summaryrefslogtreecommitdiff
path: root/lib/replace/libreplace.m4
blob: 5a4184493e23ecbbfe28da6d5bedfc059a45d563 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
AC_DEFUN_ONCE(AC_LIBREPLACE_LOCATION_CHECKS,
[
echo "LIBREPLACE_LOCATION_CHECKS: START"

dnl find the libreplace sources. This is meant to work both for 
dnl libreplace standalone builds, and builds of packages using libreplace
libreplacedir=""
libreplacepaths="$srcdir $srcdir/lib/replace $srcdir/libreplace $srcdir/../libreplace $srcdir/../replace $srcdir/../lib/replace $srcdir/../../../lib/replace"
for d in $libreplacepaths; do
	if test -f "$d/replace.c"; then
		libreplacedir="$d"		
		AC_SUBST(libreplacedir)
		break;
	fi
done
if test x"$libreplacedir" = "x"; then
	AC_MSG_ERROR([cannot find libreplace in $libreplacepaths])
fi
LIBREPLACEOBJ="$libreplacedir/replace.o"
AC_SUBST(LIBREPLACEOBJ)

AC_CANONICAL_BUILD
AC_CANONICAL_HOST
AC_CANONICAL_TARGET

echo "LIBREPLACE_LOCATION_CHECKS: END"
]) dnl end AC_LIBREPLACE_LOCATION_CHECKS


AC_DEFUN_ONCE(AC_LIBREPLACE_BROKEN_CHECKS,
[
echo "LIBREPLACE_BROKEN_CHECKS: START"

dnl find the libreplace sources. This is meant to work both for 
dnl libreplace standalone builds, and builds of packages using libreplace
libreplacedir=""
libreplacepaths="$srcdir $srcdir/lib/replace $srcdir/libreplace $srcdir/../libreplace $srcdir/../replace $srcdir/../lib/replace $srcdir/../../../lib/replace"
for d in $libreplacepaths; do
	if test -f "$d/replace.c"; then
		libreplacedir="$d"		
		AC_SUBST(libreplacedir)
		break;
	fi
done
if test x"$libreplacedir" = "x"; then
	AC_MSG_ERROR([cannot find libreplace in $libreplacepaths])
fi

LIBREPLACEOBJ="$libreplacedir/replace.o"
AC_SUBST(LIBREPLACEOBJ)

LIBREPLACEOBJ="${LIBREPLACEOBJ} $libreplacedir/snprintf.o  $libreplacedir/xattr.o"

AC_TYPE_UID_T
AC_TYPE_MODE_T
AC_TYPE_OFF_T
AC_TYPE_SIZE_T
AC_TYPE_PID_T
AC_STRUCT_ST_RDEV
AC_CHECK_TYPE(ino_t,unsigned)
AC_CHECK_TYPE(loff_t,off_t)
AC_CHECK_TYPE(offset_t,loff_t)
AC_CHECK_TYPE(blksize_t,long)
AC_CHECK_TYPE(blkcnt_t,long)

AC_FUNC_MEMCMP

AC_CHECK_FUNCS([pipe strftime srandom random srand rand usleep setbuffer lstat getpgrp utime utimes])

AC_CHECK_HEADERS(stdbool.h stdint.h sys/select.h)
AC_CHECK_HEADERS(setjmp.h utime.h)

LIBREPLACE_PROVIDE_HEADER([stdint.h])
LIBREPLACE_PROVIDE_HEADER([stdbool.h])

AC_DEFINE(HAVE_LIBREPLACE, 1, [We have libreplace])

AC_CHECK_TYPE(bool, 
[AC_DEFINE(HAVE_BOOL, 1, [Whether the bool type is available])],,
[
AC_INCLUDES_DEFAULT
#ifdef HAVE_STDBOOL_H
#include <stdbool.h>
#endif]
)

