Fix infinite loop when unpacking strings without nulls

bufferpack.js

@@ -172,6 +172,7 @@ function BufferPack() {
     bBE = (fmt.charAt(0) != '<');
 
     p = p?p:0;
+    var al = a.length;
     var re = new RegExp(this._sPattern, 'g');
     var m;
     var n;
@@ -186,6 +187,8 @@ function BufferPack() {
         n = 0; // Need to deal with empty  null term strings
         while(a[p + n] !== 0) {
           n++;
+          if (p + n >= al) // Don't read past the end of the buffer
+            return undefined;
         }
         n++; // Add one for null byte
       }

test/cstring.test.js

@@ -88,5 +88,14 @@ describe('C String', function() {
         unpacked.forth.should.equal('asdf');
       });
     });
+    describe('strings without null terminators', function() {
+      var values = [0x3c];
+      var packed = bufferpack.pack('b', values);
+
+      it('should return undefined', function() {
+        var unpacked = bufferpack.unpack('S', packed);
+        (unpacked === undefined).should.be.true;
+      });
+    });
   });
 });