improve detection of gethostbyaddr_r() and gethostbyname_r()

3 files changed, 288 insertions, 420 deletions

diff --git a/acinclude.m4 b/acinclude.m4
index c21ca89f3..90afe8545 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -2623,424 +2623,6 @@ AC_DEFUN([CURL_CHECK_INET_NTOA_R],
 ])
 
 
-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([[
-#undef _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])
-    ])
-
-    if test "$ac_cv_gethostbyaddr_r_args" = "unknown"; then
-      AC_MSG_CHECKING([if gethostbyaddr_r with -D_REENTRANT takes 5 arguments])
-      AC_COMPILE_IFELSE([
-        AC_LANG_PROGRAM([[
-#undef _REENTRANT
-#define _REENTRANT
-#include <sys/types.h>
-#include <netdb.h>
-        ]],[[
-          char * address;
-          int length;
-          int type;
-          struct hostent h;
-          struct hostent_data hdata;
-          int rc;
-          rc = gethostbyaddr_r(address, length, type, &h, &hdata);
-        ]])
-      ],[
-        AC_MSG_RESULT([yes])
-        AC_DEFINE(HAVE_GETHOSTBYADDR_R_5, 1, [gethostbyaddr_r() takes 5 args])
-        ac_cv_gethostbyaddr_r_args="5"
-      ],[
-        AC_MSG_RESULT([no])
-      ])
-    fi
-
-    if test "$ac_cv_gethostbyaddr_r_args" = "unknown"; then
-      AC_MSG_CHECKING([if gethostbyaddr_r takes 7 arguments])
-      AC_COMPILE_IFELSE([
-        AC_LANG_PROGRAM([[
-#undef _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 "$ac_cv_gethostbyaddr_r_args" = "unknown"; then
-      AC_MSG_CHECKING([if gethostbyaddr_r with -D_REENTRANT takes 7 arguments])
-      AC_COMPILE_IFELSE([
-        AC_LANG_PROGRAM([[
-#undef _REENTRANT
-#define _REENTRANT
-#include <sys/types.h>
-#include <netdb.h>
-        ]],[[
-          char * address;
-          int length;
-          int type;
-          struct hostent h;
-          char buffer[8192];
-          int h_errnop;
-          struct hostent * hp;
-          hp = gethostbyaddr_r(address, length, type, &h,
-                               buffer, 8192, &h_errnop);
-        ]])
-      ],[
-        AC_MSG_RESULT([yes])
-        AC_DEFINE(HAVE_GETHOSTBYADDR_R_7, 1, [gethostbyaddr_r() takes 7 args])
-        ac_cv_gethostbyaddr_r_args="7"
-      ],[
-        AC_MSG_RESULT([no])
-      ])
-    fi
-
-    if test "$ac_cv_gethostbyaddr_r_args" = "unknown"; then
-      AC_MSG_CHECKING([if gethostbyaddr_r takes 8 arguments])
-      AC_COMPILE_IFELSE([
-        AC_LANG_PROGRAM([[
-#undef _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 "$ac_cv_gethostbyaddr_r_args" = "unknown"; then
-      AC_MSG_CHECKING([if gethostbyaddr_r with -D_REENTRANT takes 8 arguments])
-      AC_COMPILE_IFELSE([
-        AC_LANG_PROGRAM([[
-#undef _REENTRANT
-#define _REENTRANT
-#include <sys/types.h>
-#include <netdb.h>
-        ]],[[
-          char * address;
-          int length;
-          int type;
-          struct hostent h;
-          char buffer[8192];
-          int h_errnop;
-          struct hostent * hp;
-          int rc;
-          rc = gethostbyaddr_r(address, length, type, &h,
-                               buffer, 8192, &hp, &h_errnop);
-        ]])
-      ],[
-        AC_MSG_RESULT([yes])
-        AC_DEFINE(HAVE_GETHOSTBYADDR_R_8, 1, [gethostbyaddr_r() takes 8 args])
-        ac_cv_gethostbyaddr_r_args="8"
-      ],[
-        AC_MSG_RESULT([no])
-      ])
-    fi
-
-    if test "$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"
-  fi
-])
-
-
-dnl CURL_CHECK_GETHOSTBYNAME_R
-dnl -------------------------------------------------
-dnl check number of arguments for gethostbyname_r, it
-dnl might take either 3, 5, or 6 arguments.
