+ my $d3 = $d2;
+
+ if (! $d1) {
+ print STDERR "ERROR: SDK_DIR unset\n";
+ exit 1;
+ }
+
+ if (! -d $d3) {
+ my @dirs = glob ("/Applications/Xcode.app/Contents/Developer/" .
+ "Platforms/MacOSX.platform/Developer/SDKs/" .
+ "MacOSX*sdk/usr/include/netinet");
+ @dirs = sort @dirs;
+ $d3 = $dirs[$#dirs] . "/" if @dirs;
+ }
+
+ if (! -d $d3) {
+ print STDERR "ERROR: There is no $d3 on this system!\n";
+ exit 1;
+ }
+