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From bode...@apache.org
Subject [3/3] commons-compress git commit: fix calculation of self-copy boundaries when expanding back-references
Date Thu, 06 Apr 2017 13:18:32 GMT
fix calculation of self-copy boundaries when expanding back-references


Project: http://git-wip-us.apache.org/repos/asf/commons-compress/repo
Commit: http://git-wip-us.apache.org/repos/asf/commons-compress/commit/5ce60be9
Tree: http://git-wip-us.apache.org/repos/asf/commons-compress/tree/5ce60be9
Diff: http://git-wip-us.apache.org/repos/asf/commons-compress/diff/5ce60be9

Branch: refs/heads/master
Commit: 5ce60be9d55c62b72262680249ad933850aaa064
Parents: 62202d2
Author: Stefan Bodewig <bodewig@apache.org>
Authored: Thu Apr 6 15:18:00 2017 +0200
Committer: Stefan Bodewig <bodewig@apache.org>
Committed: Thu Apr 6 15:18:00 2017 +0200

----------------------------------------------------------------------
 .../lz4/BlockLZ4CompressorOutputStream.java     |  4 ++--
 .../lz4/BlockLZ4CompressorOutputStreamTest.java | 23 ++++++++++++++++++++
 2 files changed, 25 insertions(+), 2 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/commons-compress/blob/5ce60be9/src/main/java/org/apache/commons/compress/compressors/lz4/BlockLZ4CompressorOutputStream.java
----------------------------------------------------------------------
diff --git a/src/main/java/org/apache/commons/compress/compressors/lz4/BlockLZ4CompressorOutputStream.java
b/src/main/java/org/apache/commons/compress/compressors/lz4/BlockLZ4CompressorOutputStream.java
index dfce36e..71ca713 100644
--- a/src/main/java/org/apache/commons/compress/compressors/lz4/BlockLZ4CompressorOutputStream.java
+++ b/src/main/java/org/apache/commons/compress/compressors/lz4/BlockLZ4CompressorOutputStream.java
@@ -264,9 +264,9 @@ public class BlockLZ4CompressorOutputStream extends CompressorOutputStream
{
                 copyOffset = blockOffset + block.length - offsetRemaining;
                 copyLen = Math.min(lengthRemaining, block.length - copyOffset);
             } else {
-                // offsetRemaining is negative and points into the expanded bytes
+                // offsetRemaining is negative or 0 and points into the expanded bytes
                 block = expanded;
-                copyOffset = writeOffset  + offsetRemaining;
+                copyOffset = -offsetRemaining;
                 copyLen = Math.min(lengthRemaining, writeOffset + offsetRemaining);
             }
             System.arraycopy(block, copyOffset, expanded, writeOffset, copyLen);

http://git-wip-us.apache.org/repos/asf/commons-compress/blob/5ce60be9/src/test/java/org/apache/commons/compress/compressors/lz4/BlockLZ4CompressorOutputStreamTest.java
----------------------------------------------------------------------
diff --git a/src/test/java/org/apache/commons/compress/compressors/lz4/BlockLZ4CompressorOutputStreamTest.java
b/src/test/java/org/apache/commons/compress/compressors/lz4/BlockLZ4CompressorOutputStreamTest.java
index 45bf684..fca3f88 100644
--- a/src/test/java/org/apache/commons/compress/compressors/lz4/BlockLZ4CompressorOutputStreamTest.java
+++ b/src/test/java/org/apache/commons/compress/compressors/lz4/BlockLZ4CompressorOutputStreamTest.java
@@ -319,6 +319,29 @@ public class BlockLZ4CompressorOutputStreamTest {
         Assert.assertArrayEquals(expected, compressed);
     }
 
+    @Test
+    public void rewritingWithFinalBackreferenceAndOffsetBiggerThan1() throws IOException
{
+        // this caused trouble when expandFromList() fell into the "offsetRemaining is negative"
self-copy case as the
+        // calculation of copyOffset was wrong
+        byte[] toCompress = prepareExpected(25);
+        for (int i = 0; i < toCompress.length; i += 4) {
+            toCompress[i] = 1;
+        }
+        // LZ77Compressor creates a four byte literal and a back-reference with offset 4
and length 21
+        // we'll need to split the back-reference and chop off the last 12 bytes
+        byte[] compressed = compress(toCompress);
+        byte[] expected = prepareExpected(1 + 4 + 2 + 1 + 12);
+        expected[0] = (byte) ((4<<4) | 5);
+        expected[1] = 1;
+        expected[5] = 4;
+        expected[6] = 0;
+        expected[7] = (byte) (12<<4);
+        for (int i = 11; i < expected.length; i += 4) {
+            expected[i] = 1;
+        }
+        Assert.assertArrayEquals(expected, compressed);
+    }
+
     private byte[] compress(int length) throws IOException {
         return compress(length, 0);
     }


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