Bug 1353629 - PBlob refactoring - part 8 - FileReader should use nsIAsyncInputStream if available, r=smaug

Currently FileReader API uses a nsITransport. This is not needed if the
inputStream is a nsIAsyncInputStream already, and IPCBlobInputStream is always
a nsIAsyncInputStream.

Note that, we must create a bufferedStream in order to use ReadSegments in case
the remote inputStream, received by IPCBlobInputStream, is a FileInputStream.
This was not needed with nsITransport.

dom/file/FileReader.cpp

@@ -290,10 +290,20 @@ FileReader::DoReadData(uint64_t aCount)
     mResult.GetMutableData(&buf, oldLen + aCount, fallible);
     NS_ENSURE_TRUE(buf, NS_ERROR_OUT_OF_MEMORY);
 
+    nsresult rv;
+
+    // nsFileStreams do not implement ReadSegment. In case here we are dealing
+    // with a nsIAsyncInputStream, in content process, we need to wrap a
+    // nsIBufferedInputStream around it.
+    if (!mBufferedStream) {
+      rv = NS_NewBufferedInputStream(getter_AddRefs(mBufferedStream),
+                                     mAsyncStream, 8192);
+      NS_ENSURE_SUCCESS(rv, rv);
+    }
+
     uint32_t bytesRead = 0;
-    nsresult rv =
+    rv = mBufferedStream->ReadSegments(ReadFuncBinaryString, buf + oldLen,
-      mAsyncStream->ReadSegments(ReadFuncBinaryString, buf + oldLen, aCount,
+                                       aCount, &bytesRead);
-                                 &bytesRead);
     if (NS_WARN_IF(NS_FAILED(rv))) {
       return rv;
     }
@@ -350,6 +360,7 @@ FileReader::ReadFileContent(Blob& aBlob,
   mResultArrayBuffer = nullptr;
 
   mAsyncStream = nullptr;
+  mBufferedStream = nullptr;
 
   mTransferred = 0;
   mTotal = 0;
@@ -374,27 +385,30 @@ FileReader::ReadFileContent(Blob& aBlob,
     return;
   }
 
-  nsCOMPtr<nsITransport> transport;
+  mAsyncStream = do_QueryInterface(stream);
-  aRv = sts->CreateInputTransport(stream,
+  if (!mAsyncStream) {
-                                  /* aStartOffset */ 0,
+    nsCOMPtr<nsITransport> transport;
-                                  /* aReadLimit */ -1,
+    aRv = sts->CreateInputTransport(stream,
-                                  /* aCloseWhenDone */ true,
+                                    /* aStartOffset */ 0,
-                                  getter_AddRefs(transport));
+                                    /* aReadLimit */ -1,
-  if (NS_WARN_IF(aRv.Failed())) {
+                                    /* aCloseWhenDone */ true,
-    return;
+                                    getter_AddRefs(transport));
+    if (NS_WARN_IF(aRv.Failed())) {
+      return;
+    }
+
+    nsCOMPtr<nsIInputStream> wrapper;
+    aRv = transport->OpenInputStream(/* aFlags */ 0,
+                                     /* aSegmentSize */ 0,
+                                     /* aSegmentCount */ 0,
+                                     getter_AddRefs(wrapper));
+    if (NS_WARN_IF(aRv.Failed())) {
+      return;
+    }
+
+    mAsyncStream = do_QueryInterface(wrapper);
   }
 
-  nsCOMPtr<nsIInputStream> wrapper;
-  aRv = transport->OpenInputStream(/* aFlags */ 0,
-                                   /* aSegmentSize */ 0,
-                                   /* aSegmentCount */ 0,
-                                   getter_AddRefs(wrapper));
-  if (NS_WARN_IF(aRv.Failed())) {
-    return;
-  }
-
-  MOZ_ASSERT(!mAsyncStream);
-  mAsyncStream = do_QueryInterface(wrapper);
   MOZ_ASSERT(mAsyncStream);
 
   mTotal = mBlob->GetSize(aRv);
@@ -529,6 +543,7 @@ FileReader::FreeDataAndDispatchSuccess()
   FreeFileData();
   mResult.SetIsVoid(false);
   mAsyncStream = nullptr;
+  mBufferedStream = nullptr;
   mBlob = nullptr;
 
   // Dispatch event to signify end of a successful operation
@@ -544,6 +559,7 @@ FileReader::FreeDataAndDispatchError()
   FreeFileData();
   mResult.SetIsVoid(true);
   mAsyncStream = nullptr;
+  mBufferedStream = nullptr;
   mBlob = nullptr;
 
   // Dispatch error event to signify load failure
@@ -729,6 +745,7 @@ FileReader::Abort()
   mResultArrayBuffer = nullptr;
 
   mAsyncStream = nullptr;
+  mBufferedStream = nullptr;
   mBlob = nullptr;
 
   //Clean up memory buffer
@@ -782,6 +799,11 @@ FileReader::Shutdown()
     mAsyncStream = nullptr;
   }
 
+  if (mBufferedStream) {
+    mBufferedStream->Close();
+    mBufferedStream = nullptr;
+  }
+
   FreeFileData();
   mResultArrayBuffer = nullptr;
 

dom/file/FileReader.h

@@ -180,6 +180,7 @@ private:
   bool mTimerIsActive;
 
   nsCOMPtr<nsIAsyncInputStream> mAsyncStream;
+  nsCOMPtr<nsIInputStream> mBufferedStream;
 
   RefPtr<DOMError> mError;