4 files changed, 22 insertions, 15 deletions
diff --git a/libgo/go/io/fs/fs.go b/libgo/go/io/fs/fs.go
index b691a86..3d2e2ee 100644
--- a/libgo/go/io/fs/fs.go
+++ b/libgo/go/io/fs/fs.go
@@ -10,6 +10,7 @@ package fs
 import (
 	"internal/oserror"
 	"time"
+	"unicode/utf8"
 )
 
 // An FS provides access to a hierarchical file system.
@@ -32,14 +33,22 @@ type FS interface {
 
 // ValidPath reports whether the given path name
 // is valid for use in a call to Open.
-// Path names passed to open are unrooted, slash-separated
-// sequences of path elements, like “x/y/z”.
-// Path names must not contain a “.” or “..” or empty element,
+//
+// Path names passed to open are UTF-8-encoded,
+// unrooted, slash-separated sequences of path elements, like “x/y/z”.
+// Path names must not contain an element that is “.” or “..” or the empty string,
 // except for the special case that the root directory is named “.”.
+// Paths must not start or end with a slash: “/x” and “x/” are invalid.
 //
-// Paths are slash-separated on all systems, even Windows.
-// Backslashes must not appear in path names.
+// Note that paths are slash-separated on all systems, even Windows.
+// Paths containing other characters such as backslash and colon
+// are accepted as valid, but those characters must never be
+// interpreted by an FS implementation as path element separators.
 func ValidPath(name string) bool {
+	if !utf8.ValidString(name) {
+		return false
+	}
+
 	if name == "." {
 		// special case
 		return true
@@ -49,9 +58,6 @@ func ValidPath(name string) bool {
 	for {
 		i := 0
 		for i < len(name) && name[i] != '/' {
-			if name[i] == '\\' {
-				return false
-			}
 			i++
 		}
 		elem := name[:i]
diff --git a/libgo/go/io/fs/fs_test.go b/libgo/go/io/fs/fs_test.go
index 8d395fc..aae1a76 100644
--- a/libgo/go/io/fs/fs_test.go
+++ b/libgo/go/io/fs/fs_test.go
@@ -33,9 +33,10 @@ var isValidPathTests = []struct {
 	{"x/..", false},
 	{"x/../y", false},
 	{"x//y", false},
-	{`x\`, false},
-	{`x\y`, false},
-	{`\x`, false},
+	{`x\`, true},
+	{`x\y`, true},
+	{`x:y`, true},
+	{`\x`, true},
 }
 
 func TestValidPath(t *testing.T) {
diff --git a/libgo/go/io/fs/glob.go b/libgo/go/io/fs/glob.go
index 549f217..45d9cb6 100644
--- a/libgo/go/io/fs/glob.go
+++ b/libgo/go/io/fs/glob.go
@@ -6,7 +6,6 @@ package fs
 
 import (
 	"path"
-	"runtime"
 )
 
 // A GlobFS is a file system with a Glob method.
@@ -111,8 +110,8 @@ func glob(fs FS, dir, pattern string, matches []string) (m []string, e error) {
 // recognized by path.Match.
 func hasMeta(path string) bool {
 	for i := 0; i < len(path); i++ {
-		c := path[i]
-		if c == '*' || c == '?' || c == '[' || runtime.GOOS == "windows" && c == '\\' {
+		switch path[i] {
+		case '*', '?', '[', '\\':
 			return true
 		}
 	}
diff --git a/libgo/go/io/fs/glob_test.go b/libgo/go/io/fs/glob_test.go
index 440ebd6..bcd2e1b 100644
--- a/libgo/go/io/fs/glob_test.go
+++ b/libgo/go/io/fs/glob_test.go
@@ -17,6 +17,7 @@ var globTests = []struct {
 }{
 	{os.DirFS("."), "glob.go", "glob.go"},
 	{os.DirFS("."), "gl?b.go", "glob.go"},
+	{os.DirFS("."), `gl\ob.go`, "glob.go"},
 	{os.DirFS("."), "*", "glob.go"},
 	// This test fails on gofrontend because the directory structure
 	// is different.
@@ -34,7 +35,7 @@ func TestGlob(t *testing.T) {
 			t.Errorf("Glob(%#q) = %#v want %v", tt.pattern, matches, tt.result)
 		}
 	}
-	for _, pattern := range []string{"no_match", "../*/no_match"} {
+	for _, pattern := range []string{"no_match", "../*/no_match", `\*`} {
 		matches, err := Glob(os.DirFS("."), pattern)
 		if err != nil {
 			t.Errorf("Glob error for %q: %s", pattern, err)