m4/dup2.m4

   1 #serial 18
   2 dnl Copyright (C) 2002, 2005, 2007, 2009-2012 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_DUP2],
   8 [
   9   AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
  10   AC_REQUIRE([AC_CANONICAL_HOST])
  11   m4_ifdef([gl_FUNC_DUP2_OBSOLETE], [
  12     AC_CHECK_FUNCS_ONCE([dup2])
  13     if test $ac_cv_func_dup2 = no; then
  14       HAVE_DUP2=0
  15     fi
  16   ], [
  17     AC_DEFINE([HAVE_DUP2], [1], [Define to 1 if you have the 'dup2' function.])
  18   ])
  19   if test $HAVE_DUP2 = 1; then
  20     AC_CACHE_CHECK([whether dup2 works], [gl_cv_func_dup2_works],
  21       [AC_RUN_IFELSE([
  22          AC_LANG_PROGRAM([[#include <unistd.h>
  23 #include <fcntl.h>
  24 #include <errno.h>]],
  25            [int result = 0;
  26 #ifdef FD_CLOEXEC
  27             if (fcntl (1, F_SETFD, FD_CLOEXEC) == -1)
  28               result |= 1;
  29 #endif
  30             if (dup2 (1, 1) == 0)
  31               result |= 2;
  32 #ifdef FD_CLOEXEC
  33             if (fcntl (1, F_GETFD) != FD_CLOEXEC)
  34               result |= 4;
  35 #endif
  36             close (0);
  37             if (dup2 (0, 0) != -1)
  38               result |= 8;
  39             /* Many gnulib modules require POSIX conformance of EBADF.  */
  40             if (dup2 (2, 1000000) == -1 && errno != EBADF)
  41               result |= 16;
  42             return result;
  43            ])
  44         ],
  45         [gl_cv_func_dup2_works=yes], [gl_cv_func_dup2_works=no],
  46         [case "$host_os" in
  47            mingw*) # on this platform, dup2 always returns 0 for success
  48              gl_cv_func_dup2_works="guessing no" ;;
  49            cygwin*) # on cygwin 1.5.x, dup2(1,1) returns 0
  50              gl_cv_func_dup2_works="guessing no" ;;
  51            linux*) # On linux between 2008-07-27 and 2009-05-11, dup2 of a
  52                    # closed fd may yield -EBADF instead of -1 / errno=EBADF.
  53              gl_cv_func_dup2_works="guessing no" ;;
  54            freebsd*) # on FreeBSD 6.1, dup2(1,1000000) gives EMFILE, not EBADF.
  55              gl_cv_func_dup2_works="guessing no" ;;
  56            haiku*) # on Haiku alpha 2, dup2(1, 1) resets FD_CLOEXEC.
  57              gl_cv_func_dup2_works="guessing no" ;;
  58            *) gl_cv_func_dup2_works="guessing yes" ;;
  59          esac])
  60       ])
  61     case "$gl_cv_func_dup2_works" in
  62       *yes) ;;
  63       *)
  64         REPLACE_DUP2=1
  65         ;;
  66     esac
  67   fi
  68   dnl Replace dup2() for supporting the gnulib-defined fchdir() function,
  69   dnl to keep fchdir's bookkeeping up-to-date.
  70   m4_ifdef([gl_FUNC_FCHDIR], [
  71     gl_TEST_FCHDIR
  72     if test $HAVE_FCHDIR = 0; then
  73       if test $HAVE_DUP2 = 1; then
  74         REPLACE_DUP2=1
  75       fi
  76     fi
  77   ])
  78 ])
  79
  80 # Prerequisites of lib/dup2.c.
  81 AC_DEFUN([gl_PREREQ_DUP2], [])