2 dnl Copyright (C) 2006, 2009-2011 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.
9 # Test whether the flags O_NOATIME and O_NOFOLLOW actually work.
10 # Define HAVE_WORKING_O_NOATIME to 1 if O_NOATIME works, or to 0 otherwise.
11 # Define HAVE_WORKING_O_NOFOLLOW to 1 if O_NOFOLLOW works, or to 0 otherwise.
12 AC_DEFUN([gl_FCNTL_O_FLAGS],
14 dnl Persuade glibc <fcntl.h> to define O_NOATIME and O_NOFOLLOW.
15 dnl AC_USE_SYSTEM_EXTENSIONS was introduced in autoconf 2.60 and obsoletes
17 m4_ifdef([AC_USE_SYSTEM_EXTENSIONS],
18 [AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])],
19 [AC_REQUIRE([AC_GNU_SOURCE])])
20 AC_CACHE_CHECK([for working fcntl.h], [gl_cv_header_working_fcntl_h],
23 [[#include <sys/types.h>
33 static int const constants[] =
35 O_CREAT, O_EXCL, O_NOCTTY, O_TRUNC, O_APPEND,
36 O_NONBLOCK, O_SYNC, O_ACCMODE, O_RDONLY, O_RDWR, O_WRONLY
40 int result = !constants;
42 static char const sym[] = "conftest.sym";
43 if (symlink (".", sym) != 0)
47 int fd = open (sym, O_RDONLY | O_NOFOLLOW);
57 static char const file[] = "confdefs.h";
58 int fd = open (file, O_RDONLY | O_NOATIME);
64 if (fstat (fd, &st0) != 0)
70 if (read (fd, &c, 1) != 1)
79 if (stat (file, &st1) != 0)
82 if (st0.st_atime != st1.st_atime)
90 [gl_cv_header_working_fcntl_h=yes],
92 4) gl_cv_header_working_fcntl_h='no (bad O_NOFOLLOW)';; #(
93 64) gl_cv_header_working_fcntl_h='no (bad O_NOATIME)';; #(
94 68) gl_cv_header_working_fcntl_h='no (bad O_NOATIME, O_NOFOLLOW)';; #(
95 *) gl_cv_header_working_fcntl_h='no';;
97 [gl_cv_header_working_fcntl_h=cross-compiling])])
99 case $gl_cv_header_working_fcntl_h in #(
100 *O_NOATIME* | no | cross-compiling) ac_val=0;; #(
103 AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOATIME], [$ac_val],
104 [Define to 1 if O_NOATIME works.])
106 case $gl_cv_header_working_fcntl_h in #(
107 *O_NOFOLLOW* | no | cross-compiling) ac_val=0;; #(
110 AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOFOLLOW], [$ac_val],
111 [Define to 1 if O_NOFOLLOW works.])