95 lines
2.8 KiB
Go
95 lines
2.8 KiB
Go
// +build windows
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/*
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* Copyright 2017 Dgraph Labs, Inc. and Contributors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package badger
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// OpenDir opens a directory in windows with write access for syncing.
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import (
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"fmt"
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"os"
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"path/filepath"
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"syscall"
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"github.com/pkg/errors"
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)
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func openDir(path string) (*os.File, error) {
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fd, err := openDirWin(path)
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if err != nil {
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return nil, err
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}
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return os.NewFile(uintptr(fd), path), nil
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}
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func openDirWin(path string) (fd syscall.Handle, err error) {
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if len(path) == 0 {
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return syscall.InvalidHandle, syscall.ERROR_FILE_NOT_FOUND
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}
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pathp, err := syscall.UTF16PtrFromString(path)
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if err != nil {
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return syscall.InvalidHandle, err
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}
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access := uint32(syscall.GENERIC_READ | syscall.GENERIC_WRITE)
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sharemode := uint32(syscall.FILE_SHARE_READ | syscall.FILE_SHARE_WRITE)
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createmode := uint32(syscall.OPEN_EXISTING)
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fl := uint32(syscall.FILE_FLAG_BACKUP_SEMANTICS)
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return syscall.CreateFile(pathp, access, sharemode, nil, createmode, fl, 0)
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}
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// DirectoryLockGuard holds a lock on the directory.
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type directoryLockGuard struct {
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path string
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}
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// AcquireDirectoryLock acquires exclusive access to a directory.
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func acquireDirectoryLock(dirPath string, pidFileName string, readOnly bool) (*directoryLockGuard, error) {
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if readOnly {
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return nil, ErrWindowsNotSupported
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}
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// Convert to absolute path so that Release still works even if we do an unbalanced
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// chdir in the meantime.
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absLockFilePath, err := filepath.Abs(filepath.Join(dirPath, pidFileName))
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if err != nil {
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return nil, errors.Wrap(err, "Cannot get absolute path for pid lock file")
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}
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f, err := os.OpenFile(absLockFilePath, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0666)
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if err != nil {
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return nil, errors.Wrapf(err,
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"Cannot create pid lock file %q. Another process is using this Badger database",
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absLockFilePath)
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}
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_, err = fmt.Fprintf(f, "%d\n", os.Getpid())
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closeErr := f.Close()
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if err != nil {
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return nil, errors.Wrap(err, "Cannot write to pid lock file")
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}
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if closeErr != nil {
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return nil, errors.Wrap(closeErr, "Cannot close pid lock file")
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}
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return &directoryLockGuard{path: absLockFilePath}, nil
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}
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// Release removes the directory lock.
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func (g *directoryLockGuard) release() error {
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path := g.path
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g.path = ""
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return os.Remove(path)
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}
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