backend/src/files.cpp

/*  This file is part of FediBlock-backend.
 *  Copyright © 2020 tastytea <tastytea@tastytea.de>
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, version 3.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "files.hpp"

#include "fs-compat.hpp"
#include "json.hpp"
#include "types.hpp"

#include <fmt/format.h>
#include <fmt/ostream.h> // For compatibility with fmt 4.
#include <sys/types.h>
#include <unistd.h>

#include <algorithm>
#include <cstdint>
#include <cstdlib>
#include <fstream>
#include <sstream>
#include <stdexcept>
#include <string>

namespace FediBlock::files
{

using fmt::format;
using std::getenv;
using std::ifstream;
using std::ofstream;
using std::runtime_error;
using std::sort;
using std::string;
using std::stringstream;
using std::to_string;
using std::uintmax_t;

string _tmpdir;

fs::path get_tmpdir()
{
    if (_tmpdir.empty())
    {
        _tmpdir = fs::temp_directory_path() / "fediblock-backend-XXXXXX";
        if (mkdtemp(&_tmpdir[0]) == nullptr) // mkdtemp() modifies _tmpdir.
        {
            throw runtime_error{"Could not create temporary directory: "
                                + _tmpdir};
        }
    }

    return _tmpdir;
}

void remove_tmpdir()
{
    if (fs::remove_all(get_tmpdir()) == static_cast<uintmax_t>(-1))
    {
        throw runtime_error{"Couldn't remove temporary directory: "
                            + get_tmpdir().string()};
    }
}

fs::path get_xdg_dir(const string &identifier)
{
    const string xdg_variable{format("XDG_{:s}_HOME", identifier)};
    char *env{getenv(xdg_variable.c_str())};
    if (env != nullptr)
    {
        auto path{fs::path(env) / "fediblock-backend"};
        fs::create_directories(path);
        return path;
    }
    return {};
}

fs::path get_datadir()
{
    auto path{get_xdg_dir("DATA")};
    if (!path.empty())
    {
        return path;
    }

    char *env{getenv("HOME")};
    if (env != nullptr)
    {
        path = fs::path(env);
#if defined(__linux__)
        path /= ".local/share/fediblock-backend";
#else
        path /= ".fediblock-backend";
#endif
        if (!fs::exists(path))
        {
            fs::create_directories(path);
        }
        return path;
    }

    throw runtime_error{"Could not find data dir"};
}

fs::path get_cachedir()
{
    auto path{get_xdg_dir("CACHE")};
    if (!path.empty())
    {
        return path;
    }

    char *env{getenv("HOME")};
    if (env != nullptr)
    {
        path = fs::path(env);
        path /= ".cache/fediblock-backend";
        if (!fs::exists(path))
        {
            fs::create_directories(path);
        }
        return path;
    }

    throw runtime_error{"Could not find data dir"};
}

string get_access_token()
{
    const fs::path access_token_path{get_datadir() / "gitea_access_token"};
    ifstream file(access_token_path);
    if (!file.good())
    {
        throw runtime_error{format("Could not read access token: {:s}",
                                   access_token_path.string())};
    }
    stringstream ss;
    ss << file.rdbuf();

    return ss.str().substr(0, ss.str().find('\n')); // Remove trailing newline.
}

vector<entry_type> read_json_files(const bool cache)
{
    vector<entry_type> entries;

    // clang-format off
    const auto dir_iter{[cache]
    {
        if (cache)
        {
            return fs::directory_iterator(files::get_cachedir() / "repo");
        }
        return fs::directory_iterator(files::get_tmpdir() / "repo");
    }()};
    // clang-format on

    for (const fs::path &path : dir_iter)
    {
        if (path.filename().string()[0] == '.')
        {
            continue;
        }
        if (path.extension() != ".json")
        {
            continue;
        }

        ifstream file(path);
        if (!file.good())
        {
            throw runtime_error{"Could not open file: " + path.string()};
        }
        stringstream ss;
        ss << file.rdbuf();
        auto entry{json::from_json(ss.str())};
        if (!entry.screenshot_filepaths.empty())
        {
            std::uint8_t counter{0};
            for (auto &screenshot : entry.screenshot_filepaths)
            {
                ++counter;
                const fs::path sh_path{screenshot};
                // clang-format off
                const auto compat_path{path.parent_path() /= path.stem()
                                       /= sh_path.extension()};
                // clang-format on
                if (entry.screenshot_filepaths.size() == 1
                    && fs::exists(compat_path))
                {
                    // Compatibility for old entries.
                    screenshot = path.stem().string() += sh_path.extension();
                }
                else
                {
                    // clang-format off
                    screenshot = (path.stem().string() += '-')
                                 += to_string(counter) += sh_path.extension();
                    // clang-format on
                }
            }
        }
        entries.push_back(entry);
    }

    // clang-format off
    sort(entries.begin(), entries.end(), [](const auto &a, const auto &b)
         { return a.report_time > b.report_time; }); // Newest first.
    // clang-format on

    return entries;
}

fs::path get_lockfile()
{
#if defined(__linux__)
    fs::path path{format("/run/user/{:d}", getuid())}; // pam_systemd
    if (!fs::exists(path))
    {
        path = "/run/lock"; // Linux
    }
#else
    fs::path path{"/var/lock"}; // UNIX
    if (!fs::exists(path))
    {
        path = "/var/run"; // UNIX
    }
#endif
    if (!fs::exists(path))
    {
        path = "/tmp"; // fallback
    }

    return path / "fediblock.lock";
}

bool create_lockfile()
{
    const string lockfile{get_lockfile()};
    if (fs::exists(lockfile))
    {
        return false;
    }

    ofstream file;
    file.exceptions(std::ofstream::failbit | std::ofstream::badbit);
    try
    {
        file.open(lockfile);
        file << getpid();
    }
    catch (const std::ofstream::failure &e)
    {
        throw std::runtime_error{
            format("Could not write lockfile: {:s}", e.what())};
    }

    return true;
}

void remove_lockfile()
{
    const string lockfile{get_lockfile()};
    if (fs::exists(lockfile))
    {
        fs::remove(lockfile);
    }
}

} // namespace FediBlock::files