NAME
attr_set, attr_setf - set the value of a user attribute of a filesystem
object
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);
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.
DIAGNOSTICS
On success, zero is returned. On error, -1 is returned, and errno is
set appropriately.
SEE ALSO
attr(1), attr_get(3), attr_list(3), attr_multi(3), and attr_remove(3).