support building modules which require other modules

We use 'go list -json -export' to locate required modules. This works
fine to locate direct module dependencies; since we're building in the
current module, we run 'go list' in the correct directory.

However, if we're building one of those module dependencies, and it has
other module dependencies of its own, we would fail with cryptic errors
like:

	typecheck error: [...] go list error: updates to go.sum needed, disabled by -mod=readonly

This is because we would try to run 'go list' outside of the main
module, probably inside the module cache. Instead, use a $GARBLE_DIR env
var from the top-level 'garble build' call to always run 'go list' in
the original directory.

We add a few small modules to properly test this.

Updates #9.

README.md

@@ -8,7 +8,7 @@ Obfuscate a Go build. Requires Go 1.13 or later.
 
 which is equivalent to the longer:
 
-	go build -a -trimpath -toolexec=garble [build flags] [packages]
+	GARBLE_DIR="$PWD" go build -a -trimpath -toolexec=garble [build flags] [packages]
 
 ### Purpose
 

main.go

@@ -66,6 +66,11 @@ type jsonExport struct {
 func objLookup(path string) (io.ReadCloser, error) {
 	// objPath := buildInfo.imports[path].packagefile
 	cmd := exec.Command("go", "list", "-json", "-export", path)
+	dir := os.Getenv("GARBLE_DIR")
+	if dir == "" {
+		return nil, fmt.Errorf("$GARBLE_DIR unset; did you run via 'garble build'?")
+	}
+	cmd.Dir = dir
 	out, err := cmd.CombinedOutput()
 	if err != nil {
 		return nil, fmt.Errorf("go list error: %v: %s", err, out)
@@ -109,6 +114,11 @@ func mainErr(args []string) error {
 	// If we recognise an argument, we're not running within -toolexec.
 	switch cmd := args[0]; cmd {
 	case "build", "test":
+		wd, err := os.Getwd()
+		if err != nil {
+			return err
+		}
+		os.Setenv("GARBLE_DIR", wd)
 		execPath, err := os.Executable()
 		if err != nil {
 			return err

main_test.go

@@ -13,16 +13,34 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/rogpeppe/go-internal/goproxytest"
 	"github.com/rogpeppe/go-internal/gotooltest"
 	"github.com/rogpeppe/go-internal/testscript"
 )
 
+var proxyURL string
+
 func TestMain(m *testing.M) {
-	os.Exit(testscript.RunMain(m, map[string]func() int{
+	os.Exit(testscript.RunMain(garbleMain{m}, map[string]func() int{
 		"garble": main1,
 	}))
 }
 
+type garbleMain struct {
+	m *testing.M
+}
+
+func (m garbleMain) Run() int {
+	// Start the Go proxy server running for all tests.
+	srv, err := goproxytest.NewServer("testdata/mod", "")
+	if err != nil {
+		panic(fmt.Sprintf("cannot start proxy: %v", err))
+	}
+	proxyURL = srv.URL
+
+	return m.m.Run()
+}
+
 var update = flag.Bool("u", false, "update testscript output files")
 
 func TestScripts(t *testing.T) {
@@ -31,6 +49,10 @@ func TestScripts(t *testing.T) {
 	p := testscript.Params{
 		Dir: filepath.Join("testdata", "scripts"),
 		Setup: func(env *testscript.Env) error {
+			env.Vars = append(env.Vars,
+				"GOPROXY="+proxyURL,
+				"GONOSUMDB=*",
+			)
 			bindir := filepath.Join(env.WorkDir, ".bin")
 			if err := os.Mkdir(bindir, 0777); err != nil {
 				return err

