setxattr, lsetxattr, fsetxattr - set an extended attribute value
#include <sys/types.h>
#include <sys/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 fd, const char *name,
const void *value, size_t size, int flags);
Extended attributes are
name:
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
stat(2) data). A complete overview of extended attributes concepts can
be found in
xattr(7).
setxattr() sets the
value of the extended attribute identified by
name and associated with the given
path in the filesystem. The
size argument specifies the size (in bytes) of
value; a
zero-length value is permitted.
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 referred to by
fd (as returned by
open(2)) in place of
path.
An extended attribute name is a 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.
By default (i.e.,
flags is zero), the extended attribute will be created
if it does not exist, or the value will be replaced if the attribute already
exists. To modify these semantics, one of the following values can be
specified in
flags:
- XATTR_CREATE
- Perform a pure create, which fails if the named attribute exists
already.
- XATTR_REPLACE
- Perform a pure replace operation, which fails if the named attribute does
not already exist.
On success, zero is returned. On failure, -1 is returned and
errno is set
appropriately.
- EDQUOT
- Disk quota limits meant that there is insufficient space remaining to
store the extended attribute.
- EEXIST
- XATTR_CREATE was specified, and the attribute exists already.
- ENODATA
- XATTR_REPLACE was specified, and the attribute does not exist.
- ENOSPC
- There is insufficient space remaining to store the extended
attribute.
- ENOTSUP
- The namespace prefix of name is not valid.
- ENOTSUP
- Extended attributes are not supported by the filesystem, or are
disabled,
- EPERM
- The file is marked immutable or append-only. (See
ioctl_iflags(2).)
In addition, the errors documented in
stat(2) can also occur.
- ERANGE
- The size of name or value exceeds a filesystem-specific
limit.
These system calls have been available on Linux since kernel 2.4; glibc support
is provided since version 2.3.
These system calls are Linux-specific.
getfattr(1),
setfattr(1),
getxattr(2),
listxattr(2),
open(2),
removexattr(2),
stat(2),
symlink(7),
xattr(7)