man-pages/man2/setxattr.2

.\"
.\" Extended attributes system calls manual pages
.\"
.\" (C) Andreas Gruenbacher, February 2001
.\" (C) Silicon Graphics Inc, September 2001
.\"
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.TH SETXATTR 2 2001-12-31 "Linux" "Linux Programmer's Manual"
.SH NAME
setxattr, lsetxattr, fsetxattr \- set an extended attribute value
.SH SYNOPSIS
.fam C
.nf
.B #include <sys/types.h>
.B #include <attr/xattr.h>
.sp
.BI "int setxattr(const char\ *" path ", const char\ *" name ,
.BI "              const void\ *" value ", size_t " size ", int " flags );
.BI "int lsetxattr(const char\ *" path ", const char\ *" name ,
.BI "              const void\ *" value ", size_t " size ", int " flags );
.BI "int fsetxattr(int " filedes ", const char\ *" name ,
.BI "              const void\ *" value ", size_t " size ", int " flags );
.fi
.fam T
.SH DESCRIPTION
Extended attributes are
.IR name :\c
.I value
pairs associated with inodes (files, directories, symbolic links, etc.).
They are extensions to the normal attributes which are associated
with all inodes in the system (i.e., the
.BR stat (2)
data).
A complete overview of extended attributes concepts can be found in
.BR attr (5).
.PP
.BR setxattr ()
sets the
.I value
of the extended attribute identified by
.I name
and associated with the given
.I path
in the filesystem.
The
.I size
of the
.I value
must be specified.
.PP
.BR lsetxattr ()
is identical to
.BR setxattr (),
except in the case of a symbolic link, where the extended attribute is
set on the link itself, not the file that it refers to.
.PP
.BR fsetxattr ()
is identical to
.BR setxattr (),
only the extended attribute is set on the open file pointed to by
.I filedes
(as returned by
.BR open (2))
in place of
.IR path .
.PP
An extended attribute name is a simple null-terminated string.
The
.I name
includes a namespace prefix; there may be several, disjoint
namespaces associated with an individual inode.
The
.I value
of an extended attribute is a chunk of arbitrary textual or
binary data of specified length.
.PP
The
.I flags
parameter can be used to refine the semantics of the operation.
.B XATTR_CREATE
specifies a pure create, which fails if the named
attribute exists already.
.B XATTR_REPLACE
specifies a pure replace operation, which fails if the
named attribute does not already exist.
By default (no flags), the extended attribute will be created if
need be, or will simply replace the value if the attribute exists.
.SH RETURN VALUE
On success, zero is returned.
On failure, \-1 is returned and
.I errno
is set appropriately.
.PP
If
.B XATTR_CREATE
is specified, and the attribute exists already,
.I errno
is set to
.BR EEXIST .
If
.B XATTR_REPLACE
is specified, and the attribute does not exist,
.I errno
is set to
.BR ENOATTR .
.PP
If there is insufficient space remaining to store the extended attribute,
.I errno
is set to either
.BR ENOSPC ,
or
.B EDQUOT
if quota enforcement was the cause.
.PP
If extended attributes are not supported by the filesystem, or are disabled,
.I errno
is set to
.BR ENOTSUP .
.PP
The errors documented for the
.BR stat (2)
system call are also applicable here.
.SH VERSIONS
These system calls have been available on Linux since kernel 2.4;
glibc support is provided since version 2.3.
.SH "CONFORMING TO"
These system calls are Linux specific.
.\" .SH AUTHORS
.\" Andreas Gruenbacher,
.\" .RI < a.gruenbacher@computer.org >
.\" and the SGI XFS development team,
.\" .RI < linux-xfs@oss.sgi.com >.
.\" Please send any bug reports or comments to these addresses.
.SH SEE ALSO
.BR getfattr (1),
.BR setfattr (1),
.BR getxattr (2),
.BR listxattr (2),
.BR open (2),
.BR removexattr (2),
.BR stat (2),
.BR attr (5)