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dnl and XPG3, while the other different ways for different systems (old BSD,
dnl Windows and Amiga).
dnl
dnl There are two known platforms (AIX 3.x and SunOS 4.1.x) where the
dnl O_NONBLOCK define is found but does not work. This condition is attempted
dnl to get caught in this script by using an excessive number of #ifdefs...

AC_DEFUN([CURL_CHECK_NONBLOCKING_SOCKET], [
  AC_MSG_CHECKING([non-blocking sockets style])
  nonblock="unknown"
  #
  AC_COMPILE_IFELSE([
    AC_LANG_PROGRAM([[
/* headers for O_NONBLOCK test */
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
/* */
#if defined(sun) || defined(__sun__) || \
    defined(__SUNPRO_C) || defined(__SUNPRO_CC)
# if defined(__SVR4) || defined(__srv4__)
#  define PLATFORM_SOLARIS
# else
#  define PLATFORM_SUNOS4
# endif
#endif
#if (defined(_AIX) || defined(__xlC__)) && !defined(_AIX41)
# define PLATFORM_AIX_V3
#endif
#if defined(PLATFORM_SUNOS4) || defined(PLATFORM_AIX_V3) || defined(__BEOS__)
#error "O_NONBLOCK does not work on this platform"
#endif
    ]],[[
      /* O_NONBLOCK source test */
      int socket;
      int flags = fcntl(socket, F_SETFL, flags | O_NONBLOCK);
    ]])
  ],[
    dnl the O_NONBLOCK test was fine
    nonblock="O_NONBLOCK"
    AC_DEFINE(HAVE_O_NONBLOCK, 1,
      [use O_NONBLOCK for non-blocking sockets])
  ])
  #
  if test "$nonblock" = "unknown"; then
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
/* headers for FIONBIO test */
#include <unistd.h>
#include <stropts.h>
      ]],[[
        /* FIONBIO source test (old-style unix) */
        int socket;
        int flags = ioctl(socket, FIONBIO, &flags);
      ]])
    ],[
      dnl FIONBIO test was good
      nonblock="FIONBIO"
      AC_DEFINE(HAVE_FIONBIO, 1,
        [use FIONBIO for non-blocking sockets])
    ])
  fi
  #
  if test "$nonblock" = "unknown"; then
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
/* headers for ioctlsocket test (Windows) */
#undef inline
#ifdef HAVE_WINDOWS_H
#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif
#include <windows.h>
#ifdef HAVE_WINSOCK2_H
#include <winsock2.h>
#else
#ifdef HAVE_WINSOCK_H
#include <winsock.h>
#endif
#endif
#endif
      ]],[[
        /* ioctlsocket source code (Windows) */
        SOCKET sd;
        unsigned long flags = 0;
        sd = socket(0, 0, 0);
        ioctlsocket(sd, FIONBIO, &flags);
      ]])
    ],[
      dnl ioctlsocket test was good
      nonblock="ioctlsocket"
      AC_DEFINE(HAVE_IOCTLSOCKET, 1,
        [use ioctlsocket() for non-blocking sockets])
    ])
  fi
  #
  if test "$nonblock" = "unknown"; then
    AC_LINK_IFELSE([
      AC_LANG_PROGRAM([[
/* headers for IoctlSocket test (Amiga?) */
#include <sys/ioctl.h>
      ]],[[
        /* IoctlSocket source code (Amiga?) */
        int socket;
        int flags = IoctlSocket(socket, FIONBIO, (long)1);
      ]])
    ],[
      dnl Ioctlsocket test was good
      nonblock="IoctlSocket"
      AC_DEFINE(HAVE_IOCTLSOCKET_CASE, 1,
        [use Ioctlsocket() for non-blocking sockets])
    ])
  fi
  #
  if test "$nonblock" = "unknown"; then
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
/* headers for SO_NONBLOCK test (BeOS) */
      ]],[[
        /* SO_NONBLOCK source code (BeOS) */
        long b = 1;
        int socket;
        int flags = setsockopt(socket, SOL_SOCKET, SO_NONBLOCK, &b, sizeof(b));
      ]])
    ],[
      dnl the SO_NONBLOCK test was good
      nonblock="SO_NONBLOCK"
      AC_DEFINE(HAVE_SO_NONBLOCK, 1,
        [use SO_NONBLOCK for non-blocking sockets])
    ])
  fi
  #
  AC_MSG_RESULT($nonblock)
  #
  if test "$nonblock" = "unknown"; then
    AC_DEFINE(HAVE_DISABLED_NONBLOCKING, 1,
      [disabled non-blocking sockets])
    AC_MSG_WARN([non-block sockets disabled])
  fi
])


