dirhash: forward to golang.org/x/mod/sumdb/dirhash

It seems like x/mod/sumdb/dirhash appeared way back in 2019,
and we had not noticed until now.

dirhash/hash.go

@@ -1,103 +1,31 @@
-// Copyright 2018 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// Package dirhash defines hashes over directory trees.
+// Package dirhash is a thin forwarding layer on top of
+// [golang.org/x/mod/sumdb/dirhash]. See that package for documentation.
+//
+// Deprecated: use [golang.org/x/mod/sumdb/dirhash] instead.
 package dirhash
 
 import (
-	"archive/zip"
-	"crypto/sha256"
-	"encoding/base64"
-	"errors"
-	"fmt"
 	"io"
-	"os"
-	"path/filepath"
-	"sort"
-	"strings"
+
+	"golang.org/x/mod/sumdb/dirhash"
 )
 
-var DefaultHash = Hash1
+var DefaultHash = dirhash.Hash1
 
-type Hash func(files []string, open func(string) (io.ReadCloser, error)) (string, error)
+type Hash = dirhash.Hash
 
 func Hash1(files []string, open func(string) (io.ReadCloser, error)) (string, error) {
-	h := sha256.New()
-	files = append([]string(nil), files...)
-	sort.Strings(files)
-	for _, file := range files {
-		if strings.Contains(file, "\n") {
-			return "", errors.New("filenames with newlines are not supported")
-		}
-		r, err := open(file)
-		if err != nil {
-			return "", err
-		}
-		hf := sha256.New()
-		_, err = io.Copy(hf, r)
-		r.Close()
-		if err != nil {
-			return "", err
-		}
-		fmt.Fprintf(h, "%x  %s\n", hf.Sum(nil), file)
-	}
-	return "h1:" + base64.StdEncoding.EncodeToString(h.Sum(nil)), nil
+	return dirhash.Hash1(files, open)
 }
 
 func HashDir(dir, prefix string, hash Hash) (string, error) {
-	files, err := DirFiles(dir, prefix)
-	if err != nil {
-		return "", err
-	}
-	osOpen := func(name string) (io.ReadCloser, error) {
-		return os.Open(filepath.Join(dir, strings.TrimPrefix(name, prefix)))
-	}
-	return hash(files, osOpen)
+	return dirhash.HashDir(dir, prefix, hash)
 }
 
 func DirFiles(dir, prefix string) ([]string, error) {
-	var files []string
-	dir = filepath.Clean(dir)
-	err := filepath.Walk(dir, func(file string, info os.FileInfo, err error) error {
-		if err != nil {
-			return err
-		}
-		if info.IsDir() {
-			return nil
-		}
-		rel := file
-		if dir != "." {
-			rel = file[len(dir)+1:]
-		}
-		f := filepath.Join(prefix, rel)
-		files = append(files, filepath.ToSlash(f))
-		return nil
-	})
-	if err != nil {
-		return nil, err
-	}
-	return files, nil
+	return dirhash.DirFiles(dir, prefix)
 }
 
 func HashZip(zipfile string, hash Hash) (string, error) {
-	z, err := zip.OpenReader(zipfile)
-	if err != nil {
-		return "", err
-	}
-	defer z.Close()
-	var files []string
-	zfiles := make(map[string]*zip.File)
-	for _, file := range z.File {
-		files = append(files, file.Name)
-		zfiles[file.Name] = file
-	}
-	zipOpen := func(name string) (io.ReadCloser, error) {
-		f := zfiles[name]
-		if f == nil {
-			return nil, fmt.Errorf("file %q not found in zip", name) // should never happen
-		}
-		return f.Open()
-	}
-	return hash(files, zipOpen)
+	return dirhash.HashZip(zipfile, hash)
 }