build: multiprocess autotools changes

autoconf and automake changes to support multiprocess gui/node/wallet execution.

This adds a new --enable-multiprocess flag, and build configuration code to
detect libraries needed for multiprocess support. The --enable-multiprocess
flag builds new bitcoin-node and bitcoin-gui executables, which are updated in
https://github.com/bitcoin/bitcoin/pull/10102 to communicate across processes.
But for now they are functionally equivalent to existing bitcoind and
bitcoin-qt executables.

5 files changed, 160 insertions, 41 deletions

diff --git a/.gitignore b/.gitignore
index 1c487f43a7..5b9ec1f355 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,6 +5,8 @@
 src/bitcoin
 src/bitcoind
 src/bitcoin-cli
+src/bitcoin-gui
+src/bitcoin-node
 src/bitcoin-tx
 src/bitcoin-wallet
 src/test/fuzz
diff --git a/configure.ac b/configure.ac
index 7de6adb93a..77df712832 100644
--- a/configure.ac
+++ b/configure.ac
@@ -242,6 +242,24 @@ if test x$enable_bip70 != xno; then
   AC_MSG_ERROR([BIP70 is no longer supported!])
 fi
 
+AC_ARG_WITH([libmultiprocess],
+  [AS_HELP_STRING([--with-libmultiprocess=yes|no|auto],
+  [Build with libmultiprocess library. (default: auto, i.e. detect with pkg-config)])],
+  [with_libmultiprocess=$withval],
+  [with_libmultiprocess=auto])
+
+AC_ARG_WITH([mpgen],
+  [AS_HELP_STRING([--with-mpgen=yes|no|auto|PREFIX],
+  [Build with libmultiprocess codegen tool. Useful to specify different libmultiprocess host system library and build system codegen tool prefixes when cross-compiling (default is host system libmultiprocess prefix)])],
+  [with_mpgen=$withval],
+  [with_mpgen=auto])
+
+AC_ARG_ENABLE([multiprocess],
+  [AS_HELP_STRING([--enable-multiprocess],
+  [build multiprocess bitcoin-node, bitcoin-wallet, and bitcoin-gui executables in addition to monolithic bitcoind and bitcoin-qt executables. Requires libmultiprocess library. Experimental (default is no)])],
+  [enable_multiprocess=$enableval],
+  [enable_multiprocess=no])
+
 AC_ARG_ENABLE(man,
     [AS_HELP_STRING([--disable-man],
                     [do not install man pages (default is to install)])],,
@@ -1426,6 +1444,50 @@ AM_CONDITIONAL([EMBEDDED_UNIVALUE],[test x$need_bundled_univalue = xyes])
 AC_SUBST(UNIVALUE_CFLAGS)
 AC_SUBST(UNIVALUE_LIBS)
 
+dnl libmultiprocess library check
+
+libmultiprocess_found=no
+if test "x$with_libmultiprocess" = xyes || test "x$with_libmultiprocess" = xauto; then
+  if test "x$use_pkgconfig" = xyes; then
+    m4_ifdef([PKG_CHECK_MODULES], [PKG_CHECK_MODULES([LIBMULTIPROCESS], [libmultiprocess], [
+       libmultiprocess_found=yes;
+       libmultiprocess_prefix=`$PKG_CONFIG --variable=prefix libmultiprocess`;
+    ], [true])])
+  fi
+elif test "x$with_libmultiprocess" != xno; then
+  AC_MSG_ERROR([--with-libmultiprocess=$with_libmultiprocess value is not yes, auto, or no])
+fi
+AC_SUBST(LIBMULTIPROCESS_CFLAGS)
+AC_SUBST(LIBMULTIPROCESS_LIBS)
+
+dnl Enable multiprocess check
+
+if test "x$enable_multiprocess" = xyes; then
+  if test "x$libmultiprocess_found" != xyes; then
+    AC_MSG_ERROR([--enable-multiprocess=yes option specified but libmultiprocess library was not found. May need to install libmultiprocess library, or specify install path with PKG_CONFIG_PATH environment variable. Running 'pkg-config --debug libmultiprocess' may be helpful for debugging.])
+  fi
+  build_multiprocess=yes
+elif test "x$enable_multiprocess" = xauto; then
+  build_multiprocess=$libmultiprocess_found
+else
+  build_multiprocess=no
+fi
+
+AM_CONDITIONAL([BUILD_MULTIPROCESS],[test "x$build_multiprocess" = xyes])
+AM_CONDITIONAL([BUILD_BITCOIN_NODE], [test "x$build_multiprocess" = xyes])
+AM_CONDITIONAL([BUILD_BITCOIN_GUI], [test "x$build_multiprocess" = xyes])
+
+dnl codegen tools check
+
+if test x$build_multiprocess != xno; then
+  if test "x$with_mpgen" = xyes || test "x$with_mpgen" = xauto; then
+    MPGEN_PREFIX="$libmultiprocess_prefix"
+  elif test "x$with_mpgen" != xno; then
+    MPGEN_PREFIX="$with_mpgen";
+  fi
+  AC_SUBST(MPGEN_PREFIX)
+fi
+
 AC_MSG_CHECKING([whether to build bitcoind])
 AM_CONDITIONAL([BUILD_BITCOIND], [test x$build_bitcoind = xyes])
 AC_MSG_RESULT($build_bitcoind)
@@ -1704,6 +1766,7 @@ esac
 