dnl TYPE_IN_ADDR_T
dnl -------------------------------------------------
dnl Check for in_addr_t: it is used to receive the return code of inet_addr()

AC_DEFUN([TYPE_IN_ADDR_T], [
  AC_CHECK_TYPE([in_addr_t], ,[
    dnl in_addr_t not available
    AC_CACHE_CHECK([for in_addr_t equivalent],
      [curl_cv_in_addr_t_equiv], [
      curl_cv_in_addr_t_equiv="unknown"
      for t in "unsigned long" int size_t unsigned long; do
        if test "$curl_cv_in_addr_t_equiv" = "unknown"; then
          AC_LINK_IFELSE([
            AC_LANG_PROGRAM([[
#undef inline
#ifdef HAVE_WINDOWS_H
#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif
#include <windows.h>
#ifdef HAVE_WINSOCK2_H
#include <winsock2.h>
#else
#ifdef HAVE_WINSOCK_H
#include <winsock.h>
#endif
#endif
#else
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
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#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
            ]],[[
              $t data = inet_addr ("1.2.3.4");
            ]])
          ],[
            curl_cv_in_addr_t_equiv="$t"
          ])
        fi
      done
    ])
    case "$curl_cv_in_addr_t_equiv" in
      unknown)
        AC_MSG_ERROR([Cannot find a type to use in place of in_addr_t])
        ;;
      *)
        AC_DEFINE_UNQUOTED(in_addr_t, $curl_cv_in_addr_t_equiv,
          [Type to use in place of in_addr_t when system does not provide it.])
        ;;
    esac
  ],[
#undef inline
#ifdef HAVE_WINDOWS_H
#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif
#include <windows.h>
#ifdef HAVE_WINSOCK2_H
#include <winsock2.h>
#else
#ifdef HAVE_WINSOCK_H
#include <winsock.h>
#endif
#endif
#else
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
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#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
dnl CURL_CHECK_FUNC_CLOCK_GETTIME_MONOTONIC
dnl -------------------------------------------------
dnl Check if monotonic clock_gettime is available.
AC_DEFUN([CURL_CHECK_FUNC_CLOCK_GETTIME_MONOTONIC], [
  AC_REQUIRE([AC_HEADER_TIME])dnl
  AC_CHECK_HEADERS(sys/types.h sys/time.h time.h)
  AC_MSG_CHECKING([for monotonic clock_gettime])
    AC_LANG_PROGRAM([[
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#ifdef TIME_WITH_SYS_TIME
#include <time.h>
#endif
#else
#ifdef HAVE_TIME_H
#include <time.h>
#endif
#endif
      struct timespec ts;
      (void)clock_gettime(CLOCK_MONOTONIC, &ts);
  ],[
    AC_MSG_RESULT([yes])
    ac_cv_func_clock_gettime="yes"
  ],[
    AC_MSG_RESULT([no])
    ac_cv_func_clock_gettime="no"
  ])
  dnl Definition of HAVE_CLOCK_GETTIME_MONOTONIC is intentionally postponed
  dnl until library linking and run-time checks for clock_gettime succeed.
dnl CURL_CHECK_LIBS_CLOCK_GETTIME_MONOTONIC
dnl -------------------------------------------------
dnl If monotonic clock_gettime is available then,
dnl check and prepended to LIBS any needed libraries.