testdata/mod/golang.org_x_text_v0.0.0-20170915032832-14c0d48ead0c.txt

@@ -0,0 +1,47 @@
+written by hand - just enough to compile rsc.io/sampler, rsc.io/quote
+
+-- .mod --
+module golang.org/x/text
+-- .info --
+{"Version":"v0.0.0-20170915032832-14c0d48ead0c","Name":"v0.0.0-20170915032832-14c0d48ead0c","Short":"14c0d48ead0c","Time":"2017-09-15T03:28:32Z"}
+-- go.mod --
+module golang.org/x/text
+-- unused/unused.go --
+package unused
+-- language/lang.go --
+// 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.
+
+// This is a tiny version of golang.org/x/text.
+
+package language
+
+import "strings"
+
+type Tag string
+
+func Make(s string) Tag { return Tag(s) }
+
+func (t Tag) String() string { return string(t) }
+
+func NewMatcher(tags []Tag) Matcher { return &matcher{tags} }
+
+type Matcher interface {
+	Match(...Tag) (Tag, int, int)
+}
+
+type matcher struct {
+	tags []Tag
+}
+
+func (m *matcher) Match(prefs ...Tag) (Tag, int, int) {
+	for _, pref := range prefs {
+		for _, tag := range m.tags {
+			if tag == pref || strings.HasPrefix(string(pref), string(tag+"-")) || strings.HasPrefix(string(tag), string(pref+"-")) {
+				return tag, 0, 0
+			}
+		}
+	}
+	return m.tags[0], 0, 0
+}

testdata/mod/rsc.io_quote_v1.5.2.txt

@@ -0,0 +1,98 @@
+module rsc.io/quote@v1.5.2
+
+-- .mod --
+module "rsc.io/quote"
+
+require "rsc.io/sampler" v1.3.0
+-- .info --
+{"Version":"v1.5.2","Time":"2018-02-14T15:44:20Z"}
+-- buggy/buggy_test.go --
+// 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 buggy
+
+import "testing"
+
+func Test(t *testing.T) {
+	t.Fatal("buggy!")
+}
+-- go.mod --
+module "rsc.io/quote"
+
+require "rsc.io/sampler" v1.3.0
+-- quote.go --
+// 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 quote collects pithy sayings.
+package quote // import "rsc.io/quote"
+
+import "rsc.io/sampler"
+
+// Hello returns a greeting.
+func Hello() string {
+	return sampler.Hello()
+}
+
+// Glass returns a useful phrase for world travelers.
+func Glass() string {
+	// See http://www.oocities.org/nodotus/hbglass.html.
+	return "I can eat glass and it doesn't hurt me."
+}
+
+// Go returns a Go proverb.
+func Go() string {
+	return "Don't communicate by sharing memory, share memory by communicating."
+}
+
+// Opt returns an optimization truth.
+func Opt() string {
+	// Wisdom from ken.
+	return "If a program is too slow, it must have a loop."
+}
+-- quote_test.go --
+// 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 quote
+
+import (
+	"os"
+	"testing"
+)
+
+func init() {
+	os.Setenv("LC_ALL", "en")
+}
+
+func TestHello(t *testing.T) {
+	hello := "Hello, world."
+	if out := Hello(); out != hello {
+		t.Errorf("Hello() = %q, want %q", out, hello)
+	}
+}
+
+func TestGlass(t *testing.T) {
+	glass := "I can eat glass and it doesn't hurt me."
+	if out := Glass(); out != glass {
+		t.Errorf("Glass() = %q, want %q", out, glass)
+	}
+}
+
+func TestGo(t *testing.T) {
+	go1 := "Don't communicate by sharing memory, share memory by communicating."
+	if out := Go(); out != go1 {
+		t.Errorf("Go() = %q, want %q", out, go1)
+	}
+}
+
+func TestOpt(t *testing.T) {
+	opt := "If a program is too slow, it must have a loop."
+	if out := Opt(); out != opt {
+		t.Errorf("Opt() = %q, want %q", out, opt)
+	}
+}

