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-/* Threshold at which to diagnose ELOOP. Generic version.
- Copyright (C) 2012-2017 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
- <http://www.gnu.org/licenses/>. */
-
-#ifndef _ELOOP_THRESHOLD_H
-#define _ELOOP_THRESHOLD_H 1
-
-#include <limits.h>
-#include <sys/param.h>
-
-/* 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.
-
- So, we use the larger of the reported SYMLOOP_MAX (if any) and our
- own constant MIN_ELOOP_THRESHOLD, below. 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. */
-
-#ifndef MIN_ELOOP_THRESHOLD
-# define MIN_ELOOP_THRESHOLD 40
-#endif
-
-/* Return the maximum number of symlink traversals to permit
- before diagnosing ELOOP. */
-static inline unsigned int __attribute__ ((const))
-__eloop_threshold (void)
-{
-#ifdef SYMLOOP_MAX
- const int symloop_max = SYMLOOP_MAX;
-#else
- /* The function is marked 'const' even though we use memory and
- call a function, because sysconf is required to return the
- same value in every call and so it must always be safe to
- call __eloop_threshold exactly once and reuse the value. */
- static long int sysconf_symloop_max;
- if (sysconf_symloop_max == 0)
- sysconf_symloop_max = __sysconf (_SC_SYMLOOP_MAX);
- const unsigned int symloop_max = (sysconf_symloop_max <= 0
- ? _POSIX_SYMLOOP_MAX
- : sysconf_symloop_max);
-#endif
-
- return MAX (symloop_max, MIN_ELOOP_THRESHOLD);
-}
-
-#endif /* eloop-threshold.h */