When looking for Zip64CentralDirLocatorSignature, take account of the…

… blocks fixed size. refs icsharpcode#403/icsharpcode#375
Numpsy · Jan 7, 2020 · baed5f2 · baed5f2
1 parent 749e025
commit baed5f2
Showing 1 changed file with 10 additions and 2 deletions.
diff --git a/src/ICSharpCode.SharpZipLib/Zip/ZipFile.cs b/src/ICSharpCode.SharpZipLib/Zip/ZipFile.cs
@@ -3422,8 +3422,16 @@ private void ReadEntries()
 			}
 
 			// #357 - always check for the existance of the Zip64 central directory.
-			long locatedZip64EndOfCentralDir = LocateBlockWithSignature(ZipConstants.Zip64CentralDirLocatorSignature, locatedEndOfCentralDir, 0, 0x1000);
-			if (locatedZip64EndOfCentralDir < 0)
+			// #403 - Take account of the fixed size of the locator when searching.
+			//    Subtract from locatedEndOfCentralDir so that the endLocation is the location of EndOfCentralDirectorySignature,
+			//    rather than the data following the signature.
+			long locatedZip64EndOfCentralDirLocator = LocateBlockWithSignature(
+				ZipConstants.Zip64CentralDirLocatorSignature,
+				locatedEndOfCentralDir - 4,
+				ZipConstants.Zip64EndOfCentralDirectoryLocatorSize,
+				0);
+
+			if (locatedZip64EndOfCentralDirLocator < 0)
 			{
 				if (requireZip64)
 				{