Add drop_and_recreate in privatefile class.

When creating a private file we need to delete the file if exist.

src/common/util.cpp

@@ -122,7 +122,7 @@ namespace tools
   private_file::private_file(std::FILE* handle, std::string&& filename) noexcept
     : m_handle(handle), m_filename(std::move(filename)) {}
 
-  private_file private_file::create(std::string name)
+  private_file private_file::create(std::string name, uint32_t extra_flags)
   {
 #ifdef WIN32
     struct close_handle
@@ -175,7 +175,7 @@ namespace tools
         name.c_str(),
         GENERIC_WRITE, FILE_SHARE_READ,
         std::addressof(attributes),
-        CREATE_NEW, (FILE_ATTRIBUTE_TEMPORARY | FILE_FLAG_DELETE_ON_CLOSE),
+        CREATE_NEW, (FILE_ATTRIBUTE_TEMPORARY | FILE_FLAG_DELETE_ON_CLOSE | extra_flags),
         nullptr
       )
     };
@@ -194,7 +194,7 @@ namespace tools
       }
     }
 #else
-    const int fdr = open(name.c_str(), (O_RDONLY | O_CREAT), S_IRUSR);
+    const int fdr = open(name.c_str(), (O_RDONLY | O_CREAT | extra_flags), S_IRUSR);
     if (0 <= fdr)
     {
       struct stat rstats = {};
@@ -225,6 +225,23 @@ namespace tools
     return {};
   }
 
+  private_file private_file::drop_and_recreate(std::string filename)
+  {
+    if (epee::file_io_utils::is_file_exist(filename)) {
+      boost::system::error_code ec{};
+      boost::filesystem::remove(filename, ec);
+      if (ec) {
+        MERROR("Failed to remove " << filename << ": " << ec.message());
+        return {};
+      }
+    }
+#ifdef WIN32
+    return create(filename);
+#else
+    return create(filename, O_EXCL);
+#endif
+  }
+
   private_file::~private_file() noexcept
   {
     try

src/common/util.h

@@ -80,7 +80,11 @@ namespace tools
 
     /*! \return File only readable by owner and only used by this process
       OR `private_file{}` on error. */
-    static private_file create(std::string filename);
+    static private_file create(std::string filename, uint32_t extra_flags = 0);
+
+    /*! \return Drop and create file only readable by owner and only used
+      by this process OR `private_file{}` on error. */
+    static private_file drop_and_recreate(std::string filename);    
 
     private_file(private_file&&) = default;
     private_file& operator=(private_file&&) = default;

src/wallet/wallet_rpc_server.cpp

@@ -245,7 +245,7 @@ namespace tools
         );
 
         std::string temp = "monero-wallet-rpc." + bind_port + ".login";
-        rpc_login_file = tools::private_file::create(temp);
+        rpc_login_file = tools::private_file::drop_and_recreate(temp);
         if (!rpc_login_file.handle())
         {
           LOG_ERROR(tr("Failed to create file ") << temp << tr(". Check permissions or remove file"));