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1 dnl http://avahi.org/log/trunk/common/acx_pthread.m4
2 dnl cahngeset 1277
3 dnl
4 dnl @synopsis ACX_PTHREAD([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
5 dnl
6 dnl @summary figure out how to build C programs using POSIX threads
7 dnl
8 dnl This macro figures out how to build C programs using POSIX threads.
9 dnl It sets the PTHREAD_LIBS output variable to the threads library and
10 dnl linker flags, and the PTHREAD_CFLAGS output variable to any special
11 dnl C compiler flags that are needed. (The user can also force certain
12 dnl compiler flags/libs to be tested by setting these environment
13 dnl variables.)
14 dnl
15 dnl Also sets PTHREAD_CC to any special C compiler that is needed for
16 dnl multi-threaded programs (defaults to the value of CC otherwise).
17 dnl (This is necessary on AIX to use the special cc_r compiler alias.)
18 dnl
19 dnl NOTE: You are assumed to not only compile your program with these
20 dnl flags, but also link it with them as well. e.g. you should link
21 dnl with $PTHREAD_CC $CFLAGS $PTHREAD_CFLAGS $LDFLAGS ... $PTHREAD_LIBS
22 dnl $LIBS
23 dnl
24 dnl If you are only building threads programs, you may wish to use
25 dnl these variables in your default LIBS, CFLAGS, and CC:
26 dnl
27 dnl LIBS="$PTHREAD_LIBS $LIBS"
28 dnl CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
29 dnl CC="$PTHREAD_CC"
30 dnl
31 dnl In addition, if the PTHREAD_CREATE_JOINABLE thread-attribute
32 dnl constant has a nonstandard name, defines PTHREAD_CREATE_JOINABLE to
33 dnl that name (e.g. PTHREAD_CREATE_UNDETACHED on AIX).
34 dnl
35 dnl ACTION-IF-FOUND is a list of shell commands to run if a threads
36 dnl library is found, and ACTION-IF-NOT-FOUND is a list of commands to
37 dnl run it if it is not found. If ACTION-IF-FOUND is not specified, the
38 dnl default action will define HAVE_PTHREAD.
39 dnl
40 dnl Please let the authors know if this macro fails on any platform, or
41 dnl if you have any other suggestions or comments. This macro was based
42 dnl on work by SGJ on autoconf scripts for FFTW (www.fftw.org) (with
43 dnl help from M. Frigo), as well as ac_pthread and hb_pthread macros
44 dnl posted by Alejandro Forero Cuervo to the autoconf macro repository.
45 dnl We are also grateful for the helpful feedback of numerous users.
46 dnl
47 dnl @category InstalledPackages
48 dnl @author Steven G. Johnson <stevenj@alum.mit.edu>
49 dnl @version 2006-05-29
50 dnl @license GPLWithACException
51 dnl
52 dnl Checks for GCC shared/pthread inconsistency based on work by
53 dnl Marcin Owsiany <marcin@owsiany.pl>
54
55
56 AC_DEFUN([ACX_PTHREAD], [
57 AC_REQUIRE([AC_CANONICAL_HOST])
58 AC_LANG_SAVE
59 AC_LANG_C
60 acx_pthread_ok=no
61
62 # We used to check for pthread.h first, but this fails if pthread.h
63 # requires special compiler flags (e.g. on True64 or Sequent).
64 # It gets checked for in the link test anyway.
