1  /* Internals of mktime and related functions
       2     Copyright 2016-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4     Contributed by Paul Eggert <eggert@cs.ucla.edu>.
       5  
       6     The GNU C Library is free software; you can redistribute it and/or
       7     modify it under the terms of the GNU Lesser General Public
       8     License as published by the Free Software Foundation; either
       9     version 2.1 of the License, or (at your option) any later version.
      10  
      11     The GNU C Library is distributed in the hope that it will be useful,
      12     but WITHOUT ANY WARRANTY; without even the implied warranty of
      13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      14     Lesser General Public License for more details.
      15  
      16     You should have received a copy of the GNU Lesser General Public
      17     License along with the GNU C Library; if not, see
      18     <https://www.gnu.org/licenses/>.  */
      19  
      20  #ifndef _LIBC
      21  # include <time.h>
      22  #endif
      23  
      24  /* mktime_offset_t is a signed type wide enough to hold a UTC offset
      25     in seconds, and used as part of the type of the offset-guess
      26     argument to mktime_internal.  In Glibc, it is always long int.
      27     When in Gnulib, use time_t on platforms where time_t
      28     is signed, to be compatible with platforms like BeOS that export
      29     this implementation detail of mktime.  On platforms where time_t is
      30     unsigned, GNU and POSIX code can assume 'int' is at least 32 bits
      31     which is wide enough for a UTC offset.  */
      32  #ifdef _LIBC
      33  typedef long int mktime_offset_t;
      34  #elif defined TIME_T_IS_SIGNED
      35  typedef time_t mktime_offset_t;
      36  #else
      37  typedef int mktime_offset_t;
      38  #endif
      39  
      40  /* The source code uses identifiers like __time64_t for glibc
      41     timestamps that can contain 64-bit values even when time_t is only
      42     32 bits.  These are just macros for the ordinary identifiers unless
      43     compiling within glibc when time_t is 32 bits.  */
      44  #if ! (defined _LIBC && __TIMESIZE != 64)
      45  # undef __time64_t
      46  # define __time64_t time_t
      47  # define __gmtime64_r __gmtime_r
      48  # define __localtime64_r __localtime_r
      49  # define __mktime64 mktime
      50  # define __timegm64 timegm
      51  #endif
      52  
      53  #ifndef _LIBC
      54  
      55  /* Although glibc source code uses leading underscores, Gnulib wants
      56     ordinary names.
      57  
      58     Portable standalone applications should supply a <time.h> that
      59     declares a POSIX-compliant localtime_r, for the benefit of older
      60     implementations that lack localtime_r or have a nonstandard one.
      61     Similarly for gmtime_r.  See the gnulib time_r module for one way
      62     to implement this.  */
      63  
      64  # undef __gmtime_r
      65  # undef __localtime_r
      66  # define __gmtime_r gmtime_r
      67  # define __localtime_r localtime_r
      68  
      69  # define __mktime_internal mktime_internal
      70  
      71  #endif
      72  
      73  /* Subroutine of mktime.  Return the time_t representation of TP and
      74     normalize TP, given that a struct tm * maps to a time_t as performed
      75     by FUNC.  Record next guess for localtime-gmtime offset in *OFFSET.  */
      76  extern __time64_t __mktime_internal (struct tm *tp,
      77                                       struct tm *(*func) (__time64_t const *,
      78                                                           struct tm *),
      79                                       mktime_offset_t *offset) attribute_hidden;