m4/pselect.m4

   1 # pselect.m4 serial 9
   2 dnl Copyright (C) 2011-2021 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_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
  12   AC_CHECK_FUNCS_ONCE([pselect])
  13
  14   if test $ac_cv_func_pselect = yes; then
  15     AC_CACHE_CHECK([whether signature of pselect conforms to POSIX],
  16       [gl_cv_sig_pselect],
  17       [AC_LINK_IFELSE(
  18          [AC_LANG_PROGRAM(
  19               [[#include <sys/select.h>
  20                 ]],
  21               [[int (*p) (int, fd_set *, fd_set *, fd_set *restrict,
  22                           struct timespec const *restrict,
  23                           sigset_t const *restrict) = pselect;
  24                 return !p;]])],
  25          [gl_cv_sig_pselect=yes],
  26          [gl_cv_sig_pselect=no])])
  27
  28     dnl On FreeBSD 8.2, pselect() doesn't always reject bad fds.
  29     AC_CACHE_CHECK([whether pselect detects invalid fds],
  30       [gl_cv_func_pselect_detects_ebadf],
  31       [
  32         AC_RUN_IFELSE([AC_LANG_PROGRAM([[
  33 #include <sys/types.h>
  34 #include <sys/time.h>
  35 #if HAVE_SYS_SELECT_H
  36 # include <sys/select.h>
  37 #endif
  38 #include <unistd.h>
  39 #include <errno.h>
  40 ]GL_MDA_DEFINES],
  41 [[
  42   fd_set set;
  43   dup2(0, 16);
  44   FD_ZERO(&set);
  45   FD_SET(16, &set);
  46   close(16);
  47   struct timespec timeout;
  48   timeout.tv_sec = 0;
  49   timeout.tv_nsec = 5000;
  50   return pselect (17, &set, NULL, NULL, &timeout, NULL) != -1 || errno != EBADF;
  51 ]])], [gl_cv_func_pselect_detects_ebadf=yes],
  52       [gl_cv_func_pselect_detects_ebadf=no],
  53           [
  54            case "$host_os" in
  55                              # Guess yes on Linux systems.
  56             linux-* | linux) gl_cv_func_pselect_detects_ebadf="guessing yes" ;;
  57                              # Guess yes on glibc systems.
  58             *-gnu* | gnu*)   gl_cv_func_pselect_detects_ebadf="guessing yes" ;;
  59                              # If we don't know, obey --enable-cross-guesses.
  60             *)               gl_cv_func_pselect_detects_ebadf="$gl_cross_guess_normal" ;;
  61            esac
  62           ])
  63       ])
  64     case $gl_cv_func_pselect_detects_ebadf in
  65       *yes) ;;
  66       *) REPLACE_PSELECT=1 ;;
  67     esac
  68   fi
  69
  70   if test $ac_cv_func_pselect = no || test $gl_cv_sig_pselect = no; then
  71     REPLACE_PSELECT=1
  72   fi
  73 ])