-
-AC_DEFUN([CURL_CHECK_GETHOSTBYNAME_R], [
-  #
-  AC_MSG_CHECKING([for gethostbyname_r])
-  AC_LINK_IFELSE([
-    AC_LANG_FUNC_LINK_TRY([gethostbyname_r])
-  ],[
-    AC_MSG_RESULT([yes])
-    tmp_cv_gethostbyname_r="yes"
-  ],[
-    AC_MSG_RESULT([no])
-    tmp_cv_gethostbyname_r="no"
-  ])
-  #
-  if test "$tmp_cv_gethostbyname_r" != "yes"; then
-    AC_MSG_CHECKING([deeper for gethostbyname_r])
-    AC_LINK_IFELSE([
-      AC_LANG_PROGRAM([[
-      ]],[[
-        gethostbyname_r();
-      ]])
-    ],[
-      AC_MSG_RESULT([yes])
-      tmp_cv_gethostbyname_r="yes"
-    ],[
-      AC_MSG_RESULT([but still no])
-      tmp_cv_gethostbyname_r="no"
-    ])
-  fi
-  #
-  if test "$tmp_cv_gethostbyname_r" = "yes"; then
-
-    ac_cv_gethostbyname_r_args="unknown"
-
-    AC_MSG_CHECKING([if gethostbyname_r takes 3 arguments])
-    AC_COMPILE_IFELSE([
-      AC_LANG_PROGRAM([[
-#undef _REENTRANT
-#include <string.h>
-#include <sys/types.h>
-#include <netdb.h>
-#undef NULL
-#define NULL (void *)0
-        int
-        gethostbyname_r(const char *, struct hostent *,
-                        struct hostent_data *);
-      ]],[[
-        struct hostent_data data;
-        gethostbyname_r(NULL, NULL, NULL);
-      ]])
-    ],[
-      AC_MSG_RESULT([yes])
-      AC_DEFINE(HAVE_GETHOSTBYNAME_R_3, 1, [gethostbyname_r() takes 3 args])
-      ac_cv_gethostbyname_r_args="3"
-    ],[
-      AC_MSG_RESULT([no])
-    ])
-
-    if test "$ac_cv_gethostbyname_r_args" = "unknown"; then
-      AC_MSG_CHECKING([if gethostbyname_r with -D_REENTRANT takes 3 arguments])
-      AC_COMPILE_IFELSE([
-        AC_LANG_PROGRAM([[
-#undef _REENTRANT
-#define _REENTRANT
-#include <string.h>
-#include <sys/types.h>
-#include <netdb.h>
-#undef NULL
-#define NULL (void *)0
-          int
-          gethostbyname_r(const char *, struct hostent *,
-                          struct hostent_data *);
-        ]],[[
-          struct hostent_data data;
-          gethostbyname_r(NULL, NULL, NULL);
-        ]])
-      ],[
-        AC_MSG_RESULT([yes])
-        AC_DEFINE(HAVE_GETHOSTBYNAME_R_3, 1, [gethostbyname_r() takes 3 args])
-        ac_cv_gethostbyname_r_args="3"
-      ],[
-        AC_MSG_RESULT([no])
-      ])
-    fi
-
-    if test "$ac_cv_gethostbyname_r_args" = "unknown"; then
-      AC_MSG_CHECKING([if gethostbyname_r takes 5 arguments])
-      AC_COMPILE_IFELSE([
-        AC_LANG_PROGRAM([[
-#undef _REENTRANT
-#include <sys/types.h>
-#include <netdb.h>
-#undef NULL
-#define NULL (void *)0
-          struct hostent *
-          gethostbyname_r(const char *, struct hostent *,
-                          char *, int, int *);
-        ]],[[
-          gethostbyname_r(NULL, NULL, NULL, 0, NULL);
-        ]])
-      ],[
-        AC_MSG_RESULT([yes])
-        AC_DEFINE(HAVE_GETHOSTBYNAME_R_5, 1, [gethostbyname_r() takes 5 args])
-        ac_cv_gethostbyname_r_args="5"
-      ],[
-        AC_MSG_RESULT([no])
-      ])
-    fi
-
-    if test "$ac_cv_gethostbyname_r_args" = "unknown"; then
-      AC_MSG_CHECKING([if gethostbyname_r with -D_REENTRANT takes 5 arguments])
-      AC_COMPILE_IFELSE([
-        AC_LANG_PROGRAM([[
-#undef _REENTRANT
-#define _REENTRANT
-#include <sys/types.h>
-#include <netdb.h>
-#undef NULL
-#define NULL (void *)0
-          struct hostent *
-          gethostbyname_r(const char *, struct hostent *,
-                          char *, int, int *);
-        ]],[[
-          gethostbyname_r(NULL, NULL, NULL, 0, NULL);
-        ]])
-      ],[
-        AC_MSG_RESULT([yes])
-        AC_DEFINE(HAVE_GETHOSTBYNAME_R_5, 1, [gethostbyname_r() takes 5 args])
