xref: /dflybsd-src/share/man/man9/extattr.9 (revision 86d7f5d305c6adaa56ff4582ece9859d73106103)
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2786d7f5d3SJohn Marino.\"
2886d7f5d3SJohn Marino.Dd May 8, 2010
2986d7f5d3SJohn Marino.Dt EXTATTR 9
3086d7f5d3SJohn Marino.Os
3186d7f5d3SJohn Marino.Sh NAME
3286d7f5d3SJohn Marino.Nm extattr
3386d7f5d3SJohn Marino.Nd virtual file system named extended attributes
3486d7f5d3SJohn Marino.Sh SYNOPSIS
3586d7f5d3SJohn Marino.In sys/param.h
3686d7f5d3SJohn Marino.In sys/vnode.h
3786d7f5d3SJohn Marino.In sys/extattr.h
3886d7f5d3SJohn Marino.Sh DESCRIPTION
3986d7f5d3SJohn MarinoNamed extended attributes allow additional meta-data to be associated
4086d7f5d3SJohn Marinowith vnodes representing files and directories.
4186d7f5d3SJohn MarinoThe semantics of this additional data is that of a "name=value" pair, where
4286d7f5d3SJohn Marinoa name may be defined or undefined, and if defined, associated with zero or
4386d7f5d3SJohn Marinomore bytes of arbitrary binary data.
4486d7f5d3SJohn Marino.Pp
4586d7f5d3SJohn MarinoReads of extended attribute data may return specific contiguous regions of
4686d7f5d3SJohn Marinothe meta-data, in the style of
4786d7f5d3SJohn Marino.Xr VOP_READ 9 ,
4886d7f5d3SJohn Marinobut writes will replace the entire current "value" associated with
4986d7f5d3SJohn Marinoa given name.
5086d7f5d3SJohn MarinoAs there are a plethora of file systems with differing extended attributes,
5186d7f5d3SJohn Marinoavailability and functionality of these functions may be limited, and they
5286d7f5d3SJohn Marinoshould be used with awareness of the underlying semantics of the supporting
5386d7f5d3SJohn Marinofile system.
5486d7f5d3SJohn MarinoAuthorization schemes for extended attribute data may also vary by file
5586d7f5d3SJohn Marinosystem, as well as maximum attribute size, and whether or not any or
5686d7f5d3SJohn Marinospecific new attributes may be defined.
5786d7f5d3SJohn Marino.Pp
5886d7f5d3SJohn MarinoExtended attributes are named using a null-terminated character string.
5986d7f5d3SJohn MarinoDepending on underlying file system semantics, this name may or may not be
6086d7f5d3SJohn Marinocase-sensitive.
6186d7f5d3SJohn MarinoAppropriate vnode extended attribute calls are:
6286d7f5d3SJohn Marino.Xr VOP_GETEXTATTR 9
6386d7f5d3SJohn Marinoand
6486d7f5d3SJohn Marino.Xr VOP_SETEXTATTR 9 .
6586d7f5d3SJohn Marino.Sh SEE ALSO
6686d7f5d3SJohn Marino.Xr VFS 9 ,
6786d7f5d3SJohn Marino.Xr VOP_GETEXTATTR 9 ,
6886d7f5d3SJohn Marino.Xr VOP_SETEXTATTR 9
6986d7f5d3SJohn Marino.Sh AUTHORS
7086d7f5d3SJohn MarinoThis manual page was written by
7186d7f5d3SJohn Marino.An Robert Watson .
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