// The flock package provides a file-system mediated locking mechanism on linux
// using the `flock` system call.

package flock

import (
	"os"
	"syscall"
)


// Lock gets an exclusive lock on the file at the given path. If the file
// doesn't exist, it's created.
func Lock(path string) (*os.File, error) {
	perm := os.O_CREATE | os.O_RDWR
	fh, err := os.OpenFile(path, perm, 0600)
	if err != nil {
		return nil, err
	}

	if err := syscall.Flock(int(fh.Fd()), syscall.LOCK_EX); err != nil {
		return nil, err
	}

	return fh, nil
}

// Unlock releases the lock acquired via the Lock function.
func Unlock(f *os.File) error {
	return f.Close()
}