-        ac_cv_gethostbyname_r_args="5"
-      ],[
-        AC_MSG_RESULT([no])
-      ])
-    fi
-
-    if test "$ac_cv_gethostbyname_r_args" = "unknown"; then
-      AC_MSG_CHECKING([if gethostbyname_r takes 6 arguments])
-      AC_COMPILE_IFELSE([
-        AC_LANG_PROGRAM([[
-#undef _REENTRANT
-#include <sys/types.h>
-#include <netdb.h>
-#undef NULL
-#define NULL (void *)0
-          int
-          gethostbyname_r(const char *, struct hostent *,
-                          char *, size_t, struct hostent **, int *);
-        ]],[[
-          gethostbyname_r(NULL, NULL, NULL, 0, NULL, NULL);
-        ]])
-      ],[
-        AC_MSG_RESULT([yes])
-        AC_DEFINE(HAVE_GETHOSTBYNAME_R_6, 1, [gethostbyname_r() takes 6 args])
-        ac_cv_gethostbyname_r_args="6"
-      ],[
-        AC_MSG_RESULT([no])
-      ])
-    fi
-
-    if test "$ac_cv_gethostbyname_r_args" = "unknown"; then
-      AC_MSG_CHECKING([if gethostbyname_r with -D_REENTRANT takes 6 arguments])
-      AC_COMPILE_IFELSE([
-        AC_LANG_PROGRAM([[
-#undef _REENTRANT
-#define _REENTRANT
-#include <sys/types.h>
-#include <netdb.h>
-#undef NULL
-#define NULL (void *)0
-          int
-          gethostbyname_r(const char *, struct hostent *,
-                          char *, size_t, struct hostent **, int *);
-        ]],[[
-          gethostbyname_r(NULL, NULL, NULL, 0, NULL, NULL);
-        ]])
-      ],[
-        AC_MSG_RESULT([yes])
-        AC_DEFINE(HAVE_GETHOSTBYNAME_R_6, 1, [gethostbyname_r() takes 6 args])
-        ac_cv_gethostbyname_r_args="6"
-      ],[
-        AC_MSG_RESULT([no])
-      ])
-    fi
-
-    if test "$ac_cv_gethostbyname_r_args" = "unknown"; then
-      AC_MSG_WARN([Cannot find out how to use gethostbyname_r])
-      AC_MSG_WARN([HAVE_GETHOSTBYNAME_R will not be defined])
-      ac_cv_func_gethostbyname_r="no"
-    else
-      AC_DEFINE_UNQUOTED(HAVE_GETHOSTBYNAME_R, 1,
-        [Define to 1 if you have the gethostbyname_r function.])
-      ac_cv_func_gethostbyname_r="yes"
-    fi
-
-  else
-    ac_cv_func_gethostbyname_r="no"
-  fi
-])
-
-
 dnl **********************************************************************
 dnl CURL_DETECT_ICC ([ACTION-IF-YES])
 dnl
diff --git a/configure.ac b/configure.ac
index d4462e32d..228b686e9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1842,10 +1842,10 @@ then
 else
   if test "$ipv6" != "yes"; then
     dnl dig around for gethostbyname_r()
-    CURL_CHECK_GETHOSTBYNAME_R()
+    dnl the old gethostbyname_r check was done here
 
     dnl dig around for gethostbyaddr_r()
-    dnl CURL_CHECK_GETHOSTBYADDR_R()
+    dnl the old gethostbyaddr_r check was here BUT COMMENTED OUT
   fi
 
   dnl poke around for inet_ntoa_r()
@@ -2037,6 +2037,8 @@ CURL_CHECK_MSG_NOSIGNAL
 
 CURL_CHECK_FUNC_FDOPEN
 CURL_CHECK_FUNC_FTRUNCATE
+CURL_CHECK_FUNC_GETHOSTBYADDR_R
+CURL_CHECK_FUNC_GETHOSTBYNAME_R
 CURL_CHECK_FUNC_GETHOSTNAME
 CURL_CHECK_FUNC_GETSERVBYPORT_R
 CURL_CHECK_FUNC_GMTIME_R
diff --git a/m4/curl-functions.m4 b/m4/curl-functions.m4
index e6e1c9939..f349bf6f4 100644
--- a/m4/curl-functions.m4
+++ b/m4/curl-functions.m4
@@ -374,6 +374,290 @@ AC_DEFUN([CURL_CHECK_FUNC_FTRUNCATE], [
 ])
 
 
+dnl CURL_CHECK_FUNC_GETHOSTBYADDR_R
+dnl -------------------------------------------------
+dnl Verify if gethostbyaddr_r is available, prototyped,
+dnl and can be compiled. If all of these are true, and
+dnl usage has not been previously disallowed with
+dnl shell variable curl_disallow_gethostbyaddr_r, then
+dnl HAVE_GETHOSTBYADDR_R will be defined.
