source: trunk/src/grep/m4/fcntl-o.m4

Last change on this file was 3529, checked in by bird, 4 years ago

Imported grep 3.7 from grep-3.7.tar.gz (sha256: c22b0cf2d4f6bbe599c902387e8058990e1eee99aef333a203829e5fd3dbb342), applying minimal auto-props.
  • Property svn:eol-style set to LF
File size: 4.7 KB
Line 
1# fcntl-o.m4 serial 7
2dnl Copyright (C) 2006, 2009-2021 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
9AC_PREREQ([2.60])
10
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.
14AC_DEFUN([gl_FCNTL_O_FLAGS],
15[
16 dnl Persuade glibc <fcntl.h> to define O_NOATIME and O_NOFOLLOW.
17 AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
18
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],
23 [AC_RUN_IFELSE(
24 [AC_LANG_PROGRAM(
25 [[#include <sys/types.h>
26 #include <sys/stat.h>
27 #if HAVE_UNISTD_H
28 # include <unistd.h>
29 #else /* on Windows with MSVC */
30 # include <io.h>
31 # include <stdlib.h>
32 # defined sleep(n) _sleep ((n) * 1000)
33 #endif
34 #include <fcntl.h>
35 ]GL_MDA_DEFINES[
36 #ifndef O_NOATIME
37 #define O_NOATIME 0
38 #endif
39 #ifndef O_NOFOLLOW
40 #define O_NOFOLLOW 0
41 #endif
42 static int const constants[] =
43 {
44 O_CREAT, O_EXCL, O_NOCTTY, O_TRUNC, O_APPEND,
45 O_NONBLOCK, O_SYNC, O_ACCMODE, O_RDONLY, O_RDWR, O_WRONLY
46 };
47 ]],
48 [[
49 int result = !constants;
50 #if HAVE_SYMLINK
51 {
52 static char const sym[] = "conftest.sym";
53 if (symlink ("/dev/null", sym) != 0)
54 result |= 2;
55 else
56 {
57 int fd = open (sym, O_WRONLY | O_NOFOLLOW | O_CREAT, 0);
58 if (fd >= 0)
59 {
60 close (fd);
61 result |= 4;
62 }
63 }
64 if (unlink (sym) != 0 || symlink (".", sym) != 0)
65 result |= 2;
66 else
67 {
68 int fd = open (sym, O_RDONLY | O_NOFOLLOW);
69 if (fd >= 0)
70 {
71 close (fd);
72 result |= 4;
73 }
74 }
75 unlink (sym);
76 }
77 #endif
78 {
79 static char const file[] = "confdefs.h";
80 int fd = open (file, O_RDONLY | O_NOATIME);
81 if (fd < 0)
82 result |= 8;
83 else
84 {
85 struct stat st0;
86 if (fstat (fd, &st0) != 0)
87 result |= 16;
88 else
89 {
90 char c;
91 sleep (1);
92 if (read (fd, &c, 1) != 1)
93 result |= 24;
94 else
95 {
96 if (close (fd) != 0)
97 result |= 32;
98 else
99 {
100 struct stat st1;
101 if (stat (file, &st1) != 0)
102 result |= 40;
103 else
104 if (st0.st_atime != st1.st_atime)
105 result |= 64;
106 }
107 }
108 }
109 }
110 }
111 return result;]])],
112 [gl_cv_header_working_fcntl_h=yes],
113 [case $? in #(
114 4) gl_cv_header_working_fcntl_h='no (bad O_NOFOLLOW)';; #(
115 64) gl_cv_header_working_fcntl_h='no (bad O_NOATIME)';; #(
116 68) gl_cv_header_working_fcntl_h='no (bad O_NOATIME, O_NOFOLLOW)';; #(
117 *) gl_cv_header_working_fcntl_h='no';;
118 esac],
119 [case "$host_os" in
120 # Guess 'no' on native Windows.
121 mingw*) gl_cv_header_working_fcntl_h='no' ;;
122 *) gl_cv_header_working_fcntl_h=cross-compiling ;;
123 esac
124 ])
125 ])
126
127 case $gl_cv_header_working_fcntl_h in #(
128 *O_NOATIME* | no | cross-compiling) ac_val=0;; #(
129 *) ac_val=1;;
130 esac
131 AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOATIME], [$ac_val],
132 [Define to 1 if O_NOATIME works.])
133
134 case $gl_cv_header_working_fcntl_h in #(
135 *O_NOFOLLOW* | no | cross-compiling) ac_val=0;; #(
136 *) ac_val=1;;
137 esac
138 AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOFOLLOW], [$ac_val],
139 [Define to 1 if O_NOFOLLOW works.])
140])
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