path, err := CachePath(ctx, mod, "lock")
	if err != nil {
		return nil, err
	}
	if err := os.MkdirAll(filepath.Dir(path), 0777); err != nil {
		return nil, err
	}
	return lockedfile.MutexAt(path).Lock()
}

// SideLock locks a file within the module cache that previously guarded
// edits to files outside the cache, such as go.sum and go.mod files in the
// user's working directory.

		return "", "", err
	}

	lockfile = dir + ".lock"
	if buildX {
		fmt.Fprintf(xLog, "# lock %s\n", lockfile)
	}

	unlock, err := lockedfile.MutexAt(lockfile).Lock()
	if err != nil {
		return "", "", fmt.Errorf("codehost.WorkDir: can't find or create lock file: %v", err)
	}
	defer unlock()

	data, err := os.ReadFile(dir + ".info")