 echo
 echo "Options used to compile and link:"
+echo "  multiprocess  = $build_multiprocess"
 echo "  with wallet   = $enable_wallet"
 echo "  with gui / qt = $bitcoin_enable_qt"
 if test x$bitcoin_enable_qt != xno; then
diff --git a/doc/multiprocess.md b/doc/multiprocess.md
new file mode 100644
index 0000000000..471d8561f7
--- /dev/null
+++ b/doc/multiprocess.md
@@ -0,0 +1,35 @@
+# Multiprocess Bitcoin
+
+On unix systems, the `--enable-multiprocess` build option can be passed to `./configure` to build new `bitcoin-node`, `bitcoin-wallet`, and `bitcoin-gui` executables alongside existing `bitcoind` and `bitcoin-qt` executables.
+
+`bitcoin-node` is a drop-in replacement for `bitcoind`, and `bitcoin-gui` is a drop-in replacement for `bitcoin-qt`, and there are no differences in use or external behavior between the new and old executables. But internally (after [#10102](https://github.com/bitcoin/bitcoin/pull/10102)), `bitcoin-gui` will spawn a `bitcoin-node` process to run P2P and RPC code, communicating with it across a socket pair, and `bitcoin-node` will spawn `bitcoin-wallet` to run wallet code, also communicating over a socket pair. This will let node, wallet, and GUI code run in separate address spaces for better isolation, and allow future improvements like being able to start and stop components independently on different machines and environments.
+
+## Next steps
+
+Specific next steps after [#10102](https://github.com/bitcoin/bitcoin/pull/10102) will be:
+
+- [ ] Adding `-ipcbind` and `-ipcconnect` options to `bitcoin-node`, `bitcoin-wallet`, and `bitcoin-gui` executables so they can listen and connect to TCP ports and unix socket paths. This will allow separate processes to be started and stopped any time and connect to each other.
+- [ ] Adding `-server` and `-rpcbind` options to the `bitcoin-wallet` executable so wallet processes can handle RPC requests directly without going through the node.
+- [ ] Supporting windows, not just unix systems. The existing socket code is already cross-platform, so the only windows-specific code that needs to be written is code spawning a process and passing a socket descriptor. This can be implemented with `CreateProcess` and `WSADuplicateSocket`. Example: https://memset.wordpress.com/2010/10/13/win32-api-passing-socket-with-ipc-method/.
+- [ ] Adding sandbox features, restricting subprocess access to resources and data. See [https://eklitzke.org/multiprocess-bitcoin](https://eklitzke.org/multiprocess-bitcoin).
+
+## Debugging
+
+After [#10102](https://github.com/bitcoin/bitcoin/pull/10102), the `-debug=ipc` command line option can be used to see requests and responses between processes.
+
+## Installation
+
+The multiprocess feature requires [Cap'n Proto](https://capnproto.org/) and [libmultiprocess](https://github.com/chaincodelabs/libmultiprocess) as dependencies. A simple way to get starting using it without installing these dependencies manually is to use the [depends system](../depends) with the `MULTIPROCESS=1` [dependency option](../depends#dependency-options) passed to make:
+
+```
+cd <BITCOIN_SOURCE_DIRECTORY>
+make -C depends NO_QT=1 MULTIPROCESS=1
+./configure --prefix=$PWD/depends/x86_64-pc-linux-gnu
+make
+src/bitcoin-node -regtest -printtoconsole -debug=ipc
+BITCOIND=bitcoin-node test/functional/test_runner.py
+```
+
+The configure script will pick up settings and library locations from the depends directory, so there is no need to pass `--enable-multiprocess` as a separate flag when using the depends system (it's controlled by the `MULTIPROCESS=1` option).
+
+Alternately, you can install [Cap'n Proto](https://capnproto.org/) and [libmultiprocess](https://github.com/chaincodelabs/libmultiprocess) packages on your system, and just run `./configure --enable-multiprocess` without using the depends system. The configure script will be able to locate the installed packages via [pkg-config](https://www.freedesktop.org/wiki/Software/pkg-config/). See [Installation](https://github.com/chaincodelabs/libmultiprocess#installation) section of the libmultiprocess readme for install steps. See [build-unix.md](build-unix.md) and [build-osx.md](build-osx.md) for information about installing dependencies in general.
diff --git a/src/Makefile.am b/src/Makefile.am
index 627df97cad..a3340aa37b 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -85,6 +85,10 @@ if BUILD_BITCOIND
   bin_PROGRAMS += bitcoind
 endif
 
