1 files changed, 193 insertions, 0 deletions
diff --git a/src/common/golang/ziputils.go b/src/common/golang/ziputils.go
new file mode 100644
index 0000000..e1a7af9
--- /dev/null
+++ b/src/common/golang/ziputils.go
@@ -0,0 +1,193 @@
+// Copyright 2018 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package ziputils provides utility functions to work with zip files.
+package ziputils
+
+import (
+	"archive/zip"
+	"bytes"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"golang.org/x/sync/errgroup"
+)
+
+// Empty file contains only the End of central directory record. 0x06054b50
+// https://en.wikipedia.org/wiki/Zip_(file_format)
+var (
+	emptyzip             = append([]byte{0x50, 0x4b, 0x05, 0x06}, make([]byte, 18)...)
+	dirPerm  os.FileMode = 0755
+)
+
+// EmptyZipReader wraps an reader whose contents are the empty zip.
+type EmptyZipReader struct {
+	*bytes.Reader
+}
+
+// NewEmptyZipReader creates and returns an EmptyZipReader struct.
+func NewEmptyZipReader() *EmptyZipReader {
+	return &EmptyZipReader{bytes.NewReader(emptyzip)}
+}
+
+// EmptyZip creates empty zip archive.
+func EmptyZip(dst string) error {
+	zipfile, err := os.Create(dst)
+	if err != nil {
+		return err
+	}
+	defer zipfile.Close()
+	_, err = io.Copy(zipfile, NewEmptyZipReader())
+	return err
+}
+
+// Zip archives src into dst without compression.
+func Zip(src, dst string) error {
+	fi, err := os.Stat(src)
+	if err != nil {
+		return err
+	}
+
+	zipfile, err := os.Create(dst)
+	if err != nil {
+		return err
+	}
+	defer zipfile.Close()
+
+	archive := zip.NewWriter(zipfile)
+	defer archive.Close()
+
+	if !fi.Mode().IsDir() {
+		return WriteFile(archive, src, filepath.Base(src))
+	}
+
+	return filepath.Walk(src, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		if info.IsDir() {
+			return nil
+		}
+
+		return WriteFile(archive, path, strings.TrimPrefix(path, src+string(filepath.Separator)))
+	})
+}
+
+// WriteFile writes filename to the out zip writer.
+func WriteFile(out *zip.Writer, filename, zipFilename string) error {
+	// It's important to set timestamps to zero, otherwise we would break caching for unchanged files
+	f, err := out.CreateHeader(&zip.FileHeader{Name: zipFilename, Method: zip.Store, Modified: time.Unix(0, 0)})
+	if err != nil {
+		return err
+	}
+	contents, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return err
+	}
+	_, err = f.Write(contents)
+	return err
+}
+
+// WriteReader writes a reader to the out zip writer.
+func WriteReader(out *zip.Writer, in io.Reader, filename string) error {
+	// It's important to set timestamps to zero, otherwise we would break caching for unchanged files
+	f, err := out.CreateHeader(&zip.FileHeader{Name: filename, Method: zip.Store, Modified: time.Unix(0, 0)})
+	if err != nil {
+		return err
+	}
+	contents, err := ioutil.ReadAll(in)
+	if err != nil {
+		return err
+	}
+	_, err = f.Write(contents)
+	return err
+}
+
+// Unzip expands srcZip in dst directory
+func Unzip(srcZip, dst string) error {
+	reader, err := zip.OpenReader(srcZip)
+	if err != nil {
+		return err
+	}
+	defer reader.Close()
+
+	_, err = os.Stat(dst)
+	if err != nil && !os.IsNotExist(err) {
+		return err
+	}
+	if os.IsNotExist(err) {
+		if err := os.MkdirAll(dst, dirPerm); err != nil {
+			return err
+		}
+	}
+
+	for _, file := range reader.File {
+		path := filepath.Join(dst, file.Name)
+
+		if file.FileInfo().IsDir() {
+			if err := os.MkdirAll(path, dirPerm); err != nil {
+				return err
+			}
+			continue
+		}
+
+		dir := filepath.Dir(path)
+		_, err := os.Stat(dir)
+		if err != nil && !os.IsNotExist(err) {
+			return err
+		}
+		if os.IsNotExist(err) {
+			if err := os.MkdirAll(dir, dirPerm); err != nil {
+				return err
+			}
+		}
+
+		if err := write(file, path); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// UnzipParallel expands zip archives in parallel.
+// TODO(b/137549283) Update UnzipParallel and add test
+func UnzipParallel(srcZipDestMap map[string]string) error {
+	var eg errgroup.Group
+	for z, d := range srcZipDestMap {
+		zip, dest := z, d
+		eg.Go(func() error { return Unzip(zip, dest) })
+	}
+	return eg.Wait()
+}
+
+func write(zf *zip.File, path string) error {
+	rc, err := zf.Open()
+	if err != nil {
+		return err
+	}
+	defer rc.Close()
+	f, err := os.Create(path)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	_, err = io.Copy(f, rc)
+	return err
+}