65
66 # First of all, check if the user has set any of the PTHREAD_LIBS,
67 # etcetera environment variables, and if threads linking works using
68 # them:
69 if test x"$PTHREAD_LIBS$PTHREAD_CFLAGS" != x; then
70 save_CFLAGS="$CFLAGS"
71 CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
72 save_LIBS="$LIBS"
73 LIBS="$PTHREAD_LIBS $LIBS"
74 AC_MSG_CHECKING([for pthread_join in LIBS=$PTHREAD_LIBS with CFLAGS=$PTHREAD_CFLAGS])
75 AC_TRY_LINK_FUNC(pthread_join, acx_pthread_ok=yes)
76 AC_MSG_RESULT($acx_pthread_ok)
77 if test x"$acx_pthread_ok" = xno; then
78 PTHREAD_LIBS=""
79 PTHREAD_CFLAGS=""
80 fi
81 LIBS="$save_LIBS"
82 CFLAGS="$save_CFLAGS"
83 fi
84
85 # We must check for the threads library under a number of different
86 # names; the ordering is very important because some systems
87 # (e.g. DEC) have both -lpthread and -lpthreads, where one of the
88 # libraries is broken (non-POSIX).
89
90 # Create a list of thread flags to try. Items starting with a "-" are
91 # C compiler flags, and other items are library names, except for "none"
92 # which indicates that we try without any flags at all, and "pthread-config"
93 # which is a program returning the flags for the Pth emulation library.
94
95 acx_pthread_flags="pthreads none -Kthread -kthread lthread -pthread -pthreads -mthreads pthread --thread-safe -mt pthread-config"
96
97 # The ordering *is* (sometimes) important. Some notes on the
98 # individual items follow:
99
100 # pthreads: AIX (must check this before -lpthread)
101 # none: in case threads are in libc; should be tried before -Kthread and
102 # other compiler flags to prevent continual compiler warnings
103 # -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)
104 # -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
105 # lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
106 # -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads)
107 # -pthreads: Solaris/gcc
108 # -mthreads: Mingw32/gcc, Lynx/gcc
109 # -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
110 # doesn't hurt to check since this sometimes defines pthreads too;
111 # also defines -D_REENTRANT)
112 # ... -mt is also the pthreads flag for HP/aCC
113 # pthread: Linux, etcetera
114 # --thread-safe: KAI C++
115 # pthread-config: use pthread-config program (for GNU Pth library)
116
117 case "${host_cpu}-${host_os}" in
118 *solaris*)
119
120 # On Solaris (at least, for some versions), libc contains stubbed
121 # (non-functional) versions of the pthreads routines, so link-based
122 # tests will erroneously succeed. (We need to link with -pthreads/-mt/
123 # -lpthread.) (The stubs are missing pthread_cleanup_push, or rather
124 # a function called by this macro, so we could check for that, but
125 # who knows whether they'll stub that too in a future libc.) So,
126 # we'll just look for -pthreads and -lpthread first:
127
128 acx_pthread_flags="-pthreads pthread -mt -pthread $acx_pthread_flags"
129 ;;
130 esac
131
132 if test x"$acx_pthread_ok" = xno; then
133 for flag in $acx_pthread_flags; do
134
135 case $flag in
136 none)
137 AC_MSG_CHECKING([whether pthreads work without any flags])
138 ;;
139
140 -*)
141 AC_MSG_CHECKING([whether pthreads work with $flag])
142 PTHREAD_CFLAGS="$flag"
143 ;;
144
145 pthread-config)
146 AC_CHECK_PROG(acx_pthread_config, pthread-config, yes, no)
147 if test x"$acx_pthread_config" = xno; then continue; fi
148 PTHREAD_CFLAGS="`pthread-config --cflags`"
149 PTHREAD_LIBS="`pthread-config --ldflags` `pthread-config --libs`"
150 ;;
151
152 *)
153 AC_MSG_CHECKING([for the pthreads library -l$flag])
154 PTHREAD_LIBS="-l$flag"
155 ;;
156 esac
157
158 save_LIBS="$LIBS"
159 save_CFLAGS="$CFLAGS"
160 LIBS="$PTHREAD_LIBS $LIBS"
161 CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
162
163 # Check for various functions. We must include pthread.h,
164 # since some functions may be macros. (On the Sequent, we
165 # need a special flag -Kthread to make this header compile.)
