fix: allow foreign namespaces in SVG content documents

Main changes:
- switch to a master NVDL schema for SVG Content Document validation
  (in EPUB 3)
- allow elements and attributes in foreign namespaces in SVG Content
  Documents, except where otherwise forbidden in the spec (i.e. in the
 `foreignObject` element, where only HTML is allowed)
- allow `data-*` attributes in SVG (by removing them at parsing time)
- add more tests

Also:
- slightly refactor the attribute pre-processing in XMLParser

Fix #491

src/main/java/com/adobe/epubcheck/ops/OPSChecker.java

@@ -58,7 +58,7 @@ public class OPSChecker implements ContentChecker, DocumentValidator
       .putAll(Predicates.and(mimetype("image/svg+xml"), version(EPUBVersion.VERSION_2)),
           XMLValidators.SVG_20_RNG, XMLValidators.IDUNIQUE_20_SCH)
       .putAll(Predicates.and(mimetype("image/svg+xml"), version(EPUBVersion.VERSION_3)),
-          XMLValidators.SVG_30_RNC, XMLValidators.SVG_30_SCH)
+          XMLValidators.SVG_30_NVDL)
       .putAll(
           and(or(profile(EPUBProfile.DICT), hasPubType(OPFData.DC_TYPE_DICT)),
               mimetype("application/xhtml+xml"), version(EPUBVersion.VERSION_3)),

src/main/java/com/adobe/epubcheck/xml/XMLParser.java

@@ -60,6 +60,7 @@
 import com.adobe.epubcheck.opf.ValidationContext;
 import com.adobe.epubcheck.util.EPUBVersion;
 import com.adobe.epubcheck.util.ResourceUtil;
+import com.google.common.collect.ImmutableSet;
 import com.google.common.io.Closer;
 import com.thaiopensource.util.PropertyMapBuilder;
 import com.thaiopensource.validate.ValidateProperty;
@@ -527,59 +528,57 @@ public void startElement(String namespaceURI, String localName, String qName,
     }
   }
 
-  // 3.0.1 custom attributes handling
-  private static final Set<String> knownXHTMLContentDocsNamespaces = new HashSet<String>();
-  static
-  {
-    knownXHTMLContentDocsNamespaces.add(Namespaces.MATHML);
-    knownXHTMLContentDocsNamespaces.add(Namespaces.OPS);
-    knownXHTMLContentDocsNamespaces.add(Namespaces.SSML);
-    knownXHTMLContentDocsNamespaces.add(Namespaces.SVG);
-    knownXHTMLContentDocsNamespaces.add(Namespaces.XHTML);
-    knownXHTMLContentDocsNamespaces.add(Namespaces.XMLEVENTS);
-    knownXHTMLContentDocsNamespaces.add(Namespaces.XML);
-    knownXHTMLContentDocsNamespaces.add(Namespaces.XLINK);
-  }
-
   private Attributes preprocessAttributes(String elemNamespace, String elemName, String elemQName,
       Attributes originalAttribs)
   {
     AttributesImpl attributes = new AttributesImpl(originalAttribs);
-    if ("application/xhtml+xml".equals(context.mimeType)
-        && context.version == EPUBVersion.VERSION_3)
+    try
     {
-      try
+      for (int i = attributes.getLength() - 1; i >= 0; i--)
       {
-        for (int i = attributes.getLength() - 1; i >= 0; i--)
+        if (context.version == EPUBVersion.VERSION_3)
         {
-          if (isDataAttribute(attributes, i) || isCustomNamespaceAttribute(attributes, i))
+          // Remove data-* attributes in both XHTML and SVG
+          if (isDataAttribute(attributes, i))
           {
             attributes.removeAttribute(i);
           }
-          else if (Namespaces.XHTML.equals(elemNamespace)
+          // Remove custom namespace attributes in XHTML
+          else if ("application/xhtml+xml".equals(context.mimeType)
+              && isHTMLCustomNamespace(attributes.getURI(i)))
+          {
+            attributes.removeAttribute(i);
+          }
+          // Normalize case of case-insensitive attributes in XHTML
+          else if ("application/xhtml+xml".equals(context.mimeType)
+              && Namespaces.XHTML.equals(elemNamespace)
               && isCaseInsensitiveAttribute(attributes, i))
           {
             attributes.setValue(i, attributes.getValue(i).toLowerCase(Locale.ENGLISH));
           }
         }
-      } catch (Exception e)
-      {
-        throw new IllegalStateException("data-* removal exception", e);
       }
+    } catch (Exception e)
+    {
+      throw new IllegalStateException("Unexpected error when pre-processing attributes", e);
     }
     return attributes;
   }
 
   private static boolean isDataAttribute(Attributes attributes, int index)
   {
-    return attributes.getLocalName(index).startsWith("data-");
+    return "".equals(attributes.getURI(index))
+        && attributes.getLocalName(index).startsWith("data-");
   }
 
