+if test $ol_with_threads = auto -o $ol_with_threads = yes \
+ -o $ol_with_threads = mach ; then
+
+ dnl check for Mach CThreads
+ AC_CHECK_HEADERS(mach/cthreads.h)
+ if test $ac_cv_header_mach_cthreads_h = yes ; then
+ ol_with_threads=found
+
+ dnl check for cthread support in current $LIBS
+ AC_CHECK_FUNC(cthread_fork,[ol_link_threads=yes])
+
+ if test $ol_link_threads = no ; then
+ dnl try -all_load
+ dnl this test needs work
+ AC_CACHE_CHECK([for cthread_fork with -all_load],
+ [ol_cv_cthread_all_load], [
+ dnl save the flags
+ save_LIBS="$LIBS"
+ LIBS="-all_load $LIBS"
+ AC_TRY_LINK([#include <mach/cthreads.h>],[
+ cthread_fork((void *)0, (void *)0);
+ ], ol_cv_cthread_all_load=yes, ol_cv_cthread_all_load=no)
+ dnl restore the LIBS
+ LIBS="$save_LIBS"
+ ])
+
+ if test $ol_cv_cthread_all_load = yes ; then
+ LTHREAD_LIBS="$LTHREAD_LIBS -all_load"
+ ol_link_threads=mach
+ fi
+ fi
+
+ if test $ol_link_threads != no ; then
+ : check for cthread specific functionality here
+ AC_DEFINE(HAVE_MACH_CTHREADS,1)
+ else
+ AC_MSG_ERROR([could not link with Mach CThreads])
+ fi
+ fi
+
+ if test $ol_with_threads = mach ; then
+ AC_MSG_ERROR([could not locate Mach CThreads])
+ fi
+fi
+
+if test $ol_with_threads = auto -o $ol_with_threads = yes \
+ -o $ol_with_threads = lwp ; then
+
+ dnl check for SunOS5 LWP
+ AC_CHECK_HEADERS(thread.h synch.h)
+ if test $ac_cv_header_thread_h = yes -a $ac_cv_header_synch_h = yes ; then
+ AC_CHECK_LIB(thread, thr_create, [have_thr=yes], [have_thr=no])
+
+ if test $have_thr = yes ; then
+ AC_DEFINE(HAVE_THR)
+ LTHREAD_LIBS="$LTHREAD_LIBS -lthread"
+ ol_link_threads=thr
+
+ if test $ol_with_yielding_select = auto ; then
+ ol_with_yielding_select=yes
+ fi
+ fi
+ fi
+
+ dnl check for SunOS4 LWP
+ AC_CHECK_HEADERS(lwp/lwp.h)
+ if test $ac_cv_header_lwp_lwp_h = yes ; then
+ AC_CHECK_LIB(lwp, lwp_create, [have_lwp=yes], [have_lwp=no])
+
+ if test $have_lwp = yes ; then
+ AC_DEFINE(HAVE_LWP)
+ LTHREAD_LIBS="$LTHREAD_LIBS -llwp"
+ ol_link_threads=lwp
+
+ if test $ol_with_yielding_select = auto ; then
+ ol_with_yielding_select=no
+ fi
+ fi
+ fi
+fi
+
+if test $ol_with_yielding_select = yes ; then
+ AC_DEFINE(HAVE_YIELDING_SELECT,1)
+fi
+
+if test $ol_with_threads = manual ; then
+ dnl User thinks he can manually configure threads.
+ ol_link_threads=yes
+
+ AC_MSG_WARN([thread defines and link options must be set manually])
+
+ AC_CHECK_HEADERS(pthread.h sched.h)
+ AC_CHECK_FUNCS(sched_yield pthread_yield)
+ OL_LINUX_THREADS
+
+ AC_CHECK_HEADERS(mach/cthreads.h)
+ AC_CHECK_HEADERS(lwp/lwp.h)
+ AC_CHECK_HEADERS(thread.h synch.h)
+fi
+
+if test $ol_link_threads != no ; then
+ dnl needed to get reentrant/threadsafe versions
+ dnl
+ AC_DEFINE(REENTRANT,1)
+ AC_DEFINE(_REENTRANT,1)
+ AC_DEFINE(THREAD_SAFE,1)
+ AC_DEFINE(_THREAD_SAFE,1)
+ AC_DEFINE(THREADSAFE,1)
+ AC_DEFINE(_THREADSAFE,1)
+
+ dnl this might cause the errno symbol to be
+ dnl replaced with a function to get a thread specific errno.
+ dnl check to see if everything needs to be compiled
+ dnl with the thread libraries
+ AC_CACHE_CHECK([for thread specific errno],
+ [ol_cv_errno_thread_specific], [
+ AC_TRY_LINK([
+#include <errno.h>
+ ], [
+int x = errno;
+ ],
+ [ol_cv_errno_thread_specific=yes],
+ [ol_cv_errno_thread_specific=no])
+ ])
+
+ if test $ol_cv_errno_thread_specific != yes ; then
+ LIBS="$LTHREAD_LIBS $LIBS"
+ LTHREAD_LIBS=""
+ fi
+
+dnl When in thread environment, use
+dnl #if defined( HAVE_REENTRANT_FUNCTIONS ) \
+dnl || defined( HAVE_FUNC_R )
+dnl func_r(...);
+dnl #else
+dnl # if defined( HAVE_THREADS )
+dnl /* lock */
+dnl # endif
+dnl func(...);
+dnl # if defined( HAVE_THREADS )
+dnl /* unlock */
+dnl # endif
+dnl #endif
+dnl
+dnl HAVE_REENTRANT_FUNCTIONS is derived from:
+dnl _POSIX_REENTRANT_FUNCTIONS
+dnl _POSIX_THREAD_SAFE_FUNCTIONS
+dnl _POSIX_THREADSAFE_FUNCTIONS
+dnl
+dnl and is currently defined in lthread.h
+dnl
+dnl HAVE_THREADS is defined by lthread.h iff -UNO_THREADS
+dnl
+dnl libldap/*.c should only include <lthread.h> iff
+dnl LDAP_R_COMPILE is defined. ie:
+dnl #ifdef LDAP_R_COMPILE
+dnl # include LDAP_R_COMPILE
+dnl #endif
+dnl
+dnl LDAP_R_COMIPLE is defined by libldap_r/Makefile.in
+dnl specifically for compiling the threadsafe version of
+dnl the ldap library (-lldap_r).
+dnl
+dnl dnl check for reentrant/threadsafe functions
+dnl dnl
+dnl dnl note: these should only be used when linking
+dnl dnl with $LTHREAD_LIBS
+dnl dnl
+dnl save_CPPFLAGS="$CPPFLAGS"
+dnl save_LIBS="$LIBS"
+dnl LIBS="$LTHREAD_LIBS $LIBS"
+dnl AC_CHECK_FUNCS( \
+dnl strtok_r \
+dnl gmtime_r \
+dnl gethostbyaddr_r gethostbyname_r \
+dnl feof_unlocked unlocked_feof \
+dnl putc_unlocked unlocked_putc \
+dnl flockfile ftrylockfile \
+dnl )
+dnl CPPFLAGS="$save_CPPFLAGS"
+dnl LIBS="$save_LIBS"
+fi
+
+dnl ----------------------------------------------------------------
+