NAME
getxattr, lgetxattr, fgetxattr - retrieve an extended attribute value
SYNOPSIS
#include <sys/types.h>
#include <attr/xattr.h>
I ssize_t getxattr (const char * path , const char * name ,
I \t\t\t\t void * value , size_t size );
I ssize_t lgetxattr (const char * path , const char * name ,
I \t\t\t\t void * value , size_t size );
I ssize_t fgetxattr (int filedes , const char * name ,
I \t\t\t\t void * value , size_t size );
DESCRIPTION
Extended attributes are
R name :\c
value
pairs associated with inodes (files, directories, symlinks, etc).
They are extensions to the normal attributes which are associated
with all inodes in the system (i.e. the
stat(2)
data).
A complete overview of extended attributes concepts can be found in
attr(5).
getxattr
retrieves the
value
of the extended attribute identified by
name
and associated with the given
path
in the filesystem.
The length of the attribute
value
is returned.
lgetxattr
is identical to
R getxattr ,
except in the case of a symbolic link, where the link itself is
interrogated, not the file that it refers to.
fgetxattr
is identical to
R getxattr ,
only the open file pointed to by
filedes
(as returned by
open(2))
is interrogated in place of
R path .
An extended attribute
name
is a simple NULL-terminated string.
The name includes a namespace prefix - there may be several, disjoint
namespaces associated with an individual inode.
The value of an extended attribute is a chunk of arbitrary textual or
binary data of specified length.
An empty buffer of
size
zero can be passed into these calls to return the current size of the
named extended attribute, which can be used to estimate the size of a
buffer which is sufficiently large to hold the value associated with
the extended attribute.
The interface is designed to allow guessing of initial buffer
sizes, and to enlarge buffers when the return value indicates
that the buffer provided was too small.
RETURN VALUE
On success, a positive number is returned indicating the size of the
extended attribute value.
On failure, -1 is returned and
errno
is set appropriately.
If the named attribute does not exist, or the process has no access to
this attribute,
errno
is set to ENOATTR.
If the
size
of the
value
buffer is too small to hold the result,
errno
is set to ERANGE.
If extended attributes are not supported by the filesystem, or are disabled,
errno
is set to ENOTSUP.
The errors documented for the
stat(2)
system call are also applicable here.
AUTHORS
Andreas Gruenbacher,
<a.gruenbacher@bestbits.at>
and the SGI XFS development team,
<linux-xfs@oss.sgi.com>.
Please send any bug reports or comments to these addresses.
SEE ALSO
ČLÁNKY DO MAILU