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107 lines
3.7 KiB
Plaintext
107 lines
3.7 KiB
Plaintext
# dup2.m4
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# serial 28
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dnl Copyright (C) 2002, 2005, 2007, 2009-2024 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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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(
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[[#include <errno.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <sys/resource.h>
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#include <unistd.h>
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]GL_MDA_DEFINES[
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#ifndef RLIM_SAVED_CUR
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# define RLIM_SAVED_CUR RLIM_INFINITY
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#endif
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#ifndef RLIM_SAVED_MAX
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# define RLIM_SAVED_MAX RLIM_INFINITY
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#endif
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]],
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[[int result = 0;
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int bad_fd = INT_MAX;
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struct rlimit rlim;
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if (getrlimit (RLIMIT_NOFILE, &rlim) == 0
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&& 0 <= rlim.rlim_cur && rlim.rlim_cur <= INT_MAX
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&& rlim.rlim_cur != RLIM_INFINITY
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&& rlim.rlim_cur != RLIM_SAVED_MAX
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&& rlim.rlim_cur != RLIM_SAVED_CUR)
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bad_fd = rlim.rlim_cur;
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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) != 1)
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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, bad_fd) == -1 && errno != EBADF)
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result |= 16;
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/* Flush out some cygwin core dumps. */
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if (dup2 (2, -1) != -1 || errno != EBADF)
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result |= 32;
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dup2 (2, 255);
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dup2 (2, 256);
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/* On OS/2 kLIBC, dup2() does not work on a directory fd. */
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{
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int fd = open (".", O_RDONLY);
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if (fd == -1)
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result |= 64;
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else if (dup2 (fd, fd + 1) == -1)
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result |= 128;
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close (fd);
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}
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return result;]])
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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 "$host_os" in
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mingw* | windows*) # on this platform, dup2 always returns 0 for success
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gl_cv_func_dup2_works="guessing no" ;;
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cygwin*) # on cygwin 1.5.x, dup2(1,1) returns 0
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gl_cv_func_dup2_works="guessing no" ;;
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aix* | freebsd*)
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# on AIX 7.1 and FreeBSD 6.1, dup2 (1,toobig) gives EMFILE,
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# not EBADF.
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gl_cv_func_dup2_works="guessing no" ;;
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haiku*) # on Haiku alpha 2, dup2(1, 1) resets FD_CLOEXEC.
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gl_cv_func_dup2_works="guessing no" ;;
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*-android*) # implemented using dup3(), which fails if oldfd == newfd
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gl_cv_func_dup2_works="guessing no" ;;
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os2*) # on OS/2 kLIBC, dup2() does not work on a directory fd.
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gl_cv_func_dup2_works="guessing no" ;;
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*) gl_cv_func_dup2_works="guessing yes" ;;
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esac])
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])
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case "$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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AC_CHECK_FUNCS([setdtablesize])
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;;
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esac
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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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REPLACE_DUP2=1
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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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