math/lgamma-compat.h

   1 /* ABI compatibility for lgamma functions.
   2    Copyright (C) 2015-2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef LGAMMA_COMPAT_H
  20 #define LGAMMA_COMPAT_H 1
  21
  22 #include <math-svid-compat.h>
  23 #include <shlib-compat.h>
  24
  25 /* XSI POSIX requires lgamma to set signgam, but ISO C does not permit
  26    this.  Namespace issues can be avoided if the functions set
  27    __signgam and signgam is a weak alias, but this only works if both
  28    signgam and __signgam were exported from the glibc version the
  29    program was linked against.  Before glibc 2.23, lgamma functions
  30    set signgam which was not a weak alias for __signgam, so old
  31    binaries have dynamic symbols for signgam only and the versions of
  32    lgamma used for old binaries must set both signgam and __signgam.
  33    Those versions also do a check of _LIB_VERSION != _ISOC_ to match
  34    old glibc.
  35
  36    Users of this file define USE_AS_COMPAT to 0 when building the main
  37    version of lgamma, 1 when building the compatibility version.  */
  38
  39 #define LGAMMA_OLD_VER GLIBC_2_0
  40 #define LGAMMA_NEW_VER GLIBC_2_23
  41 #define HAVE_LGAMMA_COMPAT SHLIB_COMPAT (libm, LGAMMA_OLD_VER, LGAMMA_NEW_VER)
  42
  43 /* Whether to build this version at all.  */
  44 #define BUILD_LGAMMA (HAVE_LGAMMA_COMPAT || !USE_AS_COMPAT)
  45
  46 /* The name to use for this version.  */
  47 #if USE_AS_COMPAT
  48 # define LGFUNC(FUNC) FUNC ## _compat
  49 #else
  50 # define LGFUNC(FUNC) FUNC
  51 #endif
  52
  53 /* If there is a compatibility version, gamma (not an ISO C function,
  54    so never a problem for it to set signgam) points directly to it
  55    rather than having separate versions.  */
  56 #define GAMMA_ALIAS (USE_AS_COMPAT ? HAVE_LGAMMA_COMPAT : !HAVE_LGAMMA_COMPAT)
  57
  58 /* How to call the underlying lgamma_r function.  */
  59 #define CALL_LGAMMA(TYPE, FUNC, ARG)                    \
  60   ({                                                    \
  61     TYPE lgamma_tmp;                                    \
  62     int local_signgam;                                  \
  63     if (USE_AS_COMPAT)                                  \
  64       {                                                 \
  65         lgamma_tmp = FUNC ((ARG), &local_signgam);      \
  66         if (_LIB_VERSION != _ISOC_)                     \
  67           signgam = __signgam = local_signgam;          \
  68       }                                                 \
  69     else                                                \
  70       lgamma_tmp = FUNC ((ARG), &__signgam);            \
  71     lgamma_tmp;                                         \
  72   })
  73
  74 #endif /* lgamma-compat.h.  */