FreeBSD/Linux Kernel Cross Reference
sys/contrib/libsodium/m4/ax_pthread.m4

     # ===========================================================================
     #        https://www.gnu.org/software/autoconf-archive/ax_pthread.html
     # ===========================================================================
     #
     # SYNOPSIS
     #
     #   AX_PTHREAD([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
     #
     # DESCRIPTION
    #
    #   This macro figures out how to build C programs using POSIX threads. It
    #   sets the PTHREAD_LIBS output variable to the threads library and linker
    #   flags, and the PTHREAD_CFLAGS output variable to any special C compiler
    #   flags that are needed. (The user can also force certain compiler
    #   flags/libs to be tested by setting these environment variables.)
    #
    #   Also sets PTHREAD_CC to any special C compiler that is needed for
    #   multi-threaded programs (defaults to the value of CC otherwise). (This
    #   is necessary on AIX to use the special cc_r compiler alias.)
    #
    #   NOTE: You are assumed to not only compile your program with these flags,
    #   but also to link with them as well. For example, you might link with
    #   $PTHREAD_CC $CFLAGS $PTHREAD_CFLAGS $LDFLAGS ... $PTHREAD_LIBS $LIBS
    #
    #   If you are only building threaded programs, you may wish to use these
    #   variables in your default LIBS, CFLAGS, and CC:
    #
    #     LIBS="$PTHREAD_LIBS $LIBS"
    #     CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
    #     CC="$PTHREAD_CC"
    #
    #   In addition, if the PTHREAD_CREATE_JOINABLE thread-attribute constant
    #   has a nonstandard name, this macro defines PTHREAD_CREATE_JOINABLE to
    #   that name (e.g. PTHREAD_CREATE_UNDETACHED on AIX).
    #
    #   Also HAVE_PTHREAD_PRIO_INHERIT is defined if pthread is found and the
    #   PTHREAD_PRIO_INHERIT symbol is defined when compiling with
    #   PTHREAD_CFLAGS.
    #
    #   ACTION-IF-FOUND is a list of shell commands to run if a threads library
    #   is found, and ACTION-IF-NOT-FOUND is a list of commands to run it if it
    #   is not found. If ACTION-IF-FOUND is not specified, the default action
    #   will define HAVE_PTHREAD.
    #
    #   Please let the authors know if this macro fails on any platform, or if
    #   you have any other suggestions or comments. This macro was based on work
    #   by SGJ on autoconf scripts for FFTW (http://www.fftw.org/) (with help
    #   from M. Frigo), as well as ac_pthread and hb_pthread macros posted by
    #   Alejandro Forero Cuervo to the autoconf macro repository. We are also
    #   grateful for the helpful feedback of numerous users.
    #
    #   Updated for Autoconf 2.68 by Daniel Richard G.
    #
    # LICENSE
    #
    #   Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>
    #   Copyright (c) 2011 Daniel Richard G. <skunk@iSKUNK.ORG>
    #
    #   This program is free software: you can redistribute it and/or modify it
    #   under the terms of the GNU General Public License as published by the
    #   Free Software Foundation, either version 3 of the License, or (at your
    #   option) any later version.
    #
    #   This program is distributed in the hope that it will be useful, but
    #   WITHOUT ANY WARRANTY; without even the implied warranty of
    #   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
    #   Public License for more details.
    #
    #   You should have received a copy of the GNU General Public License along
    #   with this program. If not, see <https://www.gnu.org/licenses/>.
    #
    #   As a special exception, the respective Autoconf Macro's copyright owner
    #   gives unlimited permission to copy, distribute and modify the configure
    #   scripts that are the output of Autoconf when processing the Macro. You
    #   need not follow the terms of the GNU General Public License when using
    #   or distributing such scripts, even though portions of the text of the
    #   Macro appear in them. The GNU General Public License (GPL) does govern
    #   all other use of the material that constitutes the Autoconf Macro.
    #
    #   This special exception to the GPL applies to versions of the Autoconf
    #   Macro released by the Autoconf Archive. When you make and distribute a
    #   modified version of the Autoconf Macro, you may extend this special
    #   exception to the GPL to apply to your modified version as well.
    
