testing: drop unusual characters from TempDir directory name

Only use safe characters of the test name for the os.MkdirTemp pattern.
This currently includes the alphanumeric characters and ASCII
punctuation characters known not to interact with globs.

Fixes #46624

Change-Id: I402c34775b943fed9b97963c52f79245cc16dc1d
Reviewed-on: https://go-review.googlesource.com/c/go/+/326010
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

2 files changed, 31 insertions, 13 deletions

diff --git a/src/testing/testing.go b/src/testing/testing.go
index 85a7fec65f..fdf57a3953 100644
--- a/src/testing/testing.go
+++ b/src/testing/testing.go
@@ -252,6 +252,8 @@ import (
 	"sync"
 	"sync/atomic"
 	"time"
+	"unicode"
+	"unicode/utf8"
 )
 
 var initRan bool
@@ -908,11 +910,6 @@ func (c *common) Cleanup(f func()) {
 	c.cleanups = append(c.cleanups, fn)
 }
 
-var tempDirReplacer struct {
-	sync.Once
-	r *strings.Replacer
-}
-
 // TempDir returns a temporary directory for the test to use.
 // The directory is automatically removed by Cleanup when the test and
 // all its subtests complete.
@@ -936,13 +933,26 @@ func (c *common) TempDir() string {
 	if nonExistent {
 		c.Helper()
 
-		// os.MkdirTemp doesn't like path separators in its pattern,
-		// so mangle the name to accommodate subtests.
-		tempDirReplacer.Do(func() {
-			tempDirReplacer.r = strings.NewReplacer("/", "_", "\\", "_", ":", "_")
-		})
-		pattern := tempDirReplacer.r.Replace(c.Name())
-
+		// Drop unusual characters (such as path separators or
+		// characters interacting with globs) from the directory name to
+		// avoid surprising os.MkdirTemp behavior.
+		mapper := func(r rune) rune {
+			if r < utf8.RuneSelf {
+				const allowed = "!#$%&()+,-.=@^_{}~ "
+				if '0' <= r && r <= '9' ||
+					'a' <= r && r <= 'z' ||
+					'A' <= r && r <= 'Z' {
+					return r
+				}
+				if strings.ContainsRune(allowed, r) {
+					return r
+				}
+			} else if unicode.IsLetter(r) || unicode.IsNumber(r) {
+				return r
+			}
+			return -1
+		}
+		pattern := strings.Map(mapper, c.Name())
 		c.tempDir, c.tempDirErr = os.MkdirTemp("", pattern)
 		if c.tempDirErr == nil {
 			c.Cleanup(func() {
diff --git a/src/testing/testing_test.go b/src/testing/testing_test.go
index 55a4df4739..08ae23991f 100644
--- a/src/testing/testing_test.go
+++ b/src/testing/testing_test.go
@@ -58,6 +58,9 @@ func TestTempDir(t *testing.T) {
 	t.Run("test:subtest", testTempDir)
 	t.Run("test/..", testTempDir)
 	t.Run("../test", testTempDir)
+	t.Run("test[]", testTempDir)
+	t.Run("test*", testTempDir)
+	t.Run("äöüéè", testTempDir)
 }
 
 func testTempDir(t *testing.T) {
@@ -74,7 +77,7 @@ func testTempDir(t *testing.T) {
 			if err != nil {
 				t.Fatal(err)
 			}
-			t.Errorf("directory %q stil exists: %v, isDir=%v", dir, fi, fi.IsDir())
+			t.Errorf("directory %q still exists: %v, isDir=%v", dir, fi, fi.IsDir())
 		default:
 			if !t.Failed() {
 				t.Fatal("never received dir channel")
@@ -108,6 +111,11 @@ func testTempDir(t *testing.T) {
 	if len(files) > 0 {
 		t.Errorf("unexpected %d files in TempDir: %v", len(files), files)
 	}
+
+	glob := filepath.Join(dir, "*.txt")
+	if _, err := filepath.Glob(glob); err != nil {
+		t.Error(err)
+	}
 }
 
 func TestSetenv(t *testing.T) {