[dev.boringcrypto.go1.13] all: merge go1.13.10 into dev.boringcrypto.go1.13

Change-Id: I70aa2adce503fb9119e947b5868a0aa5427b808b

29 files changed, 328 insertions, 135 deletions

diff --git a/src/cmd/compile/internal/syntax/parser_test.go b/src/cmd/compile/internal/syntax/parser_test.go
index 3cf55defc7..673339d667 100644
--- a/src/cmd/compile/internal/syntax/parser_test.go
+++ b/src/cmd/compile/internal/syntax/parser_test.go
@@ -96,7 +96,7 @@ func walkDirs(t *testing.T, dir string, action func(string)) {
 			}
 		} else if fi.IsDir() && fi.Name() != "testdata" {
 			path := filepath.Join(dir, fi.Name())
-			if !strings.HasSuffix(path, "/test") {
+			if !strings.HasSuffix(path, string(filepath.Separator)+"test") {
 				dirs = append(dirs, path)
 			}
 		}
diff --git a/src/cmd/doc/doc_test.go b/src/cmd/doc/doc_test.go
index 11d0bdafd9..9a5c04fe4c 100644
--- a/src/cmd/doc/doc_test.go
+++ b/src/cmd/doc/doc_test.go
@@ -920,6 +920,9 @@ func TestDotSlashLookup(t *testing.T) {
 		t.Skip("scanning file system takes too long")
 	}
 	maybeSkip(t)
+	if runtime.GOOS == "windows" {
+		t.Skip("known Windows test failure on release-branch.go1.13; fix is in CL 204442 but requires non-test code changes unlikely to be appropriate for backporting this late")
+	}
 	where, err := os.Getwd()
 	if err != nil {
 		t.Fatal(err)
diff --git a/src/cmd/go/internal/generate/generate.go b/src/cmd/go/internal/generate/generate.go
index f2ae80e5dc..317d802040 100644
--- a/src/cmd/go/internal/generate/generate.go
+++ b/src/cmd/go/internal/generate/generate.go
@@ -22,6 +22,7 @@ import (
 	"cmd/go/internal/cfg"
 	"cmd/go/internal/load"
 	"cmd/go/internal/modload"
+	"cmd/go/internal/str"
 	"cmd/go/internal/work"
 )
 
@@ -438,7 +439,7 @@ func (g *Generator) exec(words []string) {
 	cmd.Stderr = os.Stderr
 	// Run the command in the package directory.
 	cmd.Dir = g.dir
-	cmd.Env = append(cfg.OrigEnv, g.env...)
+	cmd.Env = str.StringList(cfg.OrigEnv, g.env)
 	err := cmd.Run()
 	if err != nil {
 		g.errorf("running %q: %s", words[0], err)
diff --git a/src/cmd/go/internal/modcmd/verify.go b/src/cmd/go/internal/modcmd/verify.go
index 81fc44dc97..dd1665619b 100644
--- a/src/cmd/go/internal/modcmd/verify.go
+++ b/src/cmd/go/internal/modcmd/verify.go
@@ -7,6 +7,7 @@ package modcmd
 import (
 	"bytes"
 	"cmd/go/internal/cfg"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -61,12 +62,10 @@ func verifyMod(mod module.Version) bool {
 		_, zipErr = os.Stat(zip)
 	}
 	dir, dirErr := modfetch.DownloadDir(mod)
-	if dirErr == nil {
-		_, dirErr = os.Stat(dir)
-	}
 	data, err := ioutil.ReadFile(zip + "hash")
 	if err != nil {
-		if zipErr != nil && os.IsNotExist(zipErr) && dirErr != nil && os.IsNotExist(dirErr) {
+		if zipErr != nil && errors.Is(zipErr, os.ErrNotExist) &&
+			dirErr != nil && errors.Is(dirErr, os.ErrNotExist) {
 			// Nothing downloaded yet. Nothing to verify.
 			return true
 		}
@@ -75,7 +74,7 @@ func verifyMod(mod module.Version) bool {
 	}
 	h := string(bytes.TrimSpace(data))
 
-	if zipErr != nil && os.IsNotExist(zipErr) {
+	if zipErr != nil && errors.Is(zipErr, os.ErrNotExist) {
 		// ok
 	} else {
 		hZ, err := dirhash.HashZip(zip, dirhash.DefaultHash)
@@ -87,7 +86,7 @@ func verifyMod(mod module.Version) bool {
 			ok = false
 		}
 	}
-	if dirErr != nil && os.IsNotExist(dirErr) {
+	if dirErr != nil && errors.Is(dirErr, os.ErrNotExist) {
 		// ok
 	} else {
 		hD, err := dirhash.HashDir(dir, mod.Path+"@"+mod.Version, dirhash.DefaultHash)
diff --git a/src/cmd/go/internal/modfetch/cache.go b/src/cmd/go/internal/modfetch/cache.go
index c0062809d1..446c8fec8b 100644
--- a/src/cmd/go/internal/modfetch/cache.go
+++ b/src/cmd/go/internal/modfetch/cache.go
@@ -7,6 +7,7 @@ package modfetch
 import (
 	"bytes"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -57,8 +58,11 @@ func CachePath(m module.Version, suffix string) (string, error) {
 	return filepath.Join(dir, encVer+"."+suffix), nil
 }
 
