Add Swift 3/4 'servaldswift' executable

If the Swift 3 or Swift 4 compiler is present or passed to the configure script in the SWIFTC variable, then the Makefile will compile a Swift 'servaldswift' executable to ensure that the module map links correctly into a stand-alone Swift program. Use the gold linker if supported, to avoid relocation errors on symbols produced by Swift when linking dynamic libraries.
2024-12-18 20:57:56 +00:00 · 2016-10-20 16:52:53 +10:30 · 2016-10-20 16:52:53 +10:30 · f2eb2bf9ab
commit f2eb2bf9ab
parent e9d91d04ca
16 changed files with 648 additions and 64 deletions
--- a/.gitignore
+++ b/.gitignore
@ -21,6 +21,7 @@
 /config.h
 /servald
 /servaldwrap
+/servaldswift
 /serval-tests
 /directory_service
 /tfw_createfile
--- a/INSTALL.md
+++ b/INSTALL.md
@ -1,6 +1,6 @@
 Serval DNA Build and Test
 =========================
-[Serval Project][], September 2017
+[Serval Project][], December 2017

 Supported Architectures
 -----------------------
@ -54,6 +54,7 @@ Mandatory dependencies:
 Optional:

 * Java compiler and SDK 1.6.0 or later
+ * [Swift][] 3 or 4 compiler
 * ALSA sound library and headers (present on Linux, not on Android)

 Test dependencies:
@ -68,11 +69,15 @@ Test dependencies:
 OS-X using the [homebrew][] package manager.  The [Notes for Developers][] give
 more details.

-Build
-----
+Native Build
+------------

-To compile a native (ie, not cross-compiled) Serval DNA from source, run the
-following commands:
+A *native build* of Serval DNA will produce libraries and executable programs
+that can be run on the same platform on which the build is performed.  This is
+useful for development and testing.
+
+The following commands will compile a native (ie, not cross-compiled) Serval
+DNA from source:

    $ cd $HOME/src/serval-dna
    $ autoreconf -f -i -I m4
@ -125,9 +130,20 @@ A successful session should appear something like:
    LIB CC cli.c
    LIB CC cli_stdio.c
    ...
-    LINK simulator
+    LINK servald
+    CC directory_service.c
+    LINK directory_service
+    SERVALD CC servalwrap.c
+    LINK servaldwrap
    SERVALD CC test_features.c
    LINK serval-tests
+    CC fakeradio.c
+    LINK fakeradio
+    CC simulator.c
+    LINK simulator
+    CC tfw_createfile.c
+    LINK tfw_createfile
+    SWIFT servaldswift
    make[1]: Entering directory '/home/username/src/serval-dna/java-api'
    JAVAC classes
    JAVAC testclasses
@ -152,16 +168,27 @@ In the event of a build failure:
 * consult the [Notes for Developers][]
 * as a last resort, [contact the Serval Project][]

+Android build
+-------------
+
+The [batphone][] app for Android builds Serval DNA from source by including
+[Android.mk](./Android.mk) in its own build process; see the [batphone build
+instructions][] for more information.
+
+It is not necessary to perform a [native build](#native-build) before or after
+an Android build; the two produce completely unrelated artifacts.
+
 Built artifacts
 ---------------

-The build process produces the following artifacts:
+The [native build](#native-build) process produces the following artifacts:

 * **servald** is the main Serval DNA daemon executable.  All the Serval DNA
  daemon, SQLite and libsodium code is statically linked into this executable,
-  so it does not need to load any Serval or libsodium shared libraries at
-  run-time.  Its unstripped size is about 9.5 MB on a typical 64-bit system, of
-  which about 7 MB is SQLite.  Its stripped size is about 3 MB.
+  and only common system libraries are dynamically linked, which keeps its
+  run-time dependencies to a minimum.  Its unstripped size is about 9.5 MB on a
+  typical 64-bit system, of which about 7 MB is SQLite.  Its stripped size is
+  about 3 MB.

 * **servaldwrap** is a Serval DNA executable identical to *servald*, but
  it loads `libservaldaemon.so` at run-time using [dlopen(3)][] instead of
@ -182,8 +209,9 @@ The build process produces the following artifacts:

 * **libservaldaemon.so** is a dynamic library containing the complete executable
  code of the Serval DNA daemon, including [JNI][] entry points, SQLite and
-  libsodium cryptographic functions.  The Serval DNA Java API, which is used by
-  [batphone][], and the *servaldwrap* executable both use this dynamic library.
+  libsodium cryptographic functions.  The *servaldwrap* executable and the
+  Serval DNA Java API, which is used by [batphone][], both use this dynamic
+  library.

 * **directory_service** is the executable for the [Serval Infrastructure][]
  daemon.
@ -213,6 +241,16 @@ The build process produces the following artifacts:
 * **tfw_createfile** is an executable utility needed by test scripts for
  creating large data files with unique, non-repeating content.

