fixes #324 - parsing of ZIP64 extra entry

Author: Thomas Benndorf

lib/parseExtraField.js

@@ -6,19 +6,22 @@ module.exports = function(extraField, vars) {
   while(!extra && extraField && extraField.length) {
     const candidateExtra = parseBuffer.parse(extraField, [
       ['signature', 2],
-      ['partsize', 2],
-      ['uncompressedSize', 8],
-      ['compressedSize', 8],
-      ['offset', 8],
-      ['disknum', 8],
+      ['partSize', 2],
     ]);
 
     if(candidateExtra.signature === 0x0001) {
-      extra = candidateExtra;
+      // parse buffer based on data in ZIP64 central directory; order is important!
+      const fieldsToExpect = [];
+      if (vars.uncompressedSize === 0xffffffff) fieldsToExpect.push(['uncompressedSize', 8]);
+      if (vars.compressedSize === 0xffffffff) fieldsToExpect.push(['compressedSize', 8]);
+      if (vars.offsetToLocalFileHeader === 0xffffffff) fieldsToExpect.push(['offsetToLocalFileHeader', 8]);
+
+      // slice off the 4 bytes for signature and partSize
+      extra = parseBuffer.parse(extraField.slice(4), fieldsToExpect);
     } else {
       // Advance the buffer to the next part.
       // The total size of this part is the 4 byte header + partsize.
-      extraField = extraField.slice(candidateExtra.partsize + 4);
+      extraField = extraField.slice(candidateExtra.partSize + 4);
     }
   }
 
@@ -31,7 +34,7 @@ module.exports = function(extraField, vars) {
     vars.uncompressedSize= extra.uncompressedSize;
 
   if (vars.offsetToLocalFileHeader === 0xffffffff)
-    vars.offsetToLocalFileHeader= extra.offset;
+    vars.offsetToLocalFileHeader = extra.offsetToLocalFileHeader;
 
   return extra;
 };