141 lines
4.7 KiB
Plaintext
141 lines
4.7 KiB
Plaintext
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# fcntl-o.m4 serial 7
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dnl Copyright (C) 2006, 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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dnl Written by Paul Eggert.
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AC_PREREQ([2.60])
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# Test whether the flags O_NOATIME and O_NOFOLLOW actually work.
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# Define HAVE_WORKING_O_NOATIME to 1 if O_NOATIME works, or to 0 otherwise.
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# Define HAVE_WORKING_O_NOFOLLOW to 1 if O_NOFOLLOW works, or to 0 otherwise.
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AC_DEFUN([gl_FCNTL_O_FLAGS],
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[
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dnl Persuade glibc <fcntl.h> to define O_NOATIME and O_NOFOLLOW.
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AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
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AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
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AC_CHECK_HEADERS_ONCE([unistd.h])
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AC_CHECK_FUNCS_ONCE([symlink])
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AC_CACHE_CHECK([for working fcntl.h], [gl_cv_header_working_fcntl_h],
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[AC_RUN_IFELSE(
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[AC_LANG_PROGRAM(
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[[#include <sys/types.h>
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#include <sys/stat.h>
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#if HAVE_UNISTD_H
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# include <unistd.h>
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#else /* on Windows with MSVC */
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# include <io.h>
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# include <stdlib.h>
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# defined sleep(n) _sleep ((n) * 1000)
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#endif
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#include <fcntl.h>
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]GL_MDA_DEFINES[
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#ifndef O_NOATIME
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#define O_NOATIME 0
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#endif
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#ifndef O_NOFOLLOW
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#define O_NOFOLLOW 0
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#endif
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static int const constants[] =
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{
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O_CREAT, O_EXCL, O_NOCTTY, O_TRUNC, O_APPEND,
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O_NONBLOCK, O_SYNC, O_ACCMODE, O_RDONLY, O_RDWR, O_WRONLY
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};
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]],
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[[
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int result = !constants;
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#if HAVE_SYMLINK
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{
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static char const sym[] = "conftest.sym";
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if (symlink ("/dev/null", sym) != 0)
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result |= 2;
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else
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{
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int fd = open (sym, O_WRONLY | O_NOFOLLOW | O_CREAT, 0);
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if (fd >= 0)
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{
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close (fd);
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result |= 4;
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}
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}
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if (unlink (sym) != 0 || symlink (".", sym) != 0)
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result |= 2;
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else
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{
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int fd = open (sym, O_RDONLY | O_NOFOLLOW);
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if (fd >= 0)
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{
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close (fd);
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result |= 4;
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}
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}
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unlink (sym);
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}
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#endif
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{
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static char const file[] = "confdefs.h";
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int fd = open (file, O_RDONLY | O_NOATIME);
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if (fd < 0)
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result |= 8;
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else
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{
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struct stat st0;
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if (fstat (fd, &st0) != 0)
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result |= 16;
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else
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{
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char c;
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sleep (1);
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if (read (fd, &c, 1) != 1)
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result |= 24;
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else
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{
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if (close (fd) != 0)
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result |= 32;
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else
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{
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struct stat st1;
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if (stat (file, &st1) != 0)
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result |= 40;
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else
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if (st0.st_atime != st1.st_atime)
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result |= 64;
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}
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}
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}
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}
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}
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return result;]])],
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[gl_cv_header_working_fcntl_h=yes],
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[case $? in #(
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4) gl_cv_header_working_fcntl_h='no (bad O_NOFOLLOW)';; #(
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64) gl_cv_header_working_fcntl_h='no (bad O_NOATIME)';; #(
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68) gl_cv_header_working_fcntl_h='no (bad O_NOATIME, O_NOFOLLOW)';; #(
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*) gl_cv_header_working_fcntl_h='no';;
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esac],
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[case "$host_os" in
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# Guess 'no' on native Windows.
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mingw*) gl_cv_header_working_fcntl_h='no' ;;
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*) gl_cv_header_working_fcntl_h=cross-compiling ;;
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esac
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])
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])
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case $gl_cv_header_working_fcntl_h in #(
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*O_NOATIME* | no | cross-compiling) ac_val=0;; #(
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*) ac_val=1;;
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esac
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AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOATIME], [$ac_val],
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[Define to 1 if O_NOATIME works.])
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case $gl_cv_header_working_fcntl_h in #(
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*O_NOFOLLOW* | no | cross-compiling) ac_val=0;; #(
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*) ac_val=1;;
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esac
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AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOFOLLOW], [$ac_val],
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[Define to 1 if O_NOFOLLOW works.])
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])
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