glibc/sysdeps/generic/min-eloop-threshold.h

/* Minimum threshold at which to diagnose ELOOP.  Generic version.
   Copyright (C) 2012-2025 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#ifndef _MIN_ELOOP_THRESHOLD_H
#define _MIN_ELOOP_THRESHOLD_H      1

/* POSIX specifies SYMLOOP_MAX as the "Maximum number of symbolic
   links that can be reliably traversed in the resolution of a
   pathname in the absence of a loop."  This makes it a minimum that
   we should certainly accept.  But it leaves open the possibility
   that more might sometimes work--just not "reliably".

   For example, Linux implements a complex policy whereby there is a
   small limit on the number of direct symlink traversals (a symlink
   to a symlink to a symlink), but larger limit on the total number of
   symlink traversals overall.  Hence the SYMLOOP_MAX number should be
   the small one, but the limit library functions enforce on users
   should be the larger one.

   This constant should be large enough that it never rules out a file
   name and directory tree that the underlying system (i.e. calls to 'open'
   et al) would resolve successfully.  It should be small enough that
   actual loops are detected without a huge number of iterations.  */

#define MIN_ELOOP_THRESHOLD    40

#endif