testdata/mod/rsc.io_sampler_v1.2.1.txt

@@ -0,0 +1,134 @@
+generated by ./addmod.bash rsc.io/sampler@v1.2.1
+
+-- .mod --
+module "rsc.io/sampler"
+
+require "golang.org/x/text" v0.0.0-20170915032832-14c0d48ead0c
+-- .info --
+{"Version":"v1.2.1","Name":"cac3af4f8a0ab40054fa6f8d423108a63a1255bb","Short":"cac3af4f8a0a","Time":"2018-02-13T18:16:22Z"}
+-- hello.go --
+// 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.
+
+// Translations by Google Translate.
+
+package sampler
+
+var hello = newText(`
+
+English: en: Hello, world.
+French: fr: Bonjour le monde.
+Spanish: es: Hola Mundo.
+
+`)
+-- hello_test.go --
+// 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 sampler
+
+import (
+	"testing"
+
+	"golang.org/x/text/language"
+)
+
+var helloTests = []struct {
+	prefs []language.Tag
+	text  string
+}{
+	{
+		[]language.Tag{language.Make("en-US"), language.Make("fr")},
+		"Hello, world.",
+	},
+	{
+		[]language.Tag{language.Make("fr"), language.Make("en-US")},
+		"Bonjour le monde.",
+	},
+}
+
+func TestHello(t *testing.T) {
+	for _, tt := range helloTests {
+		text := Hello(tt.prefs...)
+		if text != tt.text {
+			t.Errorf("Hello(%v) = %q, want %q", tt.prefs, text, tt.text)
+		}
+	}
+}
+-- sampler.go --
+// 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 sampler shows simple texts.
+package sampler // import "rsc.io/sampler"
+
+import (
+	"os"
+	"strings"
+
+	"golang.org/x/text/language"
+)
+
+// DefaultUserPrefs returns the default user language preferences.
+// It consults the $LC_ALL, $LC_MESSAGES, and $LANG environment
+// variables, in that order.
+func DefaultUserPrefs() []language.Tag {
+	var prefs []language.Tag
+	for _, k := range []string{"LC_ALL", "LC_MESSAGES", "LANG"} {
+		if env := os.Getenv(k); env != "" {
+			prefs = append(prefs, language.Make(env))
+		}
+	}
+	return prefs
+}
+
+// Hello returns a localized greeting.
+// If no prefs are given, Hello uses DefaultUserPrefs.
+func Hello(prefs ...language.Tag) string {
+	if len(prefs) == 0 {
+		prefs = DefaultUserPrefs()
+	}
+	return hello.find(prefs)
+}
+
+// A text is a localized text.
+type text struct {
+	byTag   map[string]string
+	matcher language.Matcher
+}
+
+// newText creates a new localized text, given a list of translations.
+func newText(s string) *text {
+	t := &text{
+		byTag: make(map[string]string),
+	}
+	var tags []language.Tag
+	for _, line := range strings.Split(s, "\n") {
+		line = strings.TrimSpace(line)
+		if line == "" {
+			continue
+		}
+		f := strings.Split(line, ": ")
+		if len(f) != 3 {
+			continue
+		}
+		tag := language.Make(f[1])
+		tags = append(tags, tag)
+		t.byTag[tag.String()] = f[2]
+	}
+	t.matcher = language.NewMatcher(tags)
+	return t
+}
+
+// find finds the text to use for the given language tag preferences.
+func (t *text) find(prefs []language.Tag) string {
+	tag, _, _ := t.matcher.Match(prefs...)
+	s := t.byTag[tag.String()]
+	if strings.HasPrefix(s, "RTL ") {
+		s = "\u200F" + strings.TrimPrefix(s, "RTL ") + "\u200E"
+	}
+	return s
+}

