fix regression: only return file data when it's done

1 files changed, 35 insertions, 21 deletions

diff --git a/lib/storage.js b/lib/storage.js
index 30fe9a9..f4832f0 100644
--- a/lib/storage.js
+++ b/lib/storage.js
@@ -283,10 +283,22 @@ File.prototype.getBlobURL = function (cb) {
     return cb(new Error('file.blobURL requires window.URL and window.Blob support'))
   }
 
-  // Use the existing in-memory buffer for better memory utilization and one less copy.
-  var buffer = self.storage.buffer.slice(self.offset, self.offset + self.length)
-  var url = window.URL.createObjectURL(new window.Blob([ buffer ]))
-  cb(null, url)
+  function onBuffer (err, buffer) {
+    if (err) return cb(err)
+    var url = window.URL.createObjectURL(new window.Blob([ buffer ]))
+    cb(null, url)
+  }
+
+  if (self.storage.buffer) {
+    // Use the in-memory buffer (when possible) for better memory utilization
+    var onDone = function () {
+      onBuffer(null, self.storage.buffer.slice(self.offset, self.offset + self.length))
+    }
+    if (self.done) onDone()
+    else self.once('done', onDone)
+  } else {
+    self.getBuffer(onBuffer)
+  }
 }
 
 /**
@@ -296,26 +308,28 @@ File.prototype.getBuffer = function (cb) {
   var self = this
   cb = dezalgo(once(cb))
 
-  // Use the in-memory buffer (when possible) for better memory utilization and one less
-  // copy.
   var buffer
   if (self.storage.buffer) {
-    buffer = self.storage.buffer.slice(self.offset, self.offset + self.length)
-    cb(null, buffer)
-    return
-  }
-
-  buffer = new Buffer(self.length)
-  var start = 0
-  self.createReadStream()
-    .on('data', function (chunk) {
-      chunk.copy(buffer, start)
-      start += chunk.length
-    })
-    .on('end', function () {
+    // Use the in-memory buffer (when possible) for better memory utilization
+    var onDone = function () {
+      buffer = self.storage.buffer.slice(self.offset, self.offset + self.length)
       cb(null, buffer)
-    })
-    .on('error', cb)
+    }
+    if (self.done) onDone()
+    else self.once('done', onDone)
+  } else {
+    buffer = new Buffer(self.length)
+    var start = 0
+    self.createReadStream()
+      .on('data', function (chunk) {
+        chunk.copy(buffer, start)
+        start += chunk.length
+      })
+      .on('end', function () {
+        cb(null, buffer)
+      })
+      .on('error', cb)
+  }
 }
 
 File.prototype._checkDone = function () {