fail early if ZipFile is applied to a non-ZIP archive. PR 45463. Suggested by Alison Winters.

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@683942 13f79535-47bb-0310-9956-ffa450edef68

CONTRIBUTORS

@@ -4,6 +4,7 @@ Adam Blinkinsop
 Aleksandr Ishutin
 Alexey Panchenko
 Alexey Solofnenko
+Alison Winters
 Andreas Ames
 Andreas Mross
 Andrew Everitt

WHATSNEW

@@ -235,6 +235,10 @@ Other changes:
    relative file name).
    Bugzilla Report 28911.
 
+ * <unzip> will now detect that it was asked to extract a file that is
+   not an archive earlier if the file is big.
+   Bugzilla Report 45463.
+
 Changes from Ant 1.7.0 TO Ant 1.7.1
 =============================================
 

contributors.xml

@@ -46,6 +46,10 @@
     <first>Alexey</first>
     <last>Solofnenko</last>
   </name>
+  <name>
+    <first>Alison</first>
+    <last>Winters</last>
+  </name>
   <name>
     <first>Andreas</first>
     <last>Ames</last>

src/main/org/apache/tools/zip/ZipFile.java

@@ -366,6 +366,9 @@ public class ZipFile {
         /* the starting disk number        */ + WORD
         /* zipfile comment length          */ + SHORT;
 
+    private static final int MAX_EOCD_SIZE = MIN_EOCD_SIZE
+        /* maximum length of zipfile comment */ + 0xFFFF;
+
     private static final int CFD_LOCATOR_OFFSET =
         /* end of central dir signature    */ WORD
         /* number of this disk             */ + SHORT
@@ -386,11 +389,12 @@ public class ZipFile {
         throws IOException {
         boolean found = false;
         long off = archive.length() - MIN_EOCD_SIZE;
+        long stopSearching = Math.max(0L, archive.length() - MAX_EOCD_SIZE);
         if (off >= 0) {
             archive.seek(off);
             byte[] sig = ZipOutputStream.EOCD_SIG;
             int curr = archive.read();
-            while (curr != -1) {
+            while (off >= stopSearching && curr != -1) {
                 if (curr == sig[POS_0]) {
                     curr = archive.read();
                     if (curr == sig[POS_1]) {