testdata/mod/rsc.io_sampler_v1.3.0.txt

@@ -0,0 +1,202 @@
+rsc.io/sampler@v1.3.0
+
+-- .mod --
+module "rsc.io/sampler"
+
+require "golang.org/x/text" v0.0.0-20170915032832-14c0d48ead0c
+-- .info --
+{"Version":"v1.3.0","Name":"0cc034b51e57ed7832d4c67d526f75a900996e5c","Short":"0cc034b51e57","Time":"2018-02-13T19:05:03Z"}
+-- glass.go --
+// 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.
+
+// Translations from Frank da Cruz, Ethan Mollick, and many others.
+// See http://kermitproject.org/utf8.html.
+// http://www.oocities.org/nodotus/hbglass.html
+// https://en.wikipedia.org/wiki/I_Can_Eat_Glass
+
+package sampler
+
+var glass = newText(`
+
+English: en: I can eat glass and it doesn't hurt me.
+French: fr: Je peux manger du verre, ça ne me fait pas mal.
+Spanish: es: Puedo comer vidrio, no me hace daño.
+
+`)
+-- glass_test.go --
+// 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 sampler
+
+import (
+	"testing"
+
+	"golang.org/x/text/language"
+	_ "rsc.io/testonly"
+)
+
+var glassTests = []struct {
+	prefs []language.Tag
+	text  string
+}{
+	{
+		[]language.Tag{language.Make("en-US"), language.Make("fr")},
+		"I can eat glass and it doesn't hurt me.",
+	},
+	{
+		[]language.Tag{language.Make("fr"), language.Make("en-US")},
+		"Je peux manger du verre, ça ne me fait pas mal.",
+	},
+}
+
+func TestGlass(t *testing.T) {
+	for _, tt := range glassTests {
+		text := Glass(tt.prefs...)
+		if text != tt.text {
+			t.Errorf("Glass(%v) = %q, want %q", tt.prefs, text, tt.text)
+		}
+	}
+}
+-- go.mod --
+module "rsc.io/sampler"
+
+require "golang.org/x/text" v0.0.0-20170915032832-14c0d48ead0c
+-- hello.go --
+// 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.
+
+// Translations by Google Translate.
+
+package sampler
+
+var hello = newText(`
+
+English: en: Hello, world.
+French: fr: Bonjour le monde.
+Spanish: es: Hola Mundo.
+
+`)
+-- hello_test.go --
+// 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 sampler
+
+import (
+	"testing"
+
+	"golang.org/x/text/language"
+)
+
+var helloTests = []struct {
+	prefs []language.Tag
+	text  string
+}{
+	{
+		[]language.Tag{language.Make("en-US"), language.Make("fr")},
+		"Hello, world.",
+	},
+	{
+		[]language.Tag{language.Make("fr"), language.Make("en-US")},
+		"Bonjour le monde.",
+	},
+}
+
+func TestHello(t *testing.T) {
+	for _, tt := range helloTests {
+		text := Hello(tt.prefs...)
+		if text != tt.text {
+			t.Errorf("Hello(%v) = %q, want %q", tt.prefs, text, tt.text)
+		}
+	}
+}
+-- sampler.go --
+// 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 sampler shows simple texts.
+package sampler // import "rsc.io/sampler"
+
+import (
+	"os"
+	"strings"
+
+	"golang.org/x/text/language"
+)
+
+// DefaultUserPrefs returns the default user language preferences.
+// It consults the $LC_ALL, $LC_MESSAGES, and $LANG environment
+// variables, in that order.
+func DefaultUserPrefs() []language.Tag {
+	var prefs []language.Tag
+	for _, k := range []string{"LC_ALL", "LC_MESSAGES", "LANG"} {
+		if env := os.Getenv(k); env != "" {
+			prefs = append(prefs, language.Make(env))
+		}
+	}
+	return prefs
+}
+
+// Hello returns a localized greeting.
+// If no prefs are given, Hello uses DefaultUserPrefs.
+func Hello(prefs ...language.Tag) string {
+	if len(prefs) == 0 {
+		prefs = DefaultUserPrefs()
+	}
+	return hello.find(prefs)
+}
+
+// Glass returns a localized silly phrase.
+// If no prefs are given, Glass uses DefaultUserPrefs.
+func Glass(prefs ...language.Tag) string {
+	if len(prefs) == 0 {
+		prefs = DefaultUserPrefs()
+	}
+	return glass.find(prefs)
+}
+
+// A text is a localized text.
+type text struct {
+	byTag   map[string]string
+	matcher language.Matcher
+}
+
+// newText creates a new localized text, given a list of translations.
+func newText(s string) *text {
+	t := &text{
+		byTag: make(map[string]string),
+	}
+	var tags []language.Tag
+	for _, line := range strings.Split(s, "\n") {
+		line = strings.TrimSpace(line)
+		if line == "" {
+			continue
+		}
+		f := strings.Split(line, ": ")
+		if len(f) != 3 {
+			continue
+		}
+		tag := language.Make(f[1])
+		tags = append(tags, tag)
+		t.byTag[tag.String()] = f[2]
+	}
+	t.matcher = language.NewMatcher(tags)
+	return t
+}
+
+// find finds the text to use for the given language tag preferences.
+func (t *text) find(prefs []language.Tag) string {
+	tag, _, _ := t.matcher.Match(prefs...)
+	s := t.byTag[tag.String()]
+	if strings.HasPrefix(s, "RTL ") {
+		s = "\u200F" + strings.TrimPrefix(s, "RTL ") + "\u200E"
+	}
+	return s
+}

