--- /dev/null
+++ Libc/Libc-1669.40.2/xcodescripts/generate_features.pl
@@ -0,0 +1,227 @@
+#!/usr/bin/perl
+
+# Generates the libc-features.h files used to control #ifdef behaviour in Libc
+use warnings;
+use Data::Dumper;
+use File::Path qw(mkpath);
+
+#printf Dumper(\%ENV);
+
+my $unifdef = 0;
+my %unifdefs = ();
+my $bash = 0;
+if (scalar(@ARGV) > 0) {
+	$unifdef = 1 if $ARGV[0] =~ /--unifdef/;
+	$bash = 1 if $ARGV[0] =~ /--bash/;
+}
+
+for my $arch (split(/ /, $ENV{"ARCHS"}))
+{
+	# set ENV{"CURRENT_ARCH"} so we can predicate on it
+	$ENV{"CURRENT_ARCH"} = $arch;
+
+	my $platformName = $ENV{"VARIANT_PLATFORM_NAME"};
+	$platformName =~ s/simulator/os/;
+
+	# Try to find a platform+arch config file. If not found, try just
+	# a platform config file.
+	my $platformArchPath = $ENV{"SRCROOT"} . "/Platforms/" . $platformName . "/Makefile." . $arch . ".inc";
+	my $platformPath = $ENV{"SRCROOT"} . "/Platforms/" . $platformName . "/Makefile.inc";
+
+	my $featuresHeaderDir = $ENV{"DERIVED_FILES_DIR"}."/".$arch;
+	my $featuresHeader = $featuresHeaderDir."/libc-features.h";
+
+	open FEATURESFILE, "<$platformArchPath" or open FEATURESFILE, "<$platformPath" or die "Unable to open: $platformArchPath nor $platformPath";
+
+	my %features = ();
+	my $skip = 0;
+	my $nested = 0;
+
+	while (<FEATURESFILE>) {
+		next if $_ =~ /\s*#/;
+		
+		if ($_ =~ /^.endif/) {
+			$skip-- if $skip > 0;
+			$nested--;
+		}
+
+		elsif ($_ =~ /^\.if\s+(\S+)\s+(\S+)/) {
+			# an if statement, very rudimentary regex against envvar
+			my $envvar = $1;
+			my $regex = $2;
+			
+			$nested++;
+			if (!defined($ENV{$envvar}) || ($ENV{$envvar} !~ /$regex/)) {
+				$skip += 1;
+			}
+		}
+			
+		elsif ($_ =~ /^\s*([^= ]+)\s*=\s*(\d)/) {
+			if ($skip == 0) {
+				if ($2 == 1) {
+					$features{$1} = $2;
+				} elsif (defined($features{$1})) {
+					delete $features{$1};
+				}
+			}
+		}
+	}
+
+	close FEATURESFILE;
+	
+	if ($bash == 1) {
+		for my $f (keys %features) {
+			print "$f=$features{$f} ";
+		}
+		printf "\n";
+		exit 0;
+	}
+
+	elsif ($unifdef == 1) {
+		# assume FEATURE_BLOCKS was on by default
+		$unifdefs{"UNIFDEF_BLOCKS"} = 1;
+		$unifdefs{"UNIFDEF_DRIVERKIT"} = defined($ENV{"DRIVERKITSDK"});
+		$unifdefs{"UNIFDEF_LEGACY_64_APIS"} = defined($features{"FEATURE_LEGACY_64_APIS"});
+		$unifdefs{"UNIFDEF_LEGACY_RUNE_APIS"} = defined($features{"FEATURE_LEGACY_RUNE_APIS"});
+		$unifdefs{"UNIFDEF_LEGACY_UTMP_APIS"} = defined($features{"FEATURE_LEGACY_UTMP_APIS"});
+		$unifdefs{"UNIFDEF_POSIX_ILP32_ALLOW"} = defined($features{"FEATURE_POSIX_ILP32_ALLOW"});
+		
+		my $output = "";
+		for my $d (keys %unifdefs) {
+			$output .= " " . ($unifdefs{$d} == 1 ? "-D" : "-U") . $d;
+		}
+		
+		chomp $output;
+		print "$output\n";
+		exit 0;
+	}
+	
+	elsif ($unifdef == 0) {
+		# If we touch this file on every build, then every other iterative build in Xcode will rebuild *everything*
+		my $platform_mtime = (stat($platformArchPath))[9];
+		if (!defined($platform_mtime)) {
+			# try the other one
+			$platform_mtime = (stat($platformPath))[9];
+		}
+		my $header_mtime = (stat($featuresHeader))[9];
+
+		if (defined($header_mtime) && defined($platform_mtime) && ($header_mtime > $platform_mtime)) {
+			exit 0;
+		}
+
+		printf $arch." features:\n";
+		printf Dumper(\%features);
+
+		if ($nested != 0) {
+			die "Unbalanced .if/.endif directive";
+		}
+
+		# And the meat, new header options should go under here
+		if (! -d $featuresHeaderDir) {
+			mkpath $featuresHeaderDir or die "Unable to mkdir: $featuresHeaderDir";
+		}
+		open HEADER, ">$featuresHeader" or die "Unable to open (for writing): $featuresHeader";
