__sysconf.c

来自「一个C源代码分析器」· C语言 代码 · 共 180 行

/* Copyright (C) 1993 Free Software Foundation, Inc.
   Contributed by Brendan Kehoe ([e-mail]).

The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA.  */

#include <ansidecl.h>
#include <errno.h>
#include <limits.h>
#include <unistd.h>
#include <stdio.h>
#include <time.h>
#include <sysconfig.h>

extern int EXFUN(__sysconfig, (int));

/* Get the value of the system variable NAME.  */
long int
DEFUN(__sysconf, (name), int name)
{
  switch (name)
    {
    default:
      errno = EINVAL;
      return -1;

    case _SC_ARG_MAX:
#ifdef	ARG_MAX
      return ARG_MAX;
#else
      return -1;
#endif

    case _SC_CHILD_MAX:
#ifdef	CHILD_MAX
      return CHILD_MAX;
#else
      return -1;
#endif

    case _SC_CLK_TCK:
      return __sysconfig (_CONFIG_CLK_TCK);

    case _SC_NGROUPS_MAX:
#ifdef	NGROUPS_MAX
      return NGROUPS_MAX;
#else
      return -1;
#endif

      /* Both of these are looking for _CONFIG_OPEN_FILES.  */
    case _SC_OPEN_MAX:
    case _SC_STREAM_MAX:
      return __sysconfig (_CONFIG_OPEN_FILES);

    case _SC_TZNAME_MAX:
      return __tzname_max ();

    case _SC_JOB_CONTROL:
#ifdef	_POSIX_JOB_CONTROL
      return 1;
#else
      return -1;
#endif
    case _SC_SAVED_IDS:
#ifdef	_POSIX_SAVED_IDS
      return 1;
#else
      return -1;
#endif
    case _SC_VERSION:
      return _POSIX_VERSION;

    case _SC_PAGESIZE:
      return __sysconfig (_CONFIG_PAGESIZE);

    case _SC_BC_BASE_MAX:
#ifdef	BC_BASE_MAX
      return BC_BASE_MAX;
#else
      return -1;
#endif

    case _SC_BC_DIM_MAX:
#ifdef	BC_DIM_MAX
      return BC_DIM_MAX;
#else
      return -1;
#endif

    case _SC_BC_SCALE_MAX:
#ifdef	BC_SCALE_MAX
      return BC_SCALE_MAX;
#else
      return -1;
#endif

    case _SC_BC_STRING_MAX:
#ifdef	BC_STRING_MAX
      return BC_STRING_MAX;
#else
      return -1;
#endif

    case _SC_EQUIV_CLASS_MAX:
#ifdef	EQUIV_CLASS_MAX
      return EQUIV_CLASS_MAX;
#else
      return -1;
#endif

    case _SC_EXPR_NEST_MAX:
#ifdef	EXPR_NEST_MAX
      return EXPR_NEST_MAX;
#else
      return -1;
#endif

    case _SC_LINE_MAX:
#ifdef	LINE_MAX
      return LINE_MAX;
#else
      return -1;
#endif

    case _SC_RE_DUP_MAX:
#ifdef	RE_DUP_MAX
      return RE_DUP_MAX;
#else
      return -1;
#endif


    case _SC_2_VERSION:
      /* This is actually supposed to return the version
	 of the 1003.2 utilities on the system {POSIX2_VERSION}.  */
      return _POSIX2_C_VERSION;

    case _SC_2_C_BIND:
#ifdef	_POSIX2_C_BIND
      return _POSIX2_C_BIND;
#else
      return -1;
#endif

    case _SC_2_C_DEV:
#ifdef	_POSIX2_C_DEV
      return _POSIX2_C_DEV;
#else
      return -1;
#endif

    case _SC_2_FORT_DEV:
#ifdef	_POSIX2_FORT_DEV
      return _POSIX2_FORT_DEV;
#else
      return -1;
#endif

    case _SC_2_SW_DEV:
#ifdef	_POSIX2_SW_DEV
      return _POSIX2_SW_DEV;
#else
      return -1;
#endif
    }
}