-// DownloadDir returns the directory to which m should be downloaded.
-// Note that the directory may not yet exist.
+// DownloadDir returns the directory to which m should have been downloaded.
+// An error will be returned if the module path or version cannot be escaped.
+// An error satisfying errors.Is(err, os.ErrNotExist) will be returned
+// along with the directory if the directory does not exist or if the directory
+// is not completely populated.
 func DownloadDir(m module.Version) (string, error) {
 	if PkgMod == "" {
 		return "", fmt.Errorf("internal error: modfetch.PkgMod not set")
@@ -77,9 +81,39 @@ func DownloadDir(m module.Version) (string, error) {
 	if err != nil {
 		return "", err
 	}
-	return filepath.Join(PkgMod, enc+"@"+encVer), nil
+
+	dir := filepath.Join(PkgMod, enc+"@"+encVer)
+	if fi, err := os.Stat(dir); os.IsNotExist(err) {
+		return dir, err
+	} else if err != nil {
+		return dir, &DownloadDirPartialError{dir, err}
+	} else if !fi.IsDir() {
+		return dir, &DownloadDirPartialError{dir, errors.New("not a directory")}
+	}
+	partialPath, err := CachePath(m, "partial")
+	if err != nil {
+		return dir, err
+	}
+	if _, err := os.Stat(partialPath); err == nil {
+		return dir, &DownloadDirPartialError{dir, errors.New("not completely extracted")}
+	} else if !os.IsNotExist(err) {
+		return dir, err
+	}
+	return dir, nil
+}
+
+// DownloadDirPartialError is returned by DownloadDir if a module directory
+// exists but was not completely populated.
+//
+// DownloadDirPartialError is equivalent to os.ErrNotExist.
+type DownloadDirPartialError struct {
+	Dir string
+	Err error
 }
 
+func (e *DownloadDirPartialError) Error() string     { return fmt.Sprintf("%s: %v", e.Dir, e.Err) }
+func (e *DownloadDirPartialError) Is(err error) bool { return err == os.ErrNotExist }
+
 // lockVersion locks a file within the module cache that guards the downloading
 // and extraction of the zipfile for the given module version.
 func lockVersion(mod module.Version) (unlock func(), err error) {
diff --git a/src/cmd/go/internal/modfetch/fetch.go b/src/cmd/go/internal/modfetch/fetch.go
index 51a56028c4..d5516dd8d9 100644
--- a/src/cmd/go/internal/modfetch/fetch.go
+++ b/src/cmd/go/internal/modfetch/fetch.go
@@ -7,6 +7,7 @@ package modfetch
 import (
 	"archive/zip"
 	"bytes"
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -22,6 +23,7 @@ import (
 	"cmd/go/internal/module"
 	"cmd/go/internal/par"
 	"cmd/go/internal/renameio"
+	"cmd/go/internal/robustio"
 )
 
 var downloadCache par.Cache
@@ -41,24 +43,27 @@ func Download(mod module.Version) (dir string, err error) {
 		err error
 	}
 	c := downloadCache.Do(mod, func() interface{} {
-		dir, err := DownloadDir(mod)
+		dir, err := download(mod)
 		if err != nil {
 			return cached{"", err}
 		}
-		if err := download(mod, dir); err != nil {
-			return cached{"", err}
-		}
 		checkMod(mod)
 		return cached{dir, nil}
 	}).(cached)
 	return c.dir, c.err
 }
 
-func download(mod module.Version, dir string) (err error) {
-	// If the directory exists, the module has already been extracted.
-	fi, err := os.Stat(dir)
-	if err == nil && fi.IsDir() {
-		return nil
+func download(mod module.Version) (dir string, err error) {
+	// If the directory exists, and no .partial file exists,
+	// the module has already been completely extracted.
+	// .partial files may be created when future versions of cmd/go
+	// extract module zip directories in place instead of extracting
+	// to a random temporary directory and renaming.
+	dir, err = DownloadDir(mod)
+	if err == nil {
+		return dir, nil
+	} else if dir == "" || !errors.Is(err, os.ErrNotExist) {
+		return "", err
 	}
 
 	// To avoid cluttering the cache with extraneous files,
@@ -66,7 +71,7 @@ func download(mod module.Version, dir string) (err error) {
 	// Invoke DownloadZip before locking the file.
 	zipfile, err := DownloadZip(mod)
 	if err != nil {
-		return err
+		return "", err
 	}
 
 	if cfg.CmdName != "mod download" {
@@ -75,17 +80,19 @@ func download(mod module.Version, dir string) (err error) {
 
 	unlock, err := lockVersion(mod)
 	if err != nil {
-		return err
+		return "", err
 	}
 	defer unlock()
 
 	// Check whether the directory was populated while we were waiting on the lock.
-	fi, err = os.Stat(dir)
-	if err == nil && fi.IsDir() {
-		return nil
+	_, dirErr := DownloadDir(mod)
+	if dirErr == nil {
+		return dir, nil
 	}
+	_, dirExists := dirErr.(*DownloadDirPartialError)
 
