m4/time_r.m4

   1 dnl Reentrant time functions: localtime_r, gmtime_r.
   2
   3 dnl Copyright (C) 2003, 2006-2014 Free Software Foundation, Inc.
   4 dnl This file is free software; the Free Software Foundation
   5 dnl gives unlimited permission to copy and/or distribute it,
   6 dnl with or without modifications, as long as this notice is preserved.
   7
   8 dnl Written by Paul Eggert.
   9
  10 AC_DEFUN([gl_TIME_R],
  11 [
  12   dnl Persuade glibc and Solaris <time.h> to declare localtime_r.
  13   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
  14
  15   AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
  16   AC_REQUIRE([AC_C_RESTRICT])
  17
  18   dnl Some systems don't declare localtime_r() and gmtime_r() if _REENTRANT is
  19   dnl not defined.
  20   AC_CHECK_DECLS([localtime_r], [], [], [[#include <time.h>]])
  21   if test $ac_cv_have_decl_localtime_r = no; then
  22     HAVE_DECL_LOCALTIME_R=0
  23   fi
  24
  25   AC_CHECK_FUNCS_ONCE([localtime_r])
  26   if test $ac_cv_func_localtime_r = yes; then
  27     HAVE_LOCALTIME_R=1
  28     AC_CACHE_CHECK([whether localtime_r is compatible with its POSIX signature],
  29       [gl_cv_time_r_posix],
  30       [AC_COMPILE_IFELSE(
  31          [AC_LANG_PROGRAM(
  32             [[#include <time.h>]],
  33             [[/* We don't need to append 'restrict's to the argument types,
  34                  even though the POSIX signature has the 'restrict's,
  35                  since C99 says they can't affect type compatibility.  */
  36               struct tm * (*ptr) (time_t const *, struct tm *) = localtime_r;
  37               if (ptr) return 0;
  38               /* Check the return type is a pointer.
  39                  On HP-UX 10 it is 'int'.  */
  40               *localtime_r (0, 0);]])
  41          ],
  42          [gl_cv_time_r_posix=yes],
  43          [gl_cv_time_r_posix=no])
  44       ])
  45     if test $gl_cv_time_r_posix = yes; then
  46       REPLACE_LOCALTIME_R=0
  47     else
  48       REPLACE_LOCALTIME_R=1
  49     fi
  50   else
  51     HAVE_LOCALTIME_R=0
  52   fi
  53 ])
  54
  55 # Prerequisites of lib/time_r.c.
  56 AC_DEFUN([gl_PREREQ_TIME_R], [
  57   :
  58 ])