+In addition, the following artifacts are produced [if a Swift compiler is
+present][Swift development]:
+
+* **servaldswift** is a statically linked Serval DNA executable identical to
+  *servald*, but its *main* entry point is compiled from a [Swift][] program to
+  prove that Swift code can invoke internal Serval DNA daemon APIs.  It
+  dynamically links to many more system libraries than *servald* because of the
+  Swift language's run-time support and resultant library dependencies, so is
+  not suitable for deployment.
+
 Test scripts
 ------------

@ -270,6 +308,7 @@ This document is available under the [Creative Commons Attribution 4.0 Internati
 [Serval DNA]: ./README.md
 [serval-dna]: https://github.com/servalproject/serval-dna
 [batphone]: https://github.com/servalproject/batphone
+[batphone build instructions]: https://github.com/servalproject/batphone/blob/development/INSTALL.md
 [Android 2.2 “Froyo”]: http://developer.android.com/about/versions/android-2.2-highlights.html
 [Android NDK]: http://developer.android.com/tools/sdk/ndk/index.html
 [Xcode]: https://developer.apple.com/xcode/
@ -277,6 +316,7 @@ This document is available under the [Creative Commons Attribution 4.0 Internati
 [gcc 5]: http://gcc.gnu.org/gcc-5/
 [gcc 6]: http://gcc.gnu.org/gcc-6/
 [Notes for Developers]: ./doc/Development.md
+[Swift development]: ./doc/Development.md#swift
 [OpenWRT]: ./doc/OpenWRT.md
 [Serval Infrastructure]: ./doc/Serval-Infrastructure.md
 [Serval Mesh Extender]: http://developer.servalproject.org/dokuwiki/doku.php?id=content:meshextender:
@ -288,6 +328,7 @@ This document is available under the [Creative Commons Attribution 4.0 Internati
 [MDP API]: ./doc/Mesh-Datagram-Protocol.md#mdp-api
 [CLI API]: ./doc/CLI-API.md
 [JNI]: http://en.wikipedia.org/wiki/Java_Native_Interface
+[Swift]: https://en.wikipedia.org/wiki/Swift_(programming_language)
 [Bash]: http://en.wikipedia.org/wiki/Bash_(Unix_shell)
 [GNU make]: http://www.gnu.org/software/make/
 [Git]: http://git-scm.com/
--- a/Makefile.in
+++ b/Makefile.in
@ -8,7 +8,21 @@ sysconfdir=@sysconfdir@
 localstatedir=@localstatedir@
 srcdir=@srcdir@

-SQLITE3_AMALGAMATION = sqlite-amalgamation-3140200
+CC = 			@CC@
+AR =			@AR@
+RANLIB =		@RANLIB@
+JAVAC= 			@JAVAC@
+SWIFTC= 		@SWIFTC@
+
+SWIFTCFLAGS= 		@SWIFTCFLAGS@ -I. -I $(srcdir)
+SWIFTLIBS=		@LIBS@
+SWIFT_MODULE_NAME=	ServalDNA
+
+INSTALL=        	install
+INSTALL_PROGRAM=	$(INSTALL)
+INSTALL_DATA=   	$(INSTALL) -m 644
+
+SQLITE3_AMALGAMATION = 	sqlite-amalgamation-3140200

 include $(srcdir)/sourcefiles.mk
 include $(srcdir)/headerfiles.mk
@ -62,8 +76,6 @@ SIMULATOR_OBJS = \
 PREFIXED_HEADERS = $(addprefix $(srcdir)/, $(HDRS))
 PREFIXED_SOURCES = $(addprefix $(srcdir)/, $(ALL_SOURCES))

-CC= @CC@
-
 LDFLAGS=@LDFLAGS@ @LIBS@

 CFLAGS= -I. -I$(srcdir)/$(SQLITE3_AMALGAMATION) @CPPFLAGS@ @CFLAGS@
@ -83,35 +95,38 @@ CFLAGS+=-DSHA2_USE_INTTYPES_H -D_XOPEN_SOURCE=600 -D_XOPEN_SOURCE_EXTENDED=1 -D_
 CFLAGS+=-D_DARWIN_C_SOURCE
 CFLAGS_SQLITE= @CFLAGS_SQLITE@

-JAVAC= 		@JAVAC@
-
-INSTALL=        install
-INSTALL_PROGRAM=$(INSTALL)
-INSTALL_DATA=   $(INSTALL) -m 644
-
 -include $(srcdir)/Makefile.dbg

-DEFS= @DEFS@
+# More warnings, discover problems that only happen on some archs
+CFLAGS+=-Wextra
+# Security enhancements from Debian
+CFLAGS+=-Wformat -Werror=format-security -D_FORTIFY_SOURCE=2

