package syscall

import "unsafe"

// F_DUP2FD_CLOEXEC has different values on Solaris and Illumos.
const F_DUP2FD_CLOEXEC = 0x24

//go:cgo_import_dynamic libc_flock flock "libc.so"

//go:linkname procFlock libc_flock

var procFlock libcFunc

func Flock(fd int, how int) error {
	_, _, errno := sysvicall6(uintptr(unsafe.Pointer(&procFlock)), 2, uintptr(fd), uintptr(how), 0, 0, 0, 0)
	if errno != 0 {
		return errno
	}

		}
	} else {
		// child
		got := flock
		// make sure the child lock is conflicting with the parent lock
		got.Start--
		got.Len++
		if err := syscall.FcntlFlock(3, syscall.F_GETLK, &got); err != nil {
			t.Fatalf("FcntlFlock(F_GETLK) failed: %v", err)
		}
		flock.Pid = int32(syscall.Getppid())
		// Linux kernel always set Whence to 0
		flock.Whence = 0

WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package flock

import "golang.org/x/sys/unix"

// Acquire acquires a lock on a file for the duration of the process. This method
// is reentrant.
func Acquire(path string) error {
	fd, err := unix.Open(path, unix.O_CREAT|unix.O_RDWR|unix.O_CLOEXEC, 0600)

	// returned when “the lock is blocked by a lock from another process”.
	// If that process is blocked on some lock that we are holding, then the
	// resulting livelock is due to a real deadlock (and would manifest as such
	// when using, for example, the flock implementation of this package).
	// If the other process is *not* blocked on some other lock that we are
	// holding, then it will eventually release the requested lock.

	writeLock lockType = syscall.LOCK_EX
)

func lock(f File, lt lockType) (err error) {
	for {
		err = syscall.Flock(int(f.Fd()), int(lt))
		if err != syscall.EINTR {
			break
		}
	}
	if err != nil {
		return &fs.PathError{
			Op:   lt.String(),
			Path: f.Name(),
			Err:  err,
		}
	}
	return nil
}

func unlock(f File) error {
	return lock(f, syscall.LOCK_UN)

// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package syscall

import "unsafe"

// On AIX, there is no flock() system call.

// FcntlFlock performs a fcntl syscall for the [F_GETLK], [F_SETLK] or [F_SETLKW] command.
func FcntlFlock(fd uintptr, cmd int, lk *Flock_t) (err error) {

WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package flock

// Acquire is not implemented on non-unix systems.
func Acquire(path string) error {
	return nil

//  provide the address of function variable to be fixed up.

TEXT ·getPipe2Addr(SB), NOSPLIT|NOFRAME, $0-8
	MOVD $·Pipe2(SB), R8
	MOVD R8, ret+0(FP)
	RET

TEXT ·get_FlockAddr(SB), NOSPLIT|NOFRAME, $0-8
	MOVD $·Flock(SB), R8
	MOVD R8, ret+0(FP)
	RET

TEXT ·get_GetxattrAddr(SB), NOSPLIT|NOFRAME, $0-8
	MOVD $·Getxattr(SB), R8
	MOVD R8, ret+0(FP)
	RET

TEXT ·get_NanosleepAddr(SB), NOSPLIT|NOFRAME, $0-8

//
// 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/>.

package lock

import (
	"os"
	"syscall"
)

// Internal function implements support for both
// blocking and non blocking lock type.
func lockedOpenFile(path string, flag int, perm os.FileMode, lockType int) (*LockedFile, error) {
	switch flag {
	case syscall.O_RDONLY:

			return false, nil
		}
		return true, nil
	}); err != nil {
		return nil, fmt.Errorf("failed to acquire old iptables lock: %v", err)
	}

	success = true
	return l, nil
}

func grabIptablesFileLock(f *os.File) error {
	return unix.Flock(int(f.Fd()), unix.LOCK_EX|unix.LOCK_NB)