60 lines
1.5 KiB
Go
60 lines
1.5 KiB
Go
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// Package atomicfile provides the ability to write a file with an eventual
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// rename on Close (using os.Rename). This allows for a file to always be in a
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// consistent state and never represent an in-progress write.
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//
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// NOTE: `os.Rename` may not be atomic on your operating system.
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package atomicfile
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import (
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"io/ioutil"
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"os"
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"path/filepath"
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)
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// File behaves like os.File, but does an atomic rename operation at Close.
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type File struct {
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*os.File
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path string
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}
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// New creates a new temporary file that will replace the file at the given
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// path when Closed.
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func New(path string, mode os.FileMode) (*File, error) {
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f, err := ioutil.TempFile(filepath.Dir(path), filepath.Base(path))
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if err != nil {
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return nil, err
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}
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if err := os.Chmod(f.Name(), mode); err != nil {
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f.Close()
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os.Remove(f.Name())
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return nil, err
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}
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return &File{File: f, path: path}, nil
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}
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// Close the file replacing the configured file.
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func (f *File) Close() error {
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if err := f.File.Close(); err != nil {
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os.Remove(f.File.Name())
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return err
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}
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if err := os.Rename(f.Name(), f.path); err != nil {
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return err
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}
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return nil
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}
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// Abort closes the file and removes it instead of replacing the configured
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// file. This is useful if after starting to write to the file you decide you
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// don't want it anymore.
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func (f *File) Abort() error {
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if err := f.File.Close(); err != nil {
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os.Remove(f.Name())
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return err
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}
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if err := os.Remove(f.Name()); err != nil {
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return err
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}
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return nil
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}
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