summaryrefslogtreecommitdiff
path: root/m4/select.m4
blob: 098af8ee7a755128adad72c258abd58ab7c597b9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
# select.m4 serial 10
dnl Copyright (C) 2009-2018 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

AC_DEFUN([gl_FUNC_SELECT],
[
  AC_REQUIRE([gl_HEADER_SYS_SELECT])
  AC_REQUIRE([AC_C_RESTRICT])
  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
  AC_REQUIRE([gl_SOCKETS])
  if test "$ac_cv_header_winsock2_h" = yes; then
    REPLACE_SELECT=1
  else
    dnl On Interix 3.5, select(0, NULL, NULL, NULL, timeout) fails with error
    dnl EFAULT.
    AC_CHECK_HEADERS_ONCE([sys/select.h])
    AC_CACHE_CHECK([whether select supports a 0 argument],
      [gl_cv_func_select_supports0],
      [
        AC_RUN_IFELSE([AC_LANG_SOURCE([[
#include <sys/types.h>
#include <sys/time.h>
#if HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
int main ()
{
  struct timeval timeout;
  timeout.tv_sec = 0;
  timeout.tv_usec = 5;
  return select (0, (fd_set *)0, (fd_set *)0, (fd_set *)0, &timeout) < 0;
}]])], [gl_cv_func_select_supports0=yes], [gl_cv_func_select_supports0=no],
          [
changequote(,)dnl
           case "$host_os" in
                       # Guess no on Interix.
             interix*) gl_cv_func_select_supports0="guessing no";;
                       # Guess yes otherwise.
             *)        gl_cv_func_select_supports0="guessing yes";;
           esac
changequote([,])dnl
          ])
      ])
    case "$gl_cv_func_select_supports0" in
      *yes) ;;
      *) REPLACE_SELECT=1 ;;
    esac

    dnl On FreeBSD 8.2, select() doesn't always reject bad fds.
    AC_CACHE_CHECK([whether select detects invalid fds],
      [gl_cv_func_select_detects_ebadf],
      [
        AC_RUN_IFELSE([AC_LANG_PROGRAM([[
#include <sys/types.h>
#include <sys/time.h>
#if HAVE_SYS_SELECT_H
# include <sys/select.h>
#endif
#include <unistd.h>
#include <errno.h>
]],[[
  fd_set set;
  dup2(0, 16);
  FD_ZERO(&set);
  FD_SET(16, &set);
  close(16);
  struct timeval timeout;
  timeout.tv_sec = 0;
  timeout.tv_usec = 5;
  return select (17, &set, NULL, NULL, &timeout) != -1 || errno != EBADF;
]])], [gl_cv_func_select_detects_ebadf=yes],
      [gl_cv_func_select_detects_ebadf=no],
          [
           case "$host_os" in
                             # Guess yes on Linux systems.
            linux-* | linux) gl_cv_func_select_detects_ebadf="guessing yes" ;;
                             # Guess yes on glibc systems.
            *-gnu* | gnu*)   gl_cv_func_select_detects_ebadf="guessing yes" ;;
                             # If we don't know, assume the worst.
            *)               gl_cv_func_select_detects_ebadf="guessing no" ;;
           esac
          ])
      ])
    case $gl_cv_func_select_detects_ebadf in
      *yes) ;;
      *) REPLACE_SELECT=1 ;;
    esac
  fi

  dnl Determine the needed libraries.
  LIB_SELECT="$LIBSOCKET"
  if test $REPLACE_SELECT = 1; then
    case "$host_os" in
      mingw*)
        dnl On the MSVC platform, the function MsgWaitForMultipleObjects
        dnl (used in lib/select.c) requires linking with -luser32. On mingw,
        dnl it is implicit.
        AC_LINK_IFELSE(
          [AC_LANG_SOURCE([[
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
int
main ()
{
  MsgWaitForMultipleObjects (0, NULL, 0, 0, 0);
  return 0;
}]])],
          [],
          [LIB_SELECT="$LIB_SELECT -luser32"])
        ;;
    esac
  fi
  AC_SUBST([LIB_SELECT])
])