os: don't use a symlink's target path for FileInfo#Name on windows

Use an original name instead of a symlink's target path.

Fixes #20064

Change-Id: I9be3837a156bdcda0e9e065abbb425d535b27be3
Reviewed-on: https://go-review.googlesource.com/41310Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/os/os_test.go

@@ -712,55 +712,58 @@ func TestSymlink(t *testing.T) {
 	Remove(from) // Just in case.
 	file, err := Create(to)
 	if err != nil {
-		t.Fatalf("open %q failed: %v", to, err)
+		t.Fatalf("Create(%q) failed: %v", to, err)
 	}
 	defer Remove(to)
 	if err = file.Close(); err != nil {
-		t.Errorf("close %q failed: %v", to, err)
+		t.Errorf("Close(%q) failed: %v", to, err)
 	}
 	err = Symlink(to, from)
 	if err != nil {
-		t.Fatalf("symlink %q, %q failed: %v", to, from, err)
+		t.Fatalf("Symlink(%q, %q) failed: %v", to, from, err)
 	}
 	defer Remove(from)
 	tostat, err := Lstat(to)
 	if err != nil {
-		t.Fatalf("stat %q failed: %v", to, err)
+		t.Fatalf("Lstat(%q) failed: %v", to, err)
 	}
 	if tostat.Mode()&ModeSymlink != 0 {
-		t.Fatalf("stat %q claims to have found a symlink", to)
+		t.Fatalf("Lstat(%q).Mode()&ModeSymlink = %v, want 0", to, tostat.Mode()&ModeSymlink)
 	}
 	fromstat, err := Stat(from)
 	if err != nil {
-		t.Fatalf("stat %q failed: %v", from, err)
+		t.Fatalf("Stat(%q) failed: %v", from, err)
 	}
 	if !SameFile(tostat, fromstat) {
-		t.Errorf("symlink %q, %q did not create symlink", to, from)
+		t.Errorf("Symlink(%q, %q) did not create symlink", to, from)
 	}
 	fromstat, err = Lstat(from)
 	if err != nil {
-		t.Fatalf("lstat %q failed: %v", from, err)
+		t.Fatalf("Lstat(%q) failed: %v", from, err)
 	}
 	if fromstat.Mode()&ModeSymlink == 0 {
-		t.Fatalf("symlink %q, %q did not create symlink", to, from)
+		t.Fatalf("Lstat(%q).Mode()&ModeSymlink = 0, want %v", from, ModeSymlink)
 	}
 	fromstat, err = Stat(from)
 	if err != nil {
-		t.Fatalf("stat %q failed: %v", from, err)
+		t.Fatalf("Stat(%q) failed: %v", from, err)
+	}
+	if fromstat.Name() != from {
+		t.Errorf("Stat(%q).Name() = %q, want %q", from, fromstat.Name(), from)
 	}
 	if fromstat.Mode()&ModeSymlink != 0 {
-		t.Fatalf("stat %q did not follow symlink", from)
+		t.Fatalf("Stat(%q).Mode()&ModeSymlink = %v, want 0", from, fromstat.Mode()&ModeSymlink)
 	}
 	s, err := Readlink(from)
 	if err != nil {
-		t.Fatalf("readlink %q failed: %v", from, err)
+		t.Fatalf("Readlink(%q) failed: %v", from, err)
 	}
 	if s != to {
-		t.Fatalf("after symlink %q != %q", s, to)
+		t.Fatalf("Readlink(%q) = %q, want %q", from, s, to)
 	}
 	file, err = Open(from)
 	if err != nil {
-		t.Fatalf("open %q failed: %v", from, err)
+		t.Fatalf("Open(%q) failed: %v", from, err)
 	}
 	file.Close()
 }

src/os/os_windows_test.go

@@ -105,6 +105,10 @@ func testDirLinks(t *testing.T, tests []dirLinkTest) {
 	if err != nil {
 		t.Fatal(err)
 	}
+	fi, err := os.Stat(dir)
+	if err != nil {
+		t.Fatal(err)
+	}
 	err = ioutil.WriteFile(filepath.Join(dir, "abc"), []byte("abc"), 0644)
 	if err != nil {
 		t.Fatal(err)
@@ -113,7 +117,7 @@ func testDirLinks(t *testing.T, tests []dirLinkTest) {
 		link := filepath.Join(tmpdir, test.name+"_link")
 		err := test.mklink(link, dir)
 		if err != nil {
-			t.Errorf("creating link for %s test failed: %v", test.name, err)
+			t.Errorf("creating link for %q test failed: %v", test.name, err)
 			continue
 		}
 
@@ -132,15 +136,21 @@ func testDirLinks(t *testing.T, tests []dirLinkTest) {
 			continue
 		}
 
-		fi, err := os.Stat(link)
+		fi1, err := os.Stat(link)
 		if err != nil {
 			t.Errorf("failed to stat link %v: %v", link, err)
 			continue
 		}
-		expected := filepath.Base(dir)
-		got := fi.Name()
-		if !fi.IsDir() || expected != got {
-			t.Errorf("link should point to %v but points to %v instead", expected, got)
+		if !fi1.IsDir() {
+			t.Errorf("%q should be a directory", link)
+			continue
+		}
+		if fi1.Name() != filepath.Base(link) {
+			t.Errorf("Stat(%q).Name() = %q, want %q", link, fi1.Name(), filepath.Base(link))
+			continue
+		}
+		if !os.SameFile(fi, fi1) {
+			t.Errorf("%q should point to %q", link, dir)
 			continue
 		}
 	}

src/os/stat_windows.go

@@ -63,25 +63,27 @@ func (file *File) Stat() (FileInfo, error) {
 func Stat(name string) (FileInfo, error) {
 	var fi FileInfo
 	var err error
+	link := name
 	for i := 0; i < 255; i++ {
-		fi, err = Lstat(name)
+		fi, err = Lstat(link)
 		if err != nil {
 			return nil, err
 		}
 		if fi.Mode()&ModeSymlink == 0 {
+			fi.(*fileStat).name = basename(name)
 			return fi, nil
 		}
-		newname, err := Readlink(name)
+		newlink, err := Readlink(link)
 		if err != nil {
 			return nil, err
 		}
 		switch {
-		case isAbs(newname):
-			name = newname
-		case len(newname) > 0 && IsPathSeparator(newname[0]):
-			name = volumeName(name) + newname
+		case isAbs(newlink):
+			link = newlink
+		case len(newlink) > 0 && IsPathSeparator(newlink[0]):
+			link = volumeName(link) + newlink
 		default:
-			name = dirname(name) + `\` + newname
+			link = dirname(link) + `\` + newlink
 		}
 	}
 	return nil, &PathError{"Stat", name, syscall.ELOOP}