-  private boolean isCustomNamespaceAttribute(Attributes attributes, int index)
+  private static final Set<String> KNOWN_XHTML_NAMESPACES = ImmutableSet.of(Namespaces.XHTML,
+      Namespaces.XML, Namespaces.OPS, Namespaces.SVG, Namespaces.MATHML, Namespaces.SSML,
+      Namespaces.XMLEVENTS, Namespaces.XLINK);
+
+  private static boolean isHTMLCustomNamespace(String namespace)
   {
-    String ns = attributes.getURI(index);
-    return (ns != null && ns.trim().length() > 0
-        && !knownXHTMLContentDocsNamespaces.contains(ns.trim()));
+    if (namespace == null || namespace.trim().isEmpty()) return false;
+    return !KNOWN_XHTML_NAMESPACES.contains(namespace.trim());
   }
 
   private static boolean isCaseInsensitiveAttribute(Attributes attributes, int index)

src/main/java/com/adobe/epubcheck/xml/XMLValidators.java

@@ -37,6 +37,7 @@ public enum XMLValidators
   SIG_30_RNC("schema/30/ocf-signatures-30.rnc"),
   SVG_20_RNG("schema/20/rng/svg11.rng"),
   SVG_30_RNC("schema/30/epub-svg-30.rnc"),
+  SVG_30_NVDL("schema/30/epub-svg-30.nvdl"),
   SVG_30_SCH("schema/30/epub-svg-30.sch"),
   XHTML_20_NVDL("schema/20/rng/ops20.nvdl"),
   XHTML_20_SCH("schema/20/sch/xhtml.sch"),

src/main/resources/com/adobe/epubcheck/schema/30/epub-svg-30.nvdl

@@ -1,15 +1,54 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <rules xmlns="http://purl.oclc.org/dsdl/nvdl/ns/structure/1.0" startMode="svg">
-  <mode name="svg">
-    <namespace ns="http://www.w3.org/2000/svg">
-      <validate schema="epub-svg-30.rnc" schemaType="application/relax-ng-compact-syntax"
-        useMode="attach"/>
-      <validate schema="epub-svg-30.sch" useMode="attach"/>
-    </namespace>
-  </mode>
-  <mode name="attach">
-    <anyNamespace>
-      <attach/>
-    </anyNamespace>
-  </mode>
+	<mode name="svg">
+		<namespace ns="http://www.w3.org/2000/svg">
+			<validate schema="epub-svg-30.rnc" schemaType="application/relax-ng-compact-syntax"
+				useMode="allowForeignNS">
+				<context path="foreignObject" useMode="allowHTMLOnly"/>
+			</validate>
+			<validate schema="epub-svg-30.sch" useMode="attachAnyNS"/>
+		</namespace>
+	</mode>
+	<mode name="allowForeignNS">
+		<namespace ns="http://www.w3.org/1999/xhtml">
+			<attach/>
+		</namespace>
+		<namespace ns="http://www.idpf.org/2007/ops" match="attributes">
+			<attach/>
+		</namespace>
+		<namespace ns="http://www.w3.org/1999/xlink" match="attributes">
+			<attach/>
+		</namespace>
+		<namespace ns="http://www.w3.org/XML/1998/namespace" match="attributes">
+			<attach/>
+		</namespace>
+		<namespace ns="" match="attributes">
+			<attach/>
+		</namespace>
+		<anyNamespace match="elements attributes">
+			<allow/>
+		</anyNamespace>
+	</mode>
+	<mode name="allowHTMLOnly">
+		<namespace ns="http://www.w3.org/1999/xhtml">
+			<attach/>
+		</namespace>
+		<namespace ns="http://www.idpf.org/2007/ops" match="attributes">
+			<attach/>
+		</namespace>
+		<namespace ns="http://www.w3.org/1999/xlink" match="attributes">
+			<attach/>
+		</namespace>
+		<namespace ns="http://www.w3.org/XML/1998/namespace" match="attributes">
+			<attach/>
+		</namespace>
+		<namespace ns="" match="attributes">
+			<attach/>
+		</namespace>
+	</mode>
+	<mode name="attachAnyNS">
+		<anyNamespace>
+			<attach/>
+		</anyNamespace>
+	</mode>
 </rules>