+
+AC_DEFUN([CURL_CHECK_FUNC_GETHOSTBYADDR_R], [
+  AC_REQUIRE([CURL_INCLUDES_SYS_UIO])dnl
+  #
+  tst_links_gethostbyaddr_r="unknown"
+  tst_proto_gethostbyaddr_r="unknown"
+  tst_compi_gethostbyaddr_r="unknown"
+  tst_allow_gethostbyaddr_r="unknown"
+  tst_nargs_gethostbyaddr_r="unknown"
+  #
+  AC_MSG_CHECKING([if gethostbyaddr_r can be linked])
+  AC_LINK_IFELSE([
+    AC_LANG_FUNC_LINK_TRY([gethostbyaddr_r])
+  ],[
+    AC_MSG_RESULT([yes])
+    tst_links_gethostbyaddr_r="yes"
+  ],[
+    AC_MSG_RESULT([no])
+    tst_links_gethostbyaddr_r="no"
+  ])
+  #
+  if test "$tst_links_gethostbyaddr_r" = "yes"; then
+    AC_MSG_CHECKING([if gethostbyaddr_r is prototyped])
+    AC_EGREP_CPP([gethostbyaddr_r],[
+      $curl_includes_netdb
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_proto_gethostbyaddr_r="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_proto_gethostbyaddr_r="no"
+    ])
+  fi
+  #
+  if test "$tst_proto_gethostbyaddr_r" = "yes"; then
+    if test "$tst_nargs_gethostbyaddr_r" = "unknown"; then
+      AC_MSG_CHECKING([if gethostbyaddr_r takes 5 args.])
+      AC_COMPILE_IFELSE([
+        AC_LANG_PROGRAM([[
+          $curl_includes_netdb
+        ]],[[
+          if(0 != gethostbyaddr_r(0, 0, 0, 0, 0))
+            return 1;
+        ]])
+      ],[
+        AC_MSG_RESULT([yes])
+        tst_compi_gethostbyaddr_r="yes"
+        tst_nargs_gethostbyaddr_r="5"
+      ],[
+        AC_MSG_RESULT([no])
+        tst_compi_gethostbyaddr_r="no"
+      ])
+    fi
+    if test "$tst_nargs_gethostbyaddr_r" = "unknown"; then
+      AC_MSG_CHECKING([if gethostbyaddr_r takes 7 args.])
+      AC_COMPILE_IFELSE([
+        AC_LANG_PROGRAM([[
+          $curl_includes_netdb
+        ]],[[
+          if(0 != gethostbyaddr_r(0, 0, 0, 0, 0, 0, 0))
+            return 1;
+        ]])
+      ],[
+        AC_MSG_RESULT([yes])
+        tst_compi_gethostbyaddr_r="yes"
+        tst_nargs_gethostbyaddr_r="7"
+      ],[
+        AC_MSG_RESULT([no])
+        tst_compi_gethostbyaddr_r="no"
+      ])
+    fi
+    if test "$tst_nargs_gethostbyaddr_r" = "unknown"; then
+      AC_MSG_CHECKING([if gethostbyaddr_r takes 8 args.])