-CONFIG_H = @CONFIG_H@
+CONFIG_H =	@CONFIG_H@
+
+DEFS=		@DEFS@
+SWIFTDEFS=	$(addprefix -Xcc , $(DEFS))

 # Usage: $(call MERGE_STATIC_LIBS, libdest.a, libsrcfoo.a libsrcbar.a)
 MERGE_STATIC_LIBS =	echo MERGE $(1) = $(2); \
 			tmp="$$(mktemp -d)" && \
 			( cd "$$tmp" $(foreach LIB, $(2), && $(AR) -x $(abspath $(LIB))) ) && \
-			$(RM) $@ && \
-			$(AR) -cr $(1) "$$tmp"/* && \
+			$(RM) $(1) && \
+			$(AR) -cr $(1) "$$tmp"/*.o && \
+			$(RANLIB) $(1) && \
 			$(RM) -r "$$tmp"

 .PHONY: all libs test install uninstall clean

-all:	libs servald servaldwrap test
+all:	libs servald directory_service test

-libs:	libservaldaemon.so \
+libs:	libservaldaemon.so libservaldaemon.a \
 	libservalclient.so libservalclient.a \
 	libmonitorclient.so libmonitorclient.a

-test:   tfw_createfile directory_service fakeradio simulator serval-tests
+test:   servaldwrap serval-tests \
+	fakeradio simulator \
+	tfw_createfile

 install: servald
 	$(INSTALL_PROGRAM) -D servald $(DESTDIR)$(sbindir)/servald
@ -321,6 +336,26 @@ servald:	$(OBJSDIR_SERVALD)/servald_features.o \
 	@echo LINK $@
 	@$(CC) -Wall -o $@ $^ $(LDFLAGS)

+ifneq ($(SWIFTC),) # Only provide Swift targets if the Swift compiler is available.
+
+test:	servaldswift
+
+# A servald equivalent whose main entry point and logging output is implemented
+# in the Swift language, rather than the C entry point in main.c.  This exists
+# mainly to ensure that the Serval daemon library can be linked into a Swift
+# program and executed.  This linkage support is needed by the iOS framework
+# package.
+servaldswift: $(srcdir)/servaldswift.swift \
+	      $(OBJSDIR_SERVALD)/servald_features.o \
+	      $(OBJSDIR_SERVALD)/log_output_console.o \
+	      $(OBJSDIR_SERVALD)/log_output_file.o \
+	      libservaldaemon.a \
+	      $(srcdir)/module.modulemap
+	@echo SWIFT $@
+	@$(SWIFTC) -emit-executable $(SWIFTCFLAGS) $(SWIFTDEFS) -o $@ $(filter %.swift, $^) $(filter %.o, $^) $(filter %.a, $^) $(SWIFTLIBS)
+
+endif # $(SWIFTC)
+
 servaldwrap: $(OBJSDIR_SERVALD)/servalwrap.o
 	@echo LINK $@
 	@$(CC) -Wall -o $@ $^ $(LDFLAGS)
--- a/configure.ac
+++ b/configure.ac
@ -4,26 +4,13 @@ AC_INIT(servald, 0.9)
 AC_CONFIG_SRCDIR([serval_types.h])
 AC_CONFIG_MACRO_DIR([m4])

+AC_ARG_VAR([AR], [Library archiver])
+AC_ARG_VAR([RANLIB], [Archive indexer])
+AC_ARG_VAR([SWIFTC], [Swift compiler])
+AC_ARG_VAR([SWIFTCFLAGS], [Swift compiler flags])
+
 CPPFLAGS="$CPPFLAGS -D_GNU_SOURCE"

-dnl Set $host_os, which is needed by javac detection.
-AC_CANONICAL_SYSTEM
-
-dnl Various GCC function and variable attributes
-AX_GCC_FUNC_ATTRIBUTE(aligned)
-AX_GCC_FUNC_ATTRIBUTE(alloc_size)
-AX_GCC_FUNC_ATTRIBUTE(error)
-AX_GCC_FUNC_ATTRIBUTE(format)
-AX_GCC_FUNC_ATTRIBUTE(malloc)
-AX_GCC_FUNC_ATTRIBUTE(unused)
-AX_GCC_FUNC_ATTRIBUTE(used)
-AX_GCC_VAR_ATTRIBUTE(section)
-AX_GCC_VAR_ATTRIBUTE(section_seg)
-AX_GCC_STMT_ATTRIBUTE(fallthrough)
-
-dnl Init pkg-config
-PKG_PROG_PKG_CONFIG()
-
 dnl Specify default instance path
 AC_ARG_VAR([INSTANCE_PATH], [default instance path for servald])
 AS_IF([test "x$INSTANCE_PATH" != x], [AC_DEFINE_UNQUOTED([INSTANCE_PATH], ["$INSTANCE_PATH"], [default instance path])])
@ -52,10 +39,58 @@ dnl Specify default Rhizome store directory
 AC_ARG_VAR([RHIZOME_STORE_PATH], [default Rhizome store directory])
 AS_IF([test "x$RHIZOME_STORE_PATH" != x], [AC_DEFINE_UNQUOTED([RHIZOME_STORE_PATH], ["$RHIZOME_STORE_PATH"], [default Rhizome store directory])])