166 # We check for pthread_join because it is in -lpthread on IRIX
167 # while pthread_create is in libc. We check for pthread_attr_init
168 # due to DEC craziness with -lpthreads. We check for
169 # pthread_cleanup_push because it is one of the few pthread
170 # functions on Solaris that doesn't have a non-functional libc stub.
171 # We try pthread_create on general principles.
172 AC_TRY_LINK([#include <pthread.h>],
173 [pthread_t th; pthread_join(th, 0);
174 pthread_attr_init(0); pthread_cleanup_push(0, 0);
175 pthread_create(0,0,0,0); pthread_cleanup_pop(0); ],
176 [acx_pthread_ok=yes])
177
178 LIBS="$save_LIBS"
179 CFLAGS="$save_CFLAGS"
180
181 AC_MSG_RESULT($acx_pthread_ok)
182 if test "x$acx_pthread_ok" = xyes; then
183 break;
184 fi
185
186 PTHREAD_LIBS=""
187 PTHREAD_CFLAGS=""
188 done
189 fi
190
191 # Various other checks:
192 if test "x$acx_pthread_ok" = xyes; then
193 save_LIBS="$LIBS"
194 LIBS="$PTHREAD_LIBS $LIBS"
195 save_CFLAGS="$CFLAGS"
196 CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
197
198 # Detect AIX lossage: JOINABLE attribute is called UNDETACHED.
199 AC_MSG_CHECKING([for joinable pthread attribute])
200 attr_name=unknown
201 for attr in PTHREAD_CREATE_JOINABLE PTHREAD_CREATE_UNDETACHED; do
202 AC_TRY_LINK([#include <pthread.h>], [int attr=$attr; return attr;],
203 [attr_name=$attr; break])
204 done
205 AC_MSG_RESULT($attr_name)
206 if test "$attr_name" != PTHREAD_CREATE_JOINABLE; then
207 AC_DEFINE_UNQUOTED(PTHREAD_CREATE_JOINABLE, $attr_name,
208 [Define to necessary symbol if this constant
209 uses a non-standard name on your system.])
210 fi
211
212 AC_MSG_CHECKING([if more special flags are required for pthreads])
213 flag=no
214 case "${host_cpu}-${host_os}" in
215 *-aix* | *-freebsd* | *-darwin*) flag="-D_THREAD_SAFE";;
216 *solaris* | *-osf* | *-hpux*) flag="-D_REENTRANT";;
217 esac
218 AC_MSG_RESULT(${flag})
219 if test "x$flag" != xno; then
220 PTHREAD_CFLAGS="$flag $PTHREAD_CFLAGS"
221 fi
222
223 LIBS="$save_LIBS"
224 CFLAGS="$save_CFLAGS"
225 # More AIX lossage: must compile with xlc_r or cc_r
226 if test x"$GCC" != xyes; then
227 AC_CHECK_PROGS(PTHREAD_CC, xlc_r cc_r, ${CC})
228 else
229 PTHREAD_CC=$CC
230 fi
231
232 # The next part tries to detect GCC inconsistency with -shared on some
233 # architectures and systems. The problem is that in certain
234 # configurations, when -shared is specified, GCC "forgets" to
235 # internally use various flags which are still necessary.
236
237 AC_MSG_CHECKING([whether to check for GCC pthread/shared inconsistencies])
238 check_inconsistencies=yes
239 case "${host_cpu}-${host_os}" in
240 *-darwin*) check_inconsistencies=no ;;
241 esac
242 if test x"$GCC" != xyes -o "x$check_inconsistencies" != xyes ; then
243 AC_MSG_RESULT([no])
244 else
245 AC_MSG_RESULT([yes])
246
247 # In order not to create several levels of indentation, we test
248 # the value of "$ok" until we find out the cure or run out of
249 # ideas.
250 ok="no"
251
252 #
253 # Prepare the flags
254 #
255 save_CFLAGS="$CFLAGS"
256 save_LIBS="$LIBS"
257 save_CC="$CC"
258 # Try with the flags determined by the earlier checks.
