Add an "append flag" to base::PlatformFile.

base/platform_file_win.cc

 // Copyright (c) 2012 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 "base/platform_file.h"
 
 #include <io.h>
 
 #include "base/files/file_path.h"
 #include "base/logging.h"
@@ skipping 33 matching lines @@
     DCHECK(!disposition);
     DCHECK(flags & PLATFORM_FILE_WRITE);
     disposition = TRUNCATE_EXISTING;
   }
 
   if (!disposition) {
     NOTREACHED();
     return NULL;
   }
 
-  DWORD access = (flags & PLATFORM_FILE_READ) ? GENERIC_READ : 0;
+  DWORD access = 0;
   if (flags & PLATFORM_FILE_WRITE)
-    access |= GENERIC_WRITE;
+    access = GENERIC_WRITE;
+  if (flags & PLATFORM_FILE_APPEND) {
+    DCHECK(!access)

[jar (doing other things), 2013/06/05 16:39:21]

missing semicolon.

+    access = FILE_APPEND_DATA;
+  }
+  if (flags & PLATFORM_FILE_READ)
+    access |= GENERIC_READ;
   if (flags & PLATFORM_FILE_WRITE_ATTRIBUTES)
     access |= FILE_WRITE_ATTRIBUTES;
   if (flags & PLATFORM_FILE_EXECUTE)
     access |= GENERIC_EXECUTE;
 
   DWORD sharing = (flags & PLATFORM_FILE_EXCLUSIVE_READ) ? 0 : FILE_SHARE_READ;
   if (!(flags & PLATFORM_FILE_EXCLUSIVE_WRITE))
     sharing |= FILE_SHARE_WRITE;
   if (flags & PLATFORM_FILE_SHARE_DELETE)
     sharing |= FILE_SHARE_DELETE;
@@ skipping 219 matching lines @@
     case ERROR_DISK_CORRUPT:
       return PLATFORM_FILE_ERROR_IO;
     default:
       UMA_HISTOGRAM_SPARSE_SLOWLY("PlatformFile.UnknownErrors.Windows",
                                   last_error);
       return PLATFORM_FILE_ERROR_FAILED;
   }
 }
 
 }  // namespace base