minio/cmd/os-reliable.go

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/*
* MinIO Cloud Storage, (C) 2018 MinIO, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package cmd
import (
"fmt"
"os"
"path"
)
// Wrapper functions to os.RemoveAll, which calls reliableRemoveAll
// this is to ensure that if there is a racy parent directory
// create in between we can simply retry the operation.
func removeAll(dirPath string) (err error) {
if dirPath == "" {
return errInvalidArgument
}
if err = checkPathLength(dirPath); err != nil {
return err
}
if err = reliableRemoveAll(dirPath); err != nil {
switch {
case isSysErrNotDir(err):
// File path cannot be verified since one of
// the parents is a file.
return errFileAccessDenied
case isSysErrPathNotFound(err):
// This is a special case should be handled only for
// windows, because windows API does not return "not a
// directory" error message. Handle this specifically
// here.
return errFileAccessDenied
}
}
return err
}
// Reliably retries os.RemoveAll if for some reason os.RemoveAll returns
// syscall.ENOTEMPTY (children has files).
func reliableRemoveAll(dirPath string) (err error) {
i := 0
for {
// Removes all the directories and files.
if err = os.RemoveAll(dirPath); err != nil {
// Retry only for the first retryable error.
if isSysErrNotEmpty(err) && i == 0 {
i++
continue
}
}
break
}
return err
}
// Wrapper functions to os.MkdirAll, which calls reliableMkdirAll
// this is to ensure that if there is a racy parent directory
// delete in between we can simply retry the operation.
func mkdirAll(dirPath string, mode os.FileMode) (err error) {
if dirPath == "" {
return errInvalidArgument
}
if err = checkPathLength(dirPath); err != nil {
return err
}
if err = reliableMkdirAll(dirPath, mode); err != nil {
// File path cannot be verified since one of the parents is a file.
if isSysErrNotDir(err) {
return errFileAccessDenied
} else if isSysErrPathNotFound(err) {
// This is a special case should be handled only for
// windows, because windows API does not return "not a
// directory" error message. Handle this specifically here.
return errFileAccessDenied
}
}
return err
}
// Reliably retries os.MkdirAll if for some reason os.MkdirAll returns
// syscall.ENOENT (parent does not exist).
func reliableMkdirAll(dirPath string, mode os.FileMode) (err error) {
i := 0
for {
// Creates all the parent directories, with mode 0777 mkdir honors system umask.
if err = os.MkdirAll(dirPath, mode); err != nil {
// Retry only for the first retryable error.
if os.IsNotExist(err) && i == 0 {
i++
continue
}
}
break
}
return err
}
// Wrapper function to os.Rename, which calls reliableMkdirAll
// and reliableRenameAll. This is to ensure that if there is a
// racy parent directory delete in between we can simply retry
// the operation.
func renameAll(srcFilePath, dstFilePath string) (err error) {
if srcFilePath == "" || dstFilePath == "" {
return errInvalidArgument
}
if err = checkPathLength(srcFilePath); err != nil {
return err
}
if err = checkPathLength(dstFilePath); err != nil {
return err
}
if err = reliableRename(srcFilePath, dstFilePath); err != nil {
switch {
case isSysErrNotDir(err):
return errFileAccessDenied
case isSysErrPathNotFound(err):
// This is a special case should be handled only for
// windows, because windows API does not return "not a
// directory" error message. Handle this specifically here.
return errFileAccessDenied
case isSysErrCrossDevice(err):
return fmt.Errorf("%w (%s)->(%s)", errCrossDeviceLink, srcFilePath, dstFilePath)
case os.IsNotExist(err):
return errFileNotFound
case os.IsExist(err):
// This is returned only when destination is a directory and we
// are attempting a rename from file to directory.
return errIsNotRegular
default:
return err
}
}
return nil
}
// Reliably retries os.RenameAll if for some reason os.RenameAll returns
// syscall.ENOENT (parent does not exist).
func reliableRename(srcFilePath, dstFilePath string) (err error) {
if err = reliableMkdirAll(path.Dir(dstFilePath), 0777); err != nil {
return err
}
i := 0
for {
// After a successful parent directory create attempt a renameAll.
if err = os.Rename(srcFilePath, dstFilePath); err != nil {
// Retry only for the first retryable error.
if os.IsNotExist(err) && i == 0 {
i++
continue
}
}
break
}
return err
}