Issue #1258 - Part 1: Import mailnews, ldap, and mork from comm-esr52.9.1

mailnews/base/util/nsMsgFileStream.h

@@ -0,0 +1,33 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Attributes.h"
+#include "msgCore.h"
+#include "nsIInputStream.h"
+#include "nsIOutputStream.h"
+#include "nsISeekableStream.h"
+#include "prio.h"
+
+class nsMsgFileStream final : public nsIInputStream,
+                                  public nsIOutputStream,
+                                  public nsISeekableStream
+{
+public:
+  nsMsgFileStream();
+
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD Available(uint64_t *_retval) override; 
+  NS_IMETHOD Read(char * aBuf, uint32_t aCount, uint32_t *_retval) override; 
+  NS_IMETHOD ReadSegments(nsWriteSegmentFun aWriter, void * aClosure, uint32_t aCount, uint32_t *_retval) override;
+  NS_DECL_NSIOUTPUTSTREAM
+  NS_DECL_NSISEEKABLESTREAM
+
+  nsresult InitWithFile(nsIFile *localFile);
+protected:
+  ~nsMsgFileStream();
+
+  PRFileDesc *mFileDesc;
+  bool mSeekedToEnd;
+};