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//go:build !windows
// +build !windows
package utils
import (
"fmt"
"syscall"
)
// ErrLocked is returned when the flock is already held.
var ErrLocked = fmt.Errorf("fslock is already locked")
// FLock represents a file lock.
type FLock struct {
Fd int
}
// TryFLock non-blockingly attempts to acquire a lock on the file.
func TryFLock(filename string) (*FLock, error) {
fd, err := syscall.Open(filename, syscall.O_CREAT|syscall.O_RDONLY|syscall.O_CLOEXEC, syscall.S_IRUSR|syscall.S_IWUSR)
if err != nil {
return nil, err
}
err = syscall.Flock(fd, syscall.LOCK_EX|syscall.LOCK_NB)
if err == syscall.EWOULDBLOCK {
err = ErrLocked
}
if err != nil {
_ = syscall.Close(fd)
return nil, err
}
return &FLock{Fd: fd}, nil
}
// Unlock unlocks the file lock.
func (lock *FLock) Unlock() error {
return syscall.Close(lock.Fd)
}
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