-	// Clean up any remaining temporary directories from previous runs.
+	// Clean up any remaining temporary directories from previous runs, as well
+	// as partially extracted diectories created by future versions of cmd/go.
 	// This is only safe to do because the lock file ensures that their writers
 	// are no longer active.
 	parentDir := filepath.Dir(dir)
@@ -95,6 +102,19 @@ func download(mod module.Version, dir string) (err error) {
 			RemoveAll(path) // best effort
 		}
 	}
+	if dirExists {
+		if err := RemoveAll(dir); err != nil {
+			return "", err
+		}
+	}
+
+	partialPath, err := CachePath(mod, "partial")
+	if err != nil {
+		return "", err
+	}
+	if err := os.Remove(partialPath); err != nil && !os.IsNotExist(err) {
+		return "", err
+	}
 
 	// Extract the zip file to a temporary directory, then rename it to the
 	// final path. That way, we can use the existence of the source directory to
@@ -102,11 +122,11 @@ func download(mod module.Version, dir string) (err error) {
 	// the entire directory (e.g. as an attempt to prune out file corruption)
 	// the module cache will still be left in a recoverable state.
 	if err := os.MkdirAll(parentDir, 0777); err != nil {
-		return err
+		return "", err
 	}
 	tmpDir, err := ioutil.TempDir(parentDir, tmpPrefix)
 	if err != nil {
-		return err
+		return "", err
 	}
 	defer func() {
 		if err != nil {
@@ -117,17 +137,17 @@ func download(mod module.Version, dir string) (err error) {
 	modpath := mod.Path + "@" + mod.Version
 	if err := Unzip(tmpDir, zipfile, modpath, 0); err != nil {
 		fmt.Fprintf(os.Stderr, "-> %s\n", err)
-		return err
+		return "", err
 	}
 
-	if err := os.Rename(tmpDir, dir); err != nil {
-		return err
+	if err := robustio.Rename(tmpDir, dir); err != nil {
+		return "", err
 	}
 
 	// Make dir read-only only *after* renaming it.
 	// os.Rename was observed to fail for read-only directories on macOS.
 	makeDirsReadOnly(dir)
-	return nil
+	return dir, nil
 }
 
 var downloadZipCache par.Cache
diff --git a/src/cmd/go/internal/modload/build.go b/src/cmd/go/internal/modload/build.go
index ff42516c80..a0c6b0bf74 100644
--- a/src/cmd/go/internal/modload/build.go
+++ b/src/cmd/go/internal/modload/build.go
@@ -143,9 +143,7 @@ func moduleInfo(m module.Version, fromBuildList bool) *modinfo.ModulePublic {
 			}
 			dir, err := modfetch.DownloadDir(mod)
 			if err == nil {
-				if info, err := os.Stat(dir); err == nil && info.IsDir() {
-					m.Dir = dir
-				}
+				m.Dir = dir
 			}
 		}
 	}
diff --git a/src/cmd/go/internal/robustio/robustio_windows.go b/src/cmd/go/internal/robustio/robustio_windows.go
index a3d94e566f..1eb8cfbccf 100644
--- a/src/cmd/go/internal/robustio/robustio_windows.go
+++ b/src/cmd/go/internal/robustio/robustio_windows.go
@@ -14,7 +14,7 @@ import (
 	"time"
 )
 
-const arbitraryTimeout = 500 * time.Millisecond
+const arbitraryTimeout = 2000 * time.Millisecond
 
 // retry retries ephemeral errors from f up to an arbitrary timeout
 // to work around spurious filesystem errors on Windows
diff --git a/src/cmd/go/internal/test/test.go b/src/cmd/go/internal/test/test.go
index 8141e31c99..636d2fef55 100644
--- a/src/cmd/go/internal/test/test.go
+++ b/src/cmd/go/internal/test/test.go
@@ -1142,7 +1142,7 @@ func (c *runCache) builderRunTest(b *work.Builder, a *work.Action) error {
 
 	cmd := exec.Command(args[0], args[1:]...)
 	cmd.Dir = a.Package.Dir
-	cmd.Env = base.EnvForDir(cmd.Dir, cfg.OrigEnv)
+	cmd.Env = base.EnvForDir(cmd.Dir, cfg.OrigEnv[:len(cfg.OrigEnv):len(cfg.OrigEnv)])
 	cmd.Stdout = stdout
 	cmd.Stderr = stdout
 
diff --git a/src/cmd/go/testdata/script/build_trimpath.txt b/src/cmd/go/testdata/script/build_trimpath.txt
index 668f75599e..ba414372d3 100644
--- a/src/cmd/go/testdata/script/build_trimpath.txt
+++ b/src/cmd/go/testdata/script/build_trimpath.txt
@@ -1,44 +1,93 @@
 [short] skip
-
-env -r GOROOT_REGEXP=$GOROOT
-env -r WORK_REGEXP='$WORK'  # don't expand $WORK; grep replaces $WORK in text before matching.
-env GOROOT GOROOT_REGEXP WORK WORK_REGEXP
+env GO111MODULE=on
 