-dnl Check for programs.
-AC_PROG_CC
+dnl Set $host_os, which is needed by javac detection.
+AC_CANONICAL_SYSTEM

-dnl Check for compiler options
+dnl Check for C99 compiler and other tools.
+AC_PROG_CC_C99
+AC_PROG_CPP
+
+AC_CHECK_TOOL([AR], [ar], [:])
+AS_IF([test "x$AR" = x:], [AC_MSG_ERROR([Library archiver not found: ar])])
+
+AC_CHECK_TOOL([RANLIB], [ranlib], [:])
+AS_IF([test "x$RANLIB" = x:], [AC_MSG_ERROR([Archive indexer not found: ranlib])])
+
+dnl Check for a Swift 3 or 4 compiler; set SWIFTC if found.
+AC_PROG_SWIFTC
+
+AS_IF([test "x$SWIFTC" != x], [ dnl
+    dnl Check whether the Swift compiler will compile a simple Swift 4 program with the supplied flags.
+    dnl If not, report failure but keep going.
+    AC_PROG_SWIFTC_IS_SWIFT4
+    AS_IF([test "x$ac_cv_prog_swiftc_is_swift4" = xyes], [SWIFT_VERSION=4], [ dnl
+        AC_PROG_SWIFTC_IS_SWIFT3
+        AS_IF([test "x$ac_cv_prog_swiftc_is_swift3" = xyes], [SWIFT_VERSION=3], [ dnl
+            AC_MSG_WARN([$SWIFTC version is too old; omitting Swift API])
+            SWIFT_VERSION=
+            SWIFTC=
+        ])
+    ])
+])
+
+AC_SUBST([SWIFTC])
+AC_SUBST([SWIFTCFLAGS])
+AC_SUBST([SWIFT_VERSION])
+
+dnl Various GCC function and variable attributes
+AX_GCC_FUNC_ATTRIBUTE(aligned)
+AX_GCC_FUNC_ATTRIBUTE(alloc_size)
+AX_GCC_FUNC_ATTRIBUTE(error)
+AX_GCC_FUNC_ATTRIBUTE(format)
+AX_GCC_FUNC_ATTRIBUTE(malloc)
+AX_GCC_FUNC_ATTRIBUTE(unused)
+AX_GCC_FUNC_ATTRIBUTE(used)
+AX_GCC_VAR_ATTRIBUTE(section)
+AX_GCC_VAR_ATTRIBUTE(section_seg)
+AX_GCC_STMT_ATTRIBUTE(fallthrough)
+
+dnl The default GNU linker (BFD) cannot relocate some symbols produced by the
+dnl Swift compiler, so the gold linker is used to create dynamic libraries.
+dnl See doc/Development.md for details.
+AX_APPEND_LINK_FLAGS(-fuse-ld=gold)
+
+dnl Check compiler options for compiling SQLite.
 AX_APPEND_COMPILE_FLAGS(
    -Wno-empty-body \
    -Wno-unused-value \
@ -81,7 +116,7 @@ popdef([AC_MSG_ERROR])
 AC_SUBST([JAVAC])

 dnl Check Java version, ditch Java if not adequate
-if test -n "$JAVAC"; then
+AS_IF([test -n "$JAVAC"], [ dnl
    dnl Discover the version of the Java compiler
    AC_PROG_JAVAC_VERSION
    dnl Check that the Java compiler is modern enough
@ -94,9 +129,9 @@ if test -n "$JAVAC"; then
                AC_MSG_WARN([Java version $ax_cv_prog_javac_version is too old; omitting Java API])
                JAVAC=""
            ])
-fi
+])

-if test -n "$JAVAC"; then
+AS_IF([test -n "$JAVAC"], [ dnl
    dnl Discover the locations of JNI header files
    dnl *** Kludge: override AC_MSG_ERROR because AC_JNI_INCLUDE_DIR does not have
    dnl *** [if-found] and [if-not-found] action parameters.
@ -106,7 +141,7 @@ if test -n "$JAVAC"; then
        CPPFLAGS="$CPPFLAGS -I$JNI_INCLUDE_DIR"
    done
    popdef([AC_MSG_ERROR])
-fi
+])

 dnl XXX Isn't this pointless? we are always linked against libc
 AC_CHECK_LIB(c,srandomdev)
--- a/doc/Development.md
+++ b/doc/Development.md
@ -1,6 +1,6 @@
 Notes for Serval DNA Developers
 ===============================
-[Serval Project][], September 2017
+[Serval Project][], December 2017

