1 // Copyright 2016 Google Inc. All rights reserved. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package com.google.archivepatcher.generator; 16 17 import com.google.archivepatcher.shared.JreDeflateParameters; 18 import com.google.archivepatcher.shared.PatchConstants; 19 import com.google.archivepatcher.shared.TypedRange; 20 import java.io.BufferedInputStream; 21 import java.io.DataOutputStream; 22 import java.io.File; 23 import java.io.FileInputStream; 24 import java.io.IOException; 25 import java.io.OutputStream; 26 27 /** 28 * Writes patches. 29 */ 30 public class PatchWriter { 31 /** 32 * The patch plan. 33 */ 34 private final PreDiffPlan plan; 35 36 /** 37 * The expected size of the delta-friendly old file, provided as a convenience for the patch 38 * <strong>applier</strong> to reserve space on the filesystem for applying the patch. 39 */ 40 private final long deltaFriendlyOldFileSize; 41 42 /** 43 * The expected size of the delta-friendly new file, provided for forward compatibility. 44 */ 45 private final long deltaFriendlyNewFileSize; 46 47 /** 48 * The delta that transforms the old delta-friendly file into the new delta-friendly file. 49 */ 50 private final File deltaFile; 51 52 /** 53 * Creates a new patch writer. 54 * 55 * @param plan the patch plan 56 * @param deltaFriendlyOldFileSize the expected size of the delta-friendly old file, provided as a 57 * convenience for the patch <strong>applier</strong> to reserve space on the filesystem for 58 * applying the patch 59 * @param deltaFriendlyNewFileSize the expected size of the delta-friendly new file, provided for 60 * forward compatibility 61 * @param deltaFile the delta that transforms the old delta-friendly file into the new 62 * delta-friendly file 63 */ PatchWriter( PreDiffPlan plan, long deltaFriendlyOldFileSize, long deltaFriendlyNewFileSize, File deltaFile)64 public PatchWriter( 65 PreDiffPlan plan, 66 long deltaFriendlyOldFileSize, 67 long deltaFriendlyNewFileSize, 68 File deltaFile) { 69 this.plan = plan; 70 this.deltaFriendlyOldFileSize = deltaFriendlyOldFileSize; 71 this.deltaFriendlyNewFileSize = deltaFriendlyNewFileSize; 72 this.deltaFile = deltaFile; 73 } 74 75 /** 76 * Write a v1-style patch to the specified output stream. 77 * @param out the stream to write the patch to 78 * @throws IOException if anything goes wrong 79 */ writeV1Patch(OutputStream out)80 public void writeV1Patch(OutputStream out) throws IOException { 81 // Use DataOutputStream for ease of writing. This is deliberately left open, as closing it would 82 // close the output stream that was passed in and that is not part of the method's documented 83 // behavior. 84 @SuppressWarnings("resource") 85 DataOutputStream dataOut = new DataOutputStream(out); 86 87 dataOut.write(PatchConstants.IDENTIFIER.getBytes("US-ASCII")); 88 dataOut.writeInt(0); // Flags (reserved) 89 dataOut.writeLong(deltaFriendlyOldFileSize); 90 91 // Write out all the delta-friendly old file uncompression instructions 92 dataOut.writeInt(plan.getOldFileUncompressionPlan().size()); 93 for (TypedRange<Void> range : plan.getOldFileUncompressionPlan()) { 94 dataOut.writeLong(range.getOffset()); 95 dataOut.writeLong(range.getLength()); 96 } 97 98 // Write out all the delta-friendly new file recompression instructions 99 dataOut.writeInt(plan.getDeltaFriendlyNewFileRecompressionPlan().size()); 100 for (TypedRange<JreDeflateParameters> range : plan.getDeltaFriendlyNewFileRecompressionPlan()) { 101 dataOut.writeLong(range.getOffset()); 102 dataOut.writeLong(range.getLength()); 103 // Write the deflate information 104 dataOut.write(PatchConstants.CompatibilityWindowId.DEFAULT_DEFLATE.patchValue); 105 dataOut.write(range.getMetadata().level); 106 dataOut.write(range.getMetadata().strategy); 107 dataOut.write(range.getMetadata().nowrap ? 1 : 0); 108 } 109 110 // Now the delta section 111 // First write the number of deltas present in the patch. In v1, there is always exactly one 112 // delta, and it is for the entire input; in future versions there may be multiple deltas, of 113 // arbitrary types. 114 dataOut.writeInt(1); 115 // In v1 the delta format is always bsdiff, so write it unconditionally. 116 dataOut.write(PatchConstants.DeltaFormat.BSDIFF.patchValue); 117 118 // Write the working ranges. In v1 these are always the entire contents of the delta-friendly 119 // old file and the delta-friendly new file. These are for forward compatibility with future 120 // versions that may allow deltas of arbitrary formats to be mapped to arbitrary ranges. 121 dataOut.writeLong(0); // i.e., start of the working range in the delta-friendly old file 122 dataOut.writeLong(deltaFriendlyOldFileSize); // i.e., length of the working range in old 123 dataOut.writeLong(0); // i.e., start of the working range in the delta-friendly new file 124 dataOut.writeLong(deltaFriendlyNewFileSize); // i.e., length of the working range in new 125 126 // Finally, the length of the delta and the delta itself. 127 dataOut.writeLong(deltaFile.length()); 128 try (FileInputStream deltaFileIn = new FileInputStream(deltaFile); 129 BufferedInputStream deltaIn = new BufferedInputStream(deltaFileIn)) { 130 byte[] buffer = new byte[32768]; 131 int numRead = 0; 132 while ((numRead = deltaIn.read(buffer)) >= 0) { 133 dataOut.write(buffer, 0, numRead); 134 } 135 } 136 dataOut.flush(); 137 } 138 } 139