1# sys_select_h.m4 serial 20
2dnl Copyright (C) 2006-2020 Free Software Foundation, Inc.
3dnl This file is free software; the Free Software Foundation
4dnl gives unlimited permission to copy and/or distribute it,
5dnl with or without modifications, as long as this notice is preserved.
6
7AC_DEFUN([gl_HEADER_SYS_SELECT],
8[
9  AC_REQUIRE([AC_C_RESTRICT])
10  AC_REQUIRE([gl_SYS_SELECT_H_DEFAULTS])
11  AC_CACHE_CHECK([whether <sys/select.h> is self-contained],
12    [gl_cv_header_sys_select_h_selfcontained],
13    [
14      dnl Test against two bugs:
15      dnl 1. On many platforms, <sys/select.h> assumes prior inclusion of
16      dnl    <sys/types.h>.
17      dnl 2. On OSF/1 4.0, <sys/select.h> provides only a forward declaration
18      dnl    of 'struct timeval', and no definition of this type.
19      AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/select.h>]],
20                                         [[struct timeval b;]])],
21        [gl_cv_header_sys_select_h_selfcontained=yes],
22        [gl_cv_header_sys_select_h_selfcontained=no])
23      dnl Test against another bug:
24      dnl 3. On Solaris 10, <sys/select.h> provides an FD_ZERO implementation
25      dnl    that relies on memset(), but without including <string.h>.
26      if test $gl_cv_header_sys_select_h_selfcontained = yes; then
27        AC_COMPILE_IFELSE(
28          [AC_LANG_PROGRAM([[#include <sys/select.h>]],
29                           [[int memset; int bzero;]])
30          ],
31          [AC_LINK_IFELSE(
32             [AC_LANG_PROGRAM([[#include <sys/select.h>]], [[
33                  #undef memset
34                  #define memset nonexistent_memset
35                  extern
36                  #ifdef __cplusplus
37                  "C"
38                  #endif
39                  void *memset (void *, int, unsigned long);
40                  #undef bzero
41                  #define bzero nonexistent_bzero
42                  extern
43                  #ifdef __cplusplus
44                  "C"
45                  #endif
46                  void bzero (void *, unsigned long);
47                  fd_set fds;
48                  FD_ZERO (&fds);
49                ]])
50             ],
51             [],
52             [gl_cv_header_sys_select_h_selfcontained=no])
53          ])
54      fi
55    ])
56  dnl <sys/select.h> is always overridden, because of GNULIB_POSIXCHECK.
57  gl_CHECK_NEXT_HEADERS([sys/select.h])
58  if test $ac_cv_header_sys_select_h = yes; then
59    HAVE_SYS_SELECT_H=1
60  else
61    HAVE_SYS_SELECT_H=0
62  fi
63  AC_SUBST([HAVE_SYS_SELECT_H])
64  gl_PREREQ_SYS_H_WINSOCK2
65
66  dnl Check for declarations of anything we want to poison if the
67  dnl corresponding gnulib module is not in use.
68  gl_WARN_ON_USE_PREPARE([[
69/* Some systems require prerequisite headers.  */
70#include <sys/types.h>
71#if !(defined __GLIBC__ && !defined __UCLIBC__) && HAVE_SYS_TIME_H
72# include <sys/time.h>
73#endif
74#include <sys/select.h>
75    ]], [pselect select])
76])
77
78AC_DEFUN([gl_SYS_SELECT_MODULE_INDICATOR],
79[
80  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
81  AC_REQUIRE([gl_SYS_SELECT_H_DEFAULTS])
82  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
83  dnl Define it also as a C macro, for the benefit of the unit tests.
84  gl_MODULE_INDICATOR_FOR_TESTS([$1])
85])
86
87AC_DEFUN([gl_SYS_SELECT_H_DEFAULTS],
88[
89  GNULIB_PSELECT=0; AC_SUBST([GNULIB_PSELECT])
90  GNULIB_SELECT=0; AC_SUBST([GNULIB_SELECT])
91  dnl Assume proper GNU behavior unless another module says otherwise.
92  HAVE_PSELECT=1; AC_SUBST([HAVE_PSELECT])
93  REPLACE_PSELECT=0; AC_SUBST([REPLACE_PSELECT])
94  REPLACE_SELECT=0; AC_SUBST([REPLACE_SELECT])
95])
96