NAME

       attr_get, attr_getf - get the value of a user attribute of a filesystem object

C SYNOPSIS

       #include <attr/attributes.h>

       int attr_get (const char *path, const char *attrname,
                     char *attrvalue, int *valuelength, int flags);

       int attr_getf (int fd, const char *attrname,
                      char *attrvalue, int *valuelength, int flags);

DESCRIPTION

       The attr_get and attr_getf functions provide a way to retrieve the value of an attribute.

       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 exists, the value  associated  with  it
       will  be  copied  into  the attrvalue buffer.  The valuelength argument is an input/output
       argument that on the call to attr_get should contain the maximum size of  attribute  value
       the  process  is willing to accept.  On return, the valuelength will have been modified to
       show the actual size of the attribute value returned.  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_get  function  call.
              The default is to follow symbolic links.

       attr_get will fail if one or more of the following are true:

       [ENOATTR]        The  attribute name given is not associated with the indicated filesystem
                        object.  If the system libc does not define this error code, then libattr
                        will define it to ENODATA in <attr/attributes.h>.

       [E2BIG]          The  value  of  the  given attribute is too large to fit into the buffer.
                        The integer that the valuelength argument points to has been modified  to
                        show the actual number of bytes that would be required to store the value
                        of that attribute.

       [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.

       [EFAULT]         Path, attrname, attrvalue, or valuelength 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_getf will fail if:

       [ENOATTR]      The attribute name given is not associated with  the  indicated  filesystem
                      object.

       [E2BIG]        The  value of the given attribute is too large to fit into the buffer.  The
                      integer that the valuelength argument points to has been modified  to  show
                      the  actual  number  of  bytes that would be required to store the value of
                      that attribute.

       [EINVAL]       A bit was set in the flag argument that is  not  defined  for  this  system
                      call, or fd refers to a socket, not a file.

       [EFAULT]       Attrname,  attrvalue,  or  valuelength 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_list(3), attr_multi(3), attr_remove(3), attr_set(3)