 # A binary built without -trimpath should contain the current workspace
 # and GOROOT for debugging and stack traces.
 cd a
-go build -o hello.exe hello.go
-grep -q $WORK_REGEXP hello.exe
-grep -q $GOROOT_REGEXP hello.exe
+go build -o $WORK/paths-a.exe paths.go
+exec $WORK/paths-a.exe $WORK/paths-a.exe
+stdout 'binary contains GOPATH: true'
+stdout 'binary contains GOROOT: true'
 
 # A binary built with -trimpath should not contain the current workspace
 # or GOROOT.
-go build -trimpath -o hello.exe hello.go
-! grep -q $GOROOT_REGEXP hello.exe
-! grep -q $WORK_REGEXP hello.exe
-cd ..
+go build -trimpath -o $WORK/paths-a.exe paths.go
+exec $WORK/paths-a.exe $WORK/paths-a.exe
+stdout 'binary contains GOPATH: false'
+stdout 'binary contains GOROOT: false'
 
 # A binary from an external module built with -trimpath should not contain
 # the current workspace or GOROOT.
-env GO111MODULE=on
-go build -trimpath -o fortune.exe rsc.io/fortune
-! grep -q $GOROOT_REGEXP fortune.exe
-! grep -q $WORK_REGEXP fortune.exe
+cd $WORK
+go get -trimpath rsc.io/fortune
+exec $WORK/paths-a.exe $GOPATH/bin/fortune$GOEXE
+stdout 'binary contains GOPATH: false'
+stdout 'binary contains GOROOT: false'
 
 # Two binaries built from identical packages in different directories
 # should be identical.
-mkdir b
-cp a/go.mod a/hello.go b
-cd a
-go build -trimpath -o ../a.exe .
-cd ../b
-go build -trimpath -o ../b.exe .
-cd ..
-cmp -q a.exe b.exe
+# TODO(golang.org/issue/35435): at the moment, they are not.
+#mkdir $GOPATH/src/b
+#cp $GOPATH/src/a/go.mod $GOPATH/src/b/go.mod
+#cp $GOPATH/src/a/paths.go $GOPATH/src/b/paths.go
+#cd $GOPATH/src/b
+#go build -trimpath -o $WORK/paths-b.exe .
+#cmp -q $WORK/paths-a.exe $WORK/paths-b.exe
+
+[!exec:gccgo] stop
+
+# A binary built with gccgo without -trimpath should contain the current
+# GOPATH and GOROOT.
+env GO111MODULE=off # The current released gccgo does not support builds in module mode.
+cd $GOPATH/src/a
+go build -compiler=gccgo -o $WORK/gccgo-paths-a.exe .
+exec $WORK/gccgo-paths-a.exe $WORK/gccgo-paths-b.exe
+stdout 'binary contains GOPATH: true'
+stdout 'binary contains GOROOT: true'
+
+# A binary built with gccgo with -trimpath should not contain GOPATH or GOROOT.
+go build -compiler=gccgo -trimpath -o $WORK/gccgo-paths-a.exe .
+exec $WORK/gccgo-paths-a.exe $WORK/gccgo-paths-b.exe
+stdout 'binary contains GOPATH: false'
+stdout 'binary contains GOROOT: false'
 
--- a/hello.go --
+# Two binaries built from identical packages in different directories
+# should be identical.
+# TODO(golang.org/issue/35435): at the moment, they are not.
+#cd ../b
+#go build -compiler=gccgo -trimpath -o $WORK/gccgo-paths-b.exe .
+#cmp -q $WORK/gccgo-paths-a.exe $WORK/gccgo-paths-b.exe
+
+-- $GOPATH/src/a/paths.go --
 package main
-func main() { println("hello") }
 