    #serial 24
    
    AU_ALIAS([ACX_PTHREAD], [AX_PTHREAD])
    AC_DEFUN([AX_PTHREAD], [
    AC_REQUIRE([AC_CANONICAL_HOST])
    AC_REQUIRE([AC_PROG_CC])
    AC_REQUIRE([AC_PROG_SED])
    AC_LANG_PUSH([C])
    ax_pthread_ok=no
    
    # We used to check for pthread.h first, but this fails if pthread.h
    # requires special compiler flags (e.g. on Tru64 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$PTHREAD_CFLAGS$PTHREAD_LIBS" != "x"; then
           ax_pthread_save_CC="$CC"
           ax_pthread_save_CFLAGS="$CFLAGS"
           ax_pthread_save_LIBS="$LIBS"
           AS_IF([test "x$PTHREAD_CC" != "x"], [CC="$PTHREAD_CC"])
           CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
           LIBS="$PTHREAD_LIBS $LIBS"
           AC_MSG_CHECKING([for pthread_join using $CC $PTHREAD_CFLAGS $PTHREAD_LIBS])
           AC_LINK_IFELSE([AC_LANG_CALL([], [pthread_join])], [ax_pthread_ok=yes])
           AC_MSG_RESULT([$ax_pthread_ok])
           if test "x$ax_pthread_ok" = "xno"; then
                   PTHREAD_LIBS=""
                   PTHREAD_CFLAGS=""
           fi
           CC="$ax_pthread_save_CC"
           CFLAGS="$ax_pthread_save_CFLAGS"
           LIBS="$ax_pthread_save_LIBS"
   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, and "pthread-config"
   # which is a program returning the flags for the Pth emulation library.
   
   ax_pthread_flags="pthreads none -Kthread -pthread -pthreads -mthreads pthread --thread-safe -mt pthread-config"
   
   # 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)
   # -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads), Tru64
   #           (Note: HP C rejects this with "bad form for `-t' option")
   # -pthreads: Solaris/gcc (Note: HP C also rejects)
   # -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
   #      doesn't hurt to check since this sometimes defines pthreads and
   #      -D_REENTRANT too), HP C (must be checked before -lpthread, which
   #      is present but should not be used directly; and before -mthreads,
   #      because the compiler interprets this as "-mt" + "-hreads")
   # -mthreads: Mingw32/gcc, Lynx/gcc
   # pthread: Linux, etcetera
   # --thread-safe: KAI C++
   # pthread-config: use pthread-config program (for GNU Pth library)
   
   case $host_os in
   
           freebsd*)
   
           # -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
           # lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
   
           ax_pthread_flags="-kthread lthread $ax_pthread_flags"
           ;;
   
           hpux*)
   
           # From the cc(1) man page: "[-mt] Sets various -D flags to enable
           # multi-threading and also sets -lpthread."
   
           ax_pthread_flags="-mt -pthread pthread $ax_pthread_flags"
           ;;
   
           openedition*)
   
           # IBM z/OS requires a feature-test macro to be defined in order to
           # enable POSIX threads at all, so give the user a hint if this is
           # not set. (We don't define these ourselves, as they can affect
           # other portions of the system API in unpredictable ways.)
   
           AC_EGREP_CPP([AX_PTHREAD_ZOS_MISSING],
               [
   #            if !defined(_OPEN_THREADS) && !defined(_UNIX03_THREADS)
                AX_PTHREAD_ZOS_MISSING
   #            endif
               ],
               [AC_MSG_WARN([IBM z/OS requires -D_OPEN_THREADS or -D_UNIX03_THREADS to enable pthreads support.])])
           ;;
   
           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. (N.B.: 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 check first for the
           # standard Solaris way of linking pthreads (-mt -lpthread).
   
           ax_pthread_flags="-mt,pthread pthread $ax_pthread_flags"
           ;;
   esac
   
   # GCC generally uses -pthread, or -pthreads on some platforms (e.g. SPARC)
   
   AS_IF([test "x$GCC" = "xyes"],
         [ax_pthread_flags="-pthread -pthreads $ax_pthread_flags"])
   
