Add check for local desc flag in crc check

Author: Issac Gerges

headers/entryHeader.js

@@ -220,6 +220,8 @@ module.exports = function () {
             _localHeader.version = data.readUInt16LE(Constants.LOCVER);
             // general purpose bit flag
             _localHeader.flags = data.readUInt16LE(Constants.LOCFLG);
+            // desc flag
+            _localHeader.flags_desc = (_localHeader.flags & Constants.FLG_DESC) > 0;
             // compression method
             _localHeader.method = data.readUInt16LE(Constants.LOCHOW);
             // modification time (2 bytes time, 2 bytes date)

test/crc/good_crc_trailing_data_descriptor.zip

@@ -26,6 +26,24 @@ describe("crc", () => {
         });
     });
 
+    it("Good CRC - trailing data descriptor ", (done) => {
+        const goodZip = new Zip(path.join(__dirname, "good_crc_trailing_data_descriptor.zip"));
+        const entries = goodZip.getEntries();
+        assert(entries.length === 1, "Good CRC: Test archive contains exactly 1 file");
+
+        const testFile = entries.filter(function (entry) {
+            return entry.entryName === "lorem_ipsum.txt";
+        });
+        assert(testFile.length === 1, "Good CRC: lorem_ipsum.txt file exists as archive entry");
+
+        const testFileEntryName = testFile[0].entryName;
+        goodZip.readAsTextAsync(testFileEntryName, function (data, err) {
+            assert(!err, "Good CRC: error object not present");
+            assert(data && data.length, "Good CRC: buffer not empty");
+            done();
+        });
+    });
+
     it("Bad CRC - async method returns err string", (done) => {
         const badZip = new Zip(path.join(__dirname, "bad_crc.zip"));
         const entries = badZip.getEntries();

test/crc/index.js

@@ -30,7 +30,7 @@ module.exports = function (/** object */ options, /*Buffer*/ input) {
 
     function crc32OK(data) {
         // if bit 3 (0x08) of the general-purpose flags field is set, then the CRC-32 and file sizes are not known when the local header is written
-        if (!_centralHeader.flags_desc) {
+        if (!_centralHeader.flags_desc && !_centralHeader.localHeader.flags_desc) {
             if (Utils.crc32(data) !== _centralHeader.localHeader.crc) {
                 return false;
             }