 Introduction
 ------------
@ -11,12 +11,12 @@ non-developers who are experiencing errors in the [build][] process.
 Autotools
 ---------

-The [configure.ac](../configure.ac) file is an [autoconf][] script that
-contains instructions for adapting the build of Serval DNA to different
-platforms and CPU architectures.  This script makes use of many [GNU M4][]
-macros, each of which tests an aspect of the build environment, such as the
-make and version of the C compiler (eg, [GCC][], [Clang][]), the availability
-of headers, functions and system calls in the standard library, and so forth.
+The [configure.ac][] file is an [autoconf][] script that contains instructions
+for adapting the build of Serval DNA to different platforms and CPU
+architectures.  This script makes use of many [GNU M4][] macros, each of which
+tests an aspect of the build environment, such as the make and version of the C
+compiler (eg, [GCC][], [Clang][]), the availability of headers, functions and
+system calls in the standard library, and so forth.

 Most of these M4 macros are standard, either supplied with [autoconf][] or from
 the [autoconf macro archive][].  Some macros are specific to Serval DNA, either
@ -27,8 +27,7 @@ sub-directory.
 The [autoreconf][] command used in the [build][] instructions generates an
 `aclocal.m4` file that includes all the necessary files from the [m4](../m4)
 directory.  In turn, it then includes this `aclocal.m4` file when invoking [GNU
-M4][] to convert the [configure.ac](../configure.ac) file into the
-`./configure` script.
+M4][] to convert the [configure.ac][] file into the `./configure` script.

 When invoked without arguments, all [autoreconf][] versions up to 2.69 will
 emit warning messages like this:
@ -63,7 +62,18 @@ the `-I m4` option, which will eliminate the warnings:

 The `-I m4` option should be unnecessary in [autoreconf][] versions 2.70 and
 later, because they will deduce it from the `AC_CONFIG_MACRO_DIR([m4])`
-directive near the top of `configure.ac`.
+directive near the top of [configure.ac][].
+
+Linker
+------
+
+The default GNU linker (based on the BFD library) does not support relocation
+of some symbols produced by the Swift compiler:
+
+    relocation R_X86_64_PC32 against protected symbol `...' can not be used when making a shared object
+
+The Serval DNA dynamic library is linked using the GNU [gold][] linker
+(available in GNU binutils since 2008), which does not have this problem.

 libsodium
 ---------
@ -217,6 +227,34 @@ using the [homebrew][] package manager:
    /usr/local/Cellar/jq/1.5_2: 18 files, 958K
    $

+Java
+----
+
+The Serval DNA *libservaldeamon* static and dynamic libraries provide a [JNI][]
+API so that the Serval [command line][CLI] can be called from Java programs,
+and the daemon server can be run in a Java thread.
+
+Swift
+-----
+
+Serval DNA supports [Swift][], the language that Apple recommend for developing
+iOS apps for their mobile devices such as phones and tablets.  The
+`./configure` script [generated from configure.ac](#autotools) detects whether
+a [Swift 4][] compiler is present, or failing that, a [Swift 3][] compiler, and
+if so, then produces a Makefile that will compile
+[servaldswift.swift](../servaldswift.swift) into the *servaldswift* executable,
+to prove that the Swift [module map](../module.modulemap) allows Swift source
+code to invoke internal Serval DNA functions.
+
+The `./configure` script can be passed the following variables, either as
+environment variables or using the `VARNAME=value` syntax on its command line:
+
+* `SWIFTC` the path name of the Swift compiler to use; by default the configure
+  script searches `$PATH` for `swiftc`
+
+* `SWIFTCFLAGS` extra command-line arguments to pass to the Swift compiler;
+  analogous to `CFLAGS` for the C compiler
+
 About the examples
 ------------------

