cmd/sbox/sbox.go - platform/build/soong - Git at Google

 // Copyright 2017 Google Inc. 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 (
 	"bytes"
 	"crypto/sha1"
 	"encoding/hex"
 	"errors"
 	"flag"
 	"fmt"
 	"io"
 	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"strconv"
 	"strings"
 	"time"

 	"android/soong/cmd/sbox/sbox_proto"
 	"android/soong/makedeps"
 	"android/soong/response"

 	"github.com/golang/protobuf/proto"
 )

 var (
 	sandboxesRoot string
 	manifestFile  string
 	keepOutDir    bool
 )

 const (
 	depFilePlaceholder    = "__SBOX_DEPFILE__"
 	sandboxDirPlaceholder = "__SBOX_SANDBOX_DIR__"
 )

 func init() {
 	flag.StringVar(&sandboxesRoot, "sandbox-path", "",
 		"root of temp directory to put the sandbox into")
 	flag.StringVar(&manifestFile, "manifest", "",
 		"textproto manifest describing the sandboxed command(s)")
 	flag.BoolVar(&keepOutDir, "keep-out-dir", false,
 		"whether to keep the sandbox directory when done")
 }

 func usageViolation(violation string) {
 	if violation != "" {
 		fmt.Fprintf(os.Stderr, "Usage error: %s.\n\n", violation)
 	}

 	fmt.Fprintf(os.Stderr,
 		"Usage: sbox --manifest <manifest> --sandbox-path <sandboxPath>\n")

 	flag.PrintDefaults()

 	os.Exit(1)
 }

 func main() {
 	flag.Usage = func() {
 		usageViolation("")
 	}
 	flag.Parse()

 	error := run()
 	if error != nil {
 		fmt.Fprintln(os.Stderr, error)
 		os.Exit(1)
 	}
 }

 func findAllFilesUnder(root string) (paths []string) {
 	paths = []string{}
 	filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
 		if !info.IsDir() {
 			relPath, err := filepath.Rel(root, path)
 			if err != nil {
 				// couldn't find relative path from ancestor?
 				panic(err)
 			}
 			paths = append(paths, relPath)
 		}
 		return nil
 	})
 	return paths
 }

 func run() error {
 	if manifestFile == "" {
 		usageViolation("--manifest <manifest> is required and must be non-empty")
 	}
 	if sandboxesRoot == "" {
 		// In practice, the value of sandboxesRoot will mostly likely be at a fixed location relative to OUT_DIR,
 		// and the sbox executable will most likely be at a fixed location relative to OUT_DIR too, so
 		// the value of sandboxesRoot will most likely be at a fixed location relative to the sbox executable
 		// However, Soong also needs to be able to separately remove the sandbox directory on startup (if it has anything left in it)
 		// and by passing it as a parameter we don't need to duplicate its value
 		usageViolation("--sandbox-path <sandboxPath> is required and must be non-empty")
 	}

 	manifest, err := readManifest(manifestFile)

 	if len(manifest.Commands) == 0 {
 		return fmt.Errorf("at least one commands entry is required in %q", manifestFile)
 	}

 	// setup sandbox directory
 	err = os.MkdirAll(sandboxesRoot, 0777)
 	if err != nil {
 		return fmt.Errorf("failed to create %q: %w", sandboxesRoot, err)
 	}

 	// This tool assumes that there are no two concurrent runs with the same
 	// manifestFile. It should therefore be safe to use the hash of the
 	// manifestFile as the temporary directory name. We do this because it
 	// makes the temporary directory name deterministic. There are some
 	// tools that embed the name of the temporary output in the output, and
 	// they otherwise cause non-determinism, which then poisons actions
 	// depending on this one.
 	hash := sha1.New()
 	hash.Write([]byte(manifestFile))
 	tempDir := filepath.Join(sandboxesRoot, "sbox", hex.EncodeToString(hash.Sum(nil)))

 	err = os.RemoveAll(tempDir)
 	if err != nil {
 		return err
 	}
 	err = os.MkdirAll(tempDir, 0777)
 	if err != nil {
 		return fmt.Errorf("failed to create temporary dir in %q: %w", sandboxesRoot, err)
 	}

 	// In the common case, the following line of code is what removes the sandbox
 	// If a fatal error occurs (such as if our Go process is killed unexpectedly),
 	// then at the beginning of the next build, Soong will wipe the temporary
 	// directory.
 	defer func() {
 		// in some cases we decline to remove the temp dir, to facilitate debugging
 		if !keepOutDir {
 			os.RemoveAll(tempDir)
 		}
 	}()

