From 4df99d1ee01e5fe87c88d28cf82ae68b4aad0dd3 Mon Sep 17 00:00:00 2001 From: Carlos Amengual Date: Sat, 29 Jan 2022 18:39:15 +0100 Subject: [PATCH] Use the HTML5 entities as fallback if no subset is found in getExternalSubset See #3. --- .../xml/dtd/DefaultEntityResolverTest.java | 21 ++++- .../xml/dtd/StackedEntityResolverTest.java | 20 +++- .../xml/dtd/StackedEntityResolverTest2.java | 20 +++- .../doc/xml/dtd/DefaultEntityResolver.java | 91 +++++++++++++++++-- 4 files changed, 139 insertions(+), 13 deletions(-) diff --git a/junit/io/sf/carte/doc/xml/dtd/DefaultEntityResolverTest.java b/junit/io/sf/carte/doc/xml/dtd/DefaultEntityResolverTest.java index ae15fc6..2af40a0 100644 --- a/junit/io/sf/carte/doc/xml/dtd/DefaultEntityResolverTest.java +++ b/junit/io/sf/carte/doc/xml/dtd/DefaultEntityResolverTest.java @@ -45,9 +45,6 @@ public void getExternalSubsetStringString() throws SAXException, IOException { Reader re = isrc.getCharacterStream(); assertNotNull(re); re.close(); - // - isrc = resolver.getExternalSubset("foo", null); - assertNull(isrc); // SVG isrc = resolver.getExternalSubset("svg", null); assertNotNull(isrc); @@ -58,6 +55,24 @@ public void getExternalSubsetStringString() throws SAXException, IOException { re.close(); } + @Test + public void getExternalSubsetStringStringUnknownSubset() throws SAXException, IOException { + InputSource isrc = resolver.getExternalSubset("foo", null); + assertNotNull(isrc); + assertNull(isrc.getPublicId()); + assertNull(isrc.getSystemId()); + Reader re = isrc.getCharacterStream(); + assertNotNull(re); + char[] cbuf = new char[40]; + try { + re.read(cbuf); + } finally { + re.close(); + } + String sbuf = new String(cbuf); + assertEquals(" + * Documents with {@code DOCTYPE} declarations that omit an external subset can + * thus augment the declarations available for validation, entity processing, + * and attribute processing (normalization, defaulting, and reporting types + * including {@code ID}). This augmentation is reported through the + * {@link LexicalHandler#startDTD startDTD()} method as if the document text had + * originally included the external subset; this callback is made before any + * internal subset data or errors are reported. + *

+ *

+ * This method can also be used with documents that have no {@code DOCTYPE} + * declaration. When the root element is encountered but no {@code DOCTYPE} + * declaration has been seen, this method is invoked. If it returns a value for + * the external subset, that root element is declared to be the root element, + * giving the effect of splicing a {@code DOCTYPE} declaration at the end the + * prolog of a document that could not otherwise be valid. The sequence of + * parser callbacks in that case logically resembles this: + *

+ * + * 
+	 * ... comments and PIs from the prolog (as usual)
+	 * startDTD ("rootName", source.getPublicId (), source.getSystemId ());
+	 * startEntity ("[dtd]");
+	 * ... declarations, comments, and PIs from the external subset
+	 * endEntity ("[dtd]");
+	 * endDTD ();
+	 * ... then the rest of the document (as usual)
+	 * startElement (..., "rootName", ...);
+	 *
+ * + *

+ * Note that the {@code InputSource} gets no further resolution. Also, this + * method will never be used by a (non-validating) processor that is not + * including external parameter entities. + *

+ *

+ * Uses for this method include facilitating data validation when interoperating + * with XML processors that would always require undesirable network accesses + * for external entities, or which for other reasons adopt a "no DTDs" policy. + *

+ *

+ * Warning: returning an external subset modifies the input + * document. By providing definitions for general entities, it can make a + * malformed document appear to be well formed. + *

+ * + * @param name Identifies the document root element. This name comes from a + * {@code DOCTYPE} declaration (where available) or from the + * actual root element. + * @param baseURI The document's base URI, serving as an additional hint for + * selecting the external subset. This is always an absolute URI, + * unless it is {@code null} because the {@code XMLReader} was + * given an {@code InputSource} without one. + * + * @return an {@code InputSource} object describing the new external subset to + * be used by the parser. If no specific subset could be determined, an + * input source describing the HTML5 entities is returned. + * + * @throws SAXException if either the provided arguments or the input + * source were invalid or not allowed. + * @throws java.io.IOException if an I/O problem was found while loading the + * input source. + */ @Override public InputSource getExternalSubset(String name, String baseURI) throws SAXException, IOException { + InputSource is = findExternalSubset(name, baseURI); + if (is == null) { + // Give the HTML5 entities as a fallback + String fname = systemIdToFilename.get("https://www.w3.org/TR/html5/entities.dtd"); + Reader re = dtdLoader.loadDTDfromClasspath(loader, fname); + if (re != null) { + is = new InputSource(re); + } else { + throw new IOException("Could not find resource: " + fname); + } + } + return is; + } + + private InputSource findExternalSubset(String name, String baseURI) throws SAXException, IOException { InputSource is; if ("html".equalsIgnoreCase(name)) { is = resolveEntity("[dtd]", XHTML1_TRA_PUBLICID, baseURI, XHTML1_TRA_SYSTEMID); @@ -291,7 +373,6 @@ public InputSource getExternalSubset(String name, String baseURI) throws SAXExce is.setPublicId(null); is.setSystemId(null); } else { - // This method can return null safely: there is no SystemId URL to connect to. is = null; } return is; @@ -374,10 +455,7 @@ protected boolean registerSystemIdFilename(String systemId, String filename) { * the XML specification to be the one associated with the * "{@literal <}" starting the relevant declaration. * @param systemId The system identifier of the external entity being - * referenced; either a relative or absolute URI. This is never - * {@code null} when invoked by a SAX2 parser; only declared - * entities, and any external subset, are resolved by such - * parsers. + * referenced; either a relative or absolute URI. * * @return an {@code InputSource} object describing the new input source to be * used by the parser. This implementation never returns {@code null} if @@ -461,7 +539,8 @@ public final InputSource resolveEntity(String name, String publicId, String base InputStream is = con.getInputStream(); isrc.setCharacterStream(new InputStreamReader(is, charset)); } else { - isrc = getExternalSubset(name, baseURI); + isrc = findExternalSubset(name, baseURI); + // 'isrc' can be null safely: there is no SystemId URL to connect to } return isrc; }