+if BUILD_BITCOIN_NODE
+  bin_PROGRAMS += bitcoin-node
+endif
+
 if BUILD_BITCOIN_CLI
   bin_PROGRAMS += bitcoin-cli
 endif
@@ -547,22 +551,21 @@ libbitcoin_cli_a_SOURCES = \
 nodist_libbitcoin_util_a_SOURCES = $(srcdir)/obj/build.h
 #
 
-# bitcoind binary #
-bitcoind_SOURCES = bitcoind.cpp
-bitcoind_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
-bitcoind_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
-bitcoind_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
+# bitcoind & bitcoin-node binaries #
+bitcoin_daemon_sources = bitcoind.cpp
+bitcoin_bin_cppflags = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
+bitcoin_bin_cxxflags = $(AM_CXXFLAGS) $(PIE_FLAGS)
+bitcoin_bin_ldflags = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
 
 if TARGET_WINDOWS
-bitcoind_SOURCES += bitcoind-res.rc
+bitcoin_daemon_sources += bitcoind-res.rc
 endif
 
-bitcoind_LDADD = \
-  $(LIBBITCOIN_SERVER) \
+bitcoin_bin_ldadd = \
   $(LIBBITCOIN_WALLET) \
   $(LIBBITCOIN_COMMON) \
-  $(LIBUNIVALUE) \
   $(LIBBITCOIN_UTIL) \
+  $(LIBUNIVALUE) \
   $(LIBBITCOIN_ZMQ) \
   $(LIBBITCOIN_CONSENSUS) \
   $(LIBBITCOIN_CRYPTO) \
@@ -571,7 +574,19 @@ bitcoind_LDADD = \
   $(LIBMEMENV) \
   $(LIBSECP256K1)
 
