mirror of https://github.com/siddontang/go.git
52 lines
1.1 KiB
Go
52 lines
1.1 KiB
Go
|
// Copyright 2013 The LevelDB-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 filelock
|
||
|
|
|
||
|
|
import (
|
||
|
|
"io"
|
||
|
|
"os"
|
||
|
|
"syscall"
|
||
|
|
"unsafe"
|
||
|
|
)
|
||
|
|
|
||
|
|
// lockCloser hides all of an os.File's methods, except for Close.
|
||
|
|
type lockCloser struct {
|
||
|
|
f *os.File
|
||
|
|
}
|
||
|
|
|
||
|
|
func (l lockCloser) Close() error {
|
||
|
|
return l.f.Close()
|
||
|
|
}
|
||
|
|
|
||
|
|
func Lock(name string) (io.Closer, error) {
|
||
|
|
f, err := os.Create(name)
|
||
|
|
if err != nil {
|
||
|
|
return nil, err
|
||
|
|
}
|
||
|
|
|
||
|
|
// This type matches C's "struct flock" defined in /usr/include/fcntl.h.
|
||
|
|
// TODO: move this into the standard syscall package.
|
||
|
|
k := struct {
|
||
|
|
Start uint64
|
||
|
|
Len uint64
|
||
|
|
Pid uint32
|
||
|
|
Type uint32
|
||
|
|
Whence uint32
|
||
|
|
}{
|
||
|
|
Type: syscall.F_WRLCK,
|
||
|
|
Whence: uint32(os.SEEK_SET),
|
||
|
|
Start: 0,
|
||
|
|
Len: 0, // 0 means to lock the entire file.
|
||
|
|
Pid: uint32(os.Getpid()),
|
||
|
|
}
|
||
|
|
|
||
|
|
_, _, errno := syscall.Syscall(syscall.SYS_FCNTL, f.Fd(), uintptr(syscall.F_SETLK), uintptr(unsafe.Pointer(&k)))
|
||
|
|
if errno != 0 {
|
||
|
|
f.Close()
|
||
|
|
return nil, errno
|
||
|
|
}
|
||
|
|
return lockCloser{f}, nil
|
||
|
|
}
|