--- a/go.mod --
-module m
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+)
+
+func main() {
+	exe := os.Args[1]
+	data, err := ioutil.ReadFile(exe)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	gopath := []byte(filepath.ToSlash(os.Getenv("GOPATH")))
+	if len(gopath) == 0 {
+		log.Fatal("GOPATH not set")
+	}
+	fmt.Printf("binary contains GOPATH: %v\n", bytes.Contains(data, gopath))
+
+	goroot := []byte(filepath.ToSlash(os.Getenv("GOROOT")))
+	if len(goroot) == 0 {
+		log.Fatal("GOROOT not set")
+	}
+	fmt.Printf("binary contains GOROOT: %v\n", bytes.Contains(data, goroot))
+}
+-- $GOPATH/src/a/go.mod --
+module example.com/a
diff --git a/src/cmd/go/testdata/script/mod_download_partial.txt b/src/cmd/go/testdata/script/mod_download_partial.txt
new file mode 100644
index 0000000000..cda358b99f
--- /dev/null
+++ b/src/cmd/go/testdata/script/mod_download_partial.txt
@@ -0,0 +1,56 @@
+# Download a module
+go mod download rsc.io/quote
+exists $GOPATH/pkg/mod/rsc.io/quote@v1.5.2/go.mod
+
+# 'go mod verify' should fail if we delete a file.
+go mod verify
+chmod 0755 $GOPATH/pkg/mod/rsc.io/quote@v1.5.2
+rm $GOPATH/pkg/mod/rsc.io/quote@v1.5.2/go.mod
+! go mod verify
+
+# Create a .partial file to simulate an failure extracting the zip file.
+cp empty $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.2.partial
+
+# 'go mod verify' should not fail, since the module hasn't been completely
+# ingested into the cache.
+go mod verify
+
+# 'go list' should not load packages from the directory.
+# NOTE: the message "directory $dir outside available modules" is reported
+# for directories not in the main module, active modules in the module cache,
+# or local replacements. In this case, the directory is in the right place,
+# but it's incomplete, so 'go list' acts as if it's not an active module.
+! go list $GOPATH/pkg/mod/rsc.io/quote@v1.5.2
+stderr 'outside available modules'
+
+# 'go list -m' should not print the directory.
+go list -m -f '{{.Dir}}' rsc.io/quote
+! stdout .
+
+# 'go mod download' should re-extract the module and remove the .partial file.
+go mod download rsc.io/quote
+! exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.2.partial
+exists $GOPATH/pkg/mod/rsc.io/quote@v1.5.2/go.mod
+
+# 'go list' should succeed.
+go list $GOPATH/pkg/mod/rsc.io/quote@v1.5.2
+stdout '^rsc.io/quote$'
+
+# 'go list -m' should print the directory.
+go list -m -f '{{.Dir}}' rsc.io/quote
+stdout 'pkg[/\\]mod[/\\]rsc.io[/\\]quote@v1.5.2'
+
+# go mod verify should fail if we delete a file.
+go mod verify
+chmod 0755 $GOPATH/pkg/mod/rsc.io/quote@v1.5.2
+rm $GOPATH/pkg/mod/rsc.io/quote@v1.5.2/go.mod
+! go mod verify
+
+-- go.mod --
+module m
+
+go 1.14
+
+require rsc.io/quote v1.5.2
+
+-- empty --
diff --git a/src/cmd/go/testdata/script/mod_list_dir.txt b/src/cmd/go/testdata/script/mod_list_dir.txt
index a8023cce9c..39834f2249 100644
--- a/src/cmd/go/testdata/script/mod_list_dir.txt
+++ b/src/cmd/go/testdata/script/mod_list_dir.txt
@@ -1,4 +1,5 @@
 [short] skip
+[windows] skip # known Windows test failure on release-branch.go1.13; fix is in CL 206144 but requires non-test code changes unlikely to be appropriate for backporting this late
 
 # go list with path to directory should work
 
diff --git a/src/cmd/go/testdata/script/version.txt b/src/cmd/go/testdata/script/version.txt
index 9086f047e4..42526247f1 100644
--- a/src/cmd/go/testdata/script/version.txt
+++ b/src/cmd/go/testdata/script/version.txt
@@ -1,6 +1,7 @@
 env GO111MODULE=on
 [short] skip
 
+# Check that 'go version' and 'go version -m' work on a binary built in module mode.
 go build -o fortune.exe rsc.io/fortune
 go version fortune.exe
 stdout '^fortune.exe: .+'
@@ -8,6 +9,10 @@ go version -m fortune.exe
 stdout '^\tpath\trsc.io/fortune'
 stdout '^\tmod\trsc.io/fortune\tv1.0.0'
 
+# Repeat the test with -buildmode=pie.
+# TODO(golang.org/issue/27144): don't skip after -buildmode=pie is implemented
+# on Windows.
+[windows] skip # -buildmode=pie not supported
 go build -buildmode=pie -o external.exe rsc.io/fortune
 go version external.exe
 stdout '^external.exe: .+'
diff --git a/src/go/build/deps_test.go b/src/go/build/deps_test.go
index b8696ec6f9..55a77c6390 100644
--- a/src/go/build/deps_test.go
+++ b/src/go/build/deps_test.go
@@ -159,6 +159,7 @@ var pkgDeps = map[string][]string{
 	"internal/syscall/unix":             {"L0", "syscall"},
 	"internal/syscall/windows":          {"L0", "syscall", "internal/syscall/windows/sysdll"},
 	"internal/syscall/windows/registry": {"L0", "syscall", "internal/syscall/windows/sysdll", "unicode/utf16"},
+	"internal/syscall/execenv":          {"L0", "syscall", "internal/syscall/windows", "unicode/utf16"},
 	"time": {
 		// "L0" without the "io" package:
 		"errors",
@@ -176,10 +177,10 @@ var pkgDeps = map[string][]string{
 	"internal/cfg":     {"L0"},
 	"internal/poll":    {"L0", "internal/oserror", "internal/race", "syscall", "time", "unicode/utf16", "unicode/utf8", "internal/syscall/windows"},
 	"internal/testlog": {"L0"},
-	"os":               {"L1", "os", "syscall", "time", "internal/oserror", "internal/poll", "internal/syscall/windows", "internal/syscall/unix", "internal/testlog"},
+	"os":               {"L1", "os", "syscall", "time", "internal/oserror", "internal/poll", "internal/syscall/windows", "internal/syscall/unix", "internal/syscall/execenv", "internal/testlog"},
 	"path/filepath":    {"L2", "os", "syscall", "internal/syscall/windows"},
 	"io/ioutil":        {"L2", "os", "path/filepath", "time"},
-	"os/exec":          {"L2", "os", "context", "path/filepath", "syscall"},
+	"os/exec":          {"L2", "os", "context", "path/filepath", "syscall", "internal/syscall/execenv"},
 	"os/signal":        {"L2", "os", "syscall"},
 