AC_CHECK_TYPE(_Bool, 
[AC_DEFINE(HAVE__Bool, 1, [Whether the _Bool type is available])],,
[
AC_INCLUDES_DEFAULT
#ifdef HAVE_STDBOOL_H
#include <stdbool.h>
#endif]
)

AC_CHECK_HEADERS(linux/types.h)

AC_CACHE_CHECK([for working mmap],libreplace_cv_HAVE_MMAP,[
AC_TRY_RUN([#include "$libreplacedir/test/shared_mmap.c"],
           libreplace_cv_HAVE_MMAP=yes,libreplace_cv_HAVE_MMAP=no,libreplace_cv_HAVE_MMAP=cross)])
if test x"$libreplace_cv_HAVE_MMAP" = x"yes"; then
    AC_DEFINE(HAVE_MMAP,1,[Whether mmap works])
fi

AC_CACHE_CHECK([for working mremap],libreplace_cv_HAVE_MREMAP,[
AC_TRY_RUN([#include "$libreplacedir/test/shared_mremap.c"],
           libreplace_cv_HAVE_MREMAP=yes,libreplace_cv_HAVE_MREMAP=no,libreplace_cv_HAVE_MREMAP=cross)])
if test x"$libreplace_cv_HAVE_MREMAP" = x"yes"; then
    AC_DEFINE(HAVE_MREMAP,1,[Whether mremap works])
fi

AC_CACHE_CHECK([for incoherent mmap],libreplace_cv_HAVE_INCOHERENT_MMAP,[
AC_TRY_RUN([#include "$libreplacedir/test/incoherent_mmap.c"],
           libreplace_cv_HAVE_INCOHERENT_MMAP=yes,libreplace_cv_HAVE_INCOHERENT_MMAP=no,libreplace_cv_HAVE_INCOHERENT_MMAP=cross)])
if test x"$libreplace_cv_HAVE_INCOHERENT_MMAP" = x"yes"; then
    AC_DEFINE(HAVE_INCOHERENT_MMAP,1,[Whether mmap is incoherent against write])
fi


AC_CHECK_HEADERS(sys/syslog.h syslog.h)
AC_CHECK_HEADERS(sys/time.h time.h)
AC_CHECK_HEADERS(stdarg.h vararg.h)
AC_CHECK_HEADERS(sys/mount.h mntent.h)
AC_CHECK_HEADERS(stropts.h)
AC_CHECK_HEADERS(unix.h)
AC_CHECK_HEADERS(malloc.h)
AC_CHECK_HEADERS(syscall.h)
AC_CHECK_HEADERS(sys/syscall.h)

AC_CHECK_FUNCS(syscall setuid seteuid setreuid setresuid setgid setegid setregid setresgid setgroups)
AC_CHECK_FUNCS(chroot bzero strerror strerror_r memalign posix_memalign getpagesize)
AC_CHECK_FUNCS(vsyslog setlinebuf mktime ftruncate chsize rename)
AC_CHECK_FUNCS(waitpid wait4 strlcpy strlcat initgroups memmove strdup)
AC_CHECK_FUNCS(pread pwrite strndup strcasestr strtok_r mkdtemp dup2 dprintf vdprintf)
AC_CHECK_FUNCS(isatty chown lchown link readlink symlink realpath)
AC_CHECK_FUNCS(fdatasync,,[
	# if we didn't find it, look in librt (Solaris hides it there...)
	AC_CHECK_LIB(rt, fdatasync,
		[libreplace_cv_HAVE_FDATASYNC_IN_LIBRT=yes
		AC_DEFINE(HAVE_FDATASYNC, 1, Define to 1 if there is support for fdatasync)])
])
AC_HAVE_DECL(fdatasync, [#include <unistd.h>])
AC_CHECK_FUNCS(clock_gettime,libreplace_cv_have_clock_gettime=yes,[
	AC_CHECK_LIB(rt, clock_gettime,
		[libreplace_cv_HAVE_CLOCK_GETTIME_IN_LIBRT=yes
		libreplace_cv_have_clock_gettime=yes
		AC_DEFINE(HAVE_CLOCK_GETTIME, 1, Define to 1 if there is support for clock_gettime)])
])

