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51 lines
1.3 KiB
Go
51 lines
1.3 KiB
Go
// +build linux solaris darwin freebsd openbsd netbsd dragonfly
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package single
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import (
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"fmt"
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"os"
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"syscall"
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)
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// CheckLock tries to obtain an exclude lock on a lockfile and returns an error if one occurs
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func (s *Single) CheckLock() error {
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// open/create lock file
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f, err := os.OpenFile(s.Filename(), os.O_RDWR|os.O_CREATE, 0600)
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if err != nil {
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return err
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}
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s.file = f
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// set the lock type to F_WRLCK, therefor the file has to be opened writable
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flock := syscall.Flock_t{
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Type: syscall.F_WRLCK,
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Pid: int32(os.Getpid()),
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}
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// try to obtain an exclusive lock - FcntlFlock seems to be the portable *ix way
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if err := syscall.FcntlFlock(s.file.Fd(), syscall.F_SETLK, &flock); err != nil {
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return ErrAlreadyRunning
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}
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return nil
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}
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// TryUnlock unlocks, closes and removes the lockfile
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func (s *Single) TryUnlock() error {
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// set the lock type to F_UNLCK
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flock := syscall.Flock_t{
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Type: syscall.F_UNLCK,
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Pid: int32(os.Getpid()),
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}
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if err := syscall.FcntlFlock(s.file.Fd(), syscall.F_SETLK, &flock); err != nil {
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return fmt.Errorf("failed to unlock the lock file: %v", err)
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}
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if err := s.file.Close(); err != nil {
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return fmt.Errorf("failed to close the lock file: %v", err)
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}
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if err := os.Remove(s.Filename()); err != nil {
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return fmt.Errorf("failed to remove the lock file: %v", err)
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}
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return nil
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}
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