1# fcntl-o.m4 serial 3
2dnl Copyright (C) 2006, 2009-2011 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  dnl AC_USE_SYSTEM_EXTENSIONS was introduced in autoconf 2.60 and obsoletes
16  dnl AC_GNU_SOURCE.
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],
21    [AC_RUN_IFELSE(
22       [AC_LANG_PROGRAM(
23          [[#include <sys/types.h>
24           #include <sys/stat.h>
25           #include <unistd.h>
26           #include <fcntl.h>
27           #ifndef O_NOATIME
28            #define O_NOATIME 0
29           #endif
30           #ifndef O_NOFOLLOW
31            #define O_NOFOLLOW 0
32           #endif
33           static int const constants[] =
34            {
35              O_CREAT, O_EXCL, O_NOCTTY, O_TRUNC, O_APPEND,
36              O_NONBLOCK, O_SYNC, O_ACCMODE, O_RDONLY, O_RDWR, O_WRONLY
37            };
38          ]],
39          [[
40            int result = !constants;
41            {
42              static char const sym[] = "conftest.sym";
43              if (symlink (".", sym) != 0)
44                result |= 2;
45              else
46                {
47                  int fd = open (sym, O_RDONLY | O_NOFOLLOW);
48                  if (fd >= 0)
49                    {
50                      close (fd);
51                      result |= 4;
52                    }
53                }
54              unlink (sym);
55            }
56            {
57              static char const file[] = "confdefs.h";
58              int fd = open (file, O_RDONLY | O_NOATIME);
59              if (fd < 0)
60                result |= 8;
61              else
62                {
63                  struct stat st0;
64                  if (fstat (fd, &st0) != 0)
65                    result |= 16;
66                  else
67                    {
68                      char c;
69                      sleep (1);
70                      if (read (fd, &c, 1) != 1)
71                        result |= 24;
72                      else
73                        {
74                          if (close (fd) != 0)
75                            result |= 32;
76                          else
77                            {
78                              struct stat st1;
79                              if (stat (file, &st1) != 0)
80                                result |= 40;
81                              else
82                                if (st0.st_atime != st1.st_atime)
83                                  result |= 64;
84                            }
85                        }
86                    }
87                }
88            }
89            return result;]])],
90       [gl_cv_header_working_fcntl_h=yes],
91       [case $? in #(
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';;
96        esac],
97       [gl_cv_header_working_fcntl_h=cross-compiling])])
98
99  case $gl_cv_header_working_fcntl_h in #(
100  *O_NOATIME* | no | cross-compiling) ac_val=0;; #(
101  *) ac_val=1;;
102  esac
103  AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOATIME], [$ac_val],
104    [Define to 1 if O_NOATIME works.])
105
106  case $gl_cv_header_working_fcntl_h in #(
107  *O_NOFOLLOW* | no | cross-compiling) ac_val=0;; #(
108  *) ac_val=1;;
109  esac
110  AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOFOLLOW], [$ac_val],
111    [Define to 1 if O_NOFOLLOW works.])
112])
113