 	// OS enables basic operating system functionality,
diff --git a/src/internal/syscall/execenv/execenv_default.go b/src/internal/syscall/execenv/execenv_default.go
new file mode 100644
index 0000000000..4bdbb55edb
--- /dev/null
+++ b/src/internal/syscall/execenv/execenv_default.go
@@ -0,0 +1,19 @@
+// Copyright 2020 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.
+
+// +build !windows
+
+package execenv
+
+import "syscall"
+
+// Default will return the default environment
+// variables based on the process attributes
+// provided.
+//
+// Defaults to syscall.Environ() on all platforms
+// other than Windows.
+func Default(sys *syscall.SysProcAttr) ([]string, error) {
+	return syscall.Environ(), nil
+}
diff --git a/src/os/env_windows.go b/src/internal/syscall/execenv/execenv_windows.go
index e8f647e7ac..3a41a7a3fd 100644
--- a/src/os/env_windows.go
+++ b/src/internal/syscall/execenv/execenv_windows.go
@@ -1,8 +1,10 @@
-// Copyright 2019 The Go Authors. All rights reserved.
+// Copyright 2020 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 os
+// +build windows
+
+package execenv
 
 import (
 	"internal/syscall/windows"
@@ -11,9 +13,17 @@ import (
 	"unsafe"
 )
 
-func environForSysProcAttr(sys *syscall.SysProcAttr) (env []string, err error) {
+// Default will return the default environment
+// variables based on the process attributes
+// provided.
+//
+// If the process attributes contain a token, then
+// the environment variables will be sourced from
+// the defaults for that user token, otherwise they
+// will be sourced from syscall.Environ().
+func Default(sys *syscall.SysProcAttr) (env []string, err error) {
 	if sys == nil || sys.Token == 0 {
-		return Environ(), nil
+		return syscall.Environ(), nil
 	}
 	var block *uint16
 	err = windows.CreateEnvironmentBlock(&block, sys.Token, false)
diff --git a/src/net/http/main_test.go b/src/net/http/main_test.go
index 7936fb3044..85aa9096c3 100644
--- a/src/net/http/main_test.go
+++ b/src/net/http/main_test.go
@@ -122,7 +122,7 @@ func afterTest(t testing.TB) {
 		").noteClientGone(":     "a closenotifier sender",
 	}
 	var stacks string
-	for i := 0; i < 4; i++ {
+	for i := 0; i < 10; i++ {
 		bad = ""
 		stacks = strings.Join(interestingGoroutines(), "\n\n")
 		for substr, what := range badSubstring {
diff --git a/src/os/env_default.go b/src/os/env_default.go
deleted file mode 100644
index c11ccce7e3..0000000000
--- a/src/os/env_default.go
+++ /dev/null
@@ -1,13 +0,0 @@
-// Copyright 2019 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.
-
-// +build !windows
-
-package os
-
-import "syscall"
-
-func environForSysProcAttr(sys *syscall.SysProcAttr) ([]string, error) {
-	return Environ(), nil
-}
diff --git a/src/os/exec/exec.go b/src/os/exec/exec.go
index 17ef003eca..5552fd858f 100644
--- a/src/os/exec/exec.go
+++ b/src/os/exec/exec.go
@@ -24,6 +24,7 @@ import (
 	"bytes"
 	"context"
 	"errors"
+	"internal/syscall/execenv"
 	"io"
 	"os"
 	"path/filepath"
@@ -222,11 +223,11 @@ func interfaceEqual(a, b interface{}) bool {
 	return a == b
 }
 
-func (c *Cmd) envv() []string {
+func (c *Cmd) envv() ([]string, error) {
 	if c.Env != nil {
-		return c.Env
+		return c.Env, nil
 	}
-	return os.Environ()
+	return execenv.Default(c.SysProcAttr)
 }
 
 func (c *Cmd) argv() []string {
@@ -412,11 +413,15 @@ func (c *Cmd) Start() error {
 	}
 	c.childFiles = append(c.childFiles, c.ExtraFiles...)
 