 	// If there is more than one command in the manifest use a separate directory for each one.
 	useSubDir := len(manifest.Commands) > 1
 	var commandDepFiles []string

 	for i, command := range manifest.Commands {
 		localTempDir := tempDir
 		if useSubDir {
 			localTempDir = filepath.Join(localTempDir, strconv.Itoa(i))
 		}
 		depFile, err := runCommand(command, localTempDir)
 		if err != nil {
 			// Running the command failed, keep the temporary output directory around in
 			// case a user wants to inspect it for debugging purposes.  Soong will delete
 			// it at the beginning of the next build anyway.
 			keepOutDir = true
 			return err
 		}
 		if depFile != "" {
 			commandDepFiles = append(commandDepFiles, depFile)
 		}
 	}

 	outputDepFile := manifest.GetOutputDepfile()
 	if len(commandDepFiles) > 0 && outputDepFile == "" {
 		return fmt.Errorf("Sandboxed commands used %s but output depfile is not set in manifest file",
 			depFilePlaceholder)
 	}

 	if outputDepFile != "" {
 		// Merge the depfiles from each command in the manifest to a single output depfile.
 		err = rewriteDepFiles(commandDepFiles, outputDepFile)
 		if err != nil {
 			return fmt.Errorf("failed merging depfiles: %w", err)
 		}
 	}

 	return nil
 }

 // readManifest reads an sbox manifest from a textproto file.
 func readManifest(file string) (*sbox_proto.Manifest, error) {
 	manifestData, err := ioutil.ReadFile(file)
 	if err != nil {
 		return nil, fmt.Errorf("error reading manifest %q: %w", file, err)
 	}

 	manifest := sbox_proto.Manifest{}

 	err = proto.UnmarshalText(string(manifestData), &manifest)
 	if err != nil {
 		return nil, fmt.Errorf("error parsing manifest %q: %w", file, err)
 	}

 	return &manifest, nil
 }

 // runCommand runs a single command from a manifest.  If the command references the
 // __SBOX_DEPFILE__ placeholder it returns the name of the depfile that was used.
 func runCommand(command *sbox_proto.Command, tempDir string) (depFile string, err error) {
 	rawCommand := command.GetCommand()
 	if rawCommand == "" {
 		return "", fmt.Errorf("command is required")
 	}

 	pathToTempDirInSbox := tempDir
 	if command.GetChdir() {
 		pathToTempDirInSbox = "."
 	}

 	err = os.MkdirAll(tempDir, 0777)
 	if err != nil {
 		return "", fmt.Errorf("failed to create %q: %w", tempDir, err)
 	}

 	// Copy in any files specified by the manifest.
 	err = copyFiles(command.CopyBefore, "", tempDir)
 	if err != nil {
 		return "", err
 	}
 	err = copyRspFiles(command.RspFiles, tempDir, pathToTempDirInSbox)
 	if err != nil {
 		return "", err
 	}

 	if strings.Contains(rawCommand, depFilePlaceholder) {
 		depFile = filepath.Join(pathToTempDirInSbox, "deps.d")
 		rawCommand = strings.Replace(rawCommand, depFilePlaceholder, depFile, -1)
 	}

 	if strings.Contains(rawCommand, sandboxDirPlaceholder) {
 		rawCommand = strings.Replace(rawCommand, sandboxDirPlaceholder, pathToTempDirInSbox, -1)
 	}

 	// Emulate ninja's behavior of creating the directories for any output files before
 	// running the command.
 	err = makeOutputDirs(command.CopyAfter, tempDir)
 	if err != nil {
 		return "", err
 	}

 	commandDescription := rawCommand

 	cmd := exec.Command("bash", "-c", rawCommand)
 	cmd.Stdin = os.Stdin
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr

 	if command.GetChdir() {
 		cmd.Dir = tempDir
 		path := os.Getenv("PATH")
 		absPath, err := makeAbsPathEnv(path)
 		if err != nil {
 			return "", err
 		}
 		err = os.Setenv("PATH", absPath)
 		if err != nil {
 			return "", fmt.Errorf("Failed to update PATH: %w", err)
 		}
 	}
 	err = cmd.Run()

 	if exit, ok := err.(*exec.ExitError); ok && !exit.Success() {
 		return "", fmt.Errorf("sbox command failed with err:\n%s\n%w\n", commandDescription, err)
 	} else if err != nil {
 		return "", err
 	}

 	missingOutputErrors := validateOutputFiles(command.CopyAfter, tempDir)

 	if len(missingOutputErrors) > 0 {
 		// find all created files for making a more informative error message
 		createdFiles := findAllFilesUnder(tempDir)

