GIOErrorEnum g_io_error_from_errno ( gint err_no )
Converts errno.h error codes into GIO error codes. The fallback
G_IO_ERROR_FAILED is returned for error codes not currently
handled (but note that future GLib releases may return a more
specific value instead).
As %errno is global and may be modified by intermediate function calls, you should save its value as soon as the call which sets it.