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130 lines
3.6 KiB
130 lines
3.6 KiB
/*
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* Minio Cloud Storage (C) 2015-2016 Minio, Inc.
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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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// NOTE - Rename() not guaranteed to be safe on all filesystems which are not fully POSIX compatible
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// Package safe provides safe file write semantics by leveraging Rename's() safeity.
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package safe
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import (
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"io"
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"io/ioutil"
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"os"
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"path/filepath"
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)
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// Vault - vault is an interface for different implementations of safe
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// i/o semantics.
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type Vault interface {
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io.ReadWriteCloser
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SyncClose() error
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CloseAndRemove() error
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}
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// File provides for safe file writes.
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type File struct {
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*os.File
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file string
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}
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// SyncClose sync file to disk and close, returns an error if any
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func (f *File) SyncClose() error {
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// sync to the disk
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if err := f.File.Sync(); err != nil {
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return err
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}
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// Close the fd.
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if err := f.Close(); err != nil {
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return err
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}
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return nil
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}
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// Close the file, returns an error if any
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func (f *File) Close() error {
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// Close the embedded fd.
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if err := f.File.Close(); err != nil {
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return err
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}
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// Safe rename to final destination
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if err := os.Rename(f.Name(), f.file); err != nil {
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return err
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}
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return nil
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}
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// CloseAndRemove closes the temp file, and safely removes it. Returns
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// error if any.
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func (f *File) CloseAndRemove() error {
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// close the embedded fd
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f.File.Close()
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// Remove the temp file.
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if err := os.Remove(f.Name()); err != nil {
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return err
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}
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return nil
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}
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// CreateFile creates a new file at filePath for safe writes, it also
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// creates parent directories if they don't exist.
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func CreateFile(filePath string) (*File, error) {
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return CreateFileWithPrefix(filePath, "$deleteme.")
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}
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// CreateFileWithSuffix is similar to CreateFileWithPrefix, but the
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// second argument is treated as suffix for the temporary files.
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func CreateFileWithSuffix(filePath string, suffix string) (*File, error) {
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// If parent directories do not exist, ioutil.TempFile doesn't create them
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// handle such a case with os.MkdirAll()
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if err := os.MkdirAll(filepath.Dir(filePath), 0700); err != nil {
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return nil, err
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}
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f, err := ioutil.TempFile(filepath.Dir(filePath), filepath.Base(filePath)+suffix)
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if err != nil {
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return nil, err
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}
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if err = os.Chmod(f.Name(), 0600); err != nil {
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if err = os.Remove(f.Name()); err != nil {
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return nil, err
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}
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return nil, err
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}
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return &File{File: f, file: filePath}, nil
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}
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// CreateFileWithPrefix creates a new file at filePath for safe
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// writes, it also creates parent directories if they don't exist.
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// prefix specifies the prefix of the temporary files so that cleaning
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// stale temp files is easy.
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func CreateFileWithPrefix(filePath string, prefix string) (*File, error) {
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// If parent directories do not exist, ioutil.TempFile doesn't create them
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// handle such a case with os.MkdirAll()
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if err := os.MkdirAll(filepath.Dir(filePath), 0700); err != nil {
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return nil, err
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}
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f, err := ioutil.TempFile(filepath.Dir(filePath), prefix+filepath.Base(filePath))
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if err != nil {
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return nil, err
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}
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if err = os.Chmod(f.Name(), 0600); err != nil {
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if err = os.Remove(f.Name()); err != nil {
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return nil, err
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}
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return nil, err
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}
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return &File{File: f, file: filePath}, nil
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}
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