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#serial 27 |
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dnl Copyright (C) 2002, 2005, 2007, 2009-2023 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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if (dup2 (2, bad_fd) == -1 && errno != EBADF) |
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result |= 16; |
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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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{ |
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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 "$host_os" in |
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mingw*) # on this platform, dup2 always returns 0 for success |
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gl_cv_func_dup2_works="guessing no" ;; |
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cygwin*) # on cygwin 1.5.x, dup2(1,1) returns 0 |
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gl_cv_func_dup2_works="guessing no" ;; |
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aix* | freebsd*) |
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# on AIX 7.1 and FreeBSD 6.1, dup2 (1,toobig) gives EMFILE, |
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# not EBADF. |
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gl_cv_func_dup2_works="guessing no" ;; |
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haiku*) # on Haiku alpha 2, dup2(1, 1) resets FD_CLOEXEC. |
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gl_cv_func_dup2_works="guessing no" ;; |
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*-android*) # implemented using dup3(), which fails if oldfd == newfd |
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gl_cv_func_dup2_works="guessing no" ;; |
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os2*) # on OS/2 kLIBC, dup2() does not work on a directory fd. |
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gl_cv_func_dup2_works="guessing no" ;; |
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*) gl_cv_func_dup2_works="guessing yes" ;; |
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esac]) |
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]) |
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case "$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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