Adds a new method ReadUntilComplete to FileStream which ensure that a...

net/base/file_stream_win.cc

 // Copyright (c) 2008 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 "net/base/file_stream.h"
 
 #include <windows.h>
 
 #include "base/logging.h"
 #include "base/message_loop.h"
@@ skipping 216 matching lines @@
     }
   } else if (overlapped) {
     async_context_->IOCompletionIsPending(callback);
     rv = ERR_IO_PENDING;
   } else {
     rv = static_cast<int>(bytes_read);
   }
   return rv;
 }
 
+int FileStream::ReadUntilComplete(char *buf, int buf_len) {
+  int to_read = buf_len;
+  int bytes_total = 0;
+
+  do {
+    int bytes_read = Read(buf, to_read, NULL);
+    if (bytes_read <= 0) {
+      if (bytes_total == 0)
+        return bytes_read;
+
+      return bytes_total;
+    }
+
+    bytes_total += bytes_read;
+    buf += bytes_read;
+    to_read -= bytes_read;
+  } while (bytes_total < buf_len);
+
+  return bytes_total;
+}
+
 int FileStream::Write(
     const char* buf, int buf_len, CompletionCallback* callback) {
   if (!IsOpen())
     return ERR_UNEXPECTED;
   DCHECK(open_flags_ & base::PLATFORM_FILE_WRITE);
 
   OVERLAPPED* overlapped = NULL;
   if (async_context_.get()) {
     DCHECK(!async_context_->callback());
     overlapped = async_context_->overlapped();
@@ skipping 14 matching lines @@
     async_context_->IOCompletionIsPending(callback);
     rv = ERR_IO_PENDING;
   } else {
     rv = static_cast<int>(bytes_written);
   }
   return rv;
 }
 
 }  // namespace net