Chromium side patch for DB support on Linux.

base/platform_file_posix.cc

 // Copyright (c) 2006-2008 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 "base/platform_file.h"
 
 #include <fcntl.h>
 #include <errno.h>
 #include <sys/stat.h>
 
@@ skipping 34 matching lines @@
 
   int descriptor = open(WideToUTF8(name).c_str(), open_flags,
                         S_IRUSR | S_IWUSR);
 
   if (flags & PLATFORM_FILE_OPEN_ALWAYS) {
     if (descriptor > 0) {
       if (created)
         *created = false;
     } else {
       open_flags |= O_CREAT;
+      if (flags & PLATFORM_FILE_EXCLUSIVE_READ ||
+          flags & PLATFORM_FILE_EXCLUSIVE_WRITE) {
+        open_flags |= O_EXCL;   // together with O_CREAT implies O_NOFOLLOW
+      }
       descriptor = open(WideToUTF8(name).c_str(), open_flags,
                         S_IRUSR | S_IWUSR);
       if (created && descriptor > 0)
         *created = true;
     }
   }
 
+  if ((descriptor > 0) && (flags & PLATFORM_FILE_DELETE_ON_CLOSE)) {
+    unlink(WideToUTF8(name).c_str());
+  }
+
   return descriptor;
 }
 
+bool ClosePlatformFile(PlatformFile file) {
+  return close(file);
+}
+
 }  // namespace base