#403 / #375 - When looking for Zip64CentralDirLocatorSignature, take account of the blocks fixed size.

Numpsy · Numpsy · commit a60c2217860f · 2020-01-06T16:46:41.000Z
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 - sizeof(int),
+				ZipConstants.Zip64EndOfCentralDirectoryLocatorSize,
+				0);
+
+			if (locatedZip64EndOfCentralDirLocator < 0)
 			{
 				if (requireZip64)
 				{

Original file line number	Diff line number	Diff line change
`@@ -3422,8 +3422,16 @@ private void ReadEntries()`
`3422`	`3422`	`}`
`3423`	`3423`
`3424`	`3424`	`// #357 - always check for the existance of the Zip64 central directory.`
`3425`		`- long locatedZip64EndOfCentralDir = LocateBlockWithSignature(ZipConstants.Zip64CentralDirLocatorSignature, locatedEndOfCentralDir, 0, 0x1000);`
`3426`		`- if (locatedZip64EndOfCentralDir < 0)`
	`3425`	`+ // #403 - Take account of the fixed size of the locator when searching.`
	`3426`	`+ // Subtract from locatedEndOfCentralDir so that the endLocation is the location of EndOfCentralDirectorySignature,`
	`3427`	`+ // rather than the data following the signature.`
	`3428`	`+ long locatedZip64EndOfCentralDirLocator = LocateBlockWithSignature(`
	`3429`	`+ ZipConstants.Zip64CentralDirLocatorSignature,`
	`3430`	`+ locatedEndOfCentralDir - sizeof(int),`
	`3431`	`+ ZipConstants.Zip64EndOfCentralDirectoryLocatorSize,`
	`3432`	`+ 0);`
	`3433`	`+`
	`3434`	`+ if (locatedZip64EndOfCentralDirLocator < 0)`
`3427`	`3435`	`{`
`3428`	`3436`	`if (requireZip64)`
`3429`	`3437`	`{`