AC_CHECK_HEADERS(sys/attributes.h attr/xattr.h sys/xattr.h sys/extattr.h sys/uio.h)
AC_CHECK_HEADERS(sys/ea.h sys/proplist.h)

LIBREPLACE_FILESYS_LIBS=""

############################################
# Check for EA implementations
case "$host_os" in
  *freebsd4* | *dragonfly* )
	AC_DEFINE(BROKEN_EXTATTR, 1, [Does extattr API work])
  ;;
  *)
	AC_SEARCH_LIBS(getxattr, [attr])
	AC_CHECK_FUNCS(attr_get attr_getf attr_list attr_listf attropen attr_remove)
	AC_CHECK_FUNCS(attr_removef attr_set attr_setf extattr_delete_fd extattr_delete_file)
	AC_CHECK_FUNCS(extattr_get_fd extattr_get_file extattr_list_fd extattr_list_file)
	AC_CHECK_FUNCS(extattr_set_fd extattr_set_file fgetea fgetxattr flistea flistxattr)
	AC_CHECK_FUNCS(fremoveea fremovexattr fsetea fsetxattr getea getxattr listea)
	AC_CHECK_FUNCS(listxattr removeea removexattr setea setxattr)

	AC_CHECK_LIB_EXT(attr, LIBREPLACE_FILESYS_LIBS, flistea)
	AC_CHECK_LIB_EXT(attr, LIBREPLACE_FILESYS_LIBS, flistxattr)
	AC_CHECK_LIB_EXT(attr, LIBREPLACE_FILESYS_LIBS, attr_listf)
	AC_CHECK_LIB_EXT(attr, LIBREPLACE_FILESYS_LIBS, extattr_list_fd)

  ;;
esac


########################################################
# Do xattr functions take additional options like on Darwin?
if test x"$ac_cv_func_getxattr" = x"yes" ; then
	AC_CACHE_CHECK([whether xattr interface takes additional options], smb_attr_cv_xattr_add_opt, [
		old_LIBS=$LIBS
		LIBS="$LIBS $LIBREPLACE_FILESYS_LIBS"
		AC_TRY_COMPILE([
			#include <sys/types.h>
			#if HAVE_ATTR_XATTR_H
			#include <attr/xattr.h>
			#elif HAVE_SYS_XATTR_H
			#include <sys/xattr.h>
			#endif
		],[
			getxattr(0, 0, 0, 0, 0, 0);
		],
	        [smb_attr_cv_xattr_add_opt=yes],
		[smb_attr_cv_xattr_add_opt=no;LIBS=$old_LIBS])
	])
	if test x"$smb_attr_cv_xattr_add_opt" = x"yes"; then
		AC_DEFINE(XATTR_ADDITIONAL_OPTIONS, 1, [xattr functions have additional options])
	fi
fi

AC_CHECK_FUNCS(get_current_dir_name)
AC_HAVE_DECL(setresuid, [#include <unistd.h>])
AC_HAVE_DECL(setresgid, [#include <unistd.h>])
AC_HAVE_DECL(errno, [#include <errno.h>])

