1# fcntl-o.m4 serial 1
2dnl Copyright (C) 2006, 2009-2010 Free Software Foundation, Inc.
3dnl This file is free software; the Free Software Foundation
4dnl gives unlimited permission to copy and/or distribute it,
5dnl with or without modifications, as long as this notice is preserved.
6
7dnl Written by Paul Eggert.
8
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.
12AC_DEFUN([gl_FCNTL_O_FLAGS],
13[
14  dnl Persuade glibc <fcntl.h> to define O_NOATIME and O_NOFOLLOW.
15  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
16  AC_CACHE_CHECK([for working fcntl.h], [gl_cv_header_working_fcntl_h],
17    [AC_RUN_IFELSE(
18       [AC_LANG_PROGRAM(
19          [[#include <sys/types.h>
20           #include <sys/stat.h>
21           #include <unistd.h>
22           #include <fcntl.h>
23           #ifndef O_NOATIME
24            #define O_NOATIME 0
25           #endif
26           #ifndef O_NOFOLLOW
27            #define O_NOFOLLOW 0
28           #endif
29           static int const constants[] =
30            {
31              O_CREAT, O_EXCL, O_NOCTTY, O_TRUNC, O_APPEND,
32              O_NONBLOCK, O_SYNC, O_ACCMODE, O_RDONLY, O_RDWR, O_WRONLY
33            };
34          ]],
35          [[
36            int status = !constants;
37            {
38              static char const sym[] = "conftest.sym";
39              if (symlink (".", sym) != 0
40                  || close (open (sym, O_RDONLY | O_NOFOLLOW)) == 0)
41                status |= 32;
42              unlink (sym);
43            }
44            {
45              static char const file[] = "confdefs.h";
46              int fd = open (file, O_RDONLY | O_NOATIME);
47              char c;
48              struct stat st0, st1;
49              if (fd < 0
50                  || fstat (fd, &st0) != 0
51                  || sleep (1) != 0
52                  || read (fd, &c, 1) != 1
53                  || close (fd) != 0
54                  || stat (file, &st1) != 0
55                  || st0.st_atime != st1.st_atime)
56                status |= 64;
57            }
58            return status;]])],
59       [gl_cv_header_working_fcntl_h=yes],
60       [case $? in #(
61        32) gl_cv_header_working_fcntl_h='no (bad O_NOFOLLOW)';; #(
62        64) gl_cv_header_working_fcntl_h='no (bad O_NOATIME)';; #(
63        96) gl_cv_header_working_fcntl_h='no (bad O_NOATIME, O_NOFOLLOW)';; #(
64         *) gl_cv_header_working_fcntl_h='no';;
65        esac],
66       [gl_cv_header_working_fcntl_h=cross-compiling])])
67
68  case $gl_cv_header_working_fcntl_h in #(
69  *O_NOATIME* | no | cross-compiling) ac_val=0;; #(
70  *) ac_val=1;;
71  esac
72  AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOATIME], [$ac_val],
73    [Define to 1 if O_NOATIME works.])
74
75  case $gl_cv_header_working_fcntl_h in #(
76  *O_NOFOLLOW* | no | cross-compiling) ac_val=0;; #(
77  *) ac_val=1;;
78  esac
79  AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOFOLLOW], [$ac_val],
80    [Define to 1 if O_NOFOLLOW works.])
81])
82