fix(createReadStream): various issues

lib/api/createReadStream.js

@@ -21,15 +21,11 @@ module.exports = function createReadStream(path, options, cb) {
       return cb(err);
     }
 
-    var offset = new BigInt(file.EndofFile.length, options.start || 0);
-    var fileSize = BigInt.fromBuffer(file.EndofFile);
+    var offset = options.start || 0;
+    var end = BigInt.fromBuffer(file.EndofFile).toNumber();
 
-    var end = options.end;
-    if (end != null) {
-      end = new BigInt(8, end + 1);
-      if (end.gt(fileSize)) {
-        fileSize = end;
-      }
+    if (options.end < end) {
+      end = options.end + 1; // end option is inclusive
     }
 
     var close = request.bind(undefined, 'close', file, connection);
@@ -49,9 +45,9 @@ module.exports = function createReadStream(path, options, cb) {
         return;
       }
 
-      if (offset.ge(fileSize)) {
+      if (offset >= end) {
         return close(function() {
-          this.push(null);
+          stream.push(null);
         });
       }
 
@@ -60,21 +56,18 @@ module.exports = function createReadStream(path, options, cb) {
         'read',
         {
           FileId: file.FileId,
-          Length: Math.min(maxPacketSize, size),
-          Offset: offset.toBuffer(),
+          Length: Math.min(maxPacketSize, size, end - offset),
+          Offset: new BigInt(8, offset).toBuffer(),
         },
         connection,
         function(err, content) {
-          try {
-            if (err != null) {
-              return process.nextTick(stream.emit.bind(stream, 'error', err));
-            }
-
-            offset = offset.add(content.length);
-            stream.push(content);
-          } finally {
-            running = false;
+          running = false;
+          if (err != null) {
+            return process.nextTick(stream.emit.bind(stream, 'error', err));
           }
+
+          offset += content.length;
+          stream.push(content);
         }
       );
     };