+
+		printf HEADER "#ifndef _LIBC_FEATURES_H_\n";
+		printf HEADER "#define _LIBC_FEATURES_H_\n\n";
+
+		my $shortarch = $arch;
+		$shortarch =~ s/armv\d+[a-z]?/arm/g;
+
+		# map all arm64 subtypes to arm64
+		$shortarch =~ s/arm64[_a-z0-9]*/arm64/g;
+
+		printf HEADER "#if !defined(__".$shortarch."__)\n";
+		printf HEADER "#error Mismatched libc-features.h architecture\n";
+		printf HEADER "#endif\n\n";
+
+		if (defined($features{"FEATURE_LEGACY_RUNE_APIS"})) {
+			printf HEADER "#define UNIFDEF_LEGACY_RUNE_APIS 1\n";
+		} else {
+			printf HEADER "/* #undef UNIFDEF_LEGACY_RUNE_APIS */\n";
+		}
+
+		if (defined($features{"FEATURE_LEGACY_CRT1_ENVIRON"})) {
+			printf HEADER "#define LEGACY_CRT1_ENVIRON 1\n";
+		} else {
+			printf HEADER "/* #undef LEGACY_CRT1_ENVIRON */\n";
+		}
+
+		if (defined($features{"FEATURE_LEGACY_UTMP_APIS"})) {
+			printf HEADER "#define UNIFDEF_LEGACY_UTMP_APIS 1\n";
+		} else {
+			printf HEADER "/* #undef UNIFDEF_LEGACY_UTMP_APIS */\n";
+		}
+
+		if (defined($features{"FEATURE_ONLY_1050_VARIANTS"})) {
+			printf HEADER "#if !__DARWIN_ONLY_VERS_1050\n";
+			printf HEADER "#  error Feature mismatch: __DARWIN_ONLY_VERS_1050 == 0\n";
+			printf HEADER "#endif /* !__DARWIN_ONLY_VERS_1050 */\n";
+		} else {
+			printf HEADER "#if __DARWIN_ONLY_VERS_1050\n";
+			printf HEADER "#  error Feature mismatch: __DARWIN_ONLY_VERS_1050 == 1\n";
+			printf HEADER "#endif /* __DARWIN_ONLY_VERS_1050 */\n";
+		}
+
+		if (defined($features{"FEATURE_ONLY_UNIX_CONFORMANCE"})) {
+			printf HEADER "#if !__DARWIN_ONLY_UNIX_CONFORMANCE\n";
+			printf HEADER "#  error Feature mismatch: __DARWIN_ONLY_UNIX_CONFORMANCE == 0\n";
+			printf HEADER "#endif /* !__DARWIN_ONLY_UNIX_CONFORMANCE */\n";
+		} else {
+			printf HEADER "#if __DARWIN_ONLY_UNIX_CONFORMANCE\n";
+			printf HEADER "#  error Feature mismatch: __DARWIN_ONLY_UNIX_CONFORMANCE == 1\n";
+			printf HEADER "#endif /* __DARWIN_ONLY_UNIX_CONFORMANCE */\n";
+		}
+
+		if (defined($features{"FEATURE_ONLY_64_BIT_INO_T"})) {
+			printf HEADER "#if !__DARWIN_ONLY_64_BIT_INO_T\n";
+			printf HEADER "#  error Feature mismatch: __DARWIN_ONLY_64_BIT_INO_T == 0\n";
+			printf HEADER "#endif /* !__DARWIN_ONLY_64_BIT_INO_T */\n";
+		} else {
+			printf HEADER "#if __DARWIN_ONLY_64_BIT_INO_T\n";
+			printf HEADER "#  error Feature mismatch: __DARWIN_ONLY_64_BIT_INO_T == 1\n";
+			printf HEADER "#endif /* __DARWIN_ONLY_64_BIT_INO_T */\n";
+		}
+
+		if (defined($features{"FEATURE_PATCH_3417676"})) {
+			printf HEADER "#define __APPLE_PR3417676_HACK__ 1\n";
+		} else {
+			printf HEADER "/* #undef __APPLE_PR3417676_HACK__ */\n";
+		}
+
+		if (defined($features{"FEATURE_PLOCKSTAT"})) {
+			printf HEADER "#define PLOCKSTAT 1\n";
+		} else {
+			printf HEADER "/* #undef PLOCKSTAT */\n";
+		}
+
+		if (defined($features{"FEATURE_TIMEZONE_CHANGE_NOTIFICATION"})) {
+			printf HEADER "#define NOTIFY_TZ 1\n";
+		} else {
+			printf HEADER "/* #undef NOTIFY_TZ */\n";
+		}
+
+		if (defined($features{"FEATURE_SMALL_STDIOBUF"})) {
+			printf HEADER "#define FEATURE_SMALL_STDIOBUF 1\n";
+		} else {
+			printf HEADER "/* #undef FEATURE_SMALL_STDIOBUF */\n";
+		}
+
+		if (defined($features{"FEATURE_XPRINTF_PERF"})) {
+			printf HEADER "#define XPRINTF_PERF 1\n";
+		} else {
+			printf HEADER "/* #undef XPRINTF_PERF */\n";
+		}
+
+		if (defined($features{"FEATURE_SIGNAL_RESTRICTION"})) {
+			printf HEADER "#define FEATURE_SIGNAL_RESTRICTION 1\n";
+		} else {
+			printf HEADER "/* #undef FEATURE_SIGNAL_RESTRICTION */\n";
+		}
+
+		printf HEADER "#endif // _LIBC_FEATURES_H_\n";
+		close HEADER;
+	}
+}
+	
+exit 0;