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], []) 82
