m4/pselect.m4

   1 # pselect.m4 serial 2
   2 dnl Copyright (C) 2011-2016 Free Software Foundation, Inc.
   3 dnl This file is free software; the Free Software Foundation
   4 dnl gives unlimited permission to copy and/or distribute it,
   5 dnl with or without modifications, as long as this notice is preserved.
   6
   7 AC_DEFUN([gl_FUNC_PSELECT],
   8 [
   9   AC_REQUIRE([gl_HEADER_SYS_SELECT])
  10   AC_REQUIRE([AC_C_RESTRICT])
  11   AC_CHECK_FUNCS_ONCE([pselect])
  12
  13   if test $ac_cv_func_pselect = yes; then
  14     AC_CACHE_CHECK([whether signature of pselect conforms to POSIX],
  15       gl_cv_sig_pselect,
  16       [AC_LINK_IFELSE(
  17          [AC_LANG_PROGRAM(
  18               [[#include <sys/select.h>
  19                 ]],
  20               [[int (*p) (int, fd_set *, fd_set *, fd_set *restrict,
  21                           struct timespec const *restrict,
  22                           sigset_t const *restrict) = pselect;
  23                 return !p;]])],
  24          [gl_cv_sig_pselect=yes],
  25          [gl_cv_sig_pselect=no])])
  26
  27     dnl On FreeBSD 8.2, pselect() doesn't always reject bad fds.
  28     AC_CACHE_CHECK([whether pselect detects invalid fds],
  29       [gl_cv_func_pselect_detects_ebadf],
  30       [
  31         AC_RUN_IFELSE([AC_LANG_PROGRAM([[
  32 #include <sys/types.h>
  33 #include <sys/time.h>
  34 #if HAVE_SYS_SELECT_H
  35 # include <sys/select.h>
  36 #endif
  37 #include <unistd.h>
  38 #include <errno.h>
  39 ]],[[
  40   fd_set set;
  41   dup2(0, 16);
  42   FD_ZERO(&set);
  43   FD_SET(16, &set);
  44   close(16);
  45   struct timespec timeout;
  46   timeout.tv_sec = 0;
  47   timeout.tv_nsec = 5000;
  48   return pselect (17, &set, NULL, NULL, &timeout, NULL) != -1 || errno != EBADF;
  49 ]])], [gl_cv_func_pselect_detects_ebadf=yes],
  50       [gl_cv_func_pselect_detects_ebadf=no],
  51           [
  52            case "$host_os" in
  53                     # Guess yes on glibc systems.
  54             *-gnu*) gl_cv_func_pselect_detects_ebadf="guessing yes" ;;
  55                     # If we don't know, assume the worst.
  56             *)      gl_cv_func_pselect_detects_ebadf="guessing no" ;;
  57            esac
  58           ])
  59       ])
  60     case $gl_cv_func_pselect_detects_ebadf in
  61       *yes) ;;
  62       *) REPLACE_PSELECT=1 ;;
  63     esac
  64   fi
  65
  66   if test $ac_cv_func_pselect = no || test $gl_cv_sig_pselect = no; then
  67     REPLACE_PSELECT=1
  68   fi
  69 ])