src/main/resources/com/adobe/epubcheck/schema/30/epub-svg-30.sch

@@ -3,6 +3,7 @@
 
     <ns uri="http://www.w3.org/2000/svg" prefix="svg" />
 
+    <pattern></pattern>
     <include href="./mod/id-unique.sch"/>
     <include href="./mod/epub-svg11-re.sch"/>
 

src/test/java/com/adobe/epubcheck/ops/OPSCheckerTest.java

@@ -159,21 +159,7 @@ public void setup()
     expectedFatals.clear();
     expectedUsage.clear();
   }
-
-  @Test
-  public void testValidateSVGRectInvalid()
-  {
-    Collections.addAll(expectedErrors, MessageId.RSC_005, MessageId.RSC_005, MessageId.RSC_005,
-        MessageId.RSC_005);
-    testValidateDocument("svg/invalid/rect.svg", "image/svg+xml", EPUBVersion.VERSION_3);
-  }
-
-  @Test
-  public void testValidateSVGRectValid()
-  {
-    testValidateDocument("svg/valid/rect.svg", "image/svg+xml", EPUBVersion.VERSION_3);
-  }
-
+
   @Test
   public void testValidateXHTMLEdits001()
   {
@@ -706,13 +692,66 @@ public void testValidateSVG_ValidStyleWithoutType_issue688()
     testValidateDocument("svg/valid/issue688.svg", "image/svg+xml", EPUBVersion.VERSION_3);
   }
 
+  @Test
+  public void testValidateSVG_WithDataAttribute()
+  {
+    testValidateDocument("svg/valid/data-attribute.svg", "image/svg+xml", EPUBVersion.VERSION_3);
+  }
+
+  @Test
+  public void testValidateSVG_WithCustomNamespace()
+  {
+    testValidateDocument("svg/valid/custom-ns.svg", "image/svg+xml", EPUBVersion.VERSION_3);
+  }
+
   @Test
   public void testValidateSVG_Links_MisssingTitle()
   {
     expectedWarnings.add(MessageId.ACC_011);
     testValidateDocument("svg/invalid/svg-links.svg", "image/svg+xml", EPUBVersion.VERSION_3);
   }
 
+  @Test
+  public void testValidateSVG_ForeignObject()
+  {
+    // tests that 'foreignObject' conforming to the rules is accepted
+    testValidateDocument("svg/valid/foreignObject.svg", "image/svg+xml", EPUBVersion.VERSION_3);
+  }
+
+  @Test
+  public void testValidateSVG_ForeignObjectWithInvalidRequiredExtensions()
+  {
+    // tests that 'foreignObject' with a 'requiredExtensions' attribute other than the OPS NS is invalid 
+    expectedErrors.add(MessageId.RSC_005);
+    testValidateDocument("svg/invalid/foreignObject-invalid-requiredExtensions.svg", "image/svg+xml", EPUBVersion.VERSION_3);
+  }
+
+  @Test
+  public void testValidateSVG_ForeignObjectWithNonXHTMLContent()
+  {
+    // tests that 'foreignObject' can't have children that are not HTML content 
+    expectedErrors.add(MessageId.RSC_005);
+    testValidateDocument("svg/invalid/foreignObject-non-html-content.svg", "image/svg+xml", EPUBVersion.VERSION_3);
+  }
+
+  @Test
+  public void testValidateSVG_ForeignObjectWithTwoBodyElements()
+  {
+    // tests that 'foreignObject' can't have children that are not HTML content 
+    expectedErrors.add(MessageId.RSC_005);
+    testValidateDocument("svg/invalid/foreignObject-two-body.svg", "image/svg+xml", EPUBVersion.VERSION_3);
+  }
+
+
+  @Test
+  public void testValidateSVG_DuplicateIds()
+  {
+    // tests that duplicate IDs are detected 
+    Collections.addAll(expectedErrors, MessageId.RSC_005, MessageId.RSC_005);
+    testValidateDocument("svg/invalid/duplicate-ids.svg", "image/svg+xml", EPUBVersion.VERSION_3);
+  }
+
+
   @Test
   public void testValidateXHTMLIssue204()
   {