Function: Kills WordPress execution and displays XML response with an error message.

Function: Gets a filename that is sanitized and unique for the given directory.

Function: Creates a file in the upload folder with given content.

Function: Retrieves the file type based on the extension name.

Function: Determines a writable directory for temporary files.

Function: Determines if a directory is writable.

Function: Workaround for Windows bug in is_writable() function

Function: Retrieves uploads directory information.

Function: Returns an array containing the current upload directory’s path and URL.