   # The presence of a feature test macro requesting re-entrant function
   # definitions is, on some systems, a strong hint that pthreads support is
   # correctly enabled
   
   case $host_os in
           darwin* | hpux* | linux* | osf* | solaris*)
           ax_pthread_check_macro="_REENTRANT"
           ;;
   
           aix*)
           ax_pthread_check_macro="_THREAD_SAFE"
           ;;
   
           *)
           ax_pthread_check_macro="--"
           ;;
   esac
   AS_IF([test "x$ax_pthread_check_macro" = "x--"],
         [ax_pthread_check_cond=0],
         [ax_pthread_check_cond="!defined($ax_pthread_check_macro)"])
   
   # Are we compiling with Clang?
   
   AC_CACHE_CHECK([whether $CC is Clang],
       [ax_cv_PTHREAD_CLANG],
       [ax_cv_PTHREAD_CLANG=no
        # Note that Autoconf sets GCC=yes for Clang as well as GCC
        if test "x$GCC" = "xyes"; then
           AC_EGREP_CPP([AX_PTHREAD_CC_IS_CLANG],
               [/* Note: Clang 2.7 lacks __clang_[a-z]+__ */
   #            if defined(__clang__) && defined(__llvm__)
                AX_PTHREAD_CC_IS_CLANG
   #            endif
               ],
               [ax_cv_PTHREAD_CLANG=yes])
        fi
       ])
   ax_pthread_clang="$ax_cv_PTHREAD_CLANG"
   
   ax_pthread_clang_warning=no
   
   # Clang needs special handling, because older versions handle the -pthread
   # option in a rather... idiosyncratic way
   
   if test "x$ax_pthread_clang" = "xyes"; then
   
           # Clang takes -pthread; it has never supported any other flag
   
           # (Note 1: This will need to be revisited if a system that Clang
           # supports has POSIX threads in a separate library.  This tends not
           # to be the way of modern systems, but it's conceivable.)
   
           # (Note 2: On some systems, notably Darwin, -pthread is not needed
           # to get POSIX threads support; the API is always present and
           # active.  We could reasonably leave PTHREAD_CFLAGS empty.  But
           # -pthread does define _REENTRANT, and while the Darwin headers
           # ignore this macro, third-party headers might not.)
   
           PTHREAD_CFLAGS="-pthread"
           PTHREAD_LIBS=
   
           ax_pthread_ok=yes
   
           # However, older versions of Clang make a point of warning the user
           # that, in an invocation where only linking and no compilation is
           # taking place, the -pthread option has no effect ("argument unused
           # during compilation").  They expect -pthread to be passed in only
           # when source code is being compiled.
           #
           # Problem is, this is at odds with the way Automake and most other
           # C build frameworks function, which is that the same flags used in
           # compilation (CFLAGS) are also used in linking.  Many systems
           # supported by AX_PTHREAD require exactly this for POSIX threads
           # support, and in fact it is often not straightforward to specify a
           # flag that is used only in the compilation phase and not in
           # linking.  Such a scenario is extremely rare in practice.
           #
           # Even though use of the -pthread flag in linking would only print
           # a warning, this can be a nuisance for well-run software projects
           # that build with -Werror.  So if the active version of Clang has
           # this misfeature, we search for an option to squash it.
   
           AC_CACHE_CHECK([whether Clang needs flag to prevent "argument unused" warning when linking with -pthread],
               [ax_cv_PTHREAD_CLANG_NO_WARN_FLAG],
               [ax_cv_PTHREAD_CLANG_NO_WARN_FLAG=unknown
                # Create an alternate version of $ac_link that compiles and
                # links in two steps (.c -> .o, .o -> exe) instead of one
                # (.c -> exe), because the warning occurs only in the second
                # step
                ax_pthread_save_ac_link="$ac_link"
                ax_pthread_sed='s/conftest\.\$ac_ext/conftest.$ac_objext/g'
                ax_pthread_link_step=`$as_echo "$ac_link" | sed "$ax_pthread_sed"`
                ax_pthread_2step_ac_link="($ac_compile) && (echo ==== >&5) && ($ax_pthread_link_step)"
                ax_pthread_save_CFLAGS="$CFLAGS"
                for ax_pthread_try in '' -Qunused-arguments -Wno-unused-command-line-argument unknown; do
                   AS_IF([test "x$ax_pthread_try" = "xunknown"], [break])
                   CFLAGS="-Werror -Wunknown-warning-option $ax_pthread_try -pthread $ax_pthread_save_CFLAGS"
                   ac_link="$ax_pthread_save_ac_link"
                   AC_LINK_IFELSE([AC_LANG_SOURCE([[int main(void){return 0;}]])],
                       [ac_link="$ax_pthread_2step_ac_link"
                        AC_LINK_IFELSE([AC_LANG_SOURCE([[int main(void){return 0;}]])],
                            [break])
                       ])
                done
                ac_link="$ax_pthread_save_ac_link"
                CFLAGS="$ax_pthread_save_CFLAGS"
                AS_IF([test "x$ax_pthread_try" = "x"], [ax_pthread_try=no])
                ax_cv_PTHREAD_CLANG_NO_WARN_FLAG="$ax_pthread_try"
               ])
   
