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82 lines
2.7 KiB
Plaintext
82 lines
2.7 KiB
Plaintext
#serial 18
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dnl Copyright (C) 2002, 2005, 2007, 2009-2012 Free Software Foundation, Inc.
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dnl This file is free software; the Free Software Foundation
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dnl gives unlimited permission to copy and/or distribute it,
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dnl with or without modifications, as long as this notice is preserved.
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AC_DEFUN([gl_FUNC_DUP2],
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[
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AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
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AC_REQUIRE([AC_CANONICAL_HOST])
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m4_ifdef([gl_FUNC_DUP2_OBSOLETE], [
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AC_CHECK_FUNCS_ONCE([dup2])
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if test $ac_cv_func_dup2 = no; then
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HAVE_DUP2=0
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fi
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], [
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AC_DEFINE([HAVE_DUP2], [1], [Define to 1 if you have the 'dup2' function.])
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])
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if test $HAVE_DUP2 = 1; then
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AC_CACHE_CHECK([whether dup2 works], [gl_cv_func_dup2_works],
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[AC_RUN_IFELSE([
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AC_LANG_PROGRAM([[#include <unistd.h>
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#include <fcntl.h>
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#include <errno.h>]],
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[int result = 0;
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#ifdef FD_CLOEXEC
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if (fcntl (1, F_SETFD, FD_CLOEXEC) == -1)
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result |= 1;
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#endif
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if (dup2 (1, 1) == 0)
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result |= 2;
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#ifdef FD_CLOEXEC
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if (fcntl (1, F_GETFD) != FD_CLOEXEC)
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result |= 4;
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#endif
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close (0);
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if (dup2 (0, 0) != -1)
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result |= 8;
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/* Many gnulib modules require POSIX conformance of EBADF. */
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if (dup2 (2, 1000000) == -1 && errno != EBADF)
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result |= 16;
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return result;
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])
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],
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[gl_cv_func_dup2_works=yes], [gl_cv_func_dup2_works=no],
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[case "$host_os" in
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mingw*) # on this platform, dup2 always returns 0 for success
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gl_cv_func_dup2_works="guessing no" ;;
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cygwin*) # on cygwin 1.5.x, dup2(1,1) returns 0
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gl_cv_func_dup2_works="guessing no" ;;
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linux*) # On linux between 2008-07-27 and 2009-05-11, dup2 of a
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# closed fd may yield -EBADF instead of -1 / errno=EBADF.
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gl_cv_func_dup2_works="guessing no" ;;
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freebsd*) # on FreeBSD 6.1, dup2(1,1000000) gives EMFILE, not EBADF.
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gl_cv_func_dup2_works="guessing no" ;;
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haiku*) # on Haiku alpha 2, dup2(1, 1) resets FD_CLOEXEC.
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gl_cv_func_dup2_works="guessing no" ;;
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*) gl_cv_func_dup2_works="guessing yes" ;;
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esac])
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])
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case "$gl_cv_func_dup2_works" in
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*yes) ;;
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*)
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REPLACE_DUP2=1
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;;
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esac
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fi
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dnl Replace dup2() for supporting the gnulib-defined fchdir() function,
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dnl to keep fchdir's bookkeeping up-to-date.
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m4_ifdef([gl_FUNC_FCHDIR], [
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gl_TEST_FCHDIR
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if test $HAVE_FCHDIR = 0; then
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if test $HAVE_DUP2 = 1; then
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REPLACE_DUP2=1
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fi
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fi
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])
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])
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# Prerequisites of lib/dup2.c.
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AC_DEFUN([gl_PREREQ_DUP2], [])
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