Reject pack if delta exceeds array size limit

JGit's delta handling code requires the target to be a single byte
array. Any attempt to inflate a delta larger than fits in the 2GiB
limit will fail with some form of array index exceptions. Check for
this overflow early and abort pack parsing.

Change-Id: I5bb3a71f1e4f4e0e89b8a177c7019a74ee6194da

org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/PackParserTest.java

@@ -270,7 +270,7 @@ public class PackParserTest extends RepositoryTestCase {
 			fail("PackParser should have failed");
 		} catch (TooLargeObjectInPackException e) {
 			assertTrue(e.getMessage().contains("13")); // max obj size
-			assertFalse(e.getMessage().contains("14")); // no delta size
+			assertTrue(e.getMessage().contains("14")); // delta size
 		}
 	}
 

org.eclipse.jgit/src/org/eclipse/jgit/transport/PackParser.java

@@ -701,7 +701,7 @@ public abstract class PackParser {
 
 	private final void checkIfTooLarge(int typeCode, long size)
 			throws IOException {
-		if (0 < maxObjectSizeLimit && maxObjectSizeLimit < size)
+		if (0 < maxObjectSizeLimit && maxObjectSizeLimit < size) {
 			switch (typeCode) {
 			case Constants.OBJ_COMMIT:
 			case Constants.OBJ_TREE:
@@ -711,7 +711,7 @@ public abstract class PackParser {
 
 			case Constants.OBJ_OFS_DELTA:
 			case Constants.OBJ_REF_DELTA:
-				throw new TooLargeObjectInPackException(maxObjectSizeLimit);
+				throw new TooLargeObjectInPackException(size, maxObjectSizeLimit);
 
 			default:
 				throw new IOException(MessageFormat.format(
@@ -719,6 +719,10 @@ public abstract class PackParser {
 						Integer.valueOf(typeCode)));
 			}
 		}
+		if (size > Integer.MAX_VALUE - 8) {
+			throw new TooLargeObjectInPackException(size, Integer.MAX_VALUE - 8);
+		}
+	}
 
 	/**
 	 * Read the header of the current object.