1 files changed, 94 insertions, 0 deletions
diff --git a/lib/time/mkzip.go b/lib/time/mkzip.go
new file mode 100644
index 0000000..3920b11
--- /dev/null
+++ b/lib/time/mkzip.go
@@ -0,0 +1,94 @@
+// Copyright 2022 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.
+
+//go:build ignore
+
+// Mkzip writes a zoneinfo.zip with the content of the current directory
+// and its subdirectories, with no compression, suitable for package time.
+//
+// Usage:
+//
+//	go run ../../mkzip.go ../../zoneinfo.zip
+//
+// We use this program instead of 'zip -0 -r ../../zoneinfo.zip *' to get
+// a reproducible generator that does not depend on which version of the
+// external zip tool is used or the ordering of file names in a directory
+// or the current time.
+package main
+
+import (
+	"archive/zip"
+	"bytes"
+	"flag"
+	"fmt"
+	"hash/crc32"
+	"io/fs"
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+func usage() {
+	fmt.Fprintf(os.Stderr, "usage: go run mkzip.go ../../zoneinfo.zip\n")
+	os.Exit(2)
+}
+
+func main() {
+	log.SetPrefix("mkzip: ")
+	log.SetFlags(0)
+	flag.Usage = usage
+	flag.Parse()
+	args := flag.Args()
+	if len(args) != 1 || !strings.HasSuffix(args[0], ".zip") {
+		usage()
+	}
+
+	var zb bytes.Buffer
+	zw := zip.NewWriter(&zb)
+	seen := make(map[string]bool)
+	err := filepath.WalkDir(".", func(path string, d fs.DirEntry, err error) error {
+		if d.IsDir() {
+			return nil
+		}
+		data, err := os.ReadFile(path)
+		if err != nil {
+			log.Fatal(err)
+		}
+		if strings.HasSuffix(path, ".zip") {
+			log.Fatalf("unexpected file during walk: %s", path)
+		}
+		name := filepath.ToSlash(path)
+		w, err := zw.CreateRaw(&zip.FileHeader{
+			Name:               name,
+			Method:             zip.Store,
+			CompressedSize64:   uint64(len(data)),
+			UncompressedSize64: uint64(len(data)),
+			CRC32:              crc32.ChecksumIEEE(data),
+		})
+		if err != nil {
+			log.Fatal(err)
+		}
+		if _, err := w.Write(data); err != nil {
+			log.Fatal(err)
+		}
+		seen[name] = true
+		return nil
+	})
+	if err != nil {
+		log.Fatal(err)
+	}
+	if err := zw.Close(); err != nil {
+		log.Fatal(err)
+	}
+	if len(seen) == 0 {
+		log.Fatalf("did not find any files to add")
+	}
+	if !seen["US/Eastern"] {
+		log.Fatalf("did not find US/Eastern to add")
+	}
+	if err := os.WriteFile(args[0], zb.Bytes(), 0666); err != nil {
+		log.Fatal(err)
+	}
+}