 		// build error message
 		errorMessage := "mismatch between declared and actual outputs\n"
 		errorMessage += "in sbox command(" + commandDescription + ")\n\n"
 		errorMessage += "in sandbox " + tempDir + ",\n"
 		errorMessage += fmt.Sprintf("failed to create %v files:\n", len(missingOutputErrors))
 		for _, missingOutputError := range missingOutputErrors {
 			errorMessage += "  " + missingOutputError.Error() + "\n"
 		}
 		if len(createdFiles) < 1 {
 			errorMessage += "created 0 files."
 		} else {
 			errorMessage += fmt.Sprintf("did create %v files:\n", len(createdFiles))
 			creationMessages := createdFiles
 			maxNumCreationLines := 10
 			if len(creationMessages) > maxNumCreationLines {
 				creationMessages = creationMessages[:maxNumCreationLines]
 				creationMessages = append(creationMessages, fmt.Sprintf("...%v more", len(createdFiles)-maxNumCreationLines))
 			}
 			for _, creationMessage := range creationMessages {
 				errorMessage += "  " + creationMessage + "\n"
 			}
 		}

 		return "", errors.New(errorMessage)
 	}
 	// the created files match the declared files; now move them
 	err = moveFiles(command.CopyAfter, tempDir, "")

 	return depFile, nil
 }

 // makeOutputDirs creates directories in the sandbox dir for every file that has a rule to be copied
 // out of the sandbox.  This emulate's Ninja's behavior of creating directories for output files
 // so that the tools don't have to.
 func makeOutputDirs(copies []*sbox_proto.Copy, sandboxDir string) error {
 	for _, copyPair := range copies {
 		dir := joinPath(sandboxDir, filepath.Dir(copyPair.GetFrom()))
 		err := os.MkdirAll(dir, 0777)
 		if err != nil {
 			return err
 		}
 	}
 	return nil
 }

 // validateOutputFiles verifies that all files that have a rule to be copied out of the sandbox
 // were created by the command.
 func validateOutputFiles(copies []*sbox_proto.Copy, sandboxDir string) []error {
 	var missingOutputErrors []error
 	for _, copyPair := range copies {
 		fromPath := joinPath(sandboxDir, copyPair.GetFrom())
 		fileInfo, err := os.Stat(fromPath)
 		if err != nil {
 			missingOutputErrors = append(missingOutputErrors, fmt.Errorf("%s: does not exist", fromPath))
 			continue
 		}
 		if fileInfo.IsDir() {
 			missingOutputErrors = append(missingOutputErrors, fmt.Errorf("%s: not a file", fromPath))
 		}
 	}
 	return missingOutputErrors
 }

 // copyFiles copies files in or out of the sandbox.
 func copyFiles(copies []*sbox_proto.Copy, fromDir, toDir string) error {
 	for _, copyPair := range copies {
 		fromPath := joinPath(fromDir, copyPair.GetFrom())
 		toPath := joinPath(toDir, copyPair.GetTo())
 		err := copyOneFile(fromPath, toPath, copyPair.GetExecutable())
 		if err != nil {
 			return fmt.Errorf("error copying %q to %q: %w", fromPath, toPath, err)
 		}
 	}
 	return nil
 }

 // copyOneFile copies a file.
 func copyOneFile(from string, to string, executable bool) error {
 	err := os.MkdirAll(filepath.Dir(to), 0777)
 	if err != nil {
 		return err
 	}

 	stat, err := os.Stat(from)
 	if err != nil {
 		return err
 	}

 	perm := stat.Mode()
 	if executable {
 		perm = perm | 0100 // u+x
 	}

 	in, err := os.Open(from)
 	if err != nil {
 		return err
 	}
 	defer in.Close()

 	out, err := os.Create(to)
 	if err != nil {
 		return err
 	}
 	defer func() {
 		out.Close()
 		if err != nil {
 			os.Remove(to)
 		}
 	}()

 	_, err = io.Copy(out, in)
 	if err != nil {
 		return err
 	}

 	if err = out.Close(); err != nil {
 		return err
 	}

 	if err = os.Chmod(to, perm); err != nil {
 		return err
 	}

 	return nil
 }

 // copyRspFiles copies rsp files into the sandbox with path mappings, and also copies the files
 // listed into the sandbox.
 func copyRspFiles(rspFiles []*sbox_proto.RspFile, toDir, toDirInSandbox string) error {
 	for _, rspFile := range rspFiles {
 		err := copyOneRspFile(rspFile, toDir, toDirInSandbox)
 		if err != nil {
 			return err
 		}
 	}
 	return nil
 }

