Merge pull request #451 from likev/patch-1

Scanning a local file headers is not necessary (except in the case of corrupted archives)
cthackers · Mar 13, 2024 · d95c063 · d95c063
2 parents a8f7168 + ecfe95b
commit d95c063
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Showing 2 changed files with 42 additions and 20 deletions.
diff --git a/headers/entryHeader.js b/headers/entryHeader.js
@@ -170,39 +170,60 @@ module.exports = function () {
         },
 
         get realDataOffset() {
-            return _offset + Constants.LOCHDR + _dataHeader.fnameLen + _dataHeader.extraLen;
+            return _offset + Constants.LOCHDR + _fnameLen + _extraLen;
         },
 
         get dataHeader() {
-            return _dataHeader;
-        },
-
-        loadDataHeaderFromBinary: function (/*Buffer*/ input) {
-            var data = input.slice(_offset, _offset + Constants.LOCHDR);
-            // 30 bytes and should start with "PK\003\004"
-            if (data.readUInt32LE(0) !== Constants.LOCSIG) {
-                throw new Error(Utils.Errors.INVALID_LOC);
-            }
             _dataHeader = {
                 // version needed to extract
-                version: data.readUInt16LE(Constants.LOCVER),
+                version: _version,
                 // general purpose bit flag
-                flags: data.readUInt16LE(Constants.LOCFLG),
+                flags: _flags,
                 // compression method
-                method: data.readUInt16LE(Constants.LOCHOW),
+                method: _method,
                 // modification time (2 bytes time, 2 bytes date)
-                time: data.readUInt32LE(Constants.LOCTIM),
+                time: _time,
                 // uncompressed file crc-32 value
-                crc: data.readUInt32LE(Constants.LOCCRC),
+                crc: _crc,
                 // compressed size
-                compressedSize: data.readUInt32LE(Constants.LOCSIZ),
+                compressedSize: _compressedSize,
                 // uncompressed size
-                size: data.readUInt32LE(Constants.LOCLEN),
+                size: _size,
                 // filename length
-                fnameLen: data.readUInt16LE(Constants.LOCNAM),
+                fnameLen: _fnameLen,
                 // extra field length
-                extraLen: data.readUInt16LE(Constants.LOCEXT)
+                extraLen: _extraLen
             };
+
+            return _dataHeader;
+        },
+
+        loadDataHeaderFromBinary: function (/*Buffer*/ input) {
+            var data = input.slice(_offset, _offset + Constants.LOCHDR);
+            // 30 bytes and should start with "PK\003\004"
+            if (data.readUInt32LE(0) !== Constants.LOCSIG) {
+                throw new Error(Utils.Errors.INVALID_LOC);
+            }
+
+            // version needed to extract
+            _version = data.readUInt16LE(Constants.LOCVER);
+            // general purpose bit flag
+            _flags = data.readUInt16LE(Constants.LOCFLG);
+            // compression method
+            _method = data.readUInt16LE(Constants.LOCHOW);
+            // modification time (2 bytes time, 2 bytes date)
+            _time = data.readUInt32LE(Constants.LOCTIM);
+            // uncompressed file crc-32 value
+            _crc = data.readUInt32LE(Constants.LOCCRC);
+            // compressed size
+            _compressedSize = data.readUInt32LE(Constants.LOCSIZ);
+            // uncompressed size
+            _size = data.readUInt32LE(Constants.LOCLEN);
+            // filename length
+            _fnameLen = data.readUInt16LE(Constants.LOCNAM);
+            // extra field length
+            _extraLen = data.readUInt16LE(Constants.LOCEXT);
+
         },
 
         loadFromBinary: function (/*Buffer*/ data) {

diff --git a/zipEntry.js b/zipEntry.js
@@ -15,7 +15,8 @@ module.exports = function (/*Buffer*/ input) {
         if (!input || !Buffer.isBuffer(input)) {
             return Buffer.alloc(0);
         }
-        _entryHeader.loadDataHeaderFromBinary(input);
+        //Scanning a local file headers is not necessary (except in the case of corrupted archives)
+        if(!_entryHeader.compressedSize) _entryHeader.loadDataHeaderFromBinary(input);
         return input.slice(_entryHeader.realDataOffset, _entryHeader.realDataOffset + _entryHeader.compressedSize);
     }