| 1 | # fcntl-o.m4 serial 4
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| 2 | dnl Copyright (C) 2006, 2009-2012 Free Software Foundation, Inc.
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| 3 | dnl This file is free software; the Free Software Foundation
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| 4 | dnl gives unlimited permission to copy and/or distribute it,
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| 5 | dnl with or without modifications, as long as this notice is preserved.
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| 6 |
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| 7 | dnl Written by Paul Eggert.
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| 8 |
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| 9 | # Test whether the flags O_NOATIME and O_NOFOLLOW actually work.
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| 10 | # Define HAVE_WORKING_O_NOATIME to 1 if O_NOATIME works, or to 0 otherwise.
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| 11 | # Define HAVE_WORKING_O_NOFOLLOW to 1 if O_NOFOLLOW works, or to 0 otherwise.
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| 12 | AC_DEFUN([gl_FCNTL_O_FLAGS],
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| 13 | [
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| 14 | dnl Persuade glibc <fcntl.h> to define O_NOATIME and O_NOFOLLOW.
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| 15 | dnl AC_USE_SYSTEM_EXTENSIONS was introduced in autoconf 2.60 and obsoletes
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| 16 | dnl AC_GNU_SOURCE.
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| 17 | m4_ifdef([AC_USE_SYSTEM_EXTENSIONS],
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| 18 | [AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])],
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| 19 | [AC_REQUIRE([AC_GNU_SOURCE])])
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| 20 |
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| 21 | AC_CHECK_HEADERS_ONCE([unistd.h])
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| 22 | AC_CHECK_FUNCS_ONCE([symlink])
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| 23 | AC_CACHE_CHECK([for working fcntl.h], [gl_cv_header_working_fcntl_h],
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| 24 | [AC_RUN_IFELSE(
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| 25 | [AC_LANG_PROGRAM(
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| 26 | [[#include <sys/types.h>
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| 27 | #include <sys/stat.h>
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| 28 | #if HAVE_UNISTD_H
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| 29 | # include <unistd.h>
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| 30 | #else /* on Windows with MSVC */
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| 31 | # include <io.h>
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| 32 | # include <stdlib.h>
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| 33 | # defined sleep(n) _sleep ((n) * 1000)
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| 34 | #endif
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| 35 | #include <fcntl.h>
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| 36 | #ifndef O_NOATIME
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| 37 | #define O_NOATIME 0
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| 38 | #endif
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| 39 | #ifndef O_NOFOLLOW
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| 40 | #define O_NOFOLLOW 0
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| 41 | #endif
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| 42 | static int const constants[] =
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| 43 | {
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| 44 | O_CREAT, O_EXCL, O_NOCTTY, O_TRUNC, O_APPEND,
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| 45 | O_NONBLOCK, O_SYNC, O_ACCMODE, O_RDONLY, O_RDWR, O_WRONLY
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| 46 | };
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| 47 | ]],
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| 48 | [[
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| 49 | int result = !constants;
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| 50 | #if HAVE_SYMLINK
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| 51 | {
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| 52 | static char const sym[] = "conftest.sym";
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| 53 | if (symlink (".", sym) != 0)
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| 54 | result |= 2;
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| 55 | else
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| 56 | {
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| 57 | int fd = open (sym, O_RDONLY | O_NOFOLLOW);
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| 58 | if (fd >= 0)
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| 59 | {
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| 60 | close (fd);
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| 61 | result |= 4;
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| 62 | }
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| 63 | }
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| 64 | unlink (sym);
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| 65 | }
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| 66 | #endif
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| 67 | {
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| 68 | static char const file[] = "confdefs.h";
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| 69 | int fd = open (file, O_RDONLY | O_NOATIME);
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| 70 | if (fd < 0)
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| 71 | result |= 8;
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| 72 | else
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| 73 | {
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| 74 | struct stat st0;
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| 75 | if (fstat (fd, &st0) != 0)
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| 76 | result |= 16;
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| 77 | else
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| 78 | {
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| 79 | char c;
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| 80 | sleep (1);
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| 81 | if (read (fd, &c, 1) != 1)
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| 82 | result |= 24;
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| 83 | else
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| 84 | {
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| 85 | if (close (fd) != 0)
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| 86 | result |= 32;
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| 87 | else
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| 88 | {
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| 89 | struct stat st1;
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| 90 | if (stat (file, &st1) != 0)
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| 91 | result |= 40;
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| 92 | else
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| 93 | if (st0.st_atime != st1.st_atime)
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| 94 | result |= 64;
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| 95 | }
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| 96 | }
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| 97 | }
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| 98 | }
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| 99 | }
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| 100 | return result;]])],
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| 101 | [gl_cv_header_working_fcntl_h=yes],
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| 102 | [case $? in #(
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| 103 | 4) gl_cv_header_working_fcntl_h='no (bad O_NOFOLLOW)';; #(
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| 104 | 64) gl_cv_header_working_fcntl_h='no (bad O_NOATIME)';; #(
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| 105 | 68) gl_cv_header_working_fcntl_h='no (bad O_NOATIME, O_NOFOLLOW)';; #(
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| 106 | *) gl_cv_header_working_fcntl_h='no';;
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| 107 | esac],
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| 108 | [gl_cv_header_working_fcntl_h=cross-compiling])])
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| 109 |
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| 110 | case $gl_cv_header_working_fcntl_h in #(
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| 111 | *O_NOATIME* | no | cross-compiling) ac_val=0;; #(
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| 112 | *) ac_val=1;;
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| 113 | esac
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| 114 | AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOATIME], [$ac_val],
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| 115 | [Define to 1 if O_NOATIME works.])
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| 116 |
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| 117 | case $gl_cv_header_working_fcntl_h in #(
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| 118 | *O_NOFOLLOW* | no | cross-compiling) ac_val=0;; #(
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| 119 | *) ac_val=1;;
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| 120 | esac
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| 121 | AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOFOLLOW], [$ac_val],
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| 122 | [Define to 1 if O_NOFOLLOW works.])
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| 123 | ])
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