time/mktime-internal.h

   1 /* Internals of mktime and related functions
   2    Copyright 2016-2024 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;