acl_extended_fd(3) — Linux manual page


ACL_EXTENDED_FD(3)      BSD Library Functions Manual      ACL_EXTENDED_FD(3)

NAME         top

     acl_extended_fd — test for information in the ACL by file descriptor

LIBRARY         top

     Linux Access Control Lists library (libacl, -lacl).

SYNOPSIS         top

     #include <sys/types.h>
     #include <acl/libacl.h>

     acl_extended_fd(int fd);

DESCRIPTION         top

     The acl_extended_fd() function returns 1 if the file identified by the
     argument fd is associated with an extended access ACL. The function
     returns 0 if the file does not have an extended access ACL.

     An extended ACL is an ACL that contains entries other than the three
     required entries of tag types ACL_USER_OBJ, ACL_GROUP_OBJ and
     ACL_OTHER.  If the result of the acl_extended_fd() function for a file
     object is 0, then the ACL defines no discretionary access rights other
     than those already defined by the traditional file permission bits.

     Access to the file object may be further restricted by other mecha‐
     nisms, such as Mandatory Access Control schemes. The access(2) system
     call can be used to check whether a given type of access to a file
     object would be granted.

RETURN VALUE         top

     If successful, the acl_extended_fd() function returns 1 if the file
     object identified by fd has an extended access ACL, and 0 if the file
     object identified by fd does not have an extended access ACL. Other‐
     wise, the value -1 is returned and the global variable errno is set to
     indicate the error.

ERRORS         top

     If any of the following conditions occur, the acl_extended_fd() func‐
     tion returns -1 and sets errno to the corresponding value:

     [EBADF]            The fd argument is not a valid file descriptor.

     [ENOTSUP]          The file system on which the file identified by fd
                        is located does not support ACLs, or ACLs are dis‐

STANDARDS         top

     This is a non-portable, Linux specific extension to the ACL
     manipulation functions defined in IEEE Std 1003.1e draft 17
     (“POSIX.1e”, abandoned).

SEE ALSO         top

     access(2), acl_get_fd(3), acl(5)

AUTHOR         top

     Written by Andreas Gruenbacher <>.

COLOPHON         top

     This page is part of the acl (manipulating access control lists)
     project.  Information about the project can be found at  If you have a bug report for
     this manual page, see ⟨⟩.
     This page was obtained from the project's upstream Git repository
     ⟨git://⟩ on 2020-09-18.  (At that time,
     the date of the most recent commit that was found in the repository was
     2020-09-03.)  If you discover any rendering problems in this HTML ver‐
     sion of the page, or you believe there is a better or more up-to-date
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     page), send a mail to

Linux ACL                      March 23, 2002                      Linux ACL