setxattr, lsetxattr, fsetxattr — set an extended attribute value
#include <sys/types.h> #include <attr/xattr.h>
int
setxattr( |
const char * | path, |
const char * | name, | |
const void * | value, | |
size_t | size, | |
int | flags) ; |
int
lsetxattr( |
const char * | path, |
const char * | name, | |
const void * | value, | |
size_t | size, | |
int | flags) ; |
int
fsetxattr( |
int | filedes, |
const char * | name, | |
const void * | value, | |
size_t | size, | |
int | flags) ; |
Extended attributes are name
: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).
setxattr
() sets the
value
of the extended
attribute identified by name
and associated with the
given path
in the
filesystem. The size
of the value
must be
specified.
lsetxattr
() is identical to
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.
fsetxattr
() is identical to
setxattr
(), only the extended
attribute is set on the open file pointed to by filedes
(as returned by
open(2)) in place of
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.
The flags
parameter can be used to refine the semantics of the
operation. XATTR_CREATE specifies a pure create, which fails
if the named attribute exists already. 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.
On success, zero is returned. On failure, −1 is
returned and errno
is set
appropriately.
If XATTR_CREATE is specified, and the attribute exists
already, errno
is set to EEXIST.
If XATTR_REPLACE is specified, and the attribute does not
exist, errno
is set to
ENOATTR.
If there is insufficient space remaining to store the
extended attribute, errno
is set
to either ENOSPC, or EDQUOT if quota enforcement was the
cause.
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.
These system calls have been available on Linux since kernel 2.4; glibc support is provided since version 2.3.
getfattr(1), setfattr(1), getxattr(2), listxattr(2), open(2), removexattr(2), stat(2), attr(5)
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