AC_DEFUN([CURL_CHECK_LIBS_CLOCK_GETTIME_MONOTONIC], [
  AC_REQUIRE([CURL_CHECK_FUNC_CLOCK_GETTIME_MONOTONIC])dnl
  if test "$ac_cv_func_clock_gettime" = "yes"; then
    #
    AC_MSG_CHECKING([for clock_gettime in libraries])
    #
    curl_cv_save_LIBS="$LIBS"
    curl_cv_gclk_LIBS="unknown"
    #
    for x_xlibs in '' '-lrt' '-lposix4' ; do
      if test "$curl_cv_gclk_LIBS" = "unknown"; then
        if test -z "$x_xlibs"; then
          LIBS="$curl_cv_save_LIBS"
        else
          LIBS="$x_xlibs $curl_cv_save_LIBS"
        fi
        AC_LINK_IFELSE([
          AC_LANG_PROGRAM([[
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#ifdef TIME_WITH_SYS_TIME
#include <time.h>
#endif
#else
#ifdef HAVE_TIME_H
#include <time.h>
#endif
#endif
          ]],[[
            struct timespec ts;
            (void)clock_gettime(CLOCK_MONOTONIC, &ts);
          ]])
        ],[
          curl_cv_gclk_LIBS="$x_xlibs"
        ])
      fi
    done
    #
    LIBS="$curl_cv_save_LIBS"
    #
    case X-"$curl_cv_gclk_LIBS" in
      X-unknown)
        AC_MSG_RESULT([cannot find clock_gettime])
        AC_MSG_WARN([HAVE_CLOCK_GETTIME_MONOTONIC will not be defined])
        ac_cv_func_clock_gettime="no"
        ;;
      X-)
        AC_MSG_RESULT([no additional lib required])
        ac_cv_func_clock_gettime="yes"
        ;;
      *)
        if test -z "$curl_cv_save_LIBS"; then
          LIBS="$curl_cv_gclk_LIBS"
        else
          LIBS="$curl_cv_gclk_LIBS $curl_cv_save_LIBS"
        fi
        AC_MSG_RESULT([$curl_cv_gclk_LIBS])
        ac_cv_func_clock_gettime="yes"
        ;;
    esac
    #
    dnl only do runtime verification when not cross-compiling
    if test "x$cross_compiling" != "xyes" &&
      test "$ac_cv_func_clock_gettime" = "yes"; then
      AC_MSG_CHECKING([if monotonic clock_gettime works])
      AC_RUN_IFELSE([
        AC_LANG_PROGRAM([[
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#ifdef TIME_WITH_SYS_TIME
#include <time.h>
#endif
#else
#ifdef HAVE_TIME_H
#include <time.h>
#endif
#endif
        ]],[[
          struct timespec ts;
          if (0 == clock_gettime(CLOCK_MONOTONIC, &ts))
            exit(0);
        ]])
      ],[
        AC_MSG_RESULT([yes])
      ],[
        AC_MSG_RESULT([no])
        AC_MSG_WARN([HAVE_CLOCK_GETTIME_MONOTONIC will not be defined])
        ac_cv_func_clock_gettime="no"
        LIBS="$curl_cv_save_LIBS"
      ])
    fi
    #
    case "$ac_cv_func_clock_gettime" in
      yes)
        AC_DEFINE_UNQUOTED(HAVE_CLOCK_GETTIME_MONOTONIC, 1,
          [Define to 1 if you have the clock_gettime function and monotonic timer.])
        ;;
    esac
    #
  fi

dnl CURL_CHECK_FUNC_SELECT
dnl -------------------------------------------------
dnl Test if the socket select() function is available,
dnl and check its return type and the types of its
dnl arguments. If the function succeeds HAVE_SELECT
dnl will be defined, defining the types of the
dnl arguments in SELECT_TYPE_ARG1, SELECT_TYPE_ARG234
dnl and SELECT_TYPE_ARG5, defining the type of the
dnl function return value in SELECT_TYPE_RETV, and
dnl also defining the type qualifier of fifth argument
dnl in SELECT_QUAL_ARG5.

