src/com/facebook/buck/step/fs/XzStep.java

/*
 * Copyright 2012-present Facebook, Inc.
 *
 * 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.
 */

package com.facebook.buck.step.fs;

import com.facebook.buck.step.ExecutionContext;
import com.facebook.buck.step.Step;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Joiner;
import com.google.common.base.Preconditions;
import com.google.common.io.ByteStreams;

import org.tukaani.xz.LZMA2Options;
import org.tukaani.xz.XZ;
import org.tukaani.xz.XZOutputStream;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * A {@link Step} to compress a file with XZ / LZMA2.
 *
 * @see <a href="http://tukaani.org/xz/">XZ</a>
 * @see <a href="http://tukaani.org/xz/java.html">XZ for Java</a>
 * @see <a href="http://tukaani.org/xz/embedded.html">XZ Embedded</a>
 */
public class XzStep implements Step {

  private final String sourceFile;
  private final String destinationFile;
  private final int compressionLevel;
  private final boolean keep;
  private final int check;

  /**
   * Create an {@link XzStep} to compress a file using XZ.
   * @param sourceFile file to compress
   * @param destinationFile where to store compressed data
   * @param compressionLevel a value between 0-9, it impacts memory requirements for decompression
   * @param keep by default, {@code xz} deletes the source file when compressing. This argument
   *     forces {@code xz} to keep it.
   * @param check integrity check to use. Must be one of {@link XZ#CHECK_CRC32},
   *     {@link XZ#CHECK_CRC64}, {@link XZ#CHECK_SHA256}, {@link XZ#CHECK_NONE}
   *     (Note: XZ Embedded can only verify CRC32).
   */
  @VisibleForTesting
  XzStep(
      String sourceFile,
      String destinationFile,
      int compressionLevel,
      boolean keep,
      int check) {
    this.sourceFile = Preconditions.checkNotNull(sourceFile);
    this.destinationFile = Preconditions.checkNotNull(destinationFile);
    Preconditions.checkArgument(compressionLevel >= LZMA2Options.PRESET_MIN &&
        compressionLevel <= LZMA2Options.PRESET_MAX, "compressionLevel out of bounds.");
    this.compressionLevel = compressionLevel;
    this.keep = keep;
    this.check = check;
  }

  /**
   * Creates an XzStep to compress a file with XZ compression level 4.
   *
   * <p> The destination file will be {@code sourceFile} with the added {@code .xz} extension.
   * <p> Decompression will require 5MiB of RAM.
   *
   * @param sourceFile file to compress
   */
  public XzStep(String sourceFile) {
    this(
        sourceFile,
        sourceFile + ".xz",
        /* compressionLevel */ 4,
        /* keep */ false,
        XZ.CHECK_CRC32);
  }

  @Override
  public int execute(ExecutionContext context) {
    try (
        InputStream in = new BufferedInputStream(new FileInputStream(sourceFile));
        OutputStream out = new BufferedOutputStream(new FileOutputStream(getDestinationFile()));
        XZOutputStream xzOut = new XZOutputStream(out, new LZMA2Options(compressionLevel), check);
    ) {
      ByteStreams.copy(in, xzOut);
      xzOut.finish();
    } catch (IOException e) {
      e.printStackTrace(context.getStdErr());
      return 1;
    }
    if (!keep && !context.getProjectFilesystem().deleteFileAtPath(sourceFile)) {
      return 1;
    }
    return 0;
  }

  public String getDestinationFile() {
    return destinationFile;
  }

  @Override
  public String getDescription(ExecutionContext context) {
    return Joiner.on(" ").skipNulls().join(
     "xz", "-z", "-" + compressionLevel, (keep ? "--keep" : null), "--check=crc32", sourceFile);
  }

  @Override
  public String getShortName() {
    return "xz";
  }
}