snuyanzin commented on code in PR #29341: URL: https://github.com/apache/flink/pull/29341#discussion_r4156732229
########## flink-table/flink-table-runtime/src/main/java/org/apache/flink/table/runtime/functions/XmlToVariantParser.java: ########## @@ -0,0 +1,588 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.flink.table.runtime.functions; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.types.variant.BinaryVariantInternalBuilder; +import org.apache.flink.types.variant.BinaryVariantInternalBuilder.FieldEntry; +import org.apache.flink.types.variant.Variant; +import org.apache.flink.types.variant.VariantTypeException; + +import javax.annotation.Nullable; +import javax.xml.XMLConstants; +import javax.xml.stream.XMLInputFactory; +import javax.xml.stream.XMLStreamConstants; +import javax.xml.stream.XMLStreamException; +import javax.xml.stream.XMLStreamReader; + +import java.io.StringReader; +import java.math.BigDecimal; +import java.math.BigInteger; +import java.time.DateTimeException; +import java.time.Instant; +import java.time.LocalDate; +import java.time.LocalDateTime; +import java.time.LocalTime; +import java.time.OffsetDateTime; +import java.time.ZoneOffset; +import java.time.format.DateTimeFormatter; +import java.time.temporal.ChronoField; +import java.time.temporal.TemporalAccessor; +import java.util.ArrayList; +import java.util.LinkedHashMap; +import java.util.List; +import java.util.Map; +import java.util.function.Consumer; + +import static org.apache.flink.types.variant.BinaryVariantInternalBuilder.toVariantDecimal; +import static org.apache.flink.types.variant.BinaryVariantUtil.SIZE_LIMIT; +import static org.apache.flink.types.variant.BinaryVariantUtil.microsSinceEpoch; +import static org.apache.flink.types.variant.BinaryVariantUtil.nanosSinceEpoch; + +/** + * Parses XML into a {@link Variant} for {@code PARSE_XML} and {@code TRY_PARSE_XML}. The mapping is + * described in the documentation of the {@code VARIANT} data type. + * + * <p>Parsing has two steps. First, the document is read into a tree of {@link XmlElement}s, which + * group the children of each element by name and apply {@code xsi:nil} and {@code xsi:type}. Then, + * the {@link VariantEncoder} writes the tree into a variant. The variant can't be written while + * reading, because the occurrences of a repeated child become one array, and they don't have to be + * next to each other in the document. + * + * <p>Instances are not thread-safe. + */ +@Internal +public final class XmlToVariantParser { + + private static final String ATTRIBUTE_PREFIX = "@"; + private static final String TEXT_KEY = "$"; + private static final String ORDER_KEY = "#"; + + private static final String XSI_NIL = "xsi:nil"; + private static final String XSI_TYPE = "xsi:type"; + private static final String XSI_NAMESPACE_DECLARATION = "xmlns:xsi"; + + private final XMLInputFactory inputFactory = createInputFactory(); + + public Variant parse(String xml, boolean forceArray) { + final XmlElement root; + try { + root = readDocument(xml); + } catch (XMLStreamException e) { + // Only the message is kept, since the location of the exception is not serializable. + throw new IllegalArgumentException(e.getMessage()); + } + return new VariantEncoder(forceArray).encodeDocument(root); + } + + private static XMLInputFactory createInputFactory() { + // The JDK implementation, regardless of other StAX implementations on the classpath. + final XMLInputFactory factory = XMLInputFactory.newDefaultFactory(); + factory.setProperty(XMLInputFactory.IS_NAMESPACE_AWARE, false); + factory.setProperty(XMLInputFactory.IS_COALESCING, true); + // Internal entities need DTD support. External entities are enabled only so that they + // reach the resolver and fail, instead of being dropped silently. The JDK refuses all + // protocols in case a load bypasses the resolver. + factory.setProperty(XMLInputFactory.SUPPORT_DTD, true); + factory.setProperty(XMLInputFactory.IS_SUPPORTING_EXTERNAL_ENTITIES, true); + factory.setProperty(XMLConstants.ACCESS_EXTERNAL_DTD, ""); + factory.setXMLResolver( + (publicId, systemId, baseUri, namespace) -> { + throw new XMLStreamException( + String.format( + "External entities and DTDs are not supported: %s", systemId)); + }); + // Set here, so that they don't depend on the JDK version or JVM-wide settings. Apart from + // the depth and the entity sizes, these are the defaults of JDK 11 to 21. + // Each element can add an object and an array to the variant, so 500 levels give at most + // the 1000 levels that PARSE_JSON allows. + setLimit(factory, "maxElementDepth", 500); + setLimit(factory, "entityExpansionLimit", 64_000); + setLimit(factory, "totalEntitySizeLimit", SIZE_LIMIT); + setLimit(factory, "maxGeneralEntitySizeLimit", SIZE_LIMIT); + setLimit(factory, "maxParameterEntitySizeLimit", 1_000_000); + setLimit(factory, "elementAttributeLimit", 10_000); + setLimit(factory, "maxXMLNameLimit", 1_000); + return factory; + } + + private static void setLimit(XMLInputFactory factory, String limit, int value) { + factory.setProperty("http://www.oracle.com/xml/jaxp/properties/"; + limit, value); + } + + private XmlElement readDocument(String xml) throws XMLStreamException { + final XMLStreamReader reader = inputFactory.createXMLStreamReader(new StringReader(xml)); + try { + // XML 1.1 allows characters that XML 1.0 can't represent, e.g. most control characters. + // Accepting only XML 1.0 keeps every result representable as XML 1.0. + if ("1.1".equals(reader.getVersion())) { Review Comment: can we have an enum with supported version? -- This is an automated message from the Apache Git Service. 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