setxattr(2) BSD System Calls Manual setxattr(2)
NAME
setxattr, fsetxattr -- set an extended attribute value
SYNOPSIS
#include <sys/xattr.h>
int
setxattr(const char *path, const char *name, void *value, size_t size,
u_int32_t position, int options);
int
fsetxattr(int fd, const char *name, void *value, size_t size,
u_int32_t position, int options);
DESCRIPTION
Extended attributes extend the basic attributes associated with files and
directories in the file system. They are stored as name:data pairs asso-
ciated with file system objects (files, directories, symlinks, etc).
setxattr() associates name and data together as an attribute of path.
An extended attribute's name is a simple NULL-terminated UTF-8 string.
Value is a pointer to a data buffer of size bytes containing textual or
binary data to be associated with the extended attribute. Position spec-
ifies the offset within the extended attribute. In the current implemen-
tation, only the resource fork extended attribute makes use of this argu-
ment. For all others, position is reserved and should be set to zero.
options controls how the attribute is set:
XATTR_NOFOLLOW do not follow symbolic links. setxattr() normally sets
attributes on the target of path if it is a symbolic
link. With this option, setxattr() will act on the link
itself.
XATTR_CREATE fail if the named attribute already exists.
XATTR_REPLACE fail if the named attribute does not exist. Failure to
specify XATTR_REPLACE or XATTR_CREATE allows creation and
replacement.
fsetxattr() is identical to setxattr(), except that it sets an extended
attribute on an open file referenced by file descriptor fd.
NOTES
On some filesystems, such as HFS+, setting the extended attribute
com.apple.ResourceFork will update the modification time (``mtime'') of
the file.
Due to historical reasons, the XATTR_FINDERINFO_NAME (defined to be
``com.apple.FinderInfo'') extended attribute must be 32 bytes; see the
ATTR_CMN_FNDRINFO section in getattrlist(2).
The maximum supported size of extended attribute can be found out using
pathconf(2) with _PC_XATTR_SIZE_BITS option.
RETURN VALUES
On success, 0 is returned. On failure, -1 is returned and the global
variable errno is set as follows.
ERRORS
[EEXIST] options contains XATTR_CREATE and the named attribute
already exists.
[ENOATTR] options is set to XATTR_REPLACE and the named
attribute does not exist.
[ENOTSUP] The file system does not support extended attributes
or has them disabled.
[EROFS] The file system is mounted read-only.
[ERANGE] The data size of the attribute is out of range (some
attributes have size restrictions).
[EPERM] Attributes cannot be associated with this type of
object. For example, attributes are not allowed for
resource forks.
[EINVAL] name or options is invalid. name must be valid UTF-8
and options must make sense.
[ENOTDIR] A component of path is not a directory.
[ENAMETOOLONG] name exceeded XATTR_MAXNAMELEN UTF-8 bytes, or a com-
ponent of path exceeded NAME_MAX characters, or the
entire path exceeded PATH_MAX characters.
[EACCES] Search permission is denied for a component of path or
permission to set the attribute is denied.
[ELOOP] Too many symbolic links were encountered resolving
path.
[EFAULT] path or name points to an invalid address.
[EIO] An I/O error occurred while reading from or writing to
the file system.
[E2BIG] The data size of the extended attribute is too large.
[ENOSPC] Not enough space left on the file system.
SEE ALSO
getxattr(2), listxattr(2), removexattr(2), pathconf(2)
HISTORY
setxattr() and fsetxattr() first appeared in Mac OS X 10.4.
Mac OS X Oct 19, 2004 Mac OS X
Mac OS X 10.9.1 - Generated Mon Jan 6 15:25:31 CST 2014