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), attr_remove(3)