 // copyOneRspFiles copies an rsp file into the sandbox with path mappings, and also copies the files
 // listed into the sandbox.
 func copyOneRspFile(rspFile *sbox_proto.RspFile, toDir, toDirInSandbox string) error {
 	in, err := os.Open(rspFile.GetFile())
 	if err != nil {
 		return err
 	}
 	defer in.Close()

 	files, err := response.ReadRspFile(in)
 	if err != nil {
 		return err
 	}

 	for i, from := range files {
 		// Convert the real path of the input file into the path inside the sandbox using the
 		// path mappings.
 		to := applyPathMappings(rspFile.PathMappings, from)

 		// Copy the file into the sandbox.
 		err := copyOneFile(from, joinPath(toDir, to), false)
 		if err != nil {
 			return err
 		}

 		// Rewrite the name in the list of files to be relative to the sandbox directory.
 		files[i] = joinPath(toDirInSandbox, to)
 	}

 	// Convert the real path of the rsp file into the path inside the sandbox using the path
 	// mappings.
 	outRspFile := joinPath(toDir, applyPathMappings(rspFile.PathMappings, rspFile.GetFile()))

 	err = os.MkdirAll(filepath.Dir(outRspFile), 0777)
 	if err != nil {
 		return err
 	}

 	out, err := os.Create(outRspFile)
 	if err != nil {
 		return err
 	}
 	defer out.Close()

 	// Write the rsp file with converted paths into the sandbox.
 	err = response.WriteRspFile(out, files)
 	if err != nil {
 		return err
 	}

 	return nil
 }

 // applyPathMappings takes a list of path mappings and a path, and returns the path with the first
 // matching path mapping applied.  If the path does not match any of the path mappings then it is
 // returned unmodified.
 func applyPathMappings(pathMappings []*sbox_proto.PathMapping, path string) string {
 	for _, mapping := range pathMappings {
 		if strings.HasPrefix(path, mapping.GetFrom()+"/") {
 			return joinPath(mapping.GetTo()+"/", strings.TrimPrefix(path, mapping.GetFrom()+"/"))
 		}
 	}
 	return path
 }

 // moveFiles moves files specified by a set of copy rules.  It uses os.Rename, so it is restricted
 // to moving files where the source and destination are in the same filesystem.  This is OK for
 // sbox because the temporary directory is inside the out directory.  It updates the timestamp
 // of the new file.
 func moveFiles(copies []*sbox_proto.Copy, fromDir, toDir string) error {
 	for _, copyPair := range copies {
 		fromPath := joinPath(fromDir, copyPair.GetFrom())
 		toPath := joinPath(toDir, copyPair.GetTo())
 		err := os.MkdirAll(filepath.Dir(toPath), 0777)
 		if err != nil {
 			return err
 		}

 		err = os.Rename(fromPath, toPath)
 		if err != nil {
 			return err
 		}

 		// Update the timestamp of the output file in case the tool wrote an old timestamp (for example, tar can extract
 		// files with old timestamps).
 		now := time.Now()
 		err = os.Chtimes(toPath, now, now)
 		if err != nil {
 			return err
 		}
 	}
 	return nil
 }

 // Rewrite one or more depfiles so that it doesn't include the (randomized) sandbox directory
 // to an output file.
 func rewriteDepFiles(ins []string, out string) error {
 	var mergedDeps []string
 	for _, in := range ins {
 		data, err := ioutil.ReadFile(in)
 		if err != nil {
 			return err
 		}

 		deps, err := makedeps.Parse(in, bytes.NewBuffer(data))
 		if err != nil {
 			return err
 		}
 		mergedDeps = append(mergedDeps, deps.Inputs...)
 	}

 	deps := makedeps.Deps{
 		// Ninja doesn't care what the output file is, so we can use any string here.
 		Output: "outputfile",
 		Inputs: mergedDeps,
 	}

