minio/cmd/fs-v1-helpers.go
Harshavardhana 1c699d8d3f fs: Re-implement object layer to remember the fd (#3509)
This patch re-writes FS backend to support shared backend sharing locks for safe concurrent access across multiple servers.
2017-01-16 17:05:00 -08:00

374 lines
8.9 KiB
Go

/*
* Minio Cloud Storage, (C) 2016 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 (
"io"
"os"
pathutil "path"
)
// Removes only the file at given path does not remove
// any parent directories, handles long paths for
// windows automatically.
func fsRemoveFile(filePath string) (err error) {
if filePath == "" {
return errInvalidArgument
}
if err = checkPathLength(filePath); err != nil {
return err
}
if err = os.Remove(preparePath(filePath)); err != nil {
if os.IsNotExist(err) {
return errFileNotFound
} else if os.IsPermission(err) {
return errFileAccessDenied
}
return err
}
return nil
}
// Removes all files and folders at a given path, handles
// long paths for windows automatically.
func fsRemoveAll(dirPath string) (err error) {
if dirPath == "" {
return errInvalidArgument
}
if err = checkPathLength(dirPath); err != nil {
return err
}
if err = removeAll(dirPath); err != nil {
if os.IsPermission(err) {
return errVolumeAccessDenied
}
}
return err
}
// Removes a directory only if its empty, handles long
// paths for windows automatically.
func fsRemoveDir(dirPath string) (err error) {
if dirPath == "" {
return errInvalidArgument
}
if err = checkPathLength(dirPath); err != nil {
return err
}
if err = os.Remove(preparePath(dirPath)); err != nil {
if os.IsNotExist(err) {
return errVolumeNotFound
} else if isSysErrNotEmpty(err) {
return errVolumeNotEmpty
}
}
return err
}
// Creates a new directory, parent dir should exist
// otherwise returns an error. If directory already
// exists returns an error. Windows long paths
// are handled automatically.
func fsMkdir(dirPath string) (err error) {
if dirPath == "" {
return errInvalidArgument
}
if err = checkPathLength(dirPath); err != nil {
return err
}
if err = os.Mkdir(preparePath(dirPath), 0777); err != nil {
if os.IsExist(err) {
return errVolumeExists
} else if os.IsPermission(err) {
return errDiskAccessDenied
} else if isSysErrNotDir(err) {
// File path cannot be verified since
// one of the parents is a file.
return errDiskAccessDenied
} else if isSysErrPathNotFound(err) {
// Add specific case for windows.
return errDiskAccessDenied
}
}
return nil
}
// Lookup if directory exists, returns directory
// attributes upon success.
func fsStatDir(statDir string) (os.FileInfo, error) {
if statDir == "" {
return nil, errInvalidArgument
}
if err := checkPathLength(statDir); err != nil {
return nil, err
}
fi, err := os.Stat(preparePath(statDir))
if err != nil {
if os.IsNotExist(err) {
return nil, errVolumeNotFound
} else if os.IsPermission(err) {
return nil, errVolumeAccessDenied
}
return nil, err
}
if !fi.IsDir() {
return nil, errVolumeAccessDenied
}
return fi, nil
}
// Lookup if file exists, returns file attributes upon success
func fsStatFile(statFile string) (os.FileInfo, error) {
if statFile == "" {
return nil, errInvalidArgument
}
if err := checkPathLength(statFile); err != nil {
return nil, err
}
fi, err := os.Stat(preparePath(statFile))
if err != nil {
if os.IsNotExist(err) {
return nil, errFileNotFound
} else if os.IsPermission(err) {
return nil, errFileAccessDenied
} else if isSysErrNotDir(err) {
return nil, errFileAccessDenied
} else if isSysErrPathNotFound(err) {
return nil, errFileNotFound
}
return nil, err
}
if fi.IsDir() {
return nil, errFileNotFound
}
return fi, nil
}
// Opens the file at given path, optionally from an offset. Upon success returns
// a readable stream and the size of the readable stream.
func fsOpenFile(readPath string, offset int64) (io.ReadCloser, int64, error) {
if readPath == "" || offset < 0 {
return nil, 0, errInvalidArgument
}
if err := checkPathLength(readPath); err != nil {
return nil, 0, err
}
fr, err := os.Open(preparePath(readPath))
if err != nil {
if os.IsNotExist(err) {
return nil, 0, errFileNotFound
} else if os.IsPermission(err) {
return nil, 0, errFileAccessDenied
} else if isSysErrNotDir(err) {
// File path cannot be verified since one of the parents is a file.
