AU: pass whether or not we can tolerate a delta to the server

omaha_request_params.cc

 // Copyright (c) 2010 The Chromium OS 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 "update_engine/omaha_request_params.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/utsname.h>
 
@@ skipping 20 matching lines @@
   TEST_AND_RETURN_FALSE(GetMachineId(&machine_id));
   user_id = machine_id;
   os_platform = OmahaRequestParams::kOsPlatform;
   os_version = OmahaRequestParams::kOsVersion;
   app_version = GetLsbValue("CHROMEOS_RELEASE_VERSION", "");
   os_sp = app_version + "_" + GetMachineType();
   os_board = GetLsbValue("CHROMEOS_RELEASE_BOARD", "");
   app_id = OmahaRequestParams::kAppId;
   app_lang = "en-US";
   app_track = GetLsbValue("CHROMEOS_RELEASE_TRACK", "");
+  struct stat stbuf;
+  
+  // Deltas are only okay if the /.nodelta file does not exist.
+  // If we don't know (i.e. stat() returns some unexpected error),
+  // then err on the side of caution and say deltas are not okay
+  delta_okay = (stat((root_ + "/.nodelta").c_str(), &stbuf) < 0) &&
+               (errno == ENOENT);
+
   update_url = GetLsbValue("CHROMEOS_AUSERVER",
                            OmahaRequestParams::kUpdateUrl);
   return true;
 }
 
 namespace {
 const size_t kGuidDataByteLength = 128 / 8;
 const string::size_type kGuidStringLength = 38;
 // Formats 16 bytes (128 bits) of data as a GUID:
 // "{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}" where X is a hex digit
@@ skipping 55 matching lines @@
 
 string OmahaRequestDeviceParams::GetMachineType() const {
   struct utsname buf;
   string ret;
   if (uname(&buf) == 0)
     ret = buf.machine;
   return ret;
 }
 
 }  // namespace chromeos_update_engine