           case "$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG" in
                   no | unknown) ;;
                   *) PTHREAD_CFLAGS="$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG $PTHREAD_CFLAGS" ;;
           esac
   
   fi # $ax_pthread_clang = yes
   
   if test "x$ax_pthread_ok" = "xno"; then
   for ax_pthread_try_flag in $ax_pthread_flags; do
   
           case $ax_pthread_try_flag in
                   none)
                   AC_MSG_CHECKING([whether pthreads work without any flags])
                   ;;
   
                   -mt,pthread)
                   AC_MSG_CHECKING([whether pthreads work with -mt -lpthread])
                   PTHREAD_CFLAGS="-mt"
                   PTHREAD_LIBS="-lpthread"
                   ;;
   
                   -*)
                   AC_MSG_CHECKING([whether pthreads work with $ax_pthread_try_flag])
                   PTHREAD_CFLAGS="$ax_pthread_try_flag"
                   ;;
   
                   pthread-config)
                   AC_CHECK_PROG([ax_pthread_config], [pthread-config], [yes], [no])
                   AS_IF([test "x$ax_pthread_config" = "xno"], [continue])
                   PTHREAD_CFLAGS="`pthread-config --cflags`"
                   PTHREAD_LIBS="`pthread-config --ldflags` `pthread-config --libs`"
                   ;;
   
                   *)
                   AC_MSG_CHECKING([for the pthreads library -l$ax_pthread_try_flag])
                   PTHREAD_LIBS="-l$ax_pthread_try_flag"
                   ;;
           esac
   
           ax_pthread_save_CFLAGS="$CFLAGS"
           ax_pthread_save_LIBS="$LIBS"
           CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
           LIBS="$PTHREAD_LIBS $LIBS"
   
           # 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_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>
   #                       if $ax_pthread_check_cond
   #                        error "$ax_pthread_check_macro must be defined"
   #                       endif
                           static void routine(void *a) { a = 0; }
                           static void *start_routine(void *a) { return a; }],
                          [pthread_t th; pthread_attr_t attr;
                           pthread_create(&th, 0, start_routine, 0);
                           pthread_join(th, 0);
                           pthread_attr_init(&attr);
                           pthread_cleanup_push(routine, 0);
                           pthread_cleanup_pop(0) /* ; */])],
               [ax_pthread_ok=yes],
               [])
   
           CFLAGS="$ax_pthread_save_CFLAGS"
           LIBS="$ax_pthread_save_LIBS"
   
           AC_MSG_RESULT([$ax_pthread_ok])
           AS_IF([test "x$ax_pthread_ok" = "xyes"], [break])
   
           PTHREAD_LIBS=""
           PTHREAD_CFLAGS=""
   done
   fi
   
   # Various other checks:
   if test "x$ax_pthread_ok" = "xyes"; then
           ax_pthread_save_CFLAGS="$CFLAGS"
           ax_pthread_save_LIBS="$LIBS"
           CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
           LIBS="$PTHREAD_LIBS $LIBS"
   