@ -241,6 +279,7 @@ Available under the [Creative Commons Attribution 4.0 International licence][CC
 [CC BY 4.0]: ../LICENSE-DOCUMENTATION.md
 [Serval DNA]: ../README.md
 [build]: ../INSTALL.md
+[configure.ac]: ../configure.ac
 [autoconf]: http://www.gnu.org/software/autoconf/autoconf.html
 [autoconf macro archive]: http://www.gnu.org/software/autoconf-archive/
 [GNU M4]: http://www.gnu.org/software/m4/m4.html
@ -262,4 +301,11 @@ Available under the [Creative Commons Attribution 4.0 International licence][CC
 [OS X awk(1)]: https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man1/awk.1.html
 [jq(1)]: https://stedolan.github.io/jq/
 [homebrew]: http://brew.sh/
+[CLI]: ./CLI-API.md
+[JNI]: http://en.wikipedia.org/wiki/Java_Native_Interface
+[Swift]: https://en.wikipedia.org/wiki/Swift_(programming_language)
+[Swift module]: https://swift.org/package-manager/#modules
+[Swift 3]: https://swift.org/blog/swift-3-0-released/
+[Swift 4]: https://swift.org/blog/swift-4-0-released/
+[gold]: https://en.wikipedia.org/wiki/Gold_(linker)
 [Bourne shell]: http://en.wikipedia.org/wiki/Bourne_shell
--- a/m4/ax_append_link_flags.m4
+++ b/m4/ax_append_link_flags.m4
@ -0,0 +1,61 @@
+# ===========================================================================
+#   http://www.gnu.org/software/autoconf-archive/ax_append_link_flags.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_APPEND_LINK_FLAGS([FLAG1 FLAG2 ...], [FLAGS-VARIABLE], [EXTRA-FLAGS])
+#
+# DESCRIPTION
+#
+#   For every FLAG1, FLAG2 it is checked whether the linker works with the
+#   flag.  If it does, the flag is added FLAGS-VARIABLE
+#
+#   If FLAGS-VARIABLE is not specified, the linker's flags (LDFLAGS) is
+#   used. During the check the flag is always added to the linker's flags.
+#
+#   If EXTRA-FLAGS is defined, it is added to the linker's default flags
+#   when the check is done.  The check is thus made with the flags: "LDFLAGS
+#   EXTRA-FLAGS FLAG".  This can for example be used to force the linker to
+#   issue an error when a bad flag is given.
+#
+#   NOTE: This macro depends on the AX_APPEND_FLAG and AX_CHECK_LINK_FLAG.
+#   Please keep this macro in sync with AX_APPEND_COMPILE_FLAGS.
+#
+# LICENSE
+#
+#   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
+#
+#   This program is free software: you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation, either version 3 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+#serial 2
+
+AC_DEFUN([AX_APPEND_LINK_FLAGS],
+[for flag in $1; do
+  AX_CHECK_LINK_FLAG([$flag], [AX_APPEND_FLAG([$flag], [m4_default([$2], [LDFLAGS])])], [], [$3])
+done
+])dnl AX_APPEND_LINK_FLAGS
--- a/m4/ax_check_link_flag.m4
+++ b/m4/ax_check_link_flag.m4
@ -0,0 +1,71 @@
+# ===========================================================================
+#    http://www.gnu.org/software/autoconf-archive/ax_check_link_flag.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_CHECK_LINK_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS])
+#
+# DESCRIPTION
+#
+#   Check whether the given FLAG works with the linker or gives an error.
+#   (Warnings, however, are ignored)
+#
+#   ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
+#   success/failure.
+#
+#   If EXTRA-FLAGS is defined, it is added to the linker's default flags
+#   when the check is done.  The check is thus made with the flags: "LDFLAGS
+#   EXTRA-FLAGS FLAG".  This can for example be used to force the linker to
+#   issue an error when a bad flag is given.
+#
+#   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
+#   macro in sync with AX_CHECK_{PREPROC,COMPILE}_FLAG.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
+#   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
+#
+#   This program is free software: you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation, either version 3 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+#serial 2
+
+AC_DEFUN([AX_CHECK_LINK_FLAG],
+[AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_ldflags_$4_$1])dnl
+AC_CACHE_CHECK([whether the linker accepts $1], CACHEVAR, [
+  ax_check_save_flags=$LDFLAGS
+  LDFLAGS="$LDFLAGS $4 $1"
+  AC_LINK_IFELSE([AC_LANG_PROGRAM()],
+    [AS_VAR_SET(CACHEVAR,[yes])],
+    [AS_VAR_SET(CACHEVAR,[no])])
+  LDFLAGS=$ax_check_save_flags])
+AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes],
+  [m4_default([$2], :)],
+  [m4_default([$3], :)])
+AS_VAR_POPDEF([CACHEVAR])dnl
+])dnl AX_CHECK_LINK_FLAGS
--- a/m4/ax_prog_swiftc.m4
+++ b/m4/ax_prog_swiftc.m4
@ -0,0 +1,56 @@
+# Serval Project Swift language support
+#
+# SYNOPSIS
+#
+#   AX_PROG_SWIFTC
+#
+# DESCRIPTION
+#
+#   AX_PROG_SWIFTC tests for the presence of a Swift compiler.
+#
+#   Sets the SWIFTC shell variable to the name of the Swift executable (not the
+#   Swift compiler!) either relative to $PATH or an absolute path if necessary;
+#   this is usually just "swiftc".
+#
+#   To force a specific compiler, either:
+#
+#   - in configure.ac, set SWIFTC=yourcompiler before calling AX_PROG_SWIFTC,
+#     or
+#
+#   - before invoking ./configure, export SWIFTC=yourcompiler
+#
+# LICENSE
+#
+#   Copyright (C) 2016 Flinders University
+#
+#   This program is free software; you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation; either version 2 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+AU_ALIAS([AC_PROG_SWIFTC], [AX_PROG_SWIFTC])
+AC_DEFUN([AX_PROG_SWIFTC],[
+    test "x$SWIFTC" = x && AC_CHECK_PROGS(SWIFTC, swiftc)
+    AC_PROVIDE([$0])dnl
+])
--- a/m4/ax_prog_swiftc_is_swift3.m4