AC_DEFUN([CURL_CHECK_FUNC_SELECT], [
  AC_REQUIRE([CURL_CHECK_STRUCT_TIMEVAL])dnl
  AC_CHECK_HEADERS(sys/select.h sys/socket.h)
  #
  AC_MSG_CHECKING([for select])
    AC_LANG_PROGRAM([[
#undef inline
#ifdef HAVE_WINDOWS_H
#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif
#include <windows.h>
#ifdef HAVE_WINSOCK2_H
#include <winsock2.h>
#else
#ifdef HAVE_WINSOCK_H
#include <winsock.h>
#endif
#endif
#endif
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#ifdef TIME_WITH_SYS_TIME
#include <time.h>
#endif
#else
#ifdef HAVE_TIME_H
#include <time.h>
#endif
#endif
#ifndef HAVE_WINDOWS_H
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#endif
      select(0, 0, 0, 0, 0);
  ],[
    AC_MSG_RESULT([yes])
    curl_cv_select="yes"
  ],[
    AC_MSG_RESULT([no])
    curl_cv_select="no"
  ])
  #
  if test "$curl_cv_select" = "yes"; then
    AC_CACHE_CHECK([types of args and return type for select],
      [curl_cv_func_select_args], [
      curl_cv_func_select_args="unknown"
      for sel_retv in 'int' 'ssize_t'; do
        for sel_arg1 in 'int' 'ssize_t' 'size_t' 'unsigned long int' 'unsigned int'; do
          for sel_arg234 in 'fd_set *' 'int *' 'void *'; do
            for sel_arg5 in 'struct timeval *' 'const struct timeval *'; do
              if test "$curl_cv_func_select_args" = "unknown"; then
                AC_COMPILE_IFELSE([
                  AC_LANG_PROGRAM([[
#undef inline
#ifdef HAVE_WINDOWS_H
#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif
#include <windows.h>
#ifdef HAVE_WINSOCK2_H
#include <winsock2.h>
#else
#ifdef HAVE_WINSOCK_H
#include <winsock.h>
#endif
#endif
#define SELECTCALLCONV PASCAL
#endif
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#ifdef TIME_WITH_SYS_TIME
#include <time.h>
#endif
#else
#ifdef HAVE_TIME_H
#include <time.h>
#endif
#endif
#ifndef HAVE_WINDOWS_H
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#define SELECTCALLCONV
#endif
#ifndef HAVE_STRUCT_TIMEVAL
                    struct timeval {
                      long tv_sec;
                      long tv_usec;
                    };
#endif
                    extern $sel_retv SELECTCALLCONV select($sel_arg1,
                                                           $sel_arg234,
                                                           $sel_arg234,
                                                           $sel_arg234,
                                                           $sel_arg5);
                  ]],[[
                    $sel_arg1   nfds=0;
                    $sel_arg234 rfds=0;
                    $sel_arg234 wfds=0;
                    $sel_arg234 efds=0;
                    $sel_retv res = select(nfds, rfds, wfds, efds, 0);
                  ]])
                ],[
                  curl_cv_func_select_args="$sel_arg1,$sel_arg234,$sel_arg5,$sel_retv"
                ])
              fi
    if test "$curl_cv_func_select_args" = "unknown"; then
      AC_MSG_WARN([Cannot find proper types to use for select args])
      AC_MSG_WARN([HAVE_SELECT will not be defined])
    else
      select_prev_IFS=$IFS; IFS=','
      set dummy `echo "$curl_cv_func_select_args" | sed 's/\*/\*/g'`
      IFS=$select_prev_IFS
      shift
      #
      sel_qual_type_arg5=$[3]
      #
      AC_DEFINE_UNQUOTED(SELECT_TYPE_ARG1, $[1],
        [Define to the type of arg 1 for select.])
      AC_DEFINE_UNQUOTED(SELECT_TYPE_ARG234, $[2],
        [Define to the type of args 2, 3 and 4 for select.])
      AC_DEFINE_UNQUOTED(SELECT_TYPE_RETV, $[4],
        [Define to the function return type for select.])
      #
      prev_sh_opts=$-
      #
      case $prev_sh_opts in
        *f*)
          ;;
        *)
          set -f
          ;;
      esac
      #
      case "$sel_qual_type_arg5" in
        const*)
          sel_qual_arg5=const
          sel_type_arg5=`echo $sel_qual_type_arg5 | sed 's/^const //'`
        ;;
        *)
          sel_qual_arg5=
          sel_type_arg5=$sel_qual_type_arg5
        ;;
      esac
      #
      AC_DEFINE_UNQUOTED(SELECT_QUAL_ARG5, $sel_qual_arg5,
        [Define to the type qualifier of arg 5 for select.])
      AC_DEFINE_UNQUOTED(SELECT_TYPE_ARG5, $sel_type_arg5,
        [Define to the type of arg 5 for select.])
      #
      case $prev_sh_opts in
        *f*)
          ;;
        *)
          set +f
          ;;
      esac
      #
      AC_DEFINE_UNQUOTED(HAVE_SELECT, 1,
        [Define to 1 if you have the select function.])
      ac_cv_func_select="yes"
    fi
  fi
dnl ************************************************************
dnl check for working getaddrinfo() that works with AI_NUMERICHOST
AC_DEFUN([CURL_CHECK_WORKING_GETADDRINFO],[
  AC_CACHE_CHECK(for working getaddrinfo, ac_cv_working_getaddrinfo,[
  AC_TRY_RUN( [
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>

