openat64() shall establish a connection between a file and a file descriptor. It shall be identical open64() except in the case where path specifies a relative path. In this case, the file to be opened shall be determined relative to the directory associated with the file descriptor fd instead of the current working directory.
openat64() is a large-file version of the openat() function as defined in POSIX 1003.1-2008 (ISO/IEC 9945-2009). It differs from openat() in the same way that open64() differs from open(), that the open is done in large-file mode.
On success, openat64() returns a new
shall return -1 and
errno to indicate the error.