AC_CACHE_CHECK([for secure mkstemp],libreplace_cv_HAVE_SECURE_MKSTEMP,[
AC_TRY_RUN([#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
main() { 
  struct stat st;
  char tpl[20]="/tmp/test.XXXXXX";
  char tpl2[20]="/tmp/test.XXXXXX";
  int fd = mkstemp(tpl);
  int fd2 = mkstemp(tpl2);
  if (fd == -1) {
        if (fd2 != -1) {
                unlink(tpl2);
        }
        exit(1);
  }
  if (fd2 == -1) exit(1);
  unlink(tpl);
  unlink(tpl2);
  if (fstat(fd, &st) != 0) exit(1);
  if ((st.st_mode & 0777) != 0600) exit(1);
  if (strcmp(tpl, "/tmp/test.XXXXXX") == 0) {
        exit(1);
  }
  if (strcmp(tpl, tpl2) == 0) {
        exit(1);
  }
  exit(0);
}],
libreplace_cv_HAVE_SECURE_MKSTEMP=yes,
libreplace_cv_HAVE_SECURE_MKSTEMP=no,
libreplace_cv_HAVE_SECURE_MKSTEMP=cross)])
if test x"$libreplace_cv_HAVE_SECURE_MKSTEMP" = x"yes"; then
    AC_DEFINE(HAVE_SECURE_MKSTEMP,1,[Whether mkstemp is secure])
fi

dnl Provided by snprintf.c:
AC_CHECK_HEADERS(stdio.h strings.h)
AC_CHECK_DECLS([snprintf, vsnprintf, asprintf, vasprintf])
AC_CHECK_FUNCS(snprintf vsnprintf asprintf vasprintf)

AC_CACHE_CHECK([for C99 vsnprintf],libreplace_cv_HAVE_C99_VSNPRINTF,[
AC_TRY_RUN([
#include <sys/types.h>
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
void foo(const char *format, ...) { 
       va_list ap;
       int len;
       char buf[20];
       long long l = 1234567890;
       l *= 100;

       va_start(ap, format);
       len = vsnprintf(buf, 0, format, ap);
       va_end(ap);
       if (len != 5) exit(1);

       va_start(ap, format);
       len = vsnprintf(0, 0, format, ap);
       va_end(ap);
       if (len != 5) exit(2);

       if (snprintf(buf, 3, "hello") != 5 || strcmp(buf, "he") != 0) exit(3);

       if (snprintf(buf, 20, "%lld", l) != 12 || strcmp(buf, "123456789000") != 0) exit(4);
       if (snprintf(buf, 20, "%zu", 123456789) != 9 || strcmp(buf, "123456789") != 0) exit(5);
       if (snprintf(buf, 20, "%2\$d %1\$d", 3, 4) != 3 || strcmp(buf, "4 3") != 0) exit(6);
       if (snprintf(buf, 20, "%s", 0) < 3) exit(7);

       exit(0);
}
main() { foo("hello"); }
],
libreplace_cv_HAVE_C99_VSNPRINTF=yes,libreplace_cv_HAVE_C99_VSNPRINTF=no,libreplace_cv_HAVE_C99_VSNPRINTF=cross)])
if test x"$libreplace_cv_HAVE_C99_VSNPRINTF" = x"yes"; then
    AC_DEFINE(HAVE_C99_VSNPRINTF,1,[Whether there is a C99 compliant vsnprintf])
fi


dnl VA_COPY
AC_CACHE_CHECK([for va_copy],libreplace_cv_HAVE_VA_COPY,[
AC_TRY_LINK([#include <stdarg.h>
va_list ap1,ap2;], [va_copy(ap1,ap2);],
libreplace_cv_HAVE_VA_COPY=yes,libreplace_cv_HAVE_VA_COPY=no)])
if test x"$libreplace_cv_HAVE_VA_COPY" = x"yes"; then
    AC_DEFINE(HAVE_VA_COPY,1,[Whether va_copy() is available])
fi

if test x"$libreplace_cv_HAVE_VA_COPY" != x"yes"; then
AC_CACHE_CHECK([for __va_copy],libreplace_cv_HAVE___VA_COPY,[
AC_TRY_LINK([#include <stdarg.h>
va_list ap1,ap2;], [__va_copy(ap1,ap2);],
libreplace_cv_HAVE___VA_COPY=yes,libreplace_cv_HAVE___VA_COPY=no)])
if test x"$libreplace_cv_HAVE___VA_COPY" = x"yes"; then
    AC_DEFINE(HAVE___VA_COPY,1,[Whether __va_copy() is available])
fi
fi

