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7a6dbc2f SDJ |
1 | # fcntl-o.m4 serial 5 |
2 | dnl Copyright (C) 2006, 2009-2018 Free Software Foundation, Inc. | |
8690e634 JK |
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. | |
6 | ||
7 | dnl 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. | |
12 | AC_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 | ||
7a6dbc2f | 21 | AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles |
8690e634 JK |
22 | AC_CHECK_HEADERS_ONCE([unistd.h]) |
23 | AC_CHECK_FUNCS_ONCE([symlink]) | |
24 | AC_CACHE_CHECK([for working fcntl.h], [gl_cv_header_working_fcntl_h], | |
25 | [AC_RUN_IFELSE( | |
26 | [AC_LANG_PROGRAM( | |
27 | [[#include <sys/types.h> | |
28 | #include <sys/stat.h> | |
29 | #if HAVE_UNISTD_H | |
30 | # include <unistd.h> | |
31 | #else /* on Windows with MSVC */ | |
32 | # include <io.h> | |
33 | # include <stdlib.h> | |
34 | # defined sleep(n) _sleep ((n) * 1000) | |
35 | #endif | |
36 | #include <fcntl.h> | |
37 | #ifndef O_NOATIME | |
38 | #define O_NOATIME 0 | |
39 | #endif | |
40 | #ifndef O_NOFOLLOW | |
41 | #define O_NOFOLLOW 0 | |
42 | #endif | |
43 | static int const constants[] = | |
44 | { | |
45 | O_CREAT, O_EXCL, O_NOCTTY, O_TRUNC, O_APPEND, | |
46 | O_NONBLOCK, O_SYNC, O_ACCMODE, O_RDONLY, O_RDWR, O_WRONLY | |
47 | }; | |
48 | ]], | |
49 | [[ | |
50 | int result = !constants; | |
51 | #if HAVE_SYMLINK | |
52 | { | |
53 | static char const sym[] = "conftest.sym"; | |
a512b375 JB |
54 | if (symlink ("/dev/null", sym) != 0) |
55 | result |= 2; | |
56 | else | |
57 | { | |
58 | int fd = open (sym, O_WRONLY | O_NOFOLLOW | O_CREAT, 0); | |
59 | if (fd >= 0) | |
60 | { | |
61 | close (fd); | |
62 | result |= 4; | |
63 | } | |
64 | } | |
65 | if (unlink (sym) != 0 || symlink (".", sym) != 0) | |
8690e634 JK |
66 | result |= 2; |
67 | else | |
68 | { | |
69 | int fd = open (sym, O_RDONLY | O_NOFOLLOW); | |
70 | if (fd >= 0) | |
71 | { | |
72 | close (fd); | |
73 | result |= 4; | |
74 | } | |
75 | } | |
76 | unlink (sym); | |
77 | } | |
78 | #endif | |
79 | { | |
80 | static char const file[] = "confdefs.h"; | |
81 | int fd = open (file, O_RDONLY | O_NOATIME); | |
82 | if (fd < 0) | |
83 | result |= 8; | |
84 | else | |
85 | { | |
86 | struct stat st0; | |
87 | if (fstat (fd, &st0) != 0) | |
88 | result |= 16; | |
89 | else | |
90 | { | |
91 | char c; | |
92 | sleep (1); | |
93 | if (read (fd, &c, 1) != 1) | |
94 | result |= 24; | |
95 | else | |
96 | { | |
97 | if (close (fd) != 0) | |
98 | result |= 32; | |
99 | else | |
100 | { | |
101 | struct stat st1; | |
102 | if (stat (file, &st1) != 0) | |
103 | result |= 40; | |
104 | else | |
105 | if (st0.st_atime != st1.st_atime) | |
106 | result |= 64; | |
107 | } | |
108 | } | |
109 | } | |
110 | } | |
111 | } | |
112 | return result;]])], | |
113 | [gl_cv_header_working_fcntl_h=yes], | |
114 | [case $? in #( | |
115 | 4) gl_cv_header_working_fcntl_h='no (bad O_NOFOLLOW)';; #( | |
116 | 64) gl_cv_header_working_fcntl_h='no (bad O_NOATIME)';; #( | |
117 | 68) gl_cv_header_working_fcntl_h='no (bad O_NOATIME, O_NOFOLLOW)';; #( | |
118 | *) gl_cv_header_working_fcntl_h='no';; | |
119 | esac], | |
7a6dbc2f SDJ |
120 | [case "$host_os" in |
121 | # Guess 'no' on native Windows. | |
122 | mingw*) gl_cv_header_working_fcntl_h='no' ;; | |
123 | *) gl_cv_header_working_fcntl_h=cross-compiling ;; | |
124 | esac | |
125 | ]) | |
126 | ]) | |
8690e634 JK |
127 | |
128 | case $gl_cv_header_working_fcntl_h in #( | |
129 | *O_NOATIME* | no | cross-compiling) ac_val=0;; #( | |
130 | *) ac_val=1;; | |
131 | esac | |
132 | AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOATIME], [$ac_val], | |
133 | [Define to 1 if O_NOATIME works.]) | |
134 | ||
135 | case $gl_cv_header_working_fcntl_h in #( | |
136 | *O_NOFOLLOW* | no | cross-compiling) ac_val=0;; #( | |
137 | *) ac_val=1;; | |
138 | esac | |
139 | AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOFOLLOW], [$ac_val], | |
140 | [Define to 1 if O_NOFOLLOW works.]) | |
141 | ]) |