Improved configure detection of number of arguments for getservbyport_r

CHANGES

@@ -1,5 +1,9 @@
   Changelog for the c-ares project
 
+* Jul 16 2008 (Yang Tse)
+- Improved configure detection of number of arguments for getservbyport_r.
+  Detection is now based on compilation checks instead of linker ones.
+
 * Jul 15 2008 (Yang Tse)
 - Introduce definition of _REENTRANT symbol in setup.h to improve library
   usability.  Previously the configure process only used the AC_SYS_LARGEFILE

RELEASE-NOTES

@@ -7,6 +7,7 @@ This is what's new and changed in the c-ares 1.5.3 release:
  o allow --enable-largefile and --disable-largefile configurations
  o configure process no longer needs nor checks size of curl_off_t
  o library will now be built with _REENTRANT symbol defined
+ o Improved configure detection of number of arguments for getservbyport_r
 
 Thanks go to these friendly people for their efforts and contributions:
 

acinclude.m4

@@ -1803,12 +1803,47 @@ dnl Test if the getservbyport_r function is available,
 dnl and find out how many parameters it takes.
 
 AC_DEFUN([CARES_CHECK_GETSERVBYPORT_R], [
-  AC_MSG_CHECKING([how many arguments getservbyport_r takes])
-  ac_func_getservbyport_r="unknown"
-
+  AC_CHECK_HEADERS(sys/types.h netdb.h)
+  #
+  AC_MSG_CHECKING([for getservbyport_r])
   AC_LINK_IFELSE([
+    AC_LANG_FUNC_LINK_TRY([getservbyport_r])
+  ],[
+    AC_MSG_RESULT([yes])
+    cares_cv_getservbyport_r="yes"
+  ],[
+    AC_MSG_RESULT([no])
+    cares_cv_getservbyport_r="no"
+  ])
+  #
+  if test "$cares_cv_getservbyport_r" != "yes"; then
+    AC_MSG_CHECKING([deeper for getservbyport_r])
+    AC_LINK_IFELSE([
+      AC_LANG_PROGRAM([[
+      ]],[[
+        getservbyport_r();
+      ]])
+    ],[
+      AC_MSG_RESULT([yes])
+      cares_cv_getservbyport_r="yes"
+    ],[
+      AC_MSG_RESULT([but still no])
+      cares_cv_getservbyport_r="no"
+    ])
+  fi
+  #
+  if test "$cares_cv_getservbyport_r" = "yes"; then
+    AC_MSG_CHECKING([how many arguments getservbyport_r takes])
+    cares_cv_getservbyport_r_nargs="unknown"
+    #
+    AC_COMPILE_IFELSE([
       AC_LANG_PROGRAM([[
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#ifdef HAVE_NETDB_H
 #include <netdb.h>
+#endif
       ]],[[
         int p1, p5;
         char *p2, p4[4096];
@@ -1816,13 +1851,18 @@ AC_DEFUN([CARES_CHECK_GETSERVBYPORT_R], [
         getservbyport_r(p1, p2, p3, p4, p5, &p6);
       ]])
     ],[
-    ac_func_getservbyport_r="6"
+      cares_cv_getservbyport_r_nargs="6"
     ])
-
-  if test "$ac_func_getservbyport_r" = "unknown"; then
-    AC_LINK_IFELSE([
+    #
+    if test "$cares_cv_getservbyport_r_nargs" = "unknown"; then
+      AC_COMPILE_IFELSE([
         AC_LANG_PROGRAM([[
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#ifdef HAVE_NETDB_H
 #include <netdb.h>
+#endif
         ]],[[
           int p1, p5;
           char *p2, p4[4096];
@@ -1830,14 +1870,19 @@ AC_DEFUN([CARES_CHECK_GETSERVBYPORT_R], [
           getservbyport_r(p1, p2, p3, p4, p5);
         ]])
       ],[
-      ac_func_getservbyport_r="5"
+        cares_cv_getservbyport_r_nargs="5"
       ])
     fi
-
-  if test "$ac_func_getservbyport_r" = "unknown"; then
-    AC_LINK_IFELSE([
+    #
+    if test "$cares_cv_getservbyport_r_nargs" = "unknown"; then
+      AC_COMPILE_IFELSE([
         AC_LANG_PROGRAM([[
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#ifdef HAVE_NETDB_H
 #include <netdb.h>
+#endif
         ]],[[
           int p1;
           char *p2;
@@ -1846,19 +1891,20 @@ AC_DEFUN([CARES_CHECK_GETSERVBYPORT_R], [
           getservbyport_r(p1, p2, p3, &p4);
         ]])
       ],[
-      ac_func_getservbyport_r="4"
+        cares_cv_getservbyport_r_nargs="4"
       ])
     fi
-
-  if test "$ac_func_getservbyport_r" = "unknown"; then
-    AC_MSG_RESULT([not found])
+    #
+    AC_MSG_RESULT([$cares_cv_getservbyport_r_nargs])
+    #
+    if test "$cares_cv_getservbyport_r_nargs" = "unknown"; then
+      AC_MSG_WARN([HAVE_GETSERVBYPORT_R will not be defined])
     else
-    AC_MSG_RESULT($ac_func_getservbyport_r)
       AC_DEFINE(HAVE_GETSERVBYPORT_R, 1,
         [Specifies whether getservbyport_r is present])
-    AC_DEFINE_UNQUOTED(GETSERVBYPORT_R_ARGS, $ac_func_getservbyport_r,
+      AC_DEFINE_UNQUOTED(GETSERVBYPORT_R_ARGS, $cares_cv_getservbyport_r_nargs,
         [Specifies the number of arguments to getservbyport_r])
-    if test "$ac_func_getservbyport_r" = "4" ; then
+      if test "$cares_cv_getservbyport_r_nargs" = "4" ; then
         AC_DEFINE(GETSERVBYPORT_R_BUFSIZE, sizeof(struct servent_data),
           [Specifies the size of the buffer to pass to getservbyport_r])
       else
@@ -1866,5 +1912,7 @@ AC_DEFUN([CARES_CHECK_GETSERVBYPORT_R], [
           [Specifies the size of the buffer to pass to getservbyport_r])
       fi
     fi
+    #
+  fi
 ])