dnl __FUNCTION__ macro
AC_CACHE_CHECK([for __FUNCTION__ macro],libreplace_cv_HAVE_FUNCTION_MACRO,[
AC_TRY_COMPILE([#include <stdio.h>], [printf("%s\n", __FUNCTION__);],
libreplace_cv_HAVE_FUNCTION_MACRO=yes,libreplace_cv_HAVE_FUNCTION_MACRO=no)])
if test x"$libreplace_cv_HAVE_FUNCTION_MACRO" = x"yes"; then
    AC_DEFINE(HAVE_FUNCTION_MACRO,1,[Whether there is a __FUNCTION__ macro])
else
    dnl __func__ macro
    AC_CACHE_CHECK([for __func__ macro],libreplace_cv_HAVE_func_MACRO,[
    AC_TRY_COMPILE([#include <stdio.h>], [printf("%s\n", __func__);],
    libreplace_cv_HAVE_func_MACRO=yes,libreplace_cv_HAVE_func_MACRO=no)])
    if test x"$libreplace_cv_HAVE_func_MACRO" = x"yes"; then
       AC_DEFINE(HAVE_func_MACRO,1,[Whether there is a __func__ macro])
    fi
fi

AC_CHECK_HEADERS([sys/param.h limits.h])

AC_CHECK_TYPE(comparison_fn_t, 
[AC_DEFINE(HAVE_COMPARISON_FN_T, 1,[Whether or not we have comparison_fn_t])])

AC_HAVE_DECL(setenv, [#include <stdlib.h>])
AC_CHECK_FUNCS(setenv unsetenv)
AC_HAVE_DECL(environ, [#include <unistd.h>])

AC_CHECK_FUNCS(strnlen)
AC_CHECK_FUNCS(strtoull __strtoull strtouq strtoll __strtoll strtoq)

AC_CHECK_FUNCS(memmem)

# this test disabled as we don't actually need __VA_ARGS__ yet
AC_TRY_CPP([
#define eprintf(...) fprintf(stderr, __VA_ARGS__)
eprintf("bla", "bar");
], AC_DEFINE(HAVE__VA_ARGS__MACRO, 1, [Whether the __VA_ARGS__ macro is available]))


AC_CACHE_CHECK([for sig_atomic_t type],libreplace_cv_sig_atomic_t, [
    AC_TRY_COMPILE([
#include <sys/types.h>
#if STDC_HEADERS
#include <stdlib.h>
#include <stddef.h>
#endif
#include <signal.h>],[sig_atomic_t i = 0],
	libreplace_cv_sig_atomic_t=yes,libreplace_cv_sig_atomic_t=no)])
if test x"$libreplace_cv_sig_atomic_t" = x"yes"; then
   AC_DEFINE(HAVE_SIG_ATOMIC_T_TYPE,1,[Whether we have the atomic_t variable type])
fi


dnl Check if the C compiler understands volatile (it should, being ANSI).
AC_CACHE_CHECK([that the C compiler understands volatile],libreplace_cv_volatile, [
	AC_TRY_COMPILE([#include <sys/types.h>],[volatile int i = 0],
		libreplace_cv_volatile=yes,libreplace_cv_volatile=no)])
if test x"$libreplace_cv_volatile" = x"yes"; then
	AC_DEFINE(HAVE_VOLATILE, 1, [Whether the C compiler understands volatile])
fi

m4_include(system/config.m4)

