pkg/safe: remove temporary file on failure (#1774)

This commit is contained in:
Bala FA 2016-05-27 10:13:33 +05:30 committed by Harshavardhana
parent d65101a8c8
commit 51bb613fdf
4 changed files with 84 additions and 87 deletions

View file

@ -167,7 +167,7 @@ func safeCloseAndRemove(writer io.WriteCloser) error {
// If writer is a safe file, Attempt to close and remove.
safeWriter, ok := writer.(*safe.File)
if ok {
return safeWriter.CloseAndRemove()
return safeWriter.Abort()
}
wCloser, ok := writer.(*waitCloser)
if ok {

View file

@ -16,115 +16,109 @@
// NOTE - Rename() not guaranteed to be safe on all filesystems which are not fully POSIX compatible
// Package safe provides safe file write semantics by leveraging Rename's() safeity.
package safe
import (
"io"
"errors"
"io/ioutil"
"os"
"path/filepath"
)
// Vault - vault is an interface for different implementations of safe
// i/o semantics.
type Vault interface {
io.ReadWriteCloser
SyncClose() error
CloseAndRemove() error
}
// File provides for safe file writes.
// File represents safe file descriptor.
type File struct {
*os.File
file string
name string
tmpfile *os.File
closed bool
aborted bool
}
// SyncClose sync file to disk and close, returns an error if any
func (f *File) SyncClose() error {
// sync to the disk
if err := f.File.Sync(); err != nil {
return err
// Write writes len(b) bytes to the temporary File. In case of error, the temporary file is removed.
func (file *File) Write(b []byte) (n int, err error) {
if file.aborted {
err = errors.New("write on aborted file")
return
}
// Close the fd.
if err := f.Close(); err != nil {
return err
if file.closed {
err = errors.New("write on closed file")
return
}
return nil
defer func() {
if err != nil {
os.Remove(file.tmpfile.Name())
file.aborted = true
}
}()
n, err = file.tmpfile.Write(b)
return
}
// Close the file, returns an error if any
func (f *File) Close() error {
// Close the embedded fd.
if err := f.File.Close(); err != nil {
return err
// Close closes the temporary File and renames to the named file. In case of error, the temporary file is removed.
func (file *File) Close() (err error) {
defer func() {
if err != nil {
os.Remove(file.tmpfile.Name())
file.aborted = true
}
}()
if file.aborted || file.closed {
return
}
// Safe rename to final destination
if err := os.Rename(f.Name(), f.file); err != nil {
return err
if err = file.tmpfile.Close(); err != nil {
return
}
return nil
err = os.Rename(file.tmpfile.Name(), file.name)
file.closed = true
return
}
// CloseAndRemove closes the temp file, and safely removes it. Returns
// error if any.
func (f *File) CloseAndRemove() error {
// close the embedded fd
f.File.Close()
// Remove the temp file.
if err := os.Remove(f.Name()); err != nil {
return err
// Abort aborts the temporary File by closing and removing the temporary file.
func (file *File) Abort() (err error) {
if file.aborted || file.closed {
return
}
return nil
file.tmpfile.Close()
err = os.Remove(file.tmpfile.Name())
file.aborted = true
return
}
// CreateFile creates a new file at filePath for safe writes, it also
// creates parent directories if they don't exist.
func CreateFile(filePath string) (*File, error) {
return CreateFileWithPrefix(filePath, "$deleteme.")
}
// CreateFileWithSuffix is similar to CreateFileWithPrefix, but the
// second argument is treated as suffix for the temporary files.
func CreateFileWithSuffix(filePath string, suffix string) (*File, error) {
// If parent directories do not exist, ioutil.TempFile doesn't create them
// handle such a case with os.MkdirAll()
if err := os.MkdirAll(filepath.Dir(filePath), 0700); err != nil {
// CreateFile creates the named file safely from unique temporary file.
// The temporary file is renamed to the named file upon successful close
// to safeguard intermediate state in the named file. The temporary file
// is created in the name of the named file with suffixed unique number
// and prefixed "$tmpfile" string. While creating the temporary file,
// missing parent directories are also created. The temporary file is
// removed if case of any intermediate failure. Not removed temporary
// files can be cleaned up by identifying them using "$tmpfile" prefix
// string.
func CreateFile(name string) (*File, error) {
// ioutil.TempFile() fails if parent directory is missing.
// Create parent directory to avoid such error.
dname := filepath.Dir(name)
if err := os.MkdirAll(dname, 0700); err != nil {
return nil, err
}
f, err := ioutil.TempFile(filepath.Dir(filePath), filepath.Base(filePath)+suffix)
fname := filepath.Base(name)
tmpfile, err := ioutil.TempFile(dname, "$tmpfile."+fname+".")
if err != nil {
return nil, err
}
if err = os.Chmod(f.Name(), 0600); err != nil {
if err = os.Remove(f.Name()); err != nil {
return nil, err
}
return nil, err
}
return &File{File: f, file: filePath}, nil
}
// CreateFileWithPrefix creates a new file at filePath for safe
// writes, it also creates parent directories if they don't exist.
// prefix specifies the prefix of the temporary files so that cleaning
// stale temp files is easy.
func CreateFileWithPrefix(filePath string, prefix string) (*File, error) {
// If parent directories do not exist, ioutil.TempFile doesn't create them
// handle such a case with os.MkdirAll()
if err := os.MkdirAll(filepath.Dir(filePath), 0700); err != nil {
return nil, err
}
f, err := ioutil.TempFile(filepath.Dir(filePath), prefix+filepath.Base(filePath))
if err != nil {
return nil, err
}
if err = os.Chmod(f.Name(), 0600); err != nil {
if err = os.Remove(f.Name()); err != nil {
return nil, err
if err = os.Chmod(tmpfile.Name(), 0600); err != nil {
if rerr := os.Remove(tmpfile.Name()); rerr != nil {
err = rerr
}
return nil, err
}
return &File{File: f, file: filePath}, nil
return &File{name: name, tmpfile: tmpfile}, nil
}

