oxen-core/src/common/file.cpp

// Copyright (c) 2018-2020, The Loki Project
// Copyright (c) 2014-2019, The Monero Project
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
//    conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
//    of conditions and the following disclaimer in the documentation and/or other
//    materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be
//    used to endorse or promote products derived from this software without specific
//    prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
//
#include "file.h"

#include <unistd.h>

#include <cstdio>
#include <fstream>

#include "fs-format.h"
#include "logging/oxen_logger.h"

#ifdef WIN32
#include "epee/string_tools.h"
#ifndef STRSAFE_NO_DEPRECATE
#define STRSAFE_NO_DEPRECATE
#endif
#include <shlobj.h>
#include <strsafe.h>
#include <windows.h>
#else
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/utsname.h>
#endif

#ifdef __GLIBC__
#include <dirent.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

#include <cctype>
#include <cstring>
#endif

#include "cryptonote_config.h"

namespace tools {

static auto logcat = log::Cat("util");

#ifndef _WIN32
static int flock_exnb(int fd) {
    struct flock fl;
    int ret;

    memset(&fl, 0, sizeof(fl));
    fl.l_type = F_WRLCK;
    fl.l_whence = SEEK_SET;
    fl.l_start = 0;
    fl.l_len = 0;
    ret = fcntl(fd, F_SETLK, &fl);
    if (ret < 0)
        log::error(logcat, "Error locking fd {}: {} ({})", fd, errno, strerror(errno));
    return ret;
}
#endif

private_file::private_file() noexcept : m_handle(), m_filename() {}

private_file::private_file(std::FILE* handle, fs::path filename) noexcept :
        m_handle(handle), m_filename(std::move(filename)) {}

private_file private_file::create(fs::path name) {
#ifdef WIN32
    struct close_handle {
        void operator()(HANDLE handle) const noexcept { CloseHandle(handle); }
    };

    std::unique_ptr<void, close_handle> process = nullptr;
    {
        HANDLE temp{};
        const bool fail =
                OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY, std::addressof(temp)) == 0;
        process.reset(temp);
        if (fail)
            return {};
    }

    DWORD sid_size = 0;
    GetTokenInformation(process.get(), TokenOwner, nullptr, 0, std::addressof(sid_size));
    if (GetLastError() != ERROR_INSUFFICIENT_BUFFER)
        return {};

    std::unique_ptr<char[]> sid{new char[sid_size]};
    if (!GetTokenInformation(
                process.get(), TokenOwner, sid.get(), sid_size, std::addressof(sid_size)))
        return {};

    const PSID psid = reinterpret_cast<const PTOKEN_OWNER>(sid.get())->Owner;
    const DWORD daclSize =
            sizeof(ACL) + sizeof(ACCESS_ALLOWED_ACE) + GetLengthSid(psid) - sizeof(DWORD);

    const std::unique_ptr<char[]> dacl{new char[daclSize]};
    if (!InitializeAcl(reinterpret_cast<PACL>(dacl.get()), daclSize, ACL_REVISION))
        return {};

    if (!AddAccessAllowedAce(
                reinterpret_cast<PACL>(dacl.get()),
                ACL_REVISION,
                (READ_CONTROL | FILE_GENERIC_READ | DELETE),
                psid))
        return {};

    SECURITY_DESCRIPTOR descriptor{};
    if (!InitializeSecurityDescriptor(std::addressof(descriptor), SECURITY_DESCRIPTOR_REVISION))
        return {};

    if (!SetSecurityDescriptorDacl(
                std::addressof(descriptor), true, reinterpret_cast<PACL>(dacl.get()), false))
        return {};

    SECURITY_ATTRIBUTES attributes{sizeof(SECURITY_ATTRIBUTES), std::addressof(descriptor), false};
    std::unique_ptr<void, close_handle> file{CreateFileW(
            name.c_str(),
            GENERIC_WRITE,
            FILE_SHARE_READ,
            std::addressof(attributes),
            CREATE_NEW,
            (FILE_ATTRIBUTE_TEMPORARY | FILE_FLAG_DELETE_ON_CLOSE),
            nullptr)};
    if (file) {
        const int fd = _open_osfhandle(reinterpret_cast<intptr_t>(file.get()), 0);
        if (0 <= fd) {
            file.release();
            std::FILE* real_file = _fdopen(fd, "w");
            if (!real_file) {
                _close(fd);
            }
            return {real_file, std::move(name)};
        }
    }
#else
    const int fdr = open(name.c_str(), (O_RDONLY | O_CREAT), S_IRUSR);
    if (0 <= fdr) {
        struct stat rstats = {};
        if (fstat(fdr, std::addressof(rstats)) != 0) {
            close(fdr);
            return {};
        }
        fchmod(fdr, (S_IRUSR | S_IWUSR));
        const int fdw = open(name.c_str(), O_RDWR);
        fchmod(fdr, rstats.st_mode);
        close(fdr);

