[GitHub] [parquet-mr] ggershinsky commented on a change in pull request #867: PARQUET-1978: Provide a tool to show the complete footer

[GitBox <gi...@apache.org>]

ggershinsky commented on a change in pull request #867:
URL: https://github.com/apache/parquet-mr/pull/867#discussion_r573915631



##########
File path: parquet-cli/src/main/java/org/apache/parquet/cli/commands/ShowFooterCommand.java
##########
@@ -0,0 +1,150 @@
+/*
+ * 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.parquet.cli.commands;
+
+import static org.apache.parquet.bytes.BytesUtils.readIntLittleEndian;
+import static org.apache.parquet.hadoop.ParquetFileWriter.EFMAGIC;
+import static org.apache.parquet.hadoop.ParquetFileWriter.MAGIC;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+import java.util.List;
+
+import org.apache.parquet.bytes.ByteBufferInputStream;
+import org.apache.parquet.cli.BaseCommand;
+import org.apache.parquet.format.CliUtils;
+import org.apache.parquet.format.Util;
+import org.apache.parquet.hadoop.ParquetFileReader;
+import org.apache.parquet.hadoop.metadata.ParquetMetadata;
+import org.apache.parquet.hadoop.util.HadoopInputFile;
+import org.apache.parquet.io.InputFile;
+import org.apache.parquet.io.SeekableInputStream;
+import org.slf4j.Logger;
+
+import com.beust.jcommander.Parameter;
+import com.beust.jcommander.Parameters;
+import com.fasterxml.jackson.annotation.JsonAutoDetect.Visibility;
+import com.fasterxml.jackson.annotation.PropertyAccessor;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.SerializationFeature;
+
+@Parameters(commandDescription = "Print the Parquet file footer in json format")
+public class ShowFooterCommand extends BaseCommand {
+
+  public ShowFooterCommand(Logger console) {
+    super(console);
+  }
+
+  @Parameter(description = "<parquet path>", required = true)
+  String target;
+
+  @Parameter(names = { "-r", "--raw" }, description = "Print the raw thrift object of the footer")
+  boolean raw = false;
+
+  @Override
+  public int run() throws IOException {
+    InputFile inputFile = HadoopInputFile.fromPath(qualifiedPath(target), getConf());
+
+    String json;
+    if (raw) {
+      json = readRawFooter(inputFile);
+    } else {
+      json = readFooter(inputFile);
+    }
+    console.info(json);
+
+    return 0;
+  }
+
+  private String readFooter(InputFile inputFile) throws JsonProcessingException, IOException {
+    String json;
+    try (ParquetFileReader reader = ParquetFileReader.open(inputFile)) {
+      ParquetMetadata footer = reader.getFooter();
+      ObjectMapper mapper = createObjectMapper();
+      mapper.setVisibility(PropertyAccessor.ALL, Visibility.NONE);
+      mapper.setVisibility(PropertyAccessor.FIELD, Visibility.ANY);
+      json = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(footer);
+    }
+    return json;
+  }
+
+  private ObjectMapper createObjectMapper() {
+    ObjectMapper mapper = new ObjectMapper();
+    mapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
+    mapper.configure(SerializationFeature.ORDER_MAP_ENTRIES_BY_KEYS, true);
+    return mapper;
+  }
+
+  private String readRawFooter(InputFile file) throws IOException {
+    long fileLen = file.getLength();
+
+    int FOOTER_LENGTH_SIZE = 4;
+    if (fileLen < MAGIC.length + FOOTER_LENGTH_SIZE + MAGIC.length) { // MAGIC + data + footer + footerIndex + MAGIC
+      throw new RuntimeException("Not a Parquet file (length is too low: " + fileLen + ")");
+    }
+
+    try (SeekableInputStream f = file.newStream()) {
+      // Read footer length and magic string - with a single seek
+      byte[] magic = new byte[MAGIC.length];
+      long fileMetadataLengthIndex = fileLen - magic.length - FOOTER_LENGTH_SIZE;
+      f.seek(fileMetadataLengthIndex);
+      int fileMetadataLength = readIntLittleEndian(f);
+      f.readFully(magic);
+
+      if (Arrays.equals(EFMAGIC, magic)) {
+        throw new RuntimeException("Encrypted Parquet files are not supported.");

Review comment:
       technically, EFMAGIC is for encrypted files with encrypted footer. Encrypted files can also have the regular MAGIC, if created in plaintext footer mode.




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