From 4e5948b3f20d532fff947b7fabc18cccee7f73d3 Mon Sep 17 00:00:00 2001
From: Andrea Marchesini <amarchesini@mozilla.com>
Date: Tue, 9 May 2017 11:03:40 +0200
Subject: [PATCH] Bug 1360807 - FileReaderSync must work with sync inputStream
 - part 1 - SyncRead should read as much as required, r=smaug

---
 dom/workers/FileReaderSync.cpp | 38 +++++++++++++++++++++++++++-------
 dom/workers/FileReaderSync.h   |  4 ++--
 2 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/dom/workers/FileReaderSync.cpp b/dom/workers/FileReaderSync.cpp
index 4bf8e5fd6d06..8214f81356a4 100644
--- a/dom/workers/FileReaderSync.cpp
+++ b/dom/workers/FileReaderSync.cpp
@@ -78,7 +78,7 @@ FileReaderSync::ReadAsArrayBuffer(JSContext* aCx,
   }
 
   uint32_t numRead;
-  aRv = Read(stream, bufferData.get(), blobSize, &numRead);
+  aRv = SyncRead(stream, bufferData.get(), blobSize, &numRead);
   if (NS_WARN_IF(aRv.Failed())) {
     return;
   }
@@ -110,7 +110,7 @@ FileReaderSync::ReadAsBinaryString(Blob& aBlob,
   uint32_t numRead;
   do {
     char readBuf[4096];
-    aRv = Read(stream, readBuf, sizeof(readBuf), &numRead);
+    aRv = SyncRead(stream, readBuf, sizeof(readBuf), &numRead);
     if (NS_WARN_IF(aRv.Failed())) {
       return;
     }
@@ -145,7 +145,7 @@ FileReaderSync::ReadAsText(Blob& aBlob,
   }
 
   uint32_t numRead = 0;
-  aRv = Read(stream, sniffBuf.BeginWriting(), sniffBuf.Length(), &numRead);
+  aRv = SyncRead(stream, sniffBuf.BeginWriting(), sniffBuf.Length(), &numRead);
   if (NS_WARN_IF(aRv.Failed())) {
     return;
   }
@@ -361,8 +361,8 @@ NS_INTERFACE_MAP_END
 } // anonymous
 
 nsresult
-FileReaderSync::Read(nsIInputStream* aStream, char* aBuffer, uint32_t aBufferSize,
-                     uint32_t* aRead)
+FileReaderSync::SyncRead(nsIInputStream* aStream, char* aBuffer,
+                         uint32_t aBufferSize, uint32_t* aRead)
 {
   MOZ_ASSERT(aStream);
   MOZ_ASSERT(aBuffer);
@@ -370,10 +370,34 @@ FileReaderSync::Read(nsIInputStream* aStream, char* aBuffer, uint32_t aBufferSiz
 
   // Let's try to read, directly.
   nsresult rv = aStream->Read(aBuffer, aBufferSize, aRead);
-  if (NS_SUCCEEDED(rv) || rv != NS_BASE_STREAM_WOULD_BLOCK) {
+
+  // Nothing else to read.
+  if (rv == NS_BASE_STREAM_CLOSED ||
+      (NS_SUCCEEDED(rv) && *aRead == 0)) {
+    return NS_OK;
+  }
+
+  // An error.
+  if (NS_FAILED(rv) && rv != NS_BASE_STREAM_WOULD_BLOCK) {
     return rv;
   }
 
+  // All good.
+  if (NS_SUCCEEDED(rv)) {
+    // Not enough data, let's read recursively.
+    if (*aRead != aBufferSize) {
+      uint32_t byteRead = 0;
+      rv = SyncRead(aStream, aBuffer + *aRead, aBufferSize - *aRead, &byteRead);
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        return rv;
+      }
+
+      *aRead += byteRead;
+    }
+
+    return NS_OK;
+  }
+
   // We need to proceed async.
   nsCOMPtr<nsIAsyncInputStream> asyncStream = do_QueryInterface(aStream);
   if (!asyncStream) {
@@ -408,5 +432,5 @@ FileReaderSync::Read(nsIInputStream* aStream, char* aBuffer, uint32_t aBufferSiz
   }
 
   // Now, we can try to read again.
-  return Read(aStream, aBuffer, aBufferSize, aRead);
+  return SyncRead(aStream, aBuffer, aBufferSize, aRead);
 }
diff --git a/dom/workers/FileReaderSync.h b/dom/workers/FileReaderSync.h
index c23803161b92..a23877a60abc 100644
--- a/dom/workers/FileReaderSync.h
+++ b/dom/workers/FileReaderSync.h
@@ -32,8 +32,8 @@ private:
   nsresult ConvertStream(nsIInputStream *aStream, const char *aCharset,
                          nsAString &aResult);
 
-  nsresult Read(nsIInputStream* aStream, char* aBuffer, uint32_t aBufferSize,
-                uint32_t* aRead);
+  nsresult SyncRead(nsIInputStream* aStream, char* aBuffer,
+                    uint32_t aBufferSize, uint32_t* aRead);
 
 public:
   static already_AddRefed<FileReaderSync>