-bitcoind_LDADD += $(BOOST_LIBS) $(BDB_LIBS) $(MINIUPNPC_LIBS) $(EVENT_PTHREADS_LIBS) $(EVENT_LIBS) $(ZMQ_LIBS)
+bitcoin_bin_ldadd += $(BOOST_LIBS) $(BDB_LIBS) $(MINIUPNPC_LIBS) $(EVENT_PTHREADS_LIBS) $(EVENT_LIBS) $(ZMQ_LIBS)
+
+bitcoind_SOURCES = $(bitcoin_daemon_sources)
+bitcoind_CPPFLAGS = $(bitcoin_bin_cppflags)
+bitcoind_CXXFLAGS = $(bitcoin_bin_cxxflags)
+bitcoind_LDFLAGS = $(bitcoin_bin_ldflags)
+bitcoind_LDADD = $(LIBBITCOIN_SERVER) $(bitcoin_bin_ldadd)
+
+bitcoin_node_SOURCES = $(bitcoin_daemon_sources)
+bitcoin_node_CPPFLAGS = $(bitcoin_bin_cppflags)
+bitcoin_node_CXXFLAGS = $(bitcoin_bin_cxxflags)
+bitcoin_node_LDFLAGS = $(bitcoin_bin_ldflags)
+bitcoin_node_LDADD = $(LIBBITCOIN_SERVER) $(bitcoin_bin_ldadd)
 
 # bitcoin-cli binary #
 bitcoin_cli_SOURCES = bitcoin-cli.cpp
@@ -615,29 +630,14 @@ bitcoin_tx_LDADD += $(BOOST_LIBS)
 
 # bitcoin-wallet binary #
 bitcoin_wallet_SOURCES = bitcoin-wallet.cpp
-bitcoin_wallet_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
-bitcoin_wallet_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
-bitcoin_wallet_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
+bitcoin_wallet_CPPFLAGS = $(bitcoin_bin_cppflags)
+bitcoin_wallet_CXXFLAGS = $(bitcoin_bin_cxxflags)
+bitcoin_wallet_LDFLAGS = $(bitcoin_bin_ldflags)
+bitcoin_wallet_LDADD = $(LIBBITCOIN_WALLET_TOOL) $(bitcoin_bin_ldadd)
 
 if TARGET_WINDOWS
 bitcoin_wallet_SOURCES += bitcoin-wallet-res.rc
 endif
-
-bitcoin_wallet_LDADD = \
-  $(LIBBITCOIN_WALLET_TOOL) \
-  $(LIBBITCOIN_WALLET) \
-  $(LIBBITCOIN_COMMON) \
-  $(LIBBITCOIN_CONSENSUS) \
-  $(LIBBITCOIN_UTIL) \
-  $(LIBBITCOIN_CRYPTO) \
-  $(LIBBITCOIN_ZMQ) \
-  $(LIBLEVELDB) \
-  $(LIBLEVELDB_SSE42) \
-  $(LIBMEMENV) \
-  $(LIBSECP256K1) \
-  $(LIBUNIVALUE)
-
-bitcoin_wallet_LDADD += $(BOOST_LIBS) $(BDB_LIBS) $(EVENT_PTHREADS_LIBS) $(EVENT_LIBS) $(MINIUPNPC_LIBS) $(ZMQ_LIBS)
 #
 
 # bitcoinconsensus library #
diff --git a/src/Makefile.qt.include b/src/Makefile.qt.include
index cf09eee2cb..13bfea7646 100644
--- a/src/Makefile.qt.include
+++ b/src/Makefile.qt.include
@@ -3,6 +3,11 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 bin_PROGRAMS += qt/bitcoin-qt
+
+if BUILD_BITCOIN_GUI
+  bin_PROGRAMS += bitcoin-gui
+endif
+
 EXTRA_LIBRARIES += qt/libbitcoinqt.a
 
 # bitcoin qt core #
@@ -294,29 +299,43 @@ QT_FORMS_H=$(join $(dir $(QT_FORMS_UI)),$(addprefix ui_, $(notdir $(QT_FORMS_UI:
 # Most files will depend on the forms and moc files as includes. Generate them
 # before anything else.
 $(QT_MOC): $(QT_FORMS_H)
-$(qt_libbitcoinqt_a_OBJECTS) $(qt_bitcoin_qt_OBJECTS) : | $(QT_MOC)
+$(qt_libbitcoinqt_a_OBJECTS) $(qt_bitcoin_qt_OBJECTS) $(bitcoin_gui_OBJECTS) : | $(QT_MOC)
 
