// Copyright (c) 2009-2010 Satoshi Nakamoto

// Copyright (c) 2009-present 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 <bitcoin-build-config.h> // IWYU pragma: keep

#include <util/fs_helpers.h>

#include <sync.h>

#include <util/fs.h>

#include <util/log.h>

#include <util/syserror.h>

#include <cerrno>

#include <fstream>

#include <map>

#include <memory>

#include <optional>

#include <string>

#include <system_error>

#include <utility>

#ifndef WIN32

#include <fcntl.h>

#include <sys/resource.h>

#include <sys/types.h>

#include <unistd.h>

#else

#include <io.h>

#include <shlobj.h>

#endif // WIN32

#ifdef __APPLE__

#include <sys/mount.h>

#include <sys/param.h>

#endif

/** Mutex to protect dir_locks. */

static GlobalMutex cs_dir_locks;

/** 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<fsbridge::FileLock>> dir_locks GUARDED_BY(cs_dir_locks);

namespace util {

LockResult LockDirectory(const fs::path& directory, const fs::path& lockfile_name, bool probe_only)

{

    LOCK(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.contains(fs::PathToString(pathLockFile))) {

        return LockResult::Success;

    }

    // Create empty lock file if it doesn't exist.

    if (auto created{fsbridge::fopen(pathLockFile, "a")}) {

        std::fclose(created);

    } else {

        return LockResult::ErrorWrite;

    }

    auto lock = std::make_unique<fsbridge::FileLock>(pathLockFile);

    if (!lock->TryLock()) {

        LogError("Error while attempting to lock directory %s: %s\n", fs::PathToString(directory), lock->GetReason());

        return LockResult::ErrorLock;

    }

    if (!probe_only) {

        // Lock successful and we're not just probing, put it into the map

        dir_locks.emplace(fs::PathToString(pathLockFile), std::move(lock));

    }

    return LockResult::Success;

}

} // namespace util

void UnlockDirectory(const fs::path& directory, const fs::path& lockfile_name)

{

    LOCK(cs_dir_locks);

    dir_locks.erase(fs::PathToString(directory / lockfile_name));

}

void ReleaseDirectoryLocks()

{

    LOCK(cs_dir_locks);

    dir_locks.clear();

}

bool CheckDiskSpace(const fs::path& dir, uint64_t additional_bytes)

{

    constexpr uint64_t min_disk_space = 52428800; // 50 MiB

    uint64_t free_bytes_available = fs::space(dir).available;

    return free_bytes_available >= min_disk_space + additional_bytes;

}

std::streampos GetFileSize(const char* path, std::streamsize max)

{

    std::ifstream file{path, std::ios::binary};

    file.ignore(max);

    return file.gcount();

}

bool FileCommit(FILE* file)

{

    if (fflush(file) != 0) { // harmless if redundantly called

        LogError("fflush failed: %s", SysErrorString(errno));

        return false;

    }

#ifdef WIN32

    HANDLE hFile = (HANDLE)_get_osfhandle(_fileno(file));

    if (FlushFileBuffers(hFile) == 0) {

        LogError("FlushFileBuffers failed: %s", Win32ErrorString(GetLastError()));

        return false;

    }

#elif defined(__APPLE__) && defined(F_FULLFSYNC)

    if (fcntl(fileno(file), F_FULLFSYNC, 0) == -1) { // Manpage says "value other than -1" is returned on success

        LogError("fcntl F_FULLFSYNC failed: %s", SysErrorString(errno));

        return false;

    }

#elif HAVE_FDATASYNC

    if (fdatasync(fileno(file)) != 0 && errno != EINVAL) { // Ignore EINVAL for filesystems that don't support sync

        LogError("fdatasync failed: %s", SysErrorString(errno));

        return false;

    }

#else

    if (fsync(fileno(file)) != 0 && errno != EINVAL) {

        LogError("fsync failed: %s", SysErrorString(errno));

        return false;

    }

#endif

    return true;

}

void DirectoryCommit(const fs::path& dirname)

{

#ifndef WIN32

    FILE* file = fsbridge::fopen(dirname, "r");

    if (file) {

        fsync(fileno(file));

        fclose(file);

    }

#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(__APPLE__)

    // OSX specific version

    // NOTE: Contrary to other OS versions, the OSX version assumes that

    // NOTE: offset is the size of the file.

    fstore_t fst;

    fst.fst_flags = F_ALLOCATECONTIG;

    fst.fst_posmode = F_PEOFPOSMODE;

    fst.fst_offset = 0;

    fst.fst_length = length; // mac os fst_length takes the # of free bytes to allocate, not desired file size

    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), static_cast<off_t>(offset) + length);

#else

#if defined(HAVE_POSIX_FALLOCATE)

    // Version using posix_fallocate

    off_t nEndPos = (off_t)offset + length;

    if (0 == posix_fallocate(fileno(file), 0, nEndPos)) return;

#endif

    // Fallback version

    // TODO: just write one byte per block

    static const char buf[65536] = {};

    if (fseek(file, offset, SEEK_SET)) {

        return;

    }

    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

}

#ifdef WIN32

fs::path GetSpecialFolderPath(int nFolder, bool fCreate)

{

    WCHAR pszPath[MAX_PATH] = L"";

    if (SHGetSpecialFolderPathW(nullptr, pszPath, nFolder, fCreate)) {

        return fs::path(pszPath);

    }

    LogError("SHGetSpecialFolderPathW() failed, could not obtain requested path.");

    return fs::path("");

}

#endif

bool RenameOver(fs::path src, fs::path dest)

{

    std::error_code error;

    fs::rename(src, dest, error);

    return !error;

}

/**

 * Ignores exceptions thrown by 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;

}

std::string PermsToSymbolicString(fs::perms p)

{

    std::string perm_str(9, '-');

    auto set_perm = [&](size_t pos, fs::perms required_perm, char letter) {

        if ((p & required_perm) != fs::perms::none) {

            perm_str[pos] = letter;

        }

    };

    set_perm(0, fs::perms::owner_read,   'r');

    set_perm(1, fs::perms::owner_write,  'w');

    set_perm(2, fs::perms::owner_exec,   'x');

    set_perm(3, fs::perms::group_read,   'r');

    set_perm(4, fs::perms::group_write,  'w');

    set_perm(5, fs::perms::group_exec,   'x');

    set_perm(6, fs::perms::others_read,  'r');

    set_perm(7, fs::perms::others_write, 'w');

    set_perm(8, fs::perms::others_exec,  'x');

    return perm_str;

}

std::optional<fs::perms> InterpretPermString(const std::string& s)

{

    if (s == "owner") {

        return fs::perms::owner_read | fs::perms::owner_write;

    } else if (s == "group") {

        return fs::perms::owner_read | fs::perms::owner_write |

               fs::perms::group_read;

    } else if (s == "all") {

        return fs::perms::owner_read | fs::perms::owner_write |

               fs::perms::group_read |

               fs::perms::others_read;

    } else {

        return std::nullopt;

    }

}

#ifdef __APPLE__

FSType GetFilesystemType(const fs::path& path)

{

    if (struct statfs fs_info; statfs(path.c_str(), &fs_info)) {

        return FSType::ERROR;

    } else if (std::string_view{fs_info.f_fstypename} == "exfat") {

        return FSType::EXFAT;

    }

    return FSType::OTHER;

}

#endif