Integer constant indicating which extended attribute namespace the attribute name is present in.
uio
The location of the data to be read. The resulting data will be a list of attribute names. Each list entry consists of a single byte containing the length of the attribute name, followed by the attribute name. The attribute name is not terminated by ASCII NUL.
size
If not NULL, on return it will contain the number of bytes required to read the list. In most cases uio will be NULL when size is not, and vise versa.
cred
The user credentials to use in authorizing the request.
td
The thread requesting the extended attribute.
The cred pointer may be NULL to indicate that access control checks are not to be performed, if possible. This cred setting might be used to allow the kernel to authorize extended attribute retrieval that the active process might not be permitted to do.
Extended attribute semantics may vary by file system implementing the call. More information on extended attributes may be found in extattr(9).