    struct addrinfo hints, *ai;
    int error;

    memset(&hints, 0, sizeof(hints));
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    error = getaddrinfo("127.0.0.1", "8080", &hints, &ai);
    if (error) {
}
],[
  ac_cv_working_getaddrinfo="yes"
],[
  ac_cv_working_getaddrinfo="no"
],[
  ac_cv_working_getaddrinfo="yes"
])])
if test "$ac_cv_working_getaddrinfo" = "yes"; then
  AC_DEFINE(HAVE_GETADDRINFO, 1, [Define if getaddrinfo exists and works])
  AC_DEFINE(ENABLE_IPV6, 1, [Define if you want to enable IPv6 support])

  IPV6_ENABLED=1
  AC_SUBST(IPV6_ENABLED)
fi
])


  dnl check for localtime_r
  AC_CHECK_FUNCS(localtime_r,[
    AC_MSG_CHECKING(whether localtime_r is declared)
    AC_EGREP_CPP(localtime_r,[
#include <time.h>],[
      AC_MSG_RESULT(yes)],[
      AC_MSG_RESULT(no)
      AC_MSG_CHECKING(whether localtime_r with -D_REENTRANT is declared)
      AC_EGREP_CPP(localtime_r,[
#define _REENTRANT
#include <time.h>],[
        AC_MSG_RESULT(yes)],
        AC_MSG_RESULT(no))])])
dnl
dnl This function checks for strerror_r(). If it isn't found at first, it
dnl retries with _THREAD_SAFE defined, as that is what AIX seems to require
dnl in order to find this function.
dnl
dnl If the function is found, it will then proceed to check how the function
dnl actually works: glibc-style or POSIX-style.
dnl
dnl glibc:
dnl      char *strerror_r(int errnum, char *buf, size_t n);
dnl  
dnl  What this one does is to return the error string (no surprises there),
dnl  but it doesn't usually copy anything into buf!  The 'buf' and 'n'
dnl  parameters are only meant as an optional working area, in case strerror_r
dnl  needs it.  A quick test on a few systems shows that it's generally not
dnl  touched at all.
dnl
dnl POSIX:
dnl      int strerror_r(int errnum, char *buf, size_t n);
dnl
AC_DEFUN([CURL_CHECK_STRERROR_R],
[
  AC_CHECK_FUNCS(strerror_r)

