io_atomic.go

package contexting

import (
	"fmt"
	"os"
	"path/filepath"
)

func writeFileAtomic(path string, data []byte, perm os.FileMode) error {
	dir := filepath.Dir(path)
	if err := os.MkdirAll(dir, 0o755); err != nil {
		return fmt.Errorf("create directory: %w", err)
	}

	tmpFile, err := os.CreateTemp(dir, ".tmp-*.json")
	if err != nil {
		return fmt.Errorf("create temp file: %w", err)
	}
	tmpPath := tmpFile.Name()

	defer func() {
		_ = os.Remove(tmpPath)
	}()

	if _, err := tmpFile.Write(data); err != nil {
		_ = tmpFile.Close()
		return fmt.Errorf("write temp file: %w", err)
	}
	if err := tmpFile.Chmod(perm); err != nil {
		_ = tmpFile.Close()
		return fmt.Errorf("chmod temp file: %w", err)
	}
	if err := tmpFile.Close(); err != nil {
		return fmt.Errorf("close temp file: %w", err)
	}
	if err := os.Rename(tmpPath, path); err != nil {
		return fmt.Errorf("replace file: %w", err)
	}

	return nil
}