forked from External/grumble
73 lines
1.4 KiB
Go
73 lines
1.4 KiB
Go
// Copyright (c) 2011 The Grumble Authors
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// The use of this source code is goverened by a BSD-style
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// license that can be found in the LICENSE-file.
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package blobstore
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import (
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"io/ioutil"
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"os"
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"path/filepath"
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"strconv"
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"syscall"
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)
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// Acquire lockfile at path.
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func AcquireLockFile(path string) error {
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dir, fn := filepath.Split(path)
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lockfn := filepath.Join(dir, fn)
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lockfile, err := os.OpenFile(lockfn, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0600)
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if e, ok := err.(*os.PathError); ok && e.Err == os.EEXIST {
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content, err := ioutil.ReadFile(lockfn)
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if err != nil {
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return err
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}
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pid, err := strconv.Atoi(string(content))
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if err == nil {
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if syscall.Kill(pid, 0) == 0 {
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return ErrLocked
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}
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}
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lockfile, err = ioutil.TempFile(dir, "lock")
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if err != nil {
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return err
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}
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_, err = lockfile.WriteString(strconv.Itoa(syscall.Getpid()))
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if err != nil {
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lockfile.Close()
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return ErrLockAcquirement
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}
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curfn := lockfile.Name()
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err = lockfile.Close()
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if err != nil {
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return err
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}
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err = os.Rename(curfn, lockfn)
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if err != nil {
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os.Remove(curfn)
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return ErrLockAcquirement
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}
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} else if err != nil {
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return err
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} else {
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_, err = lockfile.WriteString(strconv.Itoa(syscall.Getpid()))
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if err != nil {
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return err
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}
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lockfile.Close()
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}
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return nil
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}
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// Release lockfile at path.
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func ReleaseLockFile(path string) error {
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return os.Remove(path)
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}
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