[cryptohome] make guest-mode homedir mount with -rwx------

platform.cc

 // Copyright (c) 2011 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.
 
 // Contains the implementation of class Platform
 
 #include "platform.h"
 
 #include <errno.h>
 #include <grp.h>
@@ skipping 368 matching lines @@
         return false;
     }
 
     // Set permissions on the directory itself
     if (!SetOwnership(current_dir, user_id, group_id))
       return false;
   }
   return true;
 }
 
+bool Platform::SetPermissions(const std::string& path, mode_t new_perms) {
+  if (chmod(path.c_str(), new_perms)) {
+    PLOG(ERROR) << "chmod() of " << path.c_str() << " to " << new_perms
+                << " failed.";
+    return false;
+  }
+  return true;
+}
+
 int Platform::SetMask(int new_mask) {
   return umask(new_mask);
 }
 
 bool Platform::GetUserId(const std::string& user, uid_t* user_id,
                          gid_t* group_id) {
   // Load the passwd entry
   long user_name_length = sysconf(_SC_GETPW_R_SIZE_MAX);
   if (user_name_length == -1) {
     user_name_length = kDefaultPwnameLength;
@@ skipping 167 matching lines @@
                     bool recursive,
                     std::vector<std::string>* file_list) {
   file_util::FileEnumerator dir_enum(FilePath(path), recursive,
                                      file_util::FileEnumerator::FILES);
   for (FilePath path = dir_enum.Next(); !path.empty(); path = dir_enum.Next())
     file_list->push_back(path.value());
   return true;
 }
 
 } // namespace cryptohome