attr_set, attr_setf - set the value of a user attribute of a filesystem object
#include <attr/attributes.h>
int attr_set (const char *path, const char *attrname,
const char *attrvalue, const int valuelength,
int flags);
int attr_setf (int fd, const char *attrname,
const char *attrvalue, const int valuelength,
int flags);
The
attr_set and
attr_setf functions provide a way to create
attributes and set/change their values.
Path points to a path name for a filesystem object, and
fd refers
to the file descriptor associated with a file. If the attribute
attrname does not exist, an attribute with the given name and value
will be created and associated with that indicated filesystem object. If an
attribute with that name already exists on that filesystem object, the
existing value is replaced with the new value given in this call. The new
attribute value is copied from the
attrvalue buffer for a total of
valuelength bytes. The
flags argument can contain the following
symbols bitwise OR'ed together:
- ATTR_ROOT
- Look for attrname in the root address space,
not in the user address space. (limited to use by super-user
only)
- ATTR_DONTFOLLOW
- Do not follow symbolic links when resolving a path
on an attr_set function call. The default is to follow symbolic
links.
- ATTR_CREATE
- Return an error (EEXIST) if an attribute of the given name
already exists on the indicated filesystem object, otherwise create an
attribute with the given name and value. This flag is used to implement a
pure create operation, without this flag attr_set will create the
attribute if it does not already exist. An error (EINVAL) will be returned
if both ATTR_CREATE and ATTR_REPLACE are set in the same call.
- ATTR_REPLACE
- Return an error (ENOATTR) if an attribute of the given name
does not already exist on the indicated filesystem object, otherwise
replace the existing attribute's value with the given value. This flag is
used to implement a pure replacement operation, without this flag
attr_set will create the attribute if it does not already exist. An
error (EINVAL) will be returned if both ATTR_CREATE and ATTR_REPLACE are
set in the same call.
attr_set will fail if one or more of the following are true:
- [ENOATTR]
- The attribute name given is not associated with the
indicated filesystem object and the ATTR_REPLACE flag bit was set.
- [E2BIG]
- The value of the given attribute is too large, it exceeds
the maximum allowable size of an attribute value.
- [EEXIST]
- The attribute name given is already associated with the
indicated filesystem object and the ATTR_CREATE flag bit was set.
- [ENOENT]
- The named file does not exist.
- [EPERM]
- The effective user ID does not match the
owner of the file and the effective user ID is not
super-user.
- [ENOTDIR]
- A component of the path prefix is not a directory.
- [EACCES]
- Search permission is denied on a component of the path
prefix.
- [EINVAL]
- A bit was set in the flag argument that is not
defined for this system call, or both the ATTR_CREATE and ATTR_REPLACE
flags bits were set.
- [EFAULT]
-
Path, attrname, or attrvalue points
outside the allocated address space of the process.
- [ELOOP]
- A path name lookup involved too many symbolic links.
- [ENAMETOOLONG]
- The length of path exceeds {MAXPATHLEN}, or a
pathname component is longer than {MAXNAMELEN}.
attr_setf will fail if:
- [ENOATTR]
- The attribute name given is not associated with the
indicated filesystem object and the ATTR_REPLACE flag bit was set.
- [E2BIG]
- The value of the given attribute is too large, it exceeds
the maximum allowable size of an attribute value.
- [EEXIST]
- The attribute name given is already associated with the
indicated filesystem object and the ATTR_CREATE flag bit was set.
- [EINVAL]
- A bit was set in the flag argument that is not
defined for this system call, or both the ATTR_CREATE and ATTR_REPLACE
flags bits were set, or fd refers to a socket, not a file.
- [EFAULT]
-
Attrname, or attrvalue points outside the
allocated address space of the process.
- [EBADF]
-
Fd does not refer to a valid descriptor.
On success, zero is returned. On error, -1 is returned, and
errno is set
appropriately.
attr(1),
attr_get(3),
attr_list(3),
attr_multi(3),
attr_remove(3)