 	// Make the directory for the output depfile in case it is in a different directory
 	// than any of the output files.
 	outDir := filepath.Dir(out)
 	err := os.MkdirAll(outDir, 0777)
 	if err != nil {
 		return fmt.Errorf("failed to create %q: %w", outDir, err)
 	}

 	return ioutil.WriteFile(out, deps.Print(), 0666)
 }

 // joinPath wraps filepath.Join but returns file without appending to dir if file is
 // absolute.
 func joinPath(dir, file string) string {
 	if filepath.IsAbs(file) {
 		return file
 	}
 	return filepath.Join(dir, file)
 }

 func makeAbsPathEnv(pathEnv string) (string, error) {
 	pathEnvElements := filepath.SplitList(pathEnv)
 	for i, p := range pathEnvElements {
 		if !filepath.IsAbs(p) {
 			absPath, err := filepath.Abs(p)
 			if err != nil {
 				return "", fmt.Errorf("failed to make PATH entry %q absolute: %w", p, err)
 			}
 			pathEnvElements[i] = absPath
 		}
 	}
 	return strings.Join(pathEnvElements, string(filepath.ListSeparator)), nil
 }
	// Copyright 2017 Google Inc. 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 (
	"bytes"
	"crypto/sha1"
	"encoding/hex"
	"errors"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	"android/soong/cmd/sbox/sbox_proto"
	"android/soong/makedeps"
	"android/soong/response"

	"github.com/golang/protobuf/proto"
	)

	var (
	sandboxesRoot string
	manifestFile string
	keepOutDir bool
	)

	const (
	depFilePlaceholder = "__SBOX_DEPFILE__"
	sandboxDirPlaceholder = "__SBOX_SANDBOX_DIR__"
	)

	func init() {
	flag.StringVar(&sandboxesRoot, "sandbox-path", "",
	"root of temp directory to put the sandbox into")
	flag.StringVar(&manifestFile, "manifest", "",
	"textproto manifest describing the sandboxed command(s)")
	flag.BoolVar(&keepOutDir, "keep-out-dir", false,
	"whether to keep the sandbox directory when done")
	}

	func usageViolation(violation string) {
	if violation != "" {
	fmt.Fprintf(os.Stderr, "Usage error: %s.\n\n", violation)
	}

	fmt.Fprintf(os.Stderr,
	"Usage: sbox --manifest <manifest> --sandbox-path <sandboxPath>\n")

	flag.PrintDefaults()

	os.Exit(1)
	}

	func main() {
	flag.Usage = func() {
	usageViolation("")
	}
	flag.Parse()

	error := run()
	if error != nil {
	fmt.Fprintln(os.Stderr, error)
	os.Exit(1)
	}
	}

	func findAllFilesUnder(root string) (paths []string) {
	paths = []string{}
	filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
	if !info.IsDir() {
	relPath, err := filepath.Rel(root, path)
	if err != nil {
	// couldn't find relative path from ancestor?
	panic(err)
	}
	paths = append(paths, relPath)
	}
	return nil
	})
	return paths
	}

	func run() error {
	if manifestFile == "" {
	usageViolation("--manifest <manifest> is required and must be non-empty")
	}
	if sandboxesRoot == "" {
	// In practice, the value of sandboxesRoot will mostly likely be at a fixed location relative to OUT_DIR,
	// and the sbox executable will most likely be at a fixed location relative to OUT_DIR too, so
	// the value of sandboxesRoot will most likely be at a fixed location relative to the sbox executable
	// However, Soong also needs to be able to separately remove the sandbox directory on startup (if it has anything left in it)
	// and by passing it as a parameter we don't need to duplicate its value
	usageViolation("--sandbox-path <sandboxPath> is required and must be non-empty")
	}

	manifest, err := readManifest(manifestFile)

	if len(manifest.Commands) == 0 {
	return fmt.Errorf("at least one commands entry is required in %q", manifestFile)
	}

	// setup sandbox directory
	err = os.MkdirAll(sandboxesRoot, 0777)
	if err != nil {
	return fmt.Errorf("failed to create %q: %w", sandboxesRoot, err)
	}

	// This tool assumes that there are no two concurrent runs with the same
	// manifestFile. It should therefore be safe to use the hash of the
	// manifestFile as the temporary directory name. We do this because it
	// makes the temporary directory name deterministic. There are some
	// tools that embed the name of the temporary output in the output, and
	// they otherwise cause non-determinism, which then poisons actions
	// depending on this one.
	hash := sha1.New()
	hash.Write([]byte(manifestFile))
	tempDir := filepath.Join(sandboxesRoot, "sbox", hex.EncodeToString(hash.Sum(nil)))

	err = os.RemoveAll(tempDir)
	if err != nil {
	return err
	}
	err = os.MkdirAll(tempDir, 0777)
	if err != nil {
	return fmt.Errorf("failed to create temporary dir in %q: %w", sandboxesRoot, err)
	}

