2 dnl Copyright (C) 2006, 2009-2020 Free Software Foundation, Inc.
3 dnl This file is free software; the Free Software Foundation
4 dnl gives unlimited permission to copy and/or distribute it,
5 dnl with or without modifications, as long as this notice is preserved.
7 dnl Written by Paul Eggert.
11 # Test whether the flags O_NOATIME and O_NOFOLLOW actually work.
12 # Define HAVE_WORKING_O_NOATIME to 1 if O_NOATIME works, or to 0 otherwise.
13 # Define HAVE_WORKING_O_NOFOLLOW to 1 if O_NOFOLLOW works, or to 0 otherwise.
14 AC_DEFUN([gl_FCNTL_O_FLAGS],
16 dnl Persuade glibc <fcntl.h> to define O_NOATIME and O_NOFOLLOW.
17 AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
19 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
20 AC_CHECK_HEADERS_ONCE([unistd.h])
21 AC_CHECK_FUNCS_ONCE([symlink])
22 AC_CACHE_CHECK([for working fcntl.h], [gl_cv_header_working_fcntl_h],
25 [[#include <sys/types.h>
29 #else /* on Windows with MSVC */
32 # defined sleep(n) _sleep ((n) * 1000)
41 static int const constants[] =
43 O_CREAT, O_EXCL, O_NOCTTY, O_TRUNC, O_APPEND,
44 O_NONBLOCK, O_SYNC, O_ACCMODE, O_RDONLY, O_RDWR, O_WRONLY
48 int result = !constants;
51 static char const sym[] = "conftest.sym";
52 if (symlink ("/dev/null", sym) != 0)
56 int fd = open (sym, O_WRONLY | O_NOFOLLOW | O_CREAT, 0);
63 if (unlink (sym) != 0 || symlink (".", sym) != 0)
67 int fd = open (sym, O_RDONLY | O_NOFOLLOW);
78 static char const file[] = "confdefs.h";
79 int fd = open (file, O_RDONLY | O_NOATIME);
85 if (fstat (fd, &st0) != 0)
91 if (read (fd, &c, 1) != 1)
100 if (stat (file, &st1) != 0)
103 if (st0.st_atime != st1.st_atime)
111 [gl_cv_header_working_fcntl_h=yes],
113 4) gl_cv_header_working_fcntl_h='no (bad O_NOFOLLOW)';; #(
114 64) gl_cv_header_working_fcntl_h='no (bad O_NOATIME)';; #(
115 68) gl_cv_header_working_fcntl_h='no (bad O_NOATIME, O_NOFOLLOW)';; #(
116 *) gl_cv_header_working_fcntl_h='no';;
119 # Guess 'no' on native Windows.
120 mingw*) gl_cv_header_working_fcntl_h='no' ;;
121 *) gl_cv_header_working_fcntl_h=cross-compiling ;;
126 case $gl_cv_header_working_fcntl_h in #(
127 *O_NOATIME* | no | cross-compiling) ac_val=0;; #(
130 AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOATIME], [$ac_val],
131 [Define to 1 if O_NOATIME works.])
133 case $gl_cv_header_working_fcntl_h in #(
134 *O_NOFOLLOW* | no | cross-compiling) ac_val=0;; #(
137 AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOFOLLOW], [$ac_val],
138 [Define to 1 if O_NOFOLLOW works.])