fsutil.go RawHistoryFolder

1package main
2
3import (
4	"os"
5	"path/filepath"
6)
7
8// writeFileAtomic writes data to path via a temp file + rename in the
9// same directory, so readers never observe a partially written file
10// and a crash mid-write cannot corrupt the target.
11func writeFileAtomic(path string, data []byte, perm os.FileMode) error {
12	dir := filepath.Dir(path)
13	if err := os.MkdirAll(dir, 0o755); err != nil {
14		return err
15	}
16	tmp, err := os.CreateTemp(dir, filepath.Base(path)+".tmp-*")
17	if err != nil {
18		return err
19	}
20	tmpName := tmp.Name()
21	defer os.Remove(tmpName) // no-op after successful rename
22
23	if err := tmp.Chmod(perm); err != nil {
24		tmp.Close()
25		return err
26	}
27	if _, err := tmp.Write(data); err != nil {
28		tmp.Close()
29		return err
30	}
31	if err := tmp.Close(); err != nil {
32		return err
33	}
34	return os.Rename(tmpName, path)
35}