/* Get file-specific information about a file.  Linux version.

   Copyright (C) 2003-2018 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/>.  */

#include <errno.h>

#include <fcntl.h>

#include <stdlib.h>

#include <sysdep.h>

#include <time.h>

#include <unistd.h>

#include <sys/resource.h>

#include <sys/param.h>

#include <not-cancel.h>

#include <ldsodefs.h>

/* Legacy value of ARG_MAX.  The macro is now not defined since the

   actual value varies based on the stack size.  */

#define legacy_ARG_MAX 131072

static long int posix_sysconf (int name);

#ifndef HAS_CPUCLOCK

static long int

has_cpuclock (int name)

{

# if defined __NR_clock_getres || HP_TIMING_AVAIL

  /* If we have HP_TIMING, we will fall back on that if the system

     call does not work, so we support it either way.  */

#  if !HP_TIMING_AVAIL

  /* Check using the clock_getres system call.  */

  struct timespec ts;

  INTERNAL_SYSCALL_DECL (err);

  int r = INTERNAL_SYSCALL (clock_getres, err, 2,

			    (name == _SC_CPUTIME

			     ? CLOCK_PROCESS_CPUTIME_ID

			     : CLOCK_THREAD_CPUTIME_ID),

			    &ts);

  if (INTERNAL_SYSCALL_ERROR_P (r, err))

    return -1;

#  endif

  return _POSIX_VERSION;

# else

  return -1;

# endif

}

# define HAS_CPUCLOCK(name) has_cpuclock (name)

#endif

/* Get the value of the system variable NAME.  */

long int

__sysconf (int name)

{

  const char *procfname = NULL;

  switch (name)

    {

      struct rlimit rlimit;

#ifdef __NR_clock_getres

    case _SC_MONOTONIC_CLOCK:

      /* Check using the clock_getres system call.  */

      {

	struct timespec ts;

	INTERNAL_SYSCALL_DECL (err);

	int r;

	r = INTERNAL_SYSCALL (clock_getres, err, 2, CLOCK_MONOTONIC, &ts);

	return INTERNAL_SYSCALL_ERROR_P (r, err) ? -1 : _POSIX_VERSION;

      }

#endif

    case _SC_CPUTIME:

    case _SC_THREAD_CPUTIME:

      return HAS_CPUCLOCK (name);

    case _SC_ARG_MAX:

      /* Use getrlimit to get the stack limit.  */

      if (__getrlimit (RLIMIT_STACK, &rlimit) == 0)

	return MAX (legacy_ARG_MAX, rlimit.rlim_cur / 4);

      return legacy_ARG_MAX;

    case _SC_NGROUPS_MAX:

      /* Try to read the information from the /proc/sys/kernel/ngroups_max

	 file.  */

      procfname = "/proc/sys/kernel/ngroups_max";

      break;

    case _SC_SIGQUEUE_MAX:

      if (__getrlimit (RLIMIT_SIGPENDING, &rlimit) == 0)

	return rlimit.rlim_cur;

      /* The /proc/sys/kernel/rtsig-max file contains the answer.  */

      procfname = "/proc/sys/kernel/rtsig-max";

      break;

    default:

      break;

    }

  if (procfname != NULL)

    {

      int fd = __open_nocancel (procfname, O_RDONLY);

      if (fd != -1)

	{

	  /* This is more than enough, the file contains a single integer.  */

	  char buf[32];

	  ssize_t n;

	  n = TEMP_FAILURE_RETRY (__read_nocancel (fd, buf, sizeof (buf) - 1));

	  __close_nocancel_nostatus (fd);

	  if (n > 0)

	    {

	      /* Terminate the string.  */

	      buf[n] = '\0';

	      char *endp;

	      long int res = strtol (buf, &endp, 10);

	      if (endp != buf && (*endp == '\0' || *endp == '\n'))

		return res;

	    }

	}

    }

  return posix_sysconf (name);

}

/* Now the POSIX version.  */

#undef __sysconf

#define __sysconf static posix_sysconf

#include <sysdeps/posix/sysconf.c>