-	var err error
+	envv, err := c.envv()
+	if err != nil {
+		return err
+	}
+
 	c.Process, err = os.StartProcess(c.Path, c.argv(), &os.ProcAttr{
 		Dir:   c.Dir,
 		Files: c.childFiles,
-		Env:   addCriticalEnv(dedupEnv(c.envv())),
+		Env:   addCriticalEnv(dedupEnv(envv)),
 		Sys:   c.SysProcAttr,
 	})
 	if err != nil {
diff --git a/src/os/exec_posix.go b/src/os/exec_posix.go
index 505931b488..83fdae8514 100644
--- a/src/os/exec_posix.go
+++ b/src/os/exec_posix.go
@@ -7,6 +7,7 @@
 package os
 
 import (
+	"internal/syscall/execenv"
 	"syscall"
 )
 
@@ -38,7 +39,7 @@ func startProcess(name string, argv []string, attr *ProcAttr) (p *Process, err e
 		Sys: attr.Sys,
 	}
 	if sysattr.Env == nil {
-		sysattr.Env, err = environForSysProcAttr(sysattr.Sys)
+		sysattr.Env, err = execenv.Default(sysattr.Sys)
 		if err != nil {
 			return nil, err
 		}
diff --git a/src/os/export_test.go b/src/os/export_test.go
index d17d5e6230..812432cee4 100644
--- a/src/os/export_test.go
+++ b/src/os/export_test.go
@@ -9,4 +9,3 @@ package os
 var Atime = atime
 var LstatP = &lstat
 var ErrWriteAtInAppendMode = errWriteAtInAppendMode
-var RemoveAllTestHook = &removeAllTestHook
diff --git a/src/os/path.go b/src/os/path.go
index 9d7ecad792..ba43ea3525 100644
--- a/src/os/path.go
+++ b/src/os/path.go
@@ -58,9 +58,6 @@ func MkdirAll(path string, perm FileMode) error {
 	return nil
 }
 
-// removeAllTestHook is a hook for testing.
-var removeAllTestHook = func(err error) error { return err }
-
 // RemoveAll removes path and any children it contains.
 // It removes everything it can but returns the first error
 // it encounters. If the path does not exist, RemoveAll
diff --git a/src/os/removeall_at.go b/src/os/removeall_at.go
index bc632f5a75..e619851f9c 100644
--- a/src/os/removeall_at.go
+++ b/src/os/removeall_at.go
@@ -153,7 +153,6 @@ func removeAllFrom(parent *File, base string) error {
 
 	// Remove the directory itself.
 	unlinkError := unix.Unlinkat(parentFd, base, unix.AT_REMOVEDIR)
-	unlinkError = removeAllTestHook(unlinkError)
 	if unlinkError == nil || IsNotExist(unlinkError) {
 		return nil
 	}
diff --git a/src/os/removeall_noat.go b/src/os/removeall_noat.go
index a0694fa4ce..32673c0ab0 100644
--- a/src/os/removeall_noat.go
+++ b/src/os/removeall_noat.go
@@ -124,7 +124,6 @@ func removeAll(path string) error {
 
 	// Remove directory.
 	err1 := Remove(path)
-	err1 = removeAllTestHook(err1)
 	if err1 == nil || IsNotExist(err1) {
 		return nil
 	}
diff --git a/src/os/removeall_test.go b/src/os/removeall_test.go
index 4d556f977e..050635f533 100644
--- a/src/os/removeall_test.go
+++ b/src/os/removeall_test.go
@@ -5,7 +5,6 @@
 package os_test
 
 import (
-	"errors"
 	"fmt"
 	"io/ioutil"
 	. "os"
@@ -413,14 +412,6 @@ func TestRemoveAllWithMoreErrorThanReqSize(t *testing.T) {
 		t.Skip("skipping in short mode")
 	}
 
-	defer func(oldHook func(error) error) {
-		*RemoveAllTestHook = oldHook
-	}(*RemoveAllTestHook)
-
-	*RemoveAllTestHook = func(err error) error {
-		return errors.New("error from RemoveAllTestHook")
-	}
-
 	tmpDir, err := ioutil.TempDir("", "TestRemoveAll-")
 	if err != nil {
 		t.Fatal(err)
@@ -429,7 +420,7 @@ func TestRemoveAllWithMoreErrorThanReqSize(t *testing.T) {
 
 	path := filepath.Join(tmpDir, "_TestRemoveAllWithMoreErrorThanReqSize_")
 
-	// Make directory with 1025 files and remove.
+	// Make directory with 1025 read-only files.
 	if err := MkdirAll(path, 0777); err != nil {
 		t.Fatalf("MkdirAll %q: %s", path, err)
 	}
@@ -442,13 +433,40 @@ func TestRemoveAllWithMoreErrorThanReqSize(t *testing.T) {
 		fd.Close()
 	}
 
-	// This call should not hang
-	if err := RemoveAll(path); err == nil {
-		t.Fatal("Want error from RemoveAllTestHook, got nil")
+	// Make the parent directory read-only. On some platforms, this is what
+	// prevents os.Remove from removing the files within that directory.
+	if err := Chmod(path, 0555); err != nil {
+		t.Fatal(err)
 	}
+	defer Chmod(path, 0755)
 
