLog, "w");
        if (file)
        {
            fwrite(vch.data(), 1, nBytes, file);
            fclose(file);
        }
    }
    else if (file != nullptr)
        fclose(file);
}

#ifdef WIN32
fs::path GetSpecialFolderPath(int nFolder, bool fCreate)
{
    char pszPath[MAX_PATH] = "";

    if(SHGetSpecialFolderPathA(nullptr, pszPath, nFolder, fCreate))
    {
        return fs::path(pszPath);
    }

    LogPrintf("SHGetSpecialFolderPathA() failed, could not obtain requested path.\n");
    return fs::path("");
}
#endif

void runCommand(const std::string& strCommand)
{
    if (strCommand.empty()) return;
    int nErr = ::system(strCommand.c_str());
    if (nErr)
        LogPrintf("runCommand error: system(%s) returned %d\n", strCommand, nErr);
}

void RenameThread(const char* name)
{
#if defined(PR_SET_NAME)
    // Only the first 15 characters are used (16 - NUL terminator)
    ::prctl(PR_SET_NAME, name, 0, 0, 0);
#elif (defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__DragonFly__))
    pthread_set_name_np(pthread_self(), name);

#elif defined(MAC_OSX)
    pthread_setname_np(name);
#else
    // Prevent warnings for unused parameters...
    (void)name;
#endif
}

void SetupEnvironment()
{
#ifdef HAVE_MALLOPT_ARENA_MAX
    // glibc-specific: On 32-bit systems set the number of arenas to 1.
    // By default, since glibc 2.10, the C library will create up to two heap
    // arenas per core. This is known to cause excessive virtual address space
    // usage in our usage. Work around it by setting the maximum number of
    // arenas to 1.
    if (sizeof(void*) == 4) {
        mallopt(M_ARENA_MAX, 1);
    }
#endif
    // On most POSIX systems (e.g. Linux, but not BSD) the environment's locale
    // may be invalid, in which case the "C" locale is used as fallback.
#if !defined(WIN32) && !defined(MAC_OSX) && !defined(__FreeBSD__) && !defined(__OpenBSD__)
    try {
        std::locale(""); // Raises a runtime error if current locale is invalid
    } catch (const std::runtime_error&) {
        setenv("LC_ALL", "C", 1);
    }
#endif
    // The path locale is lazy initialized and to avoid deinitialization errors
    // in multithreading environments, it is set explicitly by the main thread.
    // A dummy locale is used to extract the internal default locale, used by
    // fs::path, which is then used to explicitly imbue the path.
    std::locale loc = fs::path::imbue(std::locale::classic());
    fs::path::imbue(loc);
}

bool SetupNetworking()
{
#ifdef WIN32
    // Initialize Windows Sockets
    WSADATA wsadata;
    int ret = WSAStartup(MAKEWORD(2,2), &wsadata);
    if (ret != NO_ERROR || LOBYTE(wsadata.wVersion ) != 2 || HIBYTE(wsadata.wVersion) != 2)
        return false;
#endif
    return true;
}

int GetNumCores()
{
    return std::thread::hardware_concurrency();
}

std::string CopyrightHolders(const std::string& strPrefix)
{
    std::string strCopyrightHolders = strPrefix + strprintf(_(COPYRIGHT_HOLDERS), _(COPYRIGHT_HOLDERS_SUBSTITUTION));

    // Check for untranslated substitution to make sure Bitcoin Core copyright is not removed by accident
    if (strprintf(COPYRIGHT_HOLDERS, COPYRIGHT_HOLDERS_SUBSTITUTION).find("Bitcoin Core") == std::string::npos) {
        strCopyrightHolders += "\n" + strPrefix + "The Bitcoin Core developers";
    }
    return strCopyrightHolders;
}

// Obtain the application startup time (used for uptime calculation)
int64_t GetStartupTime()
{
    return nStartupTime;
}

fs::path AbsPathForConfigVal(const fs::path& path, bool net_specific)
{
    return fs::absolute(path, GetDataDir(net_specific));
}

int ScheduleBatchPriority(void)
{
#ifdef SCHED_BATCH
    const static sched_param param{0};
    if (int ret = pthread_setschedparam(pthread_self(), SCHED_BATCH, &param)) {
        LogPrintf("Failed to pthread_setschedparam: %s\n", strerror(errno));
        return ret;
    }
    return 0;
#else
    return 1;
#endif
}