  if test "x$ac_cv_func_strerror_r" = "xyes"; then

    AC_MSG_CHECKING(whether strerror_r is declared)
    AC_EGREP_CPP(strerror_r,[
#include <string.h>],[
      AC_MSG_RESULT(yes)],[
      AC_MSG_RESULT(no)
      AC_MSG_CHECKING(whether strerror_r with -D_REENTRANT is declared)
      AC_EGREP_CPP(strerror_r,[
#include <string.h>],[
        AC_DEFINE(HAVE_NO_STRERROR_R_DECL, 1, [we have no strerror_r() proto])
       ) dnl with _THREAD_SAFE
    ]) dnl plain cpp for it
    dnl determine if this strerror_r() is glibc or POSIX
    AC_MSG_CHECKING([for a glibc strerror_r API])
    AC_TRY_RUN([
#include <string.h>
#include <errno.h>
int
main () {
  char buffer[1024]; /* big enough to play with */
  char *string =
    strerror_r(EACCES, buffer, sizeof(buffer));
    /* this should've returned a string */
    if(!string || !string[0])
      return 99;
    return 0;
}
],
    AC_DEFINE(HAVE_GLIBC_STRERROR_R, 1, [we have a glibc-style strerror_r()])
    AC_MSG_RESULT([yes]),

    dnl Use an inferior method of strerror_r detection while cross-compiling
    AC_EGREP_CPP(yes, [
#include <features.h>
#ifdef __GLIBC__
yes
#endif
], 
      dnl looks like glibc, so assume a glibc-style strerror_r()
      GLIBC_STRERROR_R="1"
      AC_DEFINE(HAVE_GLIBC_STRERROR_R, 1, [we have a glibc-style strerror_r()])
      AC_MSG_RESULT([yes]),
      AC_MSG_NOTICE([cannot determine strerror_r() style: edit lib/config.h manually!])
    ) dnl while cross-compiling
    if test -z "$GLIBC_STRERROR_R"; then

      AC_MSG_CHECKING([for a POSIX strerror_r API])
      AC_TRY_RUN([
#include <string.h>
#include <errno.h>
int
main () {
  char buffer[1024]; /* big enough to play with */
  int error =
    strerror_r(EACCES, buffer, sizeof(buffer));
    /* This should've returned zero, and written an error string in the
       buffer.*/
    if(!buffer[0] || error)
      return 99;
    return 0;
}
],
      AC_DEFINE(HAVE_POSIX_STRERROR_R, 1, [we have a POSIX-style strerror_r()])
      AC_MSG_RESULT([yes]),
      AC_MSG_RESULT([no]) ,
      dnl cross-compiling!
      AC_MSG_NOTICE([cannot determine strerror_r() style: edit lib/config.h manually!])
    )
    fi dnl if not using glibc API

  fi dnl we have a strerror_r
[
  dnl determine if function definition for inet_ntoa_r exists.
  AC_CHECK_FUNCS(inet_ntoa_r,[
    AC_MSG_CHECKING(whether inet_ntoa_r is declared)
    AC_EGREP_CPP(inet_ntoa_r,[
#include <arpa/inet.h>],[
      AC_DEFINE(HAVE_INET_NTOA_R_DECL, 1, [inet_ntoa_r() is declared])
      AC_MSG_RESULT(yes)],[
      AC_MSG_RESULT(no)
      AC_MSG_CHECKING(whether inet_ntoa_r with -D_REENTRANT is declared)
      AC_EGREP_CPP(inet_ntoa_r,[
#define _REENTRANT
#include <arpa/inet.h>],[
        AC_DEFINE(HAVE_INET_NTOA_R_DECL, 1, [inet_ntoa_r() is declared])
        AC_MSG_RESULT(yes)],
        AC_MSG_RESULT(no))])])

dnl CURL_CHECK_GETHOSTBYADDR_R
dnl -------------------------------------------------
dnl check number of arguments for gethostbyaddr_r, it
dnl might take either 5, 7, or 8 arguments.

