BytesConsumer::endRead can return Done

third_party/WebKit/Source/modules/fetch/BodyStreamBuffer.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/fetch/BodyStreamBuffer.h"
 
 #include "bindings/core/v8/ScriptState.h"
 #include "bindings/core/v8/V8HiddenValue.h"
 #include "core/dom/DOMArrayBuffer.h"
 #include "core/dom/DOMTypedArray.h"
@@ skipping 293 matching lines @@
         m_consumer = nullptr;
     }
 }
 
 void BodyStreamBuffer::processData()
 {
     DCHECK(m_consumer);
     while (m_streamNeedsMore) {
         const char* buffer = nullptr;
         size_t available = 0;
-
-        switch (m_consumer->beginRead(&buffer, &available)) {
+        auto result = m_consumer->beginRead(&buffer, &available);
+        if (result == BytesConsumer::Result::ShouldWait)
+            return;
+        DOMUint8Array* array = nullptr;
+        if (result == BytesConsumer::Result::Ok) {
+            array = DOMUint8Array::create(reinterpret_cast<const unsigned char*>(buffer), available);
+            result = m_consumer->endRead(available);
+        }
+        switch (result) {
         case BytesConsumer::Result::Ok: {
-            DOMUint8Array* array = DOMUint8Array::create(reinterpret_cast<const unsigned char*>(buffer), available);
-            if (m_consumer->endRead(available) != BytesConsumer::Result::Ok) {
-                error();
-                return;
-            }
+            DCHECK(array);
             // Clear m_streamNeedsMore in order to detect a pull call.
             m_streamNeedsMore = false;
             controller()->enqueue(array);
             // If m_streamNeedsMore is true, it means that pull is called and
             // the stream needs more data even if the desired size is not
             // positive.
             if (!m_streamNeedsMore)
                 m_streamNeedsMore = controller()->desiredSize() > 0;
             break;
         }
         case BytesConsumer::Result::ShouldWait:
+            NOTREACHED();
             return;
         case BytesConsumer::Result::Done:
             close();
             return;
         case BytesConsumer::Result::Error:
             error();
             return;
         }
     }
 }
@@ skipping 43 matching lines @@
     }
     if (isErrored)
         return new BytesConsumerForDataConsumerHandle(m_scriptState->getExecutionContext(), createFetchDataConsumerHandleFromWebHandle(createUnexpectedErrorDataConsumerHandle()));
 
     DCHECK(consumer);
     consumer->clearClient();
     return consumer;
 }
 
 } // namespace blink