-	// We hook to inject error, but the actual files must be deleted
-	if _, err := Lstat(path); err == nil {
-		t.Fatal("directory must be deleted even with removeAllTetHook run")
+	// This call should not hang, even on a platform that disallows file deletion
+	// from read-only directories.
+	err = RemoveAll(path)
+
+	if Getuid() == 0 {
+		// On many platforms, root can remove files from read-only directories.
+		return
+	}
+	if err == nil {
+		t.Fatal("RemoveAll(<read-only directory>) = nil; want error")
+	}
+
+	dir, err := Open(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer dir.Close()
+
+	if runtime.GOOS == "windows" {
+		// Marking a directory in Windows does not prevent the os package from
+		// creating or removing files within it.
+		// (See https://golang.org/issue/35042.)
+		return
+	}
+
+	names, _ := dir.Readdirnames(1025)
+	if len(names) < 1025 {
+		t.Fatalf("RemoveAll(<read-only directory>) unexpectedly removed %d read-only files from that directory", 1025-len(names))
 	}
 }
diff --git a/src/runtime/mbitmap.go b/src/runtime/mbitmap.go
index 30ec5f1cc9..71efe33741 100644
--- a/src/runtime/mbitmap.go
+++ b/src/runtime/mbitmap.go
@@ -1912,7 +1912,11 @@ Run:
 // The bitmask starts at s.startAddr.
 // The result must be deallocated with dematerializeGCProg.
 func materializeGCProg(ptrdata uintptr, prog *byte) *mspan {
-	s := mheap_.allocManual((ptrdata/(8*sys.PtrSize)+pageSize-1)/pageSize, &memstats.gc_sys)
+	// Each word of ptrdata needs one bit in the bitmap.
+	bitmapBytes := divRoundUp(ptrdata, 8*sys.PtrSize)
+	// Compute the number of pages needed for bitmapBytes.
+	pages := divRoundUp(bitmapBytes, pageSize)
+	s := mheap_.allocManual(pages, &memstats.gc_sys)
 	runGCProg(addb(prog, 4), nil, (*byte)(unsafe.Pointer(s.startAddr)), 1)
 	return s
 }
diff --git a/src/runtime/os_windows.go b/src/runtime/os_windows.go
index 2cf81f61a9..bb631b66a9 100644
--- a/src/runtime/os_windows.go
+++ b/src/runtime/os_windows.go
@@ -263,9 +263,7 @@ func loadOptionalSyscalls() {
 
 func monitorSuspendResume() {
 	const (
-		_DEVICE_NOTIFY_CALLBACK   = 2
-		_ERROR_FILE_NOT_FOUND     = 2
-		_ERROR_INVALID_PARAMETERS = 87
+		_DEVICE_NOTIFY_CALLBACK = 2
 	)
 	type _DEVICE_NOTIFY_SUBSCRIBE_PARAMETERS struct {
 		callback uintptr
@@ -292,25 +290,8 @@ func monitorSuspendResume() {
 		callback: compileCallback(*efaceOf(&fn), true),
 	}
 	handle := uintptr(0)
-	ret := stdcall3(powerRegisterSuspendResumeNotification, _DEVICE_NOTIFY_CALLBACK,
+	stdcall3(powerRegisterSuspendResumeNotification, _DEVICE_NOTIFY_CALLBACK,
 		uintptr(unsafe.Pointer(&params)), uintptr(unsafe.Pointer(&handle)))
-	// This function doesn't use GetLastError(), so we use the return value directly.
-	switch ret {
-	case 0:
-		return // Successful, nothing more to do.
-	case _ERROR_FILE_NOT_FOUND:
-		// Systems without access to the suspend/resume notifier
-		// also have their clock on "program time", and therefore
-		// don't want or need this anyway.
-		return
-	case _ERROR_INVALID_PARAMETERS:
-		// This is seen when running in Windows Docker.
-		// See issue 36557.
-		return
-	default:
-		println("runtime: PowerRegisterSuspendResumeNotification failed with errno=", ret)
-		throw("runtime: PowerRegisterSuspendResumeNotification failure")
-	}
 }
 
 //go:nosplit
diff --git a/src/runtime/stubs.go b/src/runtime/stubs.go
index 26aaf2224d..8d1c698400 100644
--- a/src/runtime/stubs.go
+++ b/src/runtime/stubs.go
@@ -295,6 +295,13 @@ func round(n, a uintptr) uintptr {
 	return (n + a - 1) &^ (a - 1)
 }
 
+// divRoundUp returns ceil(n / a).
+func divRoundUp(n, a uintptr) uintptr {
+	// a is generally a power of two. This will get inlined and
+	// the compiler will optimize the division.
+	return (n + a - 1) / a
+}
+
 // checkASM reports whether assembly runtime checks have passed.
 func checkASM() bool
 
diff --git a/src/runtime/sys_linux_ppc64x.s b/src/runtime/sys_linux_ppc64x.s
index 13d23156bd..435cc2809a 100644
--- a/src/runtime/sys_linux_ppc64x.s
+++ b/src/runtime/sys_linux_ppc64x.s
@@ -251,7 +251,7 @@ fallback:
 	ADD	$32, R1, R4
 	SYSCALL $SYS_clock_gettime
 	MOVD	32(R1), R3
-	MOVD	48(R1), R5
+	MOVD	40(R1), R5
 	JMP	finish
 
 TEXT runtime·rtsigprocmask(SB),NOSPLIT|NOFRAME,$0-28