	// In the common case, the following line of code is what removes the sandbox
	// If a fatal error occurs (such as if our Go process is killed unexpectedly),
	// then at the beginning of the next build, Soong will wipe the temporary
	// directory.
	defer func() {
	// in some cases we decline to remove the temp dir, to facilitate debugging
	if !keepOutDir {
	os.RemoveAll(tempDir)
	}
	}()

	// If there is more than one command in the manifest use a separate directory for each one.
	useSubDir := len(manifest.Commands) > 1
	var commandDepFiles []string

	for i, command := range manifest.Commands {
	localTempDir := tempDir
	if useSubDir {
	localTempDir = filepath.Join(localTempDir, strconv.Itoa(i))
	}
	depFile, err := runCommand(command, localTempDir)
	if err != nil {
	// Running the command failed, keep the temporary output directory around in
	// case a user wants to inspect it for debugging purposes. Soong will delete
	// it at the beginning of the next build anyway.
	keepOutDir = true
	return err
	}
	if depFile != "" {
	commandDepFiles = append(commandDepFiles, depFile)
	}
	}

	outputDepFile := manifest.GetOutputDepfile()
	if len(commandDepFiles) > 0 && outputDepFile == "" {
	return fmt.Errorf("Sandboxed commands used %s but output depfile is not set in manifest file",
	depFilePlaceholder)
	}

	if outputDepFile != "" {
	// Merge the depfiles from each command in the manifest to a single output depfile.
	err = rewriteDepFiles(commandDepFiles, outputDepFile)
	if err != nil {
	return fmt.Errorf("failed merging depfiles: %w", err)
	}
	}

	return nil
	}

	// readManifest reads an sbox manifest from a textproto file.
	func readManifest(file string) (*sbox_proto.Manifest, error) {
	manifestData, err := ioutil.ReadFile(file)
	if err != nil {
	return nil, fmt.Errorf("error reading manifest %q: %w", file, err)
	}

	manifest := sbox_proto.Manifest{}

	err = proto.UnmarshalText(string(manifestData), &manifest)
	if err != nil {
	return nil, fmt.Errorf("error parsing manifest %q: %w", file, err)
	}

	return &manifest, nil
	}

	// runCommand runs a single command from a manifest. If the command references the
	// __SBOX_DEPFILE__ placeholder it returns the name of the depfile that was used.
	func runCommand(command *sbox_proto.Command, tempDir string) (depFile string, err error) {
	rawCommand := command.GetCommand()
	if rawCommand == "" {
	return "", fmt.Errorf("command is required")
	}

	pathToTempDirInSbox := tempDir
	if command.GetChdir() {
	pathToTempDirInSbox = "."
	}

	err = os.MkdirAll(tempDir, 0777)
	if err != nil {
	return "", fmt.Errorf("failed to create %q: %w", tempDir, err)
	}

	// Copy in any files specified by the manifest.
	err = copyFiles(command.CopyBefore, "", tempDir)
	if err != nil {
	return "", err
	}
	err = copyRspFiles(command.RspFiles, tempDir, pathToTempDirInSbox)
	if err != nil {
	return "", err
	}

	if strings.Contains(rawCommand, depFilePlaceholder) {
	depFile = filepath.Join(pathToTempDirInSbox, "deps.d")
	rawCommand = strings.Replace(rawCommand, depFilePlaceholder, depFile, -1)
	}

	if strings.Contains(rawCommand, sandboxDirPlaceholder) {
	rawCommand = strings.Replace(rawCommand, sandboxDirPlaceholder, pathToTempDirInSbox, -1)
	}

	// Emulate ninja's behavior of creating the directories for any output files before
	// running the command.
	err = makeOutputDirs(command.CopyAfter, tempDir)
	if err != nil {
	return "", err
	}

	commandDescription := rawCommand

	cmd := exec.Command("bash", "-c", rawCommand)
	cmd.Stdin = os.Stdin
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr

	if command.GetChdir() {
	cmd.Dir = tempDir
	path := os.Getenv("PATH")
	absPath, err := makeAbsPathEnv(path)
	if err != nil {
	return "", err
	}
	err = os.Setenv("PATH", absPath)
	if err != nil {
	return "", fmt.Errorf("Failed to update PATH: %w", err)
	}
	}
	err = cmd.Run()

	if exit, ok := err.(*exec.ExitError); ok && !exit.Success() {
	return "", fmt.Errorf("sbox command failed with err:\n%s\n%w\n", commandDescription, err)
	} else if err != nil {
	return "", err
	}

	missingOutputErrors := validateOutputFiles(command.CopyAfter, tempDir)

	if len(missingOutputErrors) > 0 {
	// find all created files for making a more informative error message
	createdFiles := findAllFilesUnder(tempDir)