AC_DEFUN([CURL_CHECK_GETHOSTBYADDR_R], [
  #
  AC_MSG_CHECKING([for gethostbyaddr_r])
  AC_LINK_IFELSE([
    AC_LANG_FUNC_LINK_TRY([gethostbyaddr_r])
  ],[
    AC_MSG_RESULT([yes])
    tmp_cv_gethostbyaddr_r="yes"
  ],[
    AC_MSG_RESULT([no])
    tmp_cv_gethostbyaddr_r="no"
  ])
  #
  if test "$tmp_cv_gethostbyaddr_r" != "yes"; then
    AC_MSG_CHECKING([deeper for gethostbyaddr_r])
    AC_LINK_IFELSE([
      AC_LANG_PROGRAM([[
      ]],[[
        gethostbyaddr_r();
      ]])
    ],[
      AC_MSG_RESULT([yes])
      tmp_cv_gethostbyaddr_r="yes"
    ],[
      AC_MSG_RESULT([but still no])
      tmp_cv_gethostbyaddr_r="no"
    ])
  fi
  #
  if test "$tmp_cv_gethostbyaddr_r" = "yes"; then

    ac_cv_gethostbyaddr_r_args="unknown"

    AC_MSG_CHECKING([if gethostbyaddr_r takes 5 arguments])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
#include <sys/types.h>
#include <netdb.h>
      ]],[[
        char * address;
        int length;
        int type;
        struct hostent h;
        struct hostent_data hdata;
        int rc;
        rc = gethostbyaddr_r(address, length, type, &h, &hdata);
      ]])
    ],[
      AC_MSG_RESULT([yes])
      AC_DEFINE(HAVE_GETHOSTBYADDR_R_5, 1, [gethostbyaddr_r() takes 5 args])
      ac_cv_gethostbyaddr_r_args="5"
    ],[
      AC_MSG_RESULT([no])
    ])

    if test "$ac_cv_gethostbyaddr_r_args" = "unknown"; then
      AC_MSG_CHECKING([if gethostbyaddr_r with -D_REENTRANT takes 5 arguments])
      AC_COMPILE_IFELSE([
        AC_LANG_PROGRAM([[
#define _REENTRANT
#include <sys/types.h>
#include <netdb.h>
        ]],[[
          char * address;
          int length;
          int type;
          struct hostent h;
          struct hostent_data hdata;
          int rc;
          rc = gethostbyaddr_r(address, length, type, &h, &hdata);
        ]])
      ],[
        AC_MSG_RESULT([yes])
        AC_DEFINE(HAVE_GETHOSTBYADDR_R_5, 1, [gethostbyaddr_r() takes 5 args])
        ac_cv_gethostbyaddr_r_args="5"
      ],[
        AC_MSG_RESULT([no])
      ])
    fi

    if test "$ac_cv_gethostbyaddr_r_args" = "unknown"; then
      AC_MSG_CHECKING([if gethostbyaddr_r takes 7 arguments])
      AC_COMPILE_IFELSE([
        AC_LANG_PROGRAM([[
#include <sys/types.h>
#include <netdb.h>
        ]],[[
          char * address;
          int length;
          int type;
          struct hostent h;
          char buffer[8192];
          int h_errnop;
          struct hostent * hp;
          hp = gethostbyaddr_r(address, length, type, &h,
                               buffer, 8192, &h_errnop);
        ]])
      ],[
        AC_MSG_RESULT([yes])
        AC_DEFINE(HAVE_GETHOSTBYADDR_R_7, 1, [gethostbyaddr_r() takes 7 args])
        ac_cv_gethostbyaddr_r_args="7"
      ],[
        AC_MSG_RESULT([no])
      ])
    fi

