content: /*
   * 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
   *
   *     https://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.avro.tool;
  
  import java.io.InputStream;
  import java.io.PrintStream;
  import java.util.List;
  
  import joptsimple.OptionParser;
  import joptsimple.OptionSet;
  import joptsimple.OptionSpec;
  
  import org.apache.avro.file.DataFileReader;
  import org.apache.avro.generic.GenericDatumReader;
  import org.apache.avro.mapred.FsInput;
  
  /** Reads a data file to get its metadata. */
  public class DataFileGetMetaTool implements Tool {
  
    @Override
    public String getName() {
      return "getmeta";
    }
  
    @Override
    public String getShortDescription() {
      return "Prints out the metadata of an Avro data file.";
    }
  
    @Override
    public int run(InputStream stdin, PrintStream out, PrintStream err, List<String> args) throws Exception {
  
      OptionParser p = new OptionParser();
      OptionSpec<String> keyOption = p.accepts("key", "Metadata key").withOptionalArg().ofType(String.class);
      OptionSet opts = p.parse(args.toArray(new String[0]));
      String keyName = keyOption.value(opts);
  
      List<String> nargs = (List<String>) opts.nonOptionArguments();
      if (nargs.size() != 1) {
        err.println("Expected 1 arg: input_file");
        p.printHelpOn(err);
        return 1;
      }
      FsInput in = Util.openSeekableFromFS(args.get(0));
      DataFileReader<Void> reader = new DataFileReader<>(in, new GenericDatumReader<>());
      if (keyName != null) {
        byte[] value = reader.getMeta(keyName);
        if (value != null) {
          out.write(value, 0, value.length);
          out.println();
        }
      } else {
        List<String> keys = reader.getMetaKeys();
        for (String key : keys) {
          out.print(escapeKey(key));
          out.print('\t');
          byte[] value = reader.getMeta(key);
          out.write(value, 0, value.length);
          out.println();
        }
      }
      reader.close();
      return 0;
    }
  
    // escape TAB, NL and CR in keys, so that output can be reliably parsed
    static String escapeKey(String key) {
      key = key.replace("\\", "\\\\"); // escape backslashes first
      key = key.replace("\t", "\\t"); // TAB
      key = key.replace("\n", "\\n"); // NL
      key = key.replace("\r", "\\r"); // CR
      return key;
    }
  
  }
  