установить значение пользовательского атрибута объекта файловой системы (set the value of a user attribute of a filesystem object)
Имя (Name)
attr_set, attr_setf - set the value of a user attribute of a
filesystem object
Синопсис C (C Synopsis)
#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);
Описание (Description)
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.
Диагностика (Diagnostic)
On success, zero is returned. On error, -1 is returned, and
errno is set appropriately.
Смотри также (See also)
attr(1), attr_get(3), attr_list(3), attr_multi(3), attr_remove(3)