+      AC_COMPILE_IFELSE([
+        AC_LANG_PROGRAM([[
+          $curl_includes_netdb
+        ]],[[
+          if(0 != gethostbyaddr_r(0, 0, 0, 0, 0, 0, 0, 0))
+            return 1;
+        ]])
+      ],[
+        AC_MSG_RESULT([yes])
+        tst_compi_gethostbyaddr_r="yes"
+        tst_nargs_gethostbyaddr_r="8"
+      ],[
+        AC_MSG_RESULT([no])
+        tst_compi_gethostbyaddr_r="no"
+      ])
+    fi
+    AC_MSG_CHECKING([if gethostbyaddr_r is compilable])
+    if test "$tst_compi_gethostbyaddr_r" = "yes"; then
+      AC_MSG_RESULT([yes])
+    else
+      AC_MSG_RESULT([no])
+    fi
+  fi
+  #
+  if test "$tst_compi_gethostbyaddr_r" = "yes"; then
+    AC_MSG_CHECKING([if gethostbyaddr_r usage allowed])
+    if test "x$curl_disallow_gethostbyaddr_r" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_gethostbyaddr_r="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_gethostbyaddr_r="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if gethostbyaddr_r might be used])
+  if test "$tst_links_gethostbyaddr_r" = "yes" &&
+     test "$tst_proto_gethostbyaddr_r" = "yes" &&
+     test "$tst_compi_gethostbyaddr_r" = "yes" &&
+     test "$tst_allow_gethostbyaddr_r" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_GETHOSTBYADDR_R, 1,
+      [Define to 1 if you have the gethostbyaddr_r function.])
+    dnl AC_DEFINE_UNQUOTED(GETHOSTBYADDR_R_ARGS, $tst_nargs_gethostbyaddr_r,
+    dnl   [Specifies the number of arguments to gethostbyaddr_r])
+    #
+    if test "$tst_nargs_getservbyport_r" -eq "5"; then
+      AC_DEFINE(HAVE_GETHOSTBYADDR_R_5, 1, [gethostbyaddr_r() takes 5 args])
+    elif test "$tst_nargs_getservbyport_r" -eq "7"; then
+      AC_DEFINE(HAVE_GETHOSTBYADDR_R_7, 1, [gethostbyaddr_r() takes 7 args])
+    elif test "$tst_nargs_getservbyport_r" -eq "6"; then
+      AC_DEFINE(HAVE_GETHOSTBYADDR_R_8, 1, [gethostbyaddr_r() takes 8 args])
+    fi
+    #
+    ac_cv_func_gethostbyaddr_r="yes"
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_gethostbyaddr_r="no"
+  fi
+])
+
+
+dnl CURL_CHECK_FUNC_GETHOSTBYNAME_R
+dnl -------------------------------------------------
+dnl Verify if gethostbyname_r is available, prototyped,
+dnl and can be compiled. If all of these are true, and
+dnl usage has not been previously disallowed with
+dnl shell variable curl_disallow_gethostbyname_r, then
+dnl HAVE_GETHOSTBYNAME_R will be defined.
+
+AC_DEFUN([CURL_CHECK_FUNC_GETHOSTBYNAME_R], [
+  AC_REQUIRE([CURL_INCLUDES_SYS_UIO])dnl
+  #
+  tst_links_gethostbyname_r="unknown"
+  tst_proto_gethostbyname_r="unknown"
+  tst_compi_gethostbyname_r="unknown"
+  tst_allow_gethostbyname_r="unknown"
+  tst_nargs_gethostbyname_r="unknown"
+  #
+  AC_MSG_CHECKING([if gethostbyname_r can be linked])
+  AC_LINK_IFELSE([
+    AC_LANG_FUNC_LINK_TRY([gethostbyname_r])
+  ],[
+    AC_MSG_RESULT([yes])
+    tst_links_gethostbyname_r="yes"
+  ],[
+    AC_MSG_RESULT([no])
+    tst_links_gethostbyname_r="no"
+  ])
+  #
+  if test "$tst_links_gethostbyname_r" = "yes"; then
+    AC_MSG_CHECKING([if gethostbyname_r is prototyped])
+    AC_EGREP_CPP([gethostbyname_r],[
+      $curl_includes_netdb
+    ],[
+      AC_MSG_RESULT([yes])
+      tst_proto_gethostbyname_r="yes"
+    ],[
+      AC_MSG_RESULT([no])
+      tst_proto_gethostbyname_r="no"
+    ])
+  fi
+  #
+  if test "$tst_proto_gethostbyname_r" = "yes"; then
+    if test "$tst_nargs_gethostbyname_r" = "unknown"; then
+      AC_MSG_CHECKING([if gethostbyname_r takes 3 args.])
