CaptureStreamHandler.java

/*
 * #%L
 * Native ARchive plugin for Maven
 * %%
 * Copyright (C) 2002 - 2014 NAR Maven Plugin developers.
 * %%
 * Licensed 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.
 * #L%
 */
// BEGINFREEHEP, fully replaced with a runner with threads
package com.github.maven_nar.cpptasks.compiler;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.util.Vector;

import org.apache.tools.ant.taskdefs.Execute;
import org.apache.tools.ant.taskdefs.ExecuteStreamHandler;

/**
 * Implements ExecuteStreamHandler to capture the output of a Execute to an
 * array of strings
 *
 * @author Curt Arnold
 */
public class CaptureStreamHandler implements ExecuteStreamHandler {

  static class Copier extends Thread {
    InputStream is;

    Vector<String> lines;

    Copier(final InputStream is) {
      this.is = is;
      this.lines = new Vector<>(10);
    }

    public Vector<String> getLines() {
      return this.lines;
    }

    @Override
    public void run() {
      try {
        final BufferedReader reader = new BufferedReader(new InputStreamReader(this.is));
        while (true) {
          final String line = reader.readLine();
          if (line == null) {
            break;
          }
          this.lines.addElement(line);
        }
      } catch (final IOException e) {
        // Ignore
      }
    }
  }

  /**
   * Executes the given command, capturing the output using a newly allocated
   * {@link CaptureStreamHandler}, which is then returned.
   * <p>
   * In contrast to {@link #run(String[])}, this method allows both the standard
   * error and standard output streams to be inspected after execution (via the
   * {@link #getStderr()} and {@link #getStdout()} methods, respectively).
   * </p>
   * 
   * @param cmdline
   *          command line arguments
   * @return The {@link CaptureStreamHandler} used to capture the output.
   */
  public static CaptureStreamHandler execute(final String[] cmdline) {
    final CaptureStreamHandler handler = new CaptureStreamHandler();
    final Execute exec = new Execute(handler);
    exec.setCommandline(cmdline);
    try {
      final int status = exec.execute();
    } catch (final IOException ex) {
    }
    return handler;
  }

  /**
   * Runs an executable and captures the output in a String array
   * 
   * @param cmdline
   *          command line arguments
   * @return output of process
   * @see CaptureStreamHandler#getOutput()
   */
  public static String[] run(final String[] cmdline) {
    final CaptureStreamHandler handler = execute(cmdline);
    return handler.getOutput() != null ? handler.getOutput() : new String[0];
  }

  private String[] stderr;

  private String[] stdout;

  private InputStream processErrorStream;

  private InputStream processOutputStream;

  public CaptureStreamHandler() {
  }

  /**
   * Reads concurrently both the process standard output and standard error.
   * The standard error is copied to the stderr string array field.
   * The standard output is copied to the stdout string array field.
   * Both fields are set to an empty array in case of any error.
   */
  public void gatherOutput() {
    try {
      final Copier errorCopier = new Copier(this.processErrorStream);
      final Copier outputCopier = new Copier(this.processOutputStream);
      errorCopier.start();
      outputCopier.start();
      errorCopier.join();
      outputCopier.join();
      this.stderr = new String[errorCopier.getLines().size()];
      errorCopier.getLines().copyInto(this.stderr);
      this.stdout = new String[outputCopier.getLines().size()];
      outputCopier.getLines().copyInto(this.stdout);
    } catch (final Exception e) {
      this.stderr = this.stdout = new String[0];
    }
  }

  /**
   * Gets the output of the execution. If standard error is not empty,
   * it is returned; otherwise, standard output is returned.
   */
  public String[] getOutput() {
    return null != this.stderr && this.stderr.length > 0 ? this.stderr : this.stdout;
  }

  /** Gets the output of the execution's standard error stream. */
  public String[] getStderr() {
    return this.stderr;
  }

  /** Gets the output of the execution's standard output stream. */
  public String[] getStdout() {
    return this.stdout;
  }

  /**
   * Install a handler for the error stream of the subprocess.
   * 
   * @param is
   *          input stream to read from the error stream from the subprocess
   */
  @Override
  public void setProcessErrorStream(final InputStream is) throws IOException {
    this.processErrorStream = is;
  }

  /**
   * Install a handler for the input stream of the subprocess.
   * 
   * @param os
   *          output stream to write to the standard input stream of the
   *          subprocess
   */
  @Override
  public void setProcessInputStream(final OutputStream os) throws IOException {
    os.close();
  }

  /**
   * Install a handler for the output stream of the subprocess.
   * 
   * @param is
   *          input stream to read from the error stream from the subprocess
   */
  @Override
  public void setProcessOutputStream(final InputStream is) throws IOException {
    this.processOutputStream = is;
  }

  /**
   * Start handling of the streams.
   */
  @Override
  public void start() throws IOException {
    gatherOutput();
  }

  /**
   * Stop handling of the streams - will not be restarted.
   */
  @Override
  public void stop() {
  }
  // ENDFREEHEP
}