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atomic.go
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atomic.go
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package file
import (
"fmt"
"os"
"path/filepath"
"github.com/hashicorp/go-uuid"
)
// WriteAtomic writes the given contents to a temporary file in the same
// directory, does an fsync and then renames the file to its real path
func WriteAtomic(path string, contents []byte) error {
return WriteAtomicWithPerms(path, contents, 0700, 0600)
}
func WriteAtomicWithPerms(path string, contents []byte, dirPerms, filePerms os.FileMode) error {
uuid, err := uuid.GenerateUUID()
if err != nil {
return err
}
tempPath := fmt.Sprintf("%s-%s.tmp", path, uuid)
if err := os.MkdirAll(filepath.Dir(path), dirPerms); err != nil {
return err
}
fh, err := os.OpenFile(tempPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, filePerms)
if err != nil {
return err
}
if _, err := fh.Write(contents); err != nil {
fh.Close()
os.Remove(tempPath)
return err
}
if err := fh.Sync(); err != nil {
fh.Close()
os.Remove(tempPath)
return err
}
if err := fh.Close(); err != nil {
os.Remove(tempPath)
return err
}
if err := os.Rename(tempPath, path); err != nil {
os.Remove(tempPath)
return err
}
return nil
}