AC_CACHE_CHECK([for O_DIRECT flag to open(2)],libreplace_cv_HAVE_OPEN_O_DIRECT,[
AC_TRY_COMPILE([
#include <unistd.h>
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif],
[int fd = open("/dev/null", O_DIRECT);],
libreplace_cv_HAVE_OPEN_O_DIRECT=yes,libreplace_cv_HAVE_OPEN_O_DIRECT=no)])
if test x"$libreplace_cv_HAVE_OPEN_O_DIRECT" = x"yes"; then
    AC_DEFINE(HAVE_OPEN_O_DIRECT,1,[Whether the open(2) accepts O_DIRECT])
fi

m4_include(dlfcn.m4)
m4_include(strptime.m4)
m4_include(win32.m4)
m4_include(timegm.m4)
m4_include(repdir.m4)
m4_include(crypt.m4)

if test x$libreplace_cv_have_clock_gettime = xyes ; then
	SMB_CHECK_CLOCK_ID(CLOCK_MONOTONIC)
	SMB_CHECK_CLOCK_ID(CLOCK_PROCESS_CPUTIME_ID)
	SMB_CHECK_CLOCK_ID(CLOCK_REALTIME)
fi

AC_CACHE_CHECK([for struct timespec type],libreplace_cv_struct_timespec, [
    AC_TRY_COMPILE([
#include <sys/types.h>
#if STDC_HEADERS
#include <stdlib.h>
#include <stddef.h>
#endif
#if TIME_WITH_SYS_TIME
# include <sys/time.h>
# include <time.h>
#else
# if HAVE_SYS_TIME_H
#  include <sys/time.h>
# else
#  include <time.h>
# endif
#endif
],[struct timespec ts;],
	libreplace_cv_struct_timespec=yes,libreplace_cv_struct_timespec=no)])
if test x"$libreplace_cv_struct_timespec" = x"yes"; then
   AC_DEFINE(HAVE_STRUCT_TIMESPEC,1,[Whether we have struct timespec])
fi

AC_CHECK_FUNCS([printf memset memcpy],,[AC_MSG_ERROR([Required function not found])])

echo "LIBREPLACE_BROKEN_CHECKS: END"
]) dnl end AC_LIBREPLACE_BROKEN_CHECKS

AC_DEFUN_ONCE(AC__LIBREPLACE_ALL_CHECKS_START,
[
#LIBREPLACE_ALL_CHECKS: START"
])
AC_DEFUN_ONCE(AC__LIBREPLACE_ALL_CHECKS_END,
[
#LIBREPLACE_ALL_CHECKS: END"
])
m4_define(AC_LIBREPLACE_ALL_CHECKS,
[
AC__LIBREPLACE_ALL_CHECKS_START
AC_LIBREPLACE_LOCATION_CHECKS
AC_LIBREPLACE_CC_CHECKS
AC_LIBREPLACE_BROKEN_CHECKS
AC__LIBREPLACE_ALL_CHECKS_END
CFLAGS="$CFLAGS -I$libreplacedir"
])

m4_include(libreplace_cc.m4)
m4_include(libreplace_ld.m4)
m4_include(libreplace_network.m4)
m4_include(libreplace_macros.m4)


dnl SMB_CHECK_CLOCK_ID(clockid)
dnl Test whether the specified clock_gettime clock ID is available. If it
dnl is, we define HAVE_clockid
AC_DEFUN([SMB_CHECK_CLOCK_ID],
[
    AC_MSG_CHECKING(for $1)
    AC_TRY_LINK([
#if TIME_WITH_SYS_TIME
# include <sys/time.h>
# include <time.h>
#else
# if HAVE_SYS_TIME_H
#  include <sys/time.h>
# else
#  include <time.h>
# endif
#endif
    ],
    [
clockid_t clk = $1;
    ],
    [
	AC_MSG_RESULT(yes)
	AC_DEFINE(HAVE_$1, 1,
	    [Whether the clock_gettime clock ID $1 is available])
    ],
    [
	AC_MSG_RESULT(no)
    ])
])
m4_ifndef([AC_USE_SYSTEM_EXTENSIONS],[m4_include(autoconf-2.60.m4)])