+++ b/m4/ax_prog_swiftc_is_swift3.m4
@ -0,0 +1,74 @@
+# Serval Project Swift language support
+#
+# SYNOPSIS
+#
+#   AX_PROG_SWIFTC_IS_SWIFT3
+#
+# DESCRIPTION
+#
+#   AX_PROG_SWIFTC_IS_SWIFT3 tests whether the Swift compiler in the SWIFTC
+#   variable (eg, as detected by the AX_PROG_SWIFTC macro) can compile a Swift
+#   3 program to a working native executable, with the given SWIFTCFLAGS
+#   compiler options.
+#
+# LICENSE
+#
+#   Copyright (C) 2016 Flinders University
+#
+#   This program is free software; you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation; either version 2 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+AU_ALIAS([AC_PROG_SWIFTC_IS_SWIFT3], [AX_PROG_SWIFTC_IS_SWIFT3])
+AC_DEFUN([AX_PROG_SWIFTC_IS_SWIFT3],[
+    AC_REQUIRE([AX_TMPDIR_SWIFT])
+    AC_CACHE_CHECK([if $SWIFTC supports Swift 3], ac_cv_prog_swiftc_is_swift3, [
+        cat <<EOF > "$ax_tmpdir_swift/Test.swift"
+/* Swift 2 uses Process.arguments, so this only compiles in Swift 3 */
+print(CommandLine.arguments)
+EOF
+        if AC_TRY_COMMAND($SWIFTC $SWIFTCFLAGS -emit-executable -o "$ax_tmpdir_swift/Test" "$ax_tmpdir_swift/Test.swift") >/dev/null 2>&1; then
+            if AC_TRY_COMMAND("$ax_tmpdir_swift/Test" one two three) > "$ax_tmpdir_swift/Test.out" 2>&1; then
+                ac_swift_test_out=`cat "$ax_tmpdir_swift/Test.out"`
+                if test "x$ac_swift_test_out" = ['x["'"$ax_tmpdir_swift"'/Test", "one", "two", "three"]']; then
+                    ac_cv_prog_swiftc_is_swift3=yes
+                else
+                    echo "incorrect output was: $ac_swift_test_out" >&AS_MESSAGE_LOG_FD
+                    ac_cv_prog_swiftc_is_swift3=no
+                fi
+            else
+                echo "failed "$ax_tmpdir_swift/Test" execution produced output:" >&AS_MESSAGE_LOG_FD
+                cat "$ax_tmpdir_swift/Test.out" >&AS_MESSAGE_LOG_FD
+                ac_cv_prog_swiftc_is_swift3=no
+            fi
+        else
+            echo "compilation failed for:" >&AS_MESSAGE_LOG_FD
+            cat "$ax_tmpdir_swift/Test.swift" >&AS_MESSAGE_LOG_FD
+            ac_cv_prog_swiftc_is_swift3=no
+        fi
+        rm -f Test.swift Test Test.out
+    ])
+    AC_PROVIDE([$0])dnl
+])
--- a/m4/ax_prog_swiftc_is_swift4.m4
+++ b/m4/ax_prog_swiftc_is_swift4.m4
@ -0,0 +1,80 @@
+# Serval Project Swift language support
+#
+# SYNOPSIS
+#
+#   AX_PROG_SWIFTC_IS_SWIFT4
+#
+# DESCRIPTION
+#
+#   AX_PROG_SWIFTC_IS_SWIFT4 tests whether the Swift compiler in the SWIFTC
+#   variable (eg, as detected by the AX_PROG_SWIFTC macro) can compile a Swift
+#   4 program to a working native executable, with the given SWIFTCFLAGS
+#   compiler options.
+#
+# LICENSE
+#
+#   Copyright (C) 2017 Flinders University
+#
+#   This program is free software; you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation; either version 2 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+AU_ALIAS([AC_PROG_SWIFTC_IS_SWIFT4], [AX_PROG_SWIFTC_IS_SWIFT4])
+AC_DEFUN([AX_PROG_SWIFTC_IS_SWIFT4],[
+    AC_REQUIRE([AX_TMPDIR_SWIFT])
+    AC_CACHE_CHECK([if $SWIFTC supports Swift 4], ac_cv_prog_swiftc_is_swift4, [
+        [
+        cat <<EOF > "$ax_tmpdir_swift/Test.swift"
+/* Substring was introduced in Swift 4 */
+let a = "test"
+let b : Substring = a[a.startIndex ... a.index(a.startIndex, offsetBy: 2)]
+precondition(b == "tes")
+/* Swift 2 uses Process.arguments, so this only compiles in Swift 3 and later */
+print(CommandLine.arguments)
+EOF
+        ]
+        if AC_TRY_COMMAND($SWIFTC $SWIFTCFLAGS -emit-executable -o "$ax_tmpdir_swift/Test" "$ax_tmpdir_swift/Test.swift") >/dev/null 2>&1; then
+            if AC_TRY_COMMAND("$ax_tmpdir_swift/Test" one two three) > "$ax_tmpdir_swift/Test.out" 2>&1; then
+                ac_swift_test_out=`cat "$ax_tmpdir_swift/Test.out"`
+                if test "x$ac_swift_test_out" = ['x["'"$ax_tmpdir_swift"'/Test", "one", "two", "three"]']; then
+                    ac_cv_prog_swiftc_is_swift4=yes
+                else
+                    echo "incorrect output was: $ac_swift_test_out" >&AS_MESSAGE_LOG_FD
+                    ac_cv_prog_swiftc_is_swift4=no
+                fi
+            else
+                echo "failed "$ax_tmpdir_swift/Test" execution produced output:" >&AS_MESSAGE_LOG_FD
+                cat "$ax_tmpdir_swift/Test.out" >&AS_MESSAGE_LOG_FD
+                ac_cv_prog_swiftc_is_swift4=no
+            fi
+        else
+            echo "compilation failed for:" >&AS_MESSAGE_LOG_FD
+            cat "$ax_tmpdir_swift/Test.swift" >&AS_MESSAGE_LOG_FD
+            ac_cv_prog_swiftc_is_swift4=no
+        fi
+        rm -f Test.swift Test Test.out
+    ])
+    AC_PROVIDE([$0])dnl
+])
--- a/m4/ax_tmpdir_swift.m4
+++ b/m4/ax_tmpdir_swift.m4
@ -0,0 +1,22 @@
+# Serval Project Swift language support
+#
+# SYNOPSIS
+#
+#   AX_TMPDIR_SWIFT
+#
+# DESCRIPTION
+#
+#   AX_TMPDIR_SWIFT creates a temporary directory prefixed with "swft" that
+#   will be deleted when the shell exits.  It sets the ax_tmpdir_swift shell
+#   variable to the absolute path of the created directory.
+#
+#   Uses AS_TMPDIR() internally but preserves the value of the 'tmp' shell
+#   variable.
+#
+
+AC_DEFUN([AX_TMPDIR_SWIFT],[
+    AS_VAR_COPY([_swift_tmp], [tmp])
+    AS_TMPDIR([swft])
+    ax_tmpdir_swift="$tmp"
+    AS_VAR_COPY([tmp], [_swift_tmp])
+])
--- a/main.c
+++ b/main.c
@ -17,7 +17,7 @@ along with this program; if not, write to the Free Software
 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