259 #
260 # -Wl,-z,defs forces link-time symbol resolution, so that the
261 # linking checks with -shared actually have any value
262 #
263 # FIXME: -fPIC is required for -shared on many architectures,
264 # so we specify it here, but the right way would probably be to
265 # properly detect whether it is actually required.
266 CFLAGS="-shared -fPIC -Wl,-z,defs $CFLAGS $PTHREAD_CFLAGS"
267 LIBS="$PTHREAD_LIBS $LIBS"
268 CC="$PTHREAD_CC"
269
270 AC_MSG_CHECKING([whether -pthread is sufficient with -shared])
271 AC_TRY_LINK([#include <pthread.h>],
272 [pthread_t th; pthread_join(th, 0);
273 pthread_attr_init(0); pthread_cleanup_push(0, 0);
274 pthread_create(0,0,0,0); pthread_cleanup_pop(0); ],
275 [ok=yes])
276
277 if test "x$ok" = xyes; then
278 AC_MSG_RESULT([yes])
279 else
280 AC_MSG_RESULT([no])
281 fi
282
283 #
284 # Linux gcc on some architectures such as mips/mipsel forgets
285 # about -lpthread
286 #
287 if test x"$ok" = xno; then
288 AC_MSG_CHECKING([whether -lpthread fixes that])
289 LIBS="-lpthread $PTHREAD_LIBS $save_LIBS"
290 AC_TRY_LINK([#include <pthread.h>],
291 [pthread_t th; pthread_join(th, 0);
292 pthread_attr_init(0); pthread_cleanup_push(0, 0);
293 pthread_create(0,0,0,0); pthread_cleanup_pop(0); ],
294 [ok=yes])
295
296 if test "x$ok" = xyes; then
297 AC_MSG_RESULT([yes])
298 PTHREAD_LIBS="-lpthread $PTHREAD_LIBS"
299 else
300 AC_MSG_RESULT([no])
301 fi
302 fi
303 #
304 # FreeBSD 4.10 gcc forgets to use -lc_r instead of -lc
305 #
306 if test x"$ok" = xno; then
307 AC_MSG_CHECKING([whether -lc_r fixes that])
308 LIBS="-lc_r $PTHREAD_LIBS $save_LIBS"
309 AC_TRY_LINK([#include <pthread.h>],
310 [pthread_t th; pthread_join(th, 0);
311 pthread_attr_init(0); pthread_cleanup_push(0, 0);
312 pthread_create(0,0,0,0); pthread_cleanup_pop(0); ],
313 [ok=yes])
314
315 if test "x$ok" = xyes; then
316 AC_MSG_RESULT([yes])
317 PTHREAD_LIBS="-lc_r $PTHREAD_LIBS"
318 else
319 AC_MSG_RESULT([no])
320 fi
321 fi
322 if test x"$ok" = xno; then
323 # OK, we have run out of ideas
324 AC_MSG_WARN([Impossible to determine how to use pthreads with shared libraries])
325
326 # so it's not safe to assume that we may use pthreads
327 acx_pthread_ok=no
328 fi
329
330 CFLAGS="$save_CFLAGS"
331 LIBS="$save_LIBS"
332 CC="$save_CC"
333 fi
334 else
335 PTHREAD_CC="$CC"
336 fi
337
338 AC_SUBST(PTHREAD_LIBS)
339 AC_SUBST(PTHREAD_CFLAGS)
340 AC_SUBST(PTHREAD_CC)
341
342 # Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
343 if test x"$acx_pthread_ok" = xyes; then
344 ifelse([$1],,AC_DEFINE(HAVE_PTHREAD,1,[Define if you have POSIX threads libraries and header files.]),[$1])
345 :
346 else
347 acx_pthread_ok=no
348 $2
349 fi
350 AC_LANG_RESTORE
351 ])dnl ACX_PTHREAD