+      AC_COMPILE_IFELSE([
+        AC_LANG_PROGRAM([[
+          $curl_includes_netdb
+        ]],[[
+          if(0 != gethostbyname_r(0, 0, 0))
+            return 1;
+        ]])
+      ],[
+        AC_MSG_RESULT([yes])
+        tst_compi_gethostbyname_r="yes"
+        tst_nargs_gethostbyname_r="3"
+      ],[
+        AC_MSG_RESULT([no])
+        tst_compi_gethostbyname_r="no"
+      ])
+    fi
+    if test "$tst_nargs_gethostbyname_r" = "unknown"; then
+      AC_MSG_CHECKING([if gethostbyname_r takes 5 args.])
+      AC_COMPILE_IFELSE([
+        AC_LANG_PROGRAM([[
+          $curl_includes_netdb
+        ]],[[
+          if(0 != gethostbyname_r(0, 0, 0, 0, 0))
+            return 1;
+        ]])
+      ],[
+        AC_MSG_RESULT([yes])
+        tst_compi_gethostbyname_r="yes"
+        tst_nargs_gethostbyname_r="5"
+      ],[
+        AC_MSG_RESULT([no])
+        tst_compi_gethostbyname_r="no"
+      ])
+    fi
+    if test "$tst_nargs_gethostbyname_r" = "unknown"; then
+      AC_MSG_CHECKING([if gethostbyname_r takes 6 args.])
+      AC_COMPILE_IFELSE([
+        AC_LANG_PROGRAM([[
+          $curl_includes_netdb
+        ]],[[
+          if(0 != gethostbyname_r(0, 0, 0, 0, 0, 0))
+            return 1;
+        ]])
+      ],[
+        AC_MSG_RESULT([yes])
+        tst_compi_gethostbyname_r="yes"
+        tst_nargs_gethostbyname_r="6"
+      ],[
+        AC_MSG_RESULT([no])
+        tst_compi_gethostbyname_r="no"
+      ])
+    fi
+    AC_MSG_CHECKING([if gethostbyname_r is compilable])
+    if test "$tst_compi_gethostbyname_r" = "yes"; then
+      AC_MSG_RESULT([yes])
+    else
+      AC_MSG_RESULT([no])
+    fi
+  fi
+  #
+  if test "$tst_compi_gethostbyname_r" = "yes"; then
+    AC_MSG_CHECKING([if gethostbyname_r usage allowed])
+    if test "x$curl_disallow_gethostbyname_r" != "xyes"; then
+      AC_MSG_RESULT([yes])
+      tst_allow_gethostbyname_r="yes"
+    else
+      AC_MSG_RESULT([no])
+      tst_allow_gethostbyname_r="no"
+    fi
+  fi
+  #
+  AC_MSG_CHECKING([if gethostbyname_r might be used])
+  if test "$tst_links_gethostbyname_r" = "yes" &&
+     test "$tst_proto_gethostbyname_r" = "yes" &&
+     test "$tst_compi_gethostbyname_r" = "yes" &&
+     test "$tst_allow_gethostbyname_r" = "yes"; then
+    AC_MSG_RESULT([yes])
+    AC_DEFINE_UNQUOTED(HAVE_GETHOSTBYNAME_R, 1,
+      [Define to 1 if you have the gethostbyname_r function.])
+    dnl AC_DEFINE_UNQUOTED(GETHOSTBYNAME_R_ARGS, $tst_nargs_gethostbyname_r,
+    dnl   [Specifies the number of arguments to gethostbyname_r])
+    #
+    if test "$tst_nargs_getservbyport_r" -eq "3"; then
+      AC_DEFINE(HAVE_GETHOSTBYNAME_R_3, 1, [gethostbyname_r() takes 3 args])
+    elif test "$tst_nargs_getservbyport_r" -eq "5"; then
+      AC_DEFINE(HAVE_GETHOSTBYNAME_R_5, 1, [gethostbyname_r() takes 5 args])
+    elif test "$tst_nargs_getservbyport_r" -eq "6"; then
+      AC_DEFINE(HAVE_GETHOSTBYNAME_R_6, 1, [gethostbyname_r() takes 6 args])
+    fi
+    #
+    ac_cv_func_gethostbyname_r="yes"
+  else
+    AC_MSG_RESULT([no])
+    ac_cv_func_gethostbyname_r="no"
+  fi
+])
+
+
 dnl CURL_CHECK_FUNC_GETHOSTNAME
 dnl -------------------------------------------------
 dnl Verify if gethostname is available, prototyped, and