-extern int servald_main(int, char**);
+#include "servald_main.h"

 int main(int argc, char **argv)
 {
--- a/module.modulemap
+++ b/module.modulemap
@ -0,0 +1,27 @@
+/*
+Serval DNA module map 
+Copyright (C) 2016-2017 Flinders University
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+*/
+
+module servald {
+
+    requires tls // thread-local storage
+
+    module main {
+        header "servald_main.h"
+    }
+}
--- a/servald_main.c
+++ b/servald_main.c
@ -19,6 +19,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

 #include <signal.h>
+#include "servald_main.h"
 #include "commandline.h"
 #include "sighandlers.h"
 #include "conf.h"
--- a/servald_main.h
+++ b/servald_main.h
@ -0,0 +1,20 @@
+/*
+Serval DNA main command-line entry point
+Copyright (C) 2016 Flinders University
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+*/
+
+int servald_main(int argc, char **argv);
--- a/servaldswift.swift
+++ b/servaldswift.swift
@ -0,0 +1,14 @@
+import Foundation
+import servald.main
+
+public func serval_daemon_main(args: [String]) -> CInt {
+    // print "args = \(args)"
+    var argv = args.map { strdup($0) }
+    argv.append(nil)
+    defer {
+        argv.forEach { free($0) }
+    }
+    return servald_main(CInt(argv.count - 1), &argv)
+}
+
+exit(serval_daemon_main(args: CommandLine.arguments))