EXTATTR(9)

NAME
extattr - virtual file system named extended attributes

SYNOPSIS
#include <sys/param.h>
#include <sys/vnode.h>
#include <sys/extattr.h>

DESCRIPTION
Named extended attributes allow additional meta-data to be associated with vnodes representing files and directories. The semantics of this additional data is that of a "name=value" pair, where a name may be defined or undefined, and if defined, associated with zero or more bytes of arbitrary binary data.

Reads of extended attribute data may return specific contiguous regions of the meta-data, in the style of VOP_READ(9), but writes will replace the entire current "value" associated with a given name. As there are a plethora of file systems with differing extended attributes, availability and functionality of these functions may be limited, and they should be used with awareness of the underlying semantics of the supporting file system. Authorization schemes for extended attribute data may also vary by file system, as well as maximum attribute size, and whether or not any or specific new attributes may be defined.

Extended attributes are named using a null-terminated character string. Depending on underlying file system semantics, this name may or may not be case-sensitive. Appropriate vnode extended attribute calls are: VOP_GETEXTATTR(9) and VOP_SETEXTATTR(9).

SEE ALSO
VFS(9), VOP_GETEXTATTR(9), VOP_SETEXTATTR(9)

AUTHORS
This manual page was written by Robert Watson.