152 lines
5.1 KiB
Plaintext
152 lines
5.1 KiB
Plaintext
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# fcntl.m4 serial 11
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dnl Copyright (C) 2009-2022 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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# For now, this module ensures that fcntl()
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# - supports F_DUPFD correctly
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# - supports or emulates F_DUPFD_CLOEXEC
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# - supports F_GETFD
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# Still to be ported to mingw:
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# - F_SETFD
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# - F_GETFL, F_SETFL
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# - F_GETOWN, F_SETOWN
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# - F_GETLK, F_SETLK, F_SETLKW
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AC_DEFUN([gl_FUNC_FCNTL],
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[
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dnl Persuade glibc to expose F_DUPFD_CLOEXEC.
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AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
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AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
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AC_REQUIRE([AC_CANONICAL_HOST])
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AC_CHECK_FUNCS_ONCE([fcntl])
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if test $ac_cv_func_fcntl = no; then
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gl_REPLACE_FCNTL
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else
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dnl cygwin 1.5.x F_DUPFD has wrong errno, and allows negative target
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dnl haiku alpha 2 F_DUPFD has wrong errno
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AC_CACHE_CHECK([whether fcntl handles F_DUPFD correctly],
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[gl_cv_func_fcntl_f_dupfd_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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if (fcntl (0, F_DUPFD, -1) != -1) result |= 1;
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if (errno != EINVAL) result |= 2;
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if (fcntl (0, F_DUPFD, bad_fd) != -1) result |= 4;
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if (errno != EINVAL) result |= 8;
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/* On OS/2 kLIBC, F_DUPFD does not work on a directory fd */
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{
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int fd;
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fd = open (".", O_RDONLY);
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if (fd == -1)
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result |= 16;
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else if (fcntl (fd, F_DUPFD, STDERR_FILENO + 1) == -1)
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result |= 32;
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close (fd);
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}
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return result;]])],
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[gl_cv_func_fcntl_f_dupfd_works=yes],
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[gl_cv_func_fcntl_f_dupfd_works=no],
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[case $host_os in
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aix* | cygwin* | haiku*)
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gl_cv_func_fcntl_f_dupfd_works="guessing no" ;;
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*) gl_cv_func_fcntl_f_dupfd_works="guessing yes" ;;
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esac])])
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case $gl_cv_func_fcntl_f_dupfd_works in
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*yes) ;;
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*) gl_REPLACE_FCNTL
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AC_DEFINE([FCNTL_DUPFD_BUGGY], [1], [Define this to 1 if F_DUPFD
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behavior does not match POSIX]) ;;
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esac
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dnl Many systems lack F_DUPFD_CLOEXEC.
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dnl NetBSD 9.0 declares F_DUPFD_CLOEXEC but it works only like F_DUPFD.
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AC_CACHE_CHECK([whether fcntl understands F_DUPFD_CLOEXEC],
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[gl_cv_func_fcntl_f_dupfd_cloexec],
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[AC_RUN_IFELSE(
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[AC_LANG_SOURCE(
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[[#include <fcntl.h>
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#include <unistd.h>
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int main (int argc, char *argv[])
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{
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if (argc == 1)
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/* parent process */
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{
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if (fcntl (1, F_DUPFD_CLOEXEC, 10) < 0)
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return 1;
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return execl ("./conftest", "./conftest", "child", NULL);
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}
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else
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/* child process */
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return (fcntl (10, F_GETFL) < 0 ? 0 : 42);
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}
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]])
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],
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[AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
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#ifdef __linux__
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/* The Linux kernel only added F_DUPFD_CLOEXEC in 2.6.24, so we always replace
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it to support the semantics on older kernels that failed with EINVAL. */
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choke me
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#endif
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]])],
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[gl_cv_func_fcntl_f_dupfd_cloexec=yes],
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[gl_cv_func_fcntl_f_dupfd_cloexec="needs runtime check"])
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],
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[gl_cv_func_fcntl_f_dupfd_cloexec=no],
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[case "$host_os" in
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# Guess no on NetBSD.
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netbsd*) gl_cv_func_fcntl_f_dupfd_cloexec="guessing no" ;;
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*) gl_cv_func_fcntl_f_dupfd_cloexec="$gl_cross_guess_normal" ;;
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esac
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])
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])
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case "$gl_cv_func_fcntl_f_dupfd_cloexec" in
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*yes) ;;
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*) gl_REPLACE_FCNTL
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dnl No witness macro needed for this bug.
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;;
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esac
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fi
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dnl Replace fcntl() 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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gl_REPLACE_FCNTL
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fi
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])
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])
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AC_DEFUN([gl_REPLACE_FCNTL],
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[
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AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
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AC_CHECK_FUNCS_ONCE([fcntl])
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if test $ac_cv_func_fcntl = no; then
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HAVE_FCNTL=0
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else
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REPLACE_FCNTL=1
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fi
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])
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