We may need threads now.

src/aclocal.m4

+# generated automatically by aclocal 1.8.3 -*- Autoconf -*-
+
+# Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
+# Free Software Foundation, Inc.
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY, to the extent permitted by law; without
+# even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+# PARTICULAR PURPOSE.
+
+m4_include([acx_pthread.m4])

src/acx_pthread.m4

+dnl @synopsis ACX_PTHREAD([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
+dnl
+dnl This macro figures out how to build C programs using POSIX
+dnl threads.  It sets the PTHREAD_LIBS output variable to the threads
+dnl library and linker flags, and the PTHREAD_CFLAGS output variable
+dnl to any special C compiler flags that are needed.  (The user can also
+dnl force certain compiler flags/libs to be tested by setting these
+dnl environment variables.)
+dnl
+dnl Also sets PTHREAD_CC to any special C compiler that is needed for
+dnl multi-threaded programs (defaults to the value of CC otherwise).
+dnl (This is necessary on AIX to use the special cc_r compiler alias.)
+dnl
+dnl NOTE: You are assumed to not only compile your program with these
+dnl flags, but also link it with them as well.  e.g. you should link
+dnl with $PTHREAD_CC $CFLAGS $PTHREAD_CFLAGS $LDFLAGS ... $PTHREAD_LIBS $LIBS
+dnl
+dnl If you are only building threads programs, you may wish to
+dnl use these variables in your default LIBS, CFLAGS, and CC:
+dnl
+dnl        LIBS="$PTHREAD_LIBS $LIBS"
+dnl        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
+dnl        CC="$PTHREAD_CC"
+dnl
+dnl In addition, if the PTHREAD_CREATE_JOINABLE thread-attribute
+dnl constant has a nonstandard name, defines PTHREAD_CREATE_JOINABLE
+dnl to that name (e.g. PTHREAD_CREATE_UNDETACHED on AIX).
+dnl
+dnl ACTION-IF-FOUND is a list of shell commands to run if a threads
+dnl library is found, and ACTION-IF-NOT-FOUND is a list of commands
+dnl to run it if it is not found.  If ACTION-IF-FOUND is not specified,
+dnl the default action will define HAVE_PTHREAD.
+dnl
+dnl Please let the authors know if this macro fails on any platform,
+dnl or if you have any other suggestions or comments.  This macro was
+dnl based on work by SGJ on autoconf scripts for FFTW (www.fftw.org)
+dnl (with help from M. Frigo), as well as ac_pthread and hb_pthread
+dnl macros posted by AFC to the autoconf macro repository.  We are also
+dnl grateful for the helpful feedback of numerous users.
+dnl
+dnl @version $Id$
+dnl @author Steven G. Johnson <stevenj@alum.mit.edu> and Alejandro Forero Cuervo <bachue@bachue.com>
+
+AC_DEFUN([ACX_PTHREAD], [
+AC_REQUIRE([AC_CANONICAL_HOST])
+AC_LANG_SAVE
+AC_LANG_C
+acx_pthread_ok=no
+
+# We used to check for pthread.h first, but this fails if pthread.h
+# requires special compiler flags (e.g. on True64 or Sequent).
+# It gets checked for in the link test anyway.
+
+# First of all, check if the user has set any of the PTHREAD_LIBS,
+# etcetera environment variables, and if threads linking works using
+# them:
+if test x"$PTHREAD_LIBS$PTHREAD_CFLAGS" != x; then
+        save_CFLAGS="$CFLAGS"
+        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
+        save_LIBS="$LIBS"
+        LIBS="$PTHREAD_LIBS $LIBS"
+        AC_MSG_CHECKING([for pthread_join in LIBS=$PTHREAD_LIBS with CFLAGS=$PTHREAD_CFLAGS])
+        AC_TRY_LINK_FUNC(pthread_join, acx_pthread_ok=yes)
+        AC_MSG_RESULT($acx_pthread_ok)
+        if test x"$acx_pthread_ok" = xno; then
+                PTHREAD_LIBS=""
+                PTHREAD_CFLAGS=""
+        fi
+        LIBS="$save_LIBS"
+        CFLAGS="$save_CFLAGS"
+fi
+
+# We must check for the threads library under a number of different
+# names; the ordering is very important because some systems
+# (e.g. DEC) have both -lpthread and -lpthreads, where one of the
+# libraries is broken (non-POSIX).
+
+# Create a list of thread flags to try.  Items starting with a "-" are
+# C compiler flags, and other items are library names, except for "none"
+# which indicates that we try without any flags at all.
+
+acx_pthread_flags="pthreads none -Kthread -kthread lthread -pthread -pthreads -mthreads pthread --thread-safe -mt"
+
+# The ordering *is* (sometimes) important.  Some notes on the
+# individual items follow:
+
+# pthreads: AIX (must check this before -lpthread)
+# none: in case threads are in libc; should be tried before -Kthread and
+#       other compiler flags to prevent continual compiler warnings
+# -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)
+# -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
+# lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
+# -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads)
+# -pthreads: Solaris/gcc
+# -mthreads: Mingw32/gcc, Lynx/gcc
+# -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
+#      doesn't hurt to check since this sometimes defines pthreads too;
