path/filepath: return special error from EvalSymlinks

CL 155597 attempted to fix #29372. But it failed to make all new
test cases pass. Also CL 155597 broke some existing code
(see #29449 for details).

Make small adjustment to CL 155597 that fixes both #29372 and #29449.

Suggested by Ian.

Updates #29372
Fixes #29449

Change-Id: I9777a615514d3f152af5acb65fb1239e696607b6
Reviewed-on: https://go-review.googlesource.com/c/156398
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

1 files changed, 27 insertions, 5 deletions

diff --git a/src/path/filepath/path_windows_test.go b/src/path/filepath/path_windows_test.go
index 63eab18116..3fcccfab78 100644
--- a/src/path/filepath/path_windows_test.go
+++ b/src/path/filepath/path_windows_test.go
@@ -536,17 +536,39 @@ func TestNTNamespaceSymlink(t *testing.T) {
 	}
 	target := strings.Trim(string(output), " \n\r")
 
-	link := filepath.Join(tmpdir, "link")
-	output, err = exec.Command("cmd", "/c", "mklink", "/J", link, target).CombinedOutput()
+	dirlink := filepath.Join(tmpdir, "dirlink")
+	output, err = exec.Command("cmd", "/c", "mklink", "/J", dirlink, target).CombinedOutput()
 	if err != nil {
-		t.Fatalf("failed to run mklink %v %v: %v %q", link, target, err, output)
+		t.Fatalf("failed to run mklink %v %v: %v %q", dirlink, target, err, output)
 	}
 
-	got, err := filepath.EvalSymlinks(link)
+	got, err := filepath.EvalSymlinks(dirlink)
 	if err != nil {
 		t.Fatal(err)
 	}
 	if want := vol + `\`; got != want {
-		t.Errorf(`EvalSymlinks(%q): got %q, want %q`, link, got, want)
+		t.Errorf(`EvalSymlinks(%q): got %q, want %q`, dirlink, got, want)
+	}
+
+	file := filepath.Join(tmpdir, "file")
+	err = ioutil.WriteFile(file, []byte(""), 0666)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	target += file[len(filepath.VolumeName(file)):]
+
+	filelink := filepath.Join(tmpdir, "filelink")
+	output, err = exec.Command("cmd", "/c", "mklink", filelink, target).CombinedOutput()
+	if err != nil {
+		t.Fatalf("failed to run mklink %v %v: %v %q", filelink, target, err, output)
+	}
+
+	got, err = filepath.EvalSymlinks(filelink)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if want := file; got != want {
+		t.Errorf(`EvalSymlinks(%q): got %q, want %q`, filelink, got, want)
 	}
 }