83 lines
1.7 KiB
Go
83 lines
1.7 KiB
Go
|
package ioutils
|
||
|
|
|
||
|
|
import (
|
||
|
|
"io"
|
||
|
|
"io/ioutil"
|
||
|
|
"os"
|
||
|
|
"path/filepath"
|
||
|
|
)
|
||
|
|
|
||
|
|
// NewAtomicFileWriter returns WriteCloser so that writing to it writes to a
|
||
|
|
// temporary file and closing it atomically changes the temporary file to
|
||
|
|
// destination path. Writing and closing concurrently is not allowed.
|
||
|
|
func NewAtomicFileWriter(filename string, perm os.FileMode) (io.WriteCloser, error) {
|
||
|
|
f, err := ioutil.TempFile(filepath.Dir(filename), ".tmp-"+filepath.Base(filename))
|
||
|
|
if err != nil {
|
||
|
|
return nil, err
|
||
|
|
}
|
||
|
|
|
||
|
|
abspath, err := filepath.Abs(filename)
|
||
|
|
if err != nil {
|
||
|
|
return nil, err
|
||
|
|
}
|
||
|
|
return &atomicFileWriter{
|
||
|
|
f: f,
|
||
|
|
fn: abspath,
|
||
|
|
perm: perm,
|
||
|
|
}, nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// AtomicWriteFile atomically writes data to a file named by filename.
|
||
|
|
func AtomicWriteFile(filename string, data []byte, perm os.FileMode) error {
|
||
|
|
f, err := NewAtomicFileWriter(filename, perm)
|
||
|
|
if err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
n, err := f.Write(data)
|
||
|
|
if err == nil && n < len(data) {
|
||
|
|
err = io.ErrShortWrite
|
||
|
|
f.(*atomicFileWriter).writeErr = err
|
||
|
|
}
|
||
|
|
if err1 := f.Close(); err == nil {
|
||
|
|
err = err1
|
||
|
|
}
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
|
||
|
|
type atomicFileWriter struct {
|
||
|
|
f *os.File
|
||
|
|
fn string
|
||
|
|
writeErr error
|
||
|
|
perm os.FileMode
|
||
|
|
}
|
||
|
|
|
||
|
|
func (w *atomicFileWriter) Write(dt []byte) (int, error) {
|
||
|
|
n, err := w.f.Write(dt)
|
||
|
|
if err != nil {
|
||
|
|
w.writeErr = err
|
||
|
|
}
|
||
|
|
return n, err
|
||
|
|
}
|
||
|
|
|
||
|
|
func (w *atomicFileWriter) Close() (retErr error) {
|
||
|
|
defer func() {
|
||
|
|
if retErr != nil || w.writeErr != nil {
|
||
|
|
os.Remove(w.f.Name())
|
||
|
|
}
|
||
|
|
}()
|
||
|
|
if err := w.f.Sync(); err != nil {
|
||
|
|
w.f.Close()
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
if err := w.f.Close(); err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
if err := os.Chmod(w.f.Name(), w.perm); err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
if w.writeErr == nil {
|
||
|
|
return os.Rename(w.f.Name(), w.fn)
|
||
|
|
}
|
||
|
|
return nil
|
||
|
|
}
|