path/filepath: walkSymlinks: return correct error for file with trailing slash

Rather than return os.ErrNotExist for /path/to/existing_file/,
walkSymLinks now returns syscall.ENOTDIR.

This is consistent with behavior of os.Lstat.

Fixes #29372

Change-Id: Id5c471d901db04b2f35d60f60a81b2a0be93cae9
Reviewed-on: https://go-review.googlesource.com/c/155597
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

1 files changed, 37 insertions, 0 deletions

diff --git a/src/path/filepath/path_test.go b/src/path/filepath/path_test.go
index 3434ea2e6e..1b9f286c4d 100644
--- a/src/path/filepath/path_test.go
+++ b/src/path/filepath/path_test.go
@@ -15,6 +15,7 @@ import (
 	"runtime"
 	"sort"
 	"strings"
+	"syscall"
 	"testing"
 )
 
@@ -1371,3 +1372,39 @@ func TestWalkSymlink(t *testing.T) {
 	testenv.MustHaveSymlink(t)
 	testWalkSymlink(t, os.Symlink)
 }
+
+func TestIssue29372(t *testing.T) {
+	f, err := ioutil.TempFile("", "issue29372")
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+	path := f.Name()
+	defer os.Remove(path)
+
+	isWin := runtime.GOOS == "windows"
+	pathSeparator := string(filepath.Separator)
+	tests := []struct {
+		path string
+		skip bool
+	}{
+		{path + strings.Repeat(pathSeparator, 1), false},
+		{path + strings.Repeat(pathSeparator, 2), false},
+		{path + strings.Repeat(pathSeparator, 1) + ".", false},
+		{path + strings.Repeat(pathSeparator, 2) + ".", false},
+		// windows.GetFinalPathNameByHandle return the directory part with trailing dot dot
+		// C:\path\to\existing_dir\existing_file\.. returns C:\path\to\existing_dir
+		{path + strings.Repeat(pathSeparator, 1) + "..", isWin},
+		{path + strings.Repeat(pathSeparator, 2) + "..", isWin},
+	}
+
+	for i, test := range tests {
+		if test.skip {
+			continue
+		}
+		_, err = filepath.EvalSymlinks(test.path)
+		if err != syscall.ENOTDIR {
+			t.Fatalf("test#%d: want %q, got %q", i, syscall.ENOTDIR, err)
+		}
+	}
+}