        if (0 <= fdw) {
            struct stat wstats = {};
            if (fstat(fdw, std::addressof(wstats)) == 0 && rstats.st_dev == wstats.st_dev &&
                rstats.st_ino == wstats.st_ino && flock_exnb(fdw) == 0 && ftruncate(fdw, 0) == 0) {
                std::FILE* file = fdopen(fdw, "w");
                if (file)
                    return {file, std::move(name)};
            }
            close(fdw);
        }
    }
#endif
    return {};
}

private_file::~private_file() noexcept {
    std::error_code ignored;
    fs::remove(filename(), ignored);
}

file_locker::file_locker(const fs::path& filename) {
#ifdef WIN32
    m_fd = INVALID_HANDLE_VALUE;
    m_fd = CreateFileW(
            filename.c_str(), GENERIC_READ, 0, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
    if (m_fd != INVALID_HANDLE_VALUE) {
        OVERLAPPED ov;
        memset(&ov, 0, sizeof(ov));
        if (!LockFileEx(m_fd, LOCKFILE_FAIL_IMMEDIATELY | LOCKFILE_EXCLUSIVE_LOCK, 0, 1, 0, &ov)) {
            log::error(
                    logcat,
                    "Failed to lock {}: {}",
                    filename,
                    std::error_code(GetLastError(), std::system_category()).message());
            CloseHandle(m_fd);
            m_fd = INVALID_HANDLE_VALUE;
        }
    } else {
        log::error(
                logcat,
                "Failed to open {}: {}",
                filename,
                std::error_code(GetLastError(), std::system_category()).message());
    }
#else
    m_fd = open(filename.c_str(), O_RDWR | O_CREAT | O_CLOEXEC, 0666);
    if (m_fd != -1) {
        if (flock_exnb(m_fd) == -1) {
            log::error(logcat, "Failed to lock {}: {}", filename, std::strerror(errno));
            close(m_fd);
            m_fd = -1;
        }
    } else {
        log::error(logcat, "Failed to open {}: {}", filename, std::strerror(errno));
    }
#endif
}
file_locker::~file_locker() {
    if (locked()) {
#ifdef WIN32
        CloseHandle(m_fd);
#else
        close(m_fd);
#endif
    }
}
bool file_locker::locked() const {
#ifdef WIN32
    return m_fd != INVALID_HANDLE_VALUE;
#else
    return m_fd != -1;
#endif
}

#ifdef _WIN32
fs::path get_special_folder_path(int nfolder, bool iscreate) {
    WCHAR psz_path[MAX_PATH] = L"";

    if (SHGetSpecialFolderPathW(NULL, psz_path, nfolder, iscreate)) {
        return fs::path{psz_path};
    }

    log::error(logcat, "SHGetSpecialFolderPathW() failed, could not obtain requested path.");
    return "";
}
#endif

// Windows < Vista: C:\Documents and Settings\Username\Application Data\...
// Windows >= Vista: C:\Users\Username\AppData\Roaming\...
// Sane OSes: ~/
static fs::path get_default_parent_dir() {
#ifdef _WIN32
    return get_special_folder_path(CSIDL_COMMON_APPDATA, true);
#else
    char* home = std::getenv("HOME");
    return home && std::strlen(home) ? fs::u8path(home) : fs::current_path();
#endif
}

fs::path get_default_data_dir() {
    return get_default_parent_dir() / fs::u8path(cryptonote::DATA_DIRNAME);
}
fs::path get_depreciated_default_data_dir() {
    return get_default_parent_dir() / fs::u8path(cryptonote::old::DATA_DIRNAME);
}

void set_strict_default_file_permissions(bool strict) {
#if defined(__MINGW32__) || defined(__MINGW__)
    // no clue about the odd one out
#else
    mode_t mode = strict ? 077 : 0;
    umask(mode);
#endif
}

bool slurp_file(const fs::path& filename, std::string& contents) {

    try {
        fs::ifstream in(filename, std::ios::binary);
        std::string content(
                (std::istreambuf_iterator<char>(in)), (std::istreambuf_iterator<char>()));
        contents = std::move(content);
        return true;
    } catch (...) {
        return false;
    }
}

bool dump_file(const fs::path& filename, std::string_view contents) {
    fs::ofstream out;
    out.exceptions(std::ifstream::failbit | std::ifstream::badbit);
    try {
        out.open(filename, std::ios::binary | std::ios::out | std::ios::trunc);
        out.write(contents.data(), contents.size());
        return true;
    } catch (...) {
        return false;
    }
}

}  // namespace tools