1 files changed, 203 insertions, 0 deletions
diff --git a/go/tools/builders/go_path.go b/go/tools/builders/go_path.go
new file mode 100644
index 00000000..58a7b8a9
--- /dev/null
+++ b/go/tools/builders/go_path.go
@@ -0,0 +1,203 @@
+// 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 main
+
+import (
+	"archive/zip"
+	"encoding/json"
+	"errors"
+	"flag"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+)
+
+type mode int
+
+const (
+	invalidMode mode = iota
+	archiveMode
+	copyMode
+	linkMode
+)
+
+func modeFromString(s string) (mode, error) {
+	switch s {
+	case "archive":
+		return archiveMode, nil
+	case "copy":
+		return copyMode, nil
+	case "link":
+		return linkMode, nil
+	default:
+		return invalidMode, fmt.Errorf("invalid mode: %s", s)
+	}
+}
+
+type manifestEntry struct {
+	Src, Dst string
+}
+
+func main() {
+	log.SetPrefix("GoPath: ")
+	log.SetFlags(0)
+	if err := run(os.Args[1:]); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func run(args []string) error {
+	var manifest, out string
+	flags := flag.NewFlagSet("go_path", flag.ContinueOnError)
+	flags.StringVar(&manifest, "manifest", "", "name of json file listing files to include")
+	flags.StringVar(&out, "out", "", "output file or directory")
+	modeFlag := flags.String("mode", "", "copy, link, or archive")
+	if err := flags.Parse(args); err != nil {
+		return err
+	}
+	if manifest == "" {
+		return errors.New("-manifest not set")
+	}
+	if out == "" {
+		return errors.New("-out not set")
+	}
+	if *modeFlag == "" {
+		return errors.New("-mode not set")
+	}
+	mode, err := modeFromString(*modeFlag)
+	if err != nil {
+		return err
+	}
+
+	entries, err := readManifest(manifest)
+	if err != nil {
+		return err
+	}
+
+	switch mode {
+	case archiveMode:
+		err = archivePath(out, entries)
+	case copyMode:
+		err = copyPath(out, entries)
+	case linkMode:
+		err = linkPath(out, entries)
+	}
+	return err
+}
+
+func readManifest(path string) ([]manifestEntry, error) {
+	data, err := ioutil.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("error reading manifest: %v", err)
+	}
+	var entries []manifestEntry
+	if err := json.Unmarshal(data, &entries); err != nil {
+		return nil, fmt.Errorf("error unmarshalling manifest %s: %v", path, err)
+	}
+	return entries, nil
+}
+
+func archivePath(out string, manifest []manifestEntry) (err error) {
+	outFile, err := os.Create(out)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		if e := outFile.Close(); err == nil && e != nil {
+			err = fmt.Errorf("error closing archive %s: %v", out, e)
+		}
+	}()
+	outZip := zip.NewWriter(outFile)
+
+	for _, entry := range manifest {
+		srcFile, err := os.Open(abs(filepath.FromSlash(entry.Src)))
+		if err != nil {
+			return err
+		}
+		w, err := outZip.Create(entry.Dst)
+		if err != nil {
+			srcFile.Close()
+			return err
+		}
+		if _, err := io.Copy(w, srcFile); err != nil {
+			srcFile.Close()
+			return err
+		}
+		if err := srcFile.Close(); err != nil {
+			return err
+		}
+	}
+
+	if err := outZip.Close(); err != nil {
+		return fmt.Errorf("error constructing archive %s: %v", out, err)
+	}
+	return nil
+}
+
+func copyPath(out string, manifest []manifestEntry) error {
+	if err := os.MkdirAll(out, 0777); err != nil {
+		return err
+	}
+	for _, entry := range manifest {
+		dst := abs(filepath.Join(out, filepath.FromSlash(entry.Dst)))
+		if err := os.MkdirAll(filepath.Dir(dst), 0777); err != nil {
+			return err
+		}
+		srcFile, err := os.Open(abs(filepath.FromSlash(entry.Src)))
+		if err != nil {
+			return err
+		}
+		dstFile, err := os.Create(dst)
+		if err != nil {
+			srcFile.Close()
+			return err
+		}
+		if _, err := io.Copy(dstFile, srcFile); err != nil {
+			dstFile.Close()
+			srcFile.Close()
+			return err
+		}
+		srcFile.Close()
+		if err := dstFile.Close(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func linkPath(out string, manifest []manifestEntry) error {
+	// out directory may already exist and may contain old symlinks. Delete.
+	if err := os.RemoveAll(out); err != nil {
+		return err
+	}
+	if err := os.MkdirAll(out, 0777); err != nil {
+		return err
+	}
+	for _, entry := range manifest {
+		dst := filepath.Join(out, filepath.FromSlash(entry.Dst))
+		dstDir := filepath.Dir(dst)
+		src, _ := filepath.Rel(dstDir, entry.Src)
+		if err := os.MkdirAll(dstDir, 0777); err != nil {
+			return err
+		}
+		if err := os.Symlink(src, dst); err != nil {
+			return err
+		}
+	}
+	return nil
+}