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// Copyright Contributors to the DNF5 project.
// Copyright Contributors to the libdnf project.
// SPDX-License-Identifier: LGPL-2.1-or-later
//
// This file is part of libdnf: https://github.com/rpm-software-management/libdnf/
//
// Libdnf is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 2.1 of the License, or
// (at your option) any later version.
//
// Libdnf 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 Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with libdnf. If not, see <https://www.gnu.org/licenses/>.
#include "libdnf5/utils/locker.hpp"
#include "libdnf5/common/exception.hpp"
#include "libdnf5/utils/bgettext/bgettext-mark-domain.h"
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
constexpr const int MODE = 0664;
namespace libdnf5::utils {
class Locker::Impl {
public:
Impl(const std::filesystem::path & path, const bool keep_file) : path{path}, keep_file{keep_file} {};
~Impl();
void unlock();
private:
friend Locker;
const std::filesystem::path path;
int lock_fd{-1};
bool keep_file{false};
};
Locker::Locker(const std::filesystem::path & path, const bool keep_file) : p_impl{new Impl{path, keep_file}} {};
const std::filesystem::path & Locker::get_path() const noexcept {
return p_impl->path;
}
bool Locker::read_lock() {
return lock(LockAccess::READ, LockBlocking::NON_BLOCKING);
}
bool Locker::write_lock() {
return lock(LockAccess::WRITE, LockBlocking::NON_BLOCKING);
}
bool Locker::lock(LockAccess access, LockBlocking blocking) {
int fcntl_flags = 0;
short type = 0;
switch (access) {
case LockAccess::READ: {
type = F_RDLCK;
} break;
case LockAccess::WRITE: {
type = F_WRLCK;
} break;
}
switch (blocking) {
case LockBlocking::BLOCKING: {
fcntl_flags |= F_SETLKW;
} break;
case LockBlocking::NON_BLOCKING: {
fcntl_flags |= F_SETLK;
} break;
}
if (p_impl->lock_fd == -1) {
open_file(access);
}
struct flock fl;
memset(&fl, 0, sizeof(fl));
fl.l_type = type;
fl.l_whence = SEEK_SET;
fl.l_start = 0;
fl.l_len = 0;
fl.l_pid = 0;
auto rc = fcntl(p_impl->lock_fd, fcntl_flags, &fl);
if (rc == -1) {
if (errno == EACCES || errno == EAGAIN) {
return false;
} else {
throw SystemError(errno, M_("Failed to obtain lock \"{}\""), p_impl->path.string());
}
}
return true;
}
void Locker::open_file(LockAccess access) {
if (p_impl->lock_fd != -1) {
throw libdnf5::RuntimeError(M_("File is already open."));
}
int open_flags = O_CREAT | O_CLOEXEC;
switch (access) {
case LockAccess::READ: {
open_flags |= O_RDONLY;
} break;
case LockAccess::WRITE: {
open_flags |= O_RDWR;
} break;
}
p_impl->lock_fd = open(p_impl->path.c_str(), open_flags, MODE);
if (p_impl->lock_fd == -1) {
throw SystemError(errno, M_("Failed to open lock file \"{}\""), p_impl->path.string());
}
}
void Locker::Impl::unlock() {
if (lock_fd != -1) {
if (close(lock_fd) == -1) {
throw SystemError(errno, M_("Failed to close lock file \"{}\""), path.string());
}
if (!keep_file) {
if (unlink(path.c_str()) == -1) {
throw SystemError(errno, M_("Failed to delete lock file \"{}\""), path.string());
}
}
lock_fd = -1;
}
}
void Locker::unlock() {
return p_impl->unlock();
}
Locker::Impl::~Impl() {
try {
unlock();
} catch (...) {
}
}
Locker::~Locker() = default;
Locker::Locker(Locker &&) noexcept = default;
Locker & Locker::operator=(Locker &&) noexcept = default;
} // namespace libdnf5::utils
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