	// build error message
	errorMessage := "mismatch between declared and actual outputs\n"
	errorMessage += "in sbox command(" + commandDescription + ")\n\n"
	errorMessage += "in sandbox " + tempDir + ",\n"
	errorMessage += fmt.Sprintf("failed to create %v files:\n", len(missingOutputErrors))
	for _, missingOutputError := range missingOutputErrors {
	errorMessage += " " + missingOutputError.Error() + "\n"
	}
	if len(createdFiles) < 1 {
	errorMessage += "created 0 files."
	} else {
	errorMessage += fmt.Sprintf("did create %v files:\n", len(createdFiles))
	creationMessages := createdFiles
	maxNumCreationLines := 10
	if len(creationMessages) > maxNumCreationLines {
	creationMessages = creationMessages[:maxNumCreationLines]
	creationMessages = append(creationMessages, fmt.Sprintf("...%v more", len(createdFiles)-maxNumCreationLines))
	}
	for _, creationMessage := range creationMessages {
	errorMessage += " " + creationMessage + "\n"
	}
	}

	return "", errors.New(errorMessage)
	}
	// the created files match the declared files; now move them
	err = moveFiles(command.CopyAfter, tempDir, "")

	return depFile, nil
	}

	// makeOutputDirs creates directories in the sandbox dir for every file that has a rule to be copied
	// out of the sandbox. This emulate's Ninja's behavior of creating directories for output files
	// so that the tools don't have to.
	func makeOutputDirs(copies []*sbox_proto.Copy, sandboxDir string) error {
	for _, copyPair := range copies {
	dir := joinPath(sandboxDir, filepath.Dir(copyPair.GetFrom()))
	err := os.MkdirAll(dir, 0777)
	if err != nil {
	return err
	}
	}
	return nil
	}

	// validateOutputFiles verifies that all files that have a rule to be copied out of the sandbox
	// were created by the command.
	func validateOutputFiles(copies []*sbox_proto.Copy, sandboxDir string) []error {
	var missingOutputErrors []error
	for _, copyPair := range copies {
	fromPath := joinPath(sandboxDir, copyPair.GetFrom())
	fileInfo, err := os.Stat(fromPath)
	if err != nil {
	missingOutputErrors = append(missingOutputErrors, fmt.Errorf("%s: does not exist", fromPath))
	continue
	}
	if fileInfo.IsDir() {
	missingOutputErrors = append(missingOutputErrors, fmt.Errorf("%s: not a file", fromPath))
	}
	}
	return missingOutputErrors
	}

	// copyFiles copies files in or out of the sandbox.
	func copyFiles(copies []*sbox_proto.Copy, fromDir, toDir string) error {
	for _, copyPair := range copies {
	fromPath := joinPath(fromDir, copyPair.GetFrom())
	toPath := joinPath(toDir, copyPair.GetTo())
	err := copyOneFile(fromPath, toPath, copyPair.GetExecutable())
	if err != nil {
	return fmt.Errorf("error copying %q to %q: %w", fromPath, toPath, err)
	}
	}
	return nil
	}

	// copyOneFile copies a file.
	func copyOneFile(from string, to string, executable bool) error {
	err := os.MkdirAll(filepath.Dir(to), 0777)
	if err != nil {
	return err
	}

	stat, err := os.Stat(from)
	if err != nil {
	return err
	}

	perm := stat.Mode()
	if executable {
	perm = perm \| 0100 // u+x
	}

	in, err := os.Open(from)
	if err != nil {
	return err
	}
	defer in.Close()

	out, err := os.Create(to)
	if err != nil {
	return err
	}
	defer func() {
	out.Close()
	if err != nil {
	os.Remove(to)
	}
	}()

	_, err = io.Copy(out, in)
	if err != nil {
	return err
	}

	if err = out.Close(); err != nil {
	return err
	}

	if err = os.Chmod(to, perm); err != nil {
	return err
	}

	return nil
	}

	// copyRspFiles copies rsp files into the sandbox with path mappings, and also copies the files
	// listed into the sandbox.
	func copyRspFiles(rspFiles []*sbox_proto.RspFile, toDir, toDirInSandbox string) error {
	for _, rspFile := range rspFiles {
	err := copyOneRspFile(rspFile, toDir, toDirInSandbox)
	if err != nil {
	return err
	}
	}
	return nil
	}