return nil, 0, errFileAccessDenied
} else if isSysErrPathNotFound(err) {
// Add specific case for windows.
return nil, 0, errFileNotFound
}
return nil, 0, err
}
// Stat to get the size of the file at path.
st, err := fr.Stat()
if err != nil {
return nil, 0, err
}
// Verify if its not a regular file, since subsequent Seek is undefined.
if !st.Mode().IsRegular() {
return nil, 0, errIsNotRegular
}
// Seek to the requested offset.
if offset > 0 {
_, err = fr.Seek(offset, os.SEEK_SET)
if err != nil {
return nil, 0, err
}
}
// Success.
return fr, st.Size(), nil
}
// Creates a file and copies data from incoming reader. Staging buffer is used by io.CopyBuffer.
func fsCreateFile(tempObjPath string, reader io.Reader, buf []byte, fallocSize int64) (int64, error) {
if tempObjPath == "" || reader == nil || buf == nil {
return 0, errInvalidArgument
}
if err := checkPathLength(tempObjPath); err != nil {
return 0, err
}
if err := mkdirAll(pathutil.Dir(tempObjPath), 0777); err != nil {
return 0, err
}
writer, err := os.OpenFile(preparePath(tempObjPath), os.O_CREATE|os.O_WRONLY, 0666)
if err != nil {
// File path cannot be verified since one of the parents is a file.
if isSysErrNotDir(err) {
return 0, errFileAccessDenied
}
return 0, err
}
defer writer.Close()
// Fallocate only if the size is final object is known.
if fallocSize > 0 {
if err = fsFAllocate(int(writer.Fd()), 0, fallocSize); err != nil {
return 0, err
}
}
bytesWritten, err := io.CopyBuffer(writer, reader, buf)
if err != nil {
return 0, err
}
return bytesWritten, nil
}
// Removes uploadID at destination path.
func fsRemoveUploadIDPath(basePath, uploadIDPath string) error {
if basePath == "" || uploadIDPath == "" {
return errInvalidArgument
}
// List all the entries in uploadID.
entries, err := readDir(uploadIDPath)
if err != nil && err != errFileNotFound {
return err
}
// Delete all the entries obtained from previous readdir.
for _, entryPath := range entries {
err = fsDeleteFile(basePath, pathJoin(uploadIDPath, entryPath))
if err != nil && err != errFileNotFound {
return err
}
}
return nil
}
// fsFAllocate is similar to Fallocate but provides a convenient
// wrapper to handle various operating system specific errors.
func fsFAllocate(fd int, offset int64, len int64) (err error) {
e := Fallocate(fd, offset, len)
// Ignore errors when Fallocate is not supported in the current system
if e != nil && !isSysErrNoSys(e) && !isSysErrOpNotSupported(e) {
switch {
case isSysErrNoSpace(e):
err = errDiskFull
case isSysErrIO(e):
err = e
default:
// For errors: EBADF, EINTR, EINVAL, ENODEV, EPERM, ESPIPE and ETXTBSY
// Appending was failed anyway, returns unexpected error
err = errUnexpected
}
return err
}
return nil
}
// Renames source path to destination path, creates all the
// missing parents if they don't exist.
func fsRenameFile(sourcePath, destPath string) error {
if err := mkdirAll(pathutil.Dir(destPath), 0777); err != nil {
return traceError(err)
}
if err := os.Rename(preparePath(sourcePath), preparePath(destPath)); err != nil {
return traceError(err)
}
return nil
}
// Delete a file and its parent if it is empty at the destination path.
// this function additionally protects the basePath from being deleted.
func fsDeleteFile(basePath, deletePath string) error {
if err := checkPathLength(basePath); err != nil {
return err
}
if err := checkPathLength(deletePath); err != nil {
return err
}
if basePath == deletePath {
return nil
}
// Verify if the path exists.
pathSt, err := os.Stat(preparePath(deletePath))
if err != nil {
if os.IsNotExist(err) {
return errFileNotFound
} else if os.IsPermission(err) {
return errFileAccessDenied
}
return err
}
if pathSt.IsDir() && !isDirEmpty(deletePath) {
// Verify if directory is empty.
return nil
}
// Attempt to remove path.
if err = os.Remove(preparePath(deletePath)); err != nil {
if os.IsNotExist(err) {
return errFileNotFound
} else if os.IsPermission(err) {
return errFileAccessDenied
} else if isSysErrNotEmpty(err) {
return errVolumeNotEmpty
}
return err
}
// Recursively go down the next path and delete again.
if err := fsDeleteFile(basePath, pathutil.Dir(deletePath)); err != nil {
return err
}
return nil
}