testdata/mod/rsc.io_sampler_v1.99.99.txt

@@ -0,0 +1,140 @@
+rsc.io/sampler@v1.99.99
+
+-- .mod --
+module "rsc.io/sampler"
+
+require "golang.org/x/text" v0.0.0-20170915032832-14c0d48ead0c
+-- .info --
+{"Version":"v1.99.99","Time":"2018-02-13T22:20:19Z"}
+-- go.mod --
+module "rsc.io/sampler"
+
+require "golang.org/x/text" v0.0.0-20170915032832-14c0d48ead0c
+-- hello.go --
+// 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.
+
+// Translations by Google Translate.
+
+package sampler
+
+var hello = newText(`
+
+English: en: 99 bottles of beer on the wall, 99 bottles of beer, ...
+
+`)
+-- hello_test.go --
+// 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 sampler
+
+import (
+	"testing"
+
+	"golang.org/x/text/language"
+)
+
+var helloTests = []struct {
+	prefs []language.Tag
+	text  string
+}{
+	{
+		[]language.Tag{language.Make("en-US"), language.Make("fr")},
+		"Hello, world.",
+	},
+	{
+		[]language.Tag{language.Make("fr"), language.Make("en-US")},
+		"Bonjour le monde.",
+	},
+}
+
+func TestHello(t *testing.T) {
+	for _, tt := range helloTests {
+		text := Hello(tt.prefs...)
+		if text != tt.text {
+			t.Errorf("Hello(%v) = %q, want %q", tt.prefs, text, tt.text)
+		}
+	}
+}
+-- sampler.go --
+// 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 sampler shows simple texts.
+package sampler // import "rsc.io/sampler"
+
+import (
+	"os"
+	"strings"
+
+	"golang.org/x/text/language"
+)
+
+// DefaultUserPrefs returns the default user language preferences.
+// It consults the $LC_ALL, $LC_MESSAGES, and $LANG environment
+// variables, in that order.
+func DefaultUserPrefs() []language.Tag {
+	var prefs []language.Tag
+	for _, k := range []string{"LC_ALL", "LC_MESSAGES", "LANG"} {
+		if env := os.Getenv(k); env != "" {
+			prefs = append(prefs, language.Make(env))
+		}
+	}
+	return prefs
+}
+
+// Hello returns a localized greeting.
+// If no prefs are given, Hello uses DefaultUserPrefs.
+func Hello(prefs ...language.Tag) string {
+	if len(prefs) == 0 {
+		prefs = DefaultUserPrefs()
+	}
+	return hello.find(prefs)
+}
+
+func Glass() string {
+	return "I can eat glass and it doesn't hurt me."
+}
+
+// A text is a localized text.
+type text struct {
+	byTag   map[string]string
+	matcher language.Matcher
+}
+
+// newText creates a new localized text, given a list of translations.
+func newText(s string) *text {
+	t := &text{
+		byTag: make(map[string]string),
+	}
+	var tags []language.Tag
+	for _, line := range strings.Split(s, "\n") {
+		line = strings.TrimSpace(line)
+		if line == "" {
+			continue
+		}
+		f := strings.Split(line, ": ")
+		if len(f) != 3 {
+			continue
+		}
+		tag := language.Make(f[1])
+		tags = append(tags, tag)
+		t.byTag[tag.String()] = f[2]
+	}
+	t.matcher = language.NewMatcher(tags)
+	return t
+}
+
+// find finds the text to use for the given language tag preferences.
+func (t *text) find(prefs []language.Tag) string {
+	tag, _, _ := t.matcher.Match(prefs...)
+	s := t.byTag[tag.String()]
+	if strings.HasPrefix(s, "RTL ") {
+		s = "\u200F" + strings.TrimPrefix(s, "RTL ") + "\u200E"
+	}
+	return s
+}

testdata/scripts/imports.txt

@@ -19,7 +19,10 @@ package main
 
 import (
 	"fmt"
+
 	"foo.com/main/imported"
+
+	"rsc.io/quote"
 )
 
 func main() {
@@ -28,12 +31,14 @@ func main() {
 	imported.ImportedFunc('x')
 	fmt.Println(imported.ImportedType(3))
 	fmt.Println(nil)
+	fmt.Println(quote.Go())
 }
 -- main.stdout --
 imported var value
 imported const value
 3
 <nil>
+Don't communicate by sharing memory, share memory by communicating.
 -- imported/imported.go --
 package imported