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package write
import (
"bufio"
"io"
"io/ioutil"
"os"
"path/filepath"
)
func tempDir(dest string) string {
tempdir := os.Getenv("TMPDIR")
if tempdir == "" {
// Convenient for development: decreases the chance that we
// cannot move files due to /tmp being on a different file
// system.
tempdir = filepath.Dir(dest)
}
return tempdir
}
func Atomically(dest string, write func(io.Writer) error) (err error) {
f, err := ioutil.TempFile(tempDir(dest), "pk4-")
if err != nil {
return err
}
defer func() {
// Remove the tempfile if an error occurred
if err != nil {
os.Remove(f.Name())
}
}()
defer f.Close()
bufw := bufio.NewWriter(f)
if err := write(bufw); err != nil {
return err
}
if err := bufw.Flush(); err != nil {
return err
}
if err := f.Chmod(0644); err != nil {
return err
}
if err := f.Close(); err != nil {
return err
}
return os.Rename(f.Name(), dest)
}
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