fix(parser): reject malformed TEXT frames and parse signed frame sizes

parser/parser_test.go

@@ -253,3 +253,66 @@ func TestDataWidthAndStatic(t *testing.T) {
 		t.Errorf("mask24 DATA should be static, got %+v", datas[2].Name)
 	}
 }
+
+// TestTruncatedFrameDollar is a regression test for a TEXT directive whose
+// frame size is missing after the $: the parser used to slice past the end
+// of the token slice and panic.  It must report a diagnostic instead.
+func TestTruncatedFrameDollar(t *testing.T) {
+	for _, src := range []string{
+		"TEXT $\n",
+		"TEXT \u00b7foo(SB), $\n",
+		"TEXT \u00b7foo(SB), NOSPLIT, $\n",
+	} {
+		var file *ast.File
+		func() {
+			defer func() {
+				if r := recover(); r != nil {
+					t.Fatalf("Parse(%q) panicked: %v", src, r)
+				}
+			}()
+			file, _ = Parse("t.s", src)
+		}()
+		if file == nil {
+			t.Fatalf("Parse(%q) returned no file", src)
+		}
+		if len(file.Decls) != 1 {
+			t.Fatalf("Parse(%q) decls = %d, want 1", src, len(file.Decls))
+		}
+		txt := file.Decls[0].(*ast.Text)
+		if txt.Frame != nil {
+			t.Errorf("Parse(%q) frame = %v, want nil", src, txt.Frame)
+		}
+	}
+}
+
+// TestFrameAndArgs parses a well-formed TEXT header and checks that the
+// frame and args operands are picked up.
+func TestFrameAndArgs(t *testing.T) {
+	file, errs := Parse("t.s", "TEXT \u00b7foo(SB), $32-16\n\tRET\n")
+	if len(errs) > 0 {
+		t.Fatalf("parse errors: %v", errs)
+	}
+	txt := file.Decls[0].(*ast.Text)
+	if txt.Frame == nil || !txt.Frame.Imm.HasVal || txt.Frame.Imm.Val != 32 {
+		t.Errorf("frame = %+v, want $32", txt.Frame)
+	}
+	if txt.Args == nil || !txt.Args.Imm.HasVal || txt.Args.Imm.Val != 16 {
+		t.Errorf("args = %+v, want -16", txt.Args)
+	}
+}
+
+// TestSignedZeroFrame covers the Go runtime's "$-0-24" spelling: a zero
+// frame with an explicit sign plus the argument area.
+func TestSignedZeroFrame(t *testing.T) {
+	file, errs := Parse("t.s", "TEXT \u00b7foo<ABIInternal>(SB), NOSPLIT, $-0-24\n\tRET\n")
+	if len(errs) > 0 {
+		t.Fatalf("parse errors: %v", errs)
+	}
+	txt := file.Decls[0].(*ast.Text)
+	if txt.Frame == nil || !txt.Frame.Imm.HasVal || txt.Frame.Imm.Val != 0 {
+		t.Errorf("frame = %+v, want $-0", txt.Frame)
+	}
+	if txt.Args == nil || !txt.Args.Imm.HasVal || txt.Args.Imm.Val != 24 {
+		t.Errorf("args = %+v, want -24", txt.Args)
+	}
+}