Integer constant indicating which extended attribute namespace the attribute name is present in.
Pointer to a null-terminated character string containing the attribute name.
The location of the data to be read or written.
The user credentials to use in authorizing the request.
The thread setting the extended attribute.
The uio structure is used in a manner similar to the argument of the same name in VOP_WRITE(9). However, as extended attributes provide a strict "name=value" semantic, non-zero offsets will be rejected.
The uio pointer may be NULL to indicate that the specified extended attribute should be deleted.
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 changes that the active process might not be permitted to make.
Extended attribute semantics may vary by file system implementing the call. More information on extended attributes may be found in extattr(9).