1dnl Reentrant time functions: localtime_r, gmtime_r.
2
3dnl Copyright (C) 2003, 2006-2020 Free Software Foundation, Inc.
4dnl This file is free software; the Free Software Foundation
5dnl gives unlimited permission to copy and/or distribute it,
6dnl with or without modifications, as long as this notice is preserved.
7
8dnl Written by Paul Eggert.
9
10AC_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], [], [],
21    [[/* mingw's <time.h> provides the functions asctime_r, ctime_r,
22         gmtime_r, localtime_r only if <unistd.h> or <pthread.h> has
23         been included before.  */
24      #if defined __MINGW32__
25      # include <unistd.h>
26      #endif
27      #include <time.h>
28    ]])
29  if test $ac_cv_have_decl_localtime_r = no; then
30    HAVE_DECL_LOCALTIME_R=0
31  fi
32
33  AC_CHECK_FUNCS_ONCE([localtime_r])
34  if test $ac_cv_func_localtime_r = yes; then
35    HAVE_LOCALTIME_R=1
36    AC_CACHE_CHECK([whether localtime_r is compatible with its POSIX signature],
37      [gl_cv_time_r_posix],
38      [AC_COMPILE_IFELSE(
39         [AC_LANG_PROGRAM(
40            [[/* mingw's <time.h> provides the functions asctime_r, ctime_r,
41                 gmtime_r, localtime_r only if <unistd.h> or <pthread.h> has
42                 been included before.  */
43              #if defined __MINGW32__
44              # include <unistd.h>
45              #endif
46              #include <time.h>
47            ]],
48            [[/* We don't need to append 'restrict's to the argument types,
49                 even though the POSIX signature has the 'restrict's,
50                 since C99 says they can't affect type compatibility.  */
51              struct tm * (*ptr) (time_t const *, struct tm *) = localtime_r;
52              if (ptr) return 0;
53              /* Check the return type is a pointer.
54                 On HP-UX 10 it is 'int'.  */
55              *localtime_r (0, 0);]])
56         ],
57         [gl_cv_time_r_posix=yes],
58         [gl_cv_time_r_posix=no])
59      ])
60    if test $gl_cv_time_r_posix = yes; then
61      REPLACE_LOCALTIME_R=0
62    else
63      REPLACE_LOCALTIME_R=1
64    fi
65  else
66    HAVE_LOCALTIME_R=0
67    dnl On mingw, localtime_r() is defined as an inline function; use through a
68    dnl direct function call works but the use as a function pointer leads to a
69    dnl link error.
70    AC_CACHE_CHECK([whether localtime_r exists as an inline function],
71      [gl_cv_func_localtime_r_inline],
72      [AC_LINK_IFELSE(
73         [AC_LANG_PROGRAM(
74            [[/* mingw's <time.h> provides the functions asctime_r, ctime_r,
75                 gmtime_r, localtime_r only if <unistd.h> or <pthread.h> has
76                 been included before.  */
77              #if defined __MINGW32__
78              # include <unistd.h>
79              #endif
80              #include <time.h>
81            ]],
82            [[time_t a;
83              struct tm r;
84              localtime_r (&a, &r);
85            ]])
86         ],
87         [gl_cv_func_localtime_r_inline=yes],
88         [gl_cv_func_localtime_r_inline=no])
89      ])
90    if test $gl_cv_func_localtime_r_inline = yes; then
91      REPLACE_LOCALTIME_R=1
92    fi
93  fi
94])
95
96# Prerequisites of lib/time_r.c.
97AC_DEFUN([gl_PREREQ_TIME_R], [
98  :
99])
100