[JGIT PATCH v2 3/3] Fix DirCache.findEntry to work on an empty cache

["Shawn O. Pearce" <spearce@spearce.org>]

If the cache has no entries, we want to return -1 rather than throw
ArrayIndexOutOfBoundsException.  This binary search loop was stolen
from some other code which contained a test before the loop to see if
the collection was empty or not, but we failed to include that here.

Flipping the loop around to a standard while loop ensures we test
the condition properly first.

Signed-off-by: Shawn O. Pearce <sop@google.com>
---
 .../spearce/jgit/dircache/DirCacheBasicTest.java   |    6 ++++++
 .../src/org/spearce/jgit/dircache/DirCache.java    |    6 ++----
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/org.spearce.jgit.test/tst/org/spearce/jgit/dircache/DirCacheBasicTest.java b/org.spearce.jgit.test/tst/org/spearce/jgit/dircache/DirCacheBasicTest.java
index b3097ac..4d737c0 100644
--- a/org.spearce.jgit.test/tst/org/spearce/jgit/dircache/DirCacheBasicTest.java
+++ b/org.spearce.jgit.test/tst/org/spearce/jgit/dircache/DirCacheBasicTest.java
@@ -39,6 +39,7 @@
 
 import java.io.File;
 
+import org.spearce.jgit.lib.Constants;
 import org.spearce.jgit.lib.RepositoryTestCase;
 
 public class DirCacheBasicTest extends RepositoryTestCase {
@@ -182,4 +183,9 @@ public void testBuildThenClear() throws Exception {
 		assertEquals(0, dc.getEntryCount());
 	}
 
+	public void testFindOnEmpty() throws Exception {
+		final DirCache dc = DirCache.newInCore();
+		final byte[] path = Constants.encode("a");
+		assertEquals(-1, dc.findEntry(path, path.length));
+	}
 }
diff --git a/org.spearce.jgit/src/org/spearce/jgit/dircache/DirCache.java b/org.spearce.jgit/src/org/spearce/jgit/dircache/DirCache.java
index bfb7925..9f0810a 100644
--- a/org.spearce.jgit/src/org/spearce/jgit/dircache/DirCache.java
+++ b/org.spearce.jgit/src/org/spearce/jgit/dircache/DirCache.java
@@ -583,8 +583,6 @@ public void unlock() {
 	 *         information. If < 0 the entry does not exist in the index.
 	 */
 	public int findEntry(final String path) {
-		if (entryCnt == 0)
-			return -1;
 		final byte[] p = Constants.encode(path);
 		return findEntry(p, p.length);
 	}
@@ -592,7 +590,7 @@ public int findEntry(final String path) {
 	int findEntry(final byte[] p, final int pLen) {
 		int low = 0;
 		int high = entryCnt;
-		do {
+		while (low < high) {
 			int mid = (low + high) >>> 1;
 			final int cmp = cmp(p, pLen, sortedEntries[mid]);
 			if (cmp < 0)
@@ -603,7 +601,7 @@ else if (cmp == 0) {
 				return mid;
 			} else
 				low = mid + 1;
-		} while (low < high);
+		}
 		return -(low + 1);
 	}
 
-- 
1.6.4.2.395.ge3d52