    if test "$ac_cv_gethostbyaddr_r_args" = "unknown"; then
      AC_MSG_CHECKING([if gethostbyaddr_r with -D_REENTRANT takes 7 arguments])
      AC_COMPILE_IFELSE([
        AC_LANG_PROGRAM([[
#undef _REENTRANT
#define _REENTRANT
#include <sys/types.h>
#include <netdb.h>
        ]],[[
          char * address;
          int length;
          int type;
          struct hostent h;
          char buffer[8192];
          int h_errnop;
          struct hostent * hp;
          hp = gethostbyaddr_r(address, length, type, &h,
                               buffer, 8192, &h_errnop);
        ]])
      ],[
        AC_MSG_RESULT([yes])
        AC_DEFINE(HAVE_GETHOSTBYADDR_R_7, 1, [gethostbyaddr_r() takes 7 args])
        ac_cv_gethostbyaddr_r_args="7"
      ],[
        AC_MSG_RESULT([no])
      ])
    fi

    if test "$ac_cv_gethostbyaddr_r_args" = "unknown"; then
      AC_MSG_CHECKING([if gethostbyaddr_r takes 8 arguments])
      AC_COMPILE_IFELSE([
        AC_LANG_PROGRAM([[
#include <sys/types.h>
#include <netdb.h>
        ]],[[
          char * address;
          int length;
          int type;
          struct hostent h;
          char buffer[8192];
          int h_errnop;
          struct hostent * hp;
          int rc;
          rc = gethostbyaddr_r(address, length, type, &h,
                               buffer, 8192, &hp, &h_errnop);
        ]])
      ],[
        AC_MSG_RESULT([yes])
        AC_DEFINE(HAVE_GETHOSTBYADDR_R_8, 1, [gethostbyaddr_r() takes 8 args])
        ac_cv_gethostbyaddr_r_args="8"
      ],[
        AC_MSG_RESULT([no])
      ])
    fi

    if test "$ac_cv_gethostbyaddr_r_args" = "unknown"; then
      AC_MSG_CHECKING([if gethostbyaddr_r with -D_REENTRANT takes 8 arguments])
      AC_COMPILE_IFELSE([
        AC_LANG_PROGRAM([[
#undef _REENTRANT
#define _REENTRANT
#include <sys/types.h>
#include <netdb.h>
        ]],[[
          char * address;
          int length;
          int type;
          struct hostent h;
          char buffer[8192];
          int h_errnop;
          struct hostent * hp;
          int rc;
          rc = gethostbyaddr_r(address, length, type, &h,
                               buffer, 8192, &hp, &h_errnop);
        ]])
      ],[
        AC_MSG_RESULT([yes])
        AC_DEFINE(HAVE_GETHOSTBYADDR_R_8, 1, [gethostbyaddr_r() takes 8 args])
        ac_cv_gethostbyaddr_r_args="8"
      ],[
        AC_MSG_RESULT([no])
      ])
    fi

    if test "$ac_cv_gethostbyaddr_r_args" = "unknown"; then
      AC_MSG_WARN([Cannot find out how to use gethostbyaddr_r])
      AC_MSG_WARN([HAVE_GETHOSTBYADDR_R will not be defined])
      ac_cv_func_gethostbyaddr_r="no"
    else
      AC_DEFINE_UNQUOTED(HAVE_GETHOSTBYADDR_R, 1,
        [Define to 1 if you have the gethostbyaddr_r function.])
      ac_cv_func_gethostbyaddr_r="yes"
    fi

  else
    ac_cv_func_gethostbyaddr_r="no"