+#      also defines -D_REENTRANT)
+# pthread: Linux, etcetera
+# --thread-safe: KAI C++
+
+case "${host_cpu}-${host_os}" in
+        *solaris*)
+
+        # On Solaris (at least, for some versions), libc contains stubbed
+        # (non-functional) versions of the pthreads routines, so link-based
+        # tests will erroneously succeed.  (We need to link with -pthread or
+        # -lpthread.)  (The stubs are missing pthread_cleanup_push, or rather
+        # a function called by this macro, so we could check for that, but
+        # who knows whether they'll stub that too in a future libc.)  So,
+        # we'll just look for -pthreads and -lpthread first:
+
+        acx_pthread_flags="-pthread -pthreads pthread -mt $acx_pthread_flags"
+        ;;
+esac
+
+if test x"$acx_pthread_ok" = xno; then
+for flag in $acx_pthread_flags; do
+
+        case $flag in
+                none)
+                AC_MSG_CHECKING([whether pthreads work without any flags])
+                ;;
+
+                -*)
+                AC_MSG_CHECKING([whether pthreads work with $flag])
+                PTHREAD_CFLAGS="$flag"
+                ;;
+
+                *)
+                AC_MSG_CHECKING([for the pthreads library -l$flag])
+                PTHREAD_LIBS="-l$flag"
+                ;;
+        esac
+
+        save_LIBS="$LIBS"
+        save_CFLAGS="$CFLAGS"
+        LIBS="$PTHREAD_LIBS $LIBS"
+        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
+
+        # Check for various functions.  We must include pthread.h,
+        # since some functions may be macros.  (On the Sequent, we
+        # need a special flag -Kthread to make this header compile.)
+        # We check for pthread_join because it is in -lpthread on IRIX
+        # while pthread_create is in libc.  We check for pthread_attr_init
+        # due to DEC craziness with -lpthreads.  We check for
+        # pthread_cleanup_push because it is one of the few pthread
+        # functions on Solaris that doesn't have a non-functional libc stub.
+        # We try pthread_create on general principles.
+        AC_TRY_LINK([#include <pthread.h>],
+                    [pthread_t th; pthread_join(th, 0);
+                     pthread_attr_init(0); pthread_cleanup_push(0, 0);
+                     pthread_create(0,0,0,0); pthread_cleanup_pop(0); ],
+                    [acx_pthread_ok=yes])
+
+        LIBS="$save_LIBS"
+        CFLAGS="$save_CFLAGS"
+
+        AC_MSG_RESULT($acx_pthread_ok)
+        if test "x$acx_pthread_ok" = xyes; then
+                break;
+        fi
+
+        PTHREAD_LIBS=""
+        PTHREAD_CFLAGS=""
+done
+fi
+
+# Various other checks:
+if test "x$acx_pthread_ok" = xyes; then
+        save_LIBS="$LIBS"
+        LIBS="$PTHREAD_LIBS $LIBS"
+        save_CFLAGS="$CFLAGS"
+        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
+
+        # Detect AIX lossage: threads are created detached by default
+        # and the JOINABLE attribute has a nonstandard name (UNDETACHED).
+        AC_MSG_CHECKING([for joinable pthread attribute])
+        AC_TRY_LINK([#include <pthread.h>],
+                    [int attr=PTHREAD_CREATE_JOINABLE;],
+                    ok=PTHREAD_CREATE_JOINABLE, ok=unknown)
+        if test x"$ok" = xunknown; then
+                AC_TRY_LINK([#include <pthread.h>],
+                            [int attr=PTHREAD_CREATE_UNDETACHED;],
+                            ok=PTHREAD_CREATE_UNDETACHED, ok=unknown)
+        fi
+        if test x"$ok" != xPTHREAD_CREATE_JOINABLE; then
+                AC_DEFINE(PTHREAD_CREATE_JOINABLE, $ok,
+                          [Define to the necessary symbol if this constant
+                           uses a non-standard name on your system.])
+        fi
+        AC_MSG_RESULT(${ok})
+        if test x"$ok" = xunknown; then
+                AC_MSG_WARN([we do not know how to create joinable pthreads])
+        fi
+
+        AC_MSG_CHECKING([if more special flags are required for pthreads])
+        flag=no
+        case "${host_cpu}-${host_os}" in
+                *-aix* | *-freebsd*)     flag="-D_THREAD_SAFE";;
+                *solaris* | *-osf* | *-hpux*) flag="-D_REENTRANT";;
+        esac
+        AC_MSG_RESULT(${flag})
+        if test "x$flag" != xno; then
+                PTHREAD_CFLAGS="$flag $PTHREAD_CFLAGS"
+        fi
+
+        LIBS="$save_LIBS"
+        CFLAGS="$save_CFLAGS"
+
+        # More AIX lossage: must compile with cc_r
+        AC_CHECK_PROG(PTHREAD_CC, cc_r, cc_r, ${CC})
+else
+        PTHREAD_CC="$CC"
+fi
+
+AC_SUBST(PTHREAD_LIBS)
+AC_SUBST(PTHREAD_CFLAGS)
+AC_SUBST(PTHREAD_CC)
+
+# Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
+if test x"$acx_pthread_ok" = xyes; then
+        ifelse([$1],,AC_DEFINE(HAVE_PTHREAD,1,[Define if you have POSIX threads libraries and header files.]),[$1])
+        :
+else
+        acx_pthread_ok=no
+        $2
+fi
+AC_LANG_RESTORE
+])dnl ACX_PTHREAD