From 1ff8552d80777107b425447ed0ac0e0dd219cceb Mon Sep 17 00:00:00 2001
From: Hank Donnay <hdonnay@redhat.com>
Date: Tue, 28 Apr 2020 09:22:47 -0400
Subject: [PATCH] oval: allow empty date attr

Signed-off-by: Hank Donnay <hdonnay@redhat.com>
---
 oval/date_test.go | 13 +++++++++++++
 oval/types.go     | 21 ++++++++++++++++++---
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/oval/date_test.go b/oval/date_test.go
index f26cdb6..7e7e4cc 100644
--- a/oval/date_test.go
+++ b/oval/date_test.go
@@ -3,6 +3,7 @@ package oval
 import (
 	"encoding/xml"
 	"os"
+	"strings"
 	"testing"
 	"time"
 
@@ -124,3 +125,15 @@ func TestUbuntuDates(t *testing.T) {
 		}
 	}
 }
+
+func TestPointlessElement(t *testing.T) {
+	const doc = xml.Header + `<div><issued date=""/></div>`
+	var got struct {
+		Date Date `xml:"issued"`
+	}
+
+	rd := strings.NewReader(doc)
+	if err := xml.NewDecoder(rd).Decode(&got); err != nil {
+		t.Error(err)
+	}
+}
diff --git a/oval/types.go b/oval/types.go
index 2c80097..b5cf5f1 100644
--- a/oval/types.go
+++ b/oval/types.go
@@ -111,6 +111,8 @@ type Date struct {
 var (
 	_ xml.Unmarshaler     = (*Date)(nil)
 	_ xml.UnmarshalerAttr = (*Date)(nil)
+
+	emptyValue = (time.Time{}).Add(1)
 )
 
 // UnmarshalXML implements xml.Unmarshaler.
@@ -126,10 +128,17 @@ func (d *Date) UnmarshalXML(dec *xml.Decoder, start xml.StartElement) error {
 	if err := dec.DecodeElement(&s, &start); err != nil {
 		return err
 	}
-	// If the date is set but an empty string is the inner element, then the
-	// date was set by an attr.
-	if s == "" && !d.Date.IsZero() {
+	switch {
+	case d.Date.Equal(emptyValue):
+		// If we set the date to this sentinel value, then this element is
+		// pointless but we need to not return an error.
+		d.Date = time.Time{}
+		return nil
+	case s == "" && !d.Date.IsZero():
+		// If the date is set but an empty string is the inner element, then the
+		// date was set by an attr.
 		return nil
+	default:
 	}
 	var err error
 	// Try a variety of formats, because everything is terrible.
@@ -156,6 +165,12 @@ func (d *Date) UnmarshalXMLAttr(attr xml.Attr) error {
 	if attr.Name.Local != name.Local {
 		return xml.UnmarshalError(fmt.Sprintf("unexpected attr : %v", attr))
 	}
+	// We want to allow for an empty value, because some vendors can't be
+	// bothered to remove empty entities from their database.
+	if attr.Value == "" {
+		d.Date = emptyValue
+		return nil
+	}
 	var err error
 	d.Date, err = time.Parse(dsfmt, attr.Value)
 	if err != nil {