	// copyOneRspFiles copies an rsp file into the sandbox with path mappings, and also copies the files
	// listed into the sandbox.
	func copyOneRspFile(rspFile *sbox_proto.RspFile, toDir, toDirInSandbox string) error {
	in, err := os.Open(rspFile.GetFile())
	if err != nil {
	return err
	}
	defer in.Close()

	files, err := response.ReadRspFile(in)
	if err != nil {
	return err
	}

	for i, from := range files {
	// Convert the real path of the input file into the path inside the sandbox using the
	// path mappings.
	to := applyPathMappings(rspFile.PathMappings, from)

	// Copy the file into the sandbox.
	err := copyOneFile(from, joinPath(toDir, to), false)
	if err != nil {
	return err
	}

	// Rewrite the name in the list of files to be relative to the sandbox directory.
	files[i] = joinPath(toDirInSandbox, to)
	}

	// Convert the real path of the rsp file into the path inside the sandbox using the path
	// mappings.
	outRspFile := joinPath(toDir, applyPathMappings(rspFile.PathMappings, rspFile.GetFile()))

	err = os.MkdirAll(filepath.Dir(outRspFile), 0777)
	if err != nil {
	return err
	}

	out, err := os.Create(outRspFile)
	if err != nil {
	return err
	}
	defer out.Close()

	// Write the rsp file with converted paths into the sandbox.
	err = response.WriteRspFile(out, files)
	if err != nil {
	return err
	}

	return nil
	}

	// applyPathMappings takes a list of path mappings and a path, and returns the path with the first
	// matching path mapping applied. If the path does not match any of the path mappings then it is
	// returned unmodified.
	func applyPathMappings(pathMappings []*sbox_proto.PathMapping, path string) string {
	for _, mapping := range pathMappings {
	if strings.HasPrefix(path, mapping.GetFrom()+"/") {
	return joinPath(mapping.GetTo()+"/", strings.TrimPrefix(path, mapping.GetFrom()+"/"))
	}
	}
	return path
	}

	// moveFiles moves files specified by a set of copy rules. It uses os.Rename, so it is restricted
	// to moving files where the source and destination are in the same filesystem. This is OK for
	// sbox because the temporary directory is inside the out directory. It updates the timestamp
	// of the new file.
	func moveFiles(copies []*sbox_proto.Copy, fromDir, toDir string) error {
	for _, copyPair := range copies {
	fromPath := joinPath(fromDir, copyPair.GetFrom())
	toPath := joinPath(toDir, copyPair.GetTo())
	err := os.MkdirAll(filepath.Dir(toPath), 0777)
	if err != nil {
	return err
	}

	err = os.Rename(fromPath, toPath)
	if err != nil {
	return err
	}

	// Update the timestamp of the output file in case the tool wrote an old timestamp (for example, tar can extract
	// files with old timestamps).
	now := time.Now()
	err = os.Chtimes(toPath, now, now)
	if err != nil {
	return err
	}
	}
	return nil
	}

	// Rewrite one or more depfiles so that it doesn't include the (randomized) sandbox directory
	// to an output file.
	func rewriteDepFiles(ins []string, out string) error {
	var mergedDeps []string
	for _, in := range ins {
	data, err := ioutil.ReadFile(in)
	if err != nil {
	return err
	}

	deps, err := makedeps.Parse(in, bytes.NewBuffer(data))
	if err != nil {
	return err
	}
	mergedDeps = append(mergedDeps, deps.Inputs...)
	}

	deps := makedeps.Deps{
	// Ninja doesn't care what the output file is, so we can use any string here.
	Output: "outputfile",
	Inputs: mergedDeps,
	}

	// Make the directory for the output depfile in case it is in a different directory
	// than any of the output files.
	outDir := filepath.Dir(out)
	err := os.MkdirAll(outDir, 0777)
	if err != nil {
	return fmt.Errorf("failed to create %q: %w", outDir, err)
	}

	return ioutil.WriteFile(out, deps.Print(), 0666)
	}

	// joinPath wraps filepath.Join but returns file without appending to dir if file is
	// absolute.
	func joinPath(dir, file string) string {
	if filepath.IsAbs(file) {
	return file
	}
	return filepath.Join(dir, file)
	}

	func makeAbsPathEnv(pathEnv string) (string, error) {
	pathEnvElements := filepath.SplitList(pathEnv)
	for i, p := range pathEnvElements {
	if !filepath.IsAbs(p) {
	absPath, err := filepath.Abs(p)
	if err != nil {
	return "", fmt.Errorf("failed to make PATH entry %q absolute: %w", p, err)
	}
	pathEnvElements[i] = absPath
	}
	}
	return strings.Join(pathEnvElements, string(filepath.ListSeparator)), nil
	}