From 82641d77bb4d421ae6190f0b99484f668ebc2106 Mon Sep 17 00:00:00 2001
From: Stefan Bodewig <bodewig@apache.org>
Date: Sun, 27 Jan 2013 16:36:52 +0000
Subject: [PATCH] don't search beyond the start of the archive

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@1439115 13f79535-47bb-0310-9956-ffa450edef68
---
 src/main/org/apache/tools/zip/ZipFile.java | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/src/main/org/apache/tools/zip/ZipFile.java b/src/main/org/apache/tools/zip/ZipFile.java
index 0f09d0fd2..393fff4ca 100644
--- a/src/main/org/apache/tools/zip/ZipFile.java
+++ b/src/main/org/apache/tools/zip/ZipFile.java
@@ -667,13 +667,19 @@ public class ZipFile {
     private void positionAtCentralDirectory()
         throws IOException {
         positionAtEndOfCentralDirectoryRecord();
-        archive.seek(archive.getFilePointer() - ZIP64_EOCDL_LENGTH);
-        archive.readFully(WORD_BUF);
-        boolean found = Arrays.equals(ZipOutputStream.ZIP64_EOCD_LOC_SIG,
-                                      WORD_BUF);
+        boolean found = false;
+        boolean searchedForZip64EOCD =
+            archive.getFilePointer() > ZIP64_EOCDL_LENGTH;
+        if (searchedForZip64EOCD) {
+            archive.seek(archive.getFilePointer() - ZIP64_EOCDL_LENGTH);
+            archive.readFully(WORD_BUF);
+            found = Arrays.equals(ZipOutputStream.ZIP64_EOCD_LOC_SIG, WORD_BUF);
+        }
         if (!found) {
             // not a ZIP64 archive
-            skipBytes(ZIP64_EOCDL_LENGTH - WORD);
+            if (searchedForZip64EOCD) {
+                skipBytes(ZIP64_EOCDL_LENGTH - WORD);
+            }
             positionAtCentralDirectory32();
         } else {
             positionAtCentralDirectory64();