View file

@ -34,13 +34,14 @@ type MySuite struct {
var _ = Suite(&MySuite{})
func (s *MySuite) SetUpSuite(c *C) {
root, err := ioutil.TempDir(os.TempDir(), "safe-")
root, err := ioutil.TempDir(os.TempDir(), "safe_test.go.")
c.Assert(err, IsNil)
s.root = root
}
func (s *MySuite) TearDownSuite(c *C) {
os.RemoveAll(s.root)
err := os.Remove(s.root)
c.Assert(err, IsNil)
}
func (s *MySuite) TestSafe(c *C) {
@ -52,15 +53,17 @@ func (s *MySuite) TestSafe(c *C) {
c.Assert(err, IsNil)
_, err = os.Stat(filepath.Join(s.root, "testfile"))
c.Assert(err, IsNil)
err = os.Remove(filepath.Join(s.root, "testfile"))
c.Assert(err, IsNil)
}
func (s *MySuite) TestSafeRemove(c *C) {
func (s *MySuite) TestSafeAbort(c *C) {
f, err := CreateFile(filepath.Join(s.root, "purgefile"))
c.Assert(err, IsNil)
_, err = os.Stat(filepath.Join(s.root, "purgefile"))
c.Assert(err, Not(IsNil))
err = f.CloseAndRemove()
err = f.Abort()
c.Assert(err, IsNil)
err = f.Close()
_, err = os.Stat(filepath.Join(s.root, "purgefile"))
c.Assert(err, Not(IsNil))
}

View file

@ -358,7 +358,7 @@ func (s fsStorage) CreateFile(volume, path string) (writeCloser io.WriteCloser,
return nil, errIsNotRegular
}
}
w, err := safe.CreateFileWithPrefix(filePath, "$tmpfile")
w, err := safe.CreateFile(filePath)
if err != nil {
// File path cannot be verified since one of the parents is a file.
if strings.Contains(err.Error(), "not a directory") {