           # Detect AIX lossage: JOINABLE attribute is called UNDETACHED.
           AC_CACHE_CHECK([for joinable pthread attribute],
               [ax_cv_PTHREAD_JOINABLE_ATTR],
               [ax_cv_PTHREAD_JOINABLE_ATTR=unknown
                for ax_pthread_attr in PTHREAD_CREATE_JOINABLE PTHREAD_CREATE_UNDETACHED; do
                    AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>],
                                                    [int attr = $ax_pthread_attr; return attr /* ; */])],
                                   [ax_cv_PTHREAD_JOINABLE_ATTR=$ax_pthread_attr; break],
                                   [])
                done
               ])
           AS_IF([test "x$ax_cv_PTHREAD_JOINABLE_ATTR" != "xunknown" && \
                  test "x$ax_cv_PTHREAD_JOINABLE_ATTR" != "xPTHREAD_CREATE_JOINABLE" && \
                  test "x$ax_pthread_joinable_attr_defined" != "xyes"],
                 [AC_DEFINE_UNQUOTED([PTHREAD_CREATE_JOINABLE],
                                     [$ax_cv_PTHREAD_JOINABLE_ATTR],
                                     [Define to necessary symbol if this constant
                                      uses a non-standard name on your system.])
                  ax_pthread_joinable_attr_defined=yes
                 ])
   
           AC_CACHE_CHECK([whether more special flags are required for pthreads],
               [ax_cv_PTHREAD_SPECIAL_FLAGS],
               [ax_cv_PTHREAD_SPECIAL_FLAGS=no
                case $host_os in
                solaris*)
                ax_cv_PTHREAD_SPECIAL_FLAGS="-D_POSIX_PTHREAD_SEMANTICS"
                ;;
                esac
               ])
           AS_IF([test "x$ax_cv_PTHREAD_SPECIAL_FLAGS" != "xno" && \
                  test "x$ax_pthread_special_flags_added" != "xyes"],
                 [PTHREAD_CFLAGS="$ax_cv_PTHREAD_SPECIAL_FLAGS $PTHREAD_CFLAGS"
                  ax_pthread_special_flags_added=yes])
   
           AC_CACHE_CHECK([for PTHREAD_PRIO_INHERIT],
               [ax_cv_PTHREAD_PRIO_INHERIT],
               [AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <pthread.h>]],
                                                [[int i = PTHREAD_PRIO_INHERIT;]])],
                               [ax_cv_PTHREAD_PRIO_INHERIT=yes],
                               [ax_cv_PTHREAD_PRIO_INHERIT=no])
               ])
           AS_IF([test "x$ax_cv_PTHREAD_PRIO_INHERIT" = "xyes" && \
                  test "x$ax_pthread_prio_inherit_defined" != "xyes"],
                 [AC_DEFINE([HAVE_PTHREAD_PRIO_INHERIT], [1], [Have PTHREAD_PRIO_INHERIT.])
                  ax_pthread_prio_inherit_defined=yes
                 ])
   
           CFLAGS="$ax_pthread_save_CFLAGS"
           LIBS="$ax_pthread_save_LIBS"
   
           # More AIX lossage: compile with *_r variant
           if test "x$GCC" != "xyes"; then
               case $host_os in
                   aix*)
                   AS_CASE(["x/$CC"],
                       [x*/c89|x*/c89_128|x*/c99|x*/c99_128|x*/cc|x*/cc128|x*/xlc|x*/xlc_v6|x*/xlc128|x*/xlc128_v6],
                       [#handle absolute path differently from PATH based program lookup
                        AS_CASE(["x$CC"],
                            [x/*],
                            [AS_IF([AS_EXECUTABLE_P([${CC}_r])],[PTHREAD_CC="${CC}_r"])],
                            [AC_CHECK_PROGS([PTHREAD_CC],[${CC}_r],[$CC])])])
                   ;;
               esac
           fi
   fi
   
   test -n "$PTHREAD_CC" || PTHREAD_CC="$CC"
   
   AC_SUBST([PTHREAD_LIBS])
   AC_SUBST([PTHREAD_CFLAGS])
   AC_SUBST([PTHREAD_CC])
   
   # Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
   if test "x$ax_pthread_ok" = "xyes"; then
           ifelse([$1],,[AC_DEFINE([HAVE_PTHREAD],[1],[Define if you have POSIX threads libraries and header files.])],[$1])
           :
   else
           ax_pthread_ok=no
           $2
   fi
   AC_LANG_POP
   ])dnl AX_PTHREAD

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