-# bitcoin-qt binary #
-qt_bitcoin_qt_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(BITCOIN_QT_INCLUDES) \
+# bitcoin-qt and bitcoin-gui binaries #
+bitcoin_qt_cppflags = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(BITCOIN_QT_INCLUDES) \
   $(QT_INCLUDES) $(QR_CFLAGS)
-qt_bitcoin_qt_CXXFLAGS = $(AM_CXXFLAGS) $(QT_PIE_FLAGS)
+bitcoin_qt_cxxflags = $(AM_CXXFLAGS) $(QT_PIE_FLAGS)
 
-qt_bitcoin_qt_SOURCES = qt/main.cpp
+bitcoin_qt_sources = qt/main.cpp
 if TARGET_WINDOWS
-  qt_bitcoin_qt_SOURCES += $(BITCOIN_RC)
+  bitcoin_qt_sources += $(BITCOIN_RC)
 endif
-qt_bitcoin_qt_LDADD = qt/libbitcoinqt.a $(LIBBITCOIN_SERVER)
+bitcoin_qt_ldadd = qt/libbitcoinqt.a $(LIBBITCOIN_SERVER)
 if ENABLE_WALLET
-qt_bitcoin_qt_LDADD += $(LIBBITCOIN_UTIL) $(LIBBITCOIN_WALLET)
+bitcoin_qt_ldadd += $(LIBBITCOIN_UTIL) $(LIBBITCOIN_WALLET)
 endif
 if ENABLE_ZMQ
-qt_bitcoin_qt_LDADD += $(LIBBITCOIN_ZMQ) $(ZMQ_LIBS)
+bitcoin_qt_ldadd += $(LIBBITCOIN_ZMQ) $(ZMQ_LIBS)
 endif
-qt_bitcoin_qt_LDADD += $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBITCOIN_UTIL) $(LIBBITCOIN_CONSENSUS) $(LIBBITCOIN_CRYPTO) $(LIBUNIVALUE) $(LIBLEVELDB) $(LIBLEVELDB_SSE42) $(LIBMEMENV) \
+bitcoin_qt_ldadd += $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBITCOIN_UTIL) $(LIBBITCOIN_CONSENSUS) $(LIBBITCOIN_CRYPTO) $(LIBUNIVALUE) $(LIBLEVELDB) $(LIBLEVELDB_SSE42) $(LIBMEMENV) \
   $(BOOST_LIBS) $(QT_LIBS) $(QT_DBUS_LIBS) $(QR_LIBS) $(BDB_LIBS) $(MINIUPNPC_LIBS) $(LIBSECP256K1) \
   $(EVENT_PTHREADS_LIBS) $(EVENT_LIBS)
-qt_bitcoin_qt_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(QT_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
-qt_bitcoin_qt_LIBTOOLFLAGS = $(AM_LIBTOOLFLAGS) --tag CXX
+bitcoin_qt_ldflags = $(RELDFLAGS) $(AM_LDFLAGS) $(QT_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
+bitcoin_qt_libtoolflags = $(AM_LIBTOOLFLAGS) --tag CXX
+
+qt_bitcoin_qt_CPPFLAGS = $(bitcoin_qt_cppflags)
+qt_bitcoin_qt_CXXFLAGS = $(bitcoin_qt_cxxflags)
+qt_bitcoin_qt_SOURCES = $(bitcoin_qt_sources)
+qt_bitcoin_qt_LDADD = $(bitcoin_qt_ldadd)
+qt_bitcoin_qt_LDFLAGS = $(bitcoin_qt_ldflags)
+qt_bitcoin_qt_LIBTOOLFLAGS = $(bitcoin_qt_libtoolflags)
+
+bitcoin_gui_CPPFLAGS = $(bitcoin_qt_cppflags)
+bitcoin_gui_CXXFLAGS = $(bitcoin_qt_cxxflags)
+bitcoin_gui_SOURCES = $(bitcoin_qt_sources)
+bitcoin_gui_LDADD = $(bitcoin_qt_ldadd)
+bitcoin_gui_LDFLAGS = $(bitcoin_qt_ldflags)
+bitcoin_gui_LIBTOOLFLAGS = $(bitcoin_qt_libtoolflags)
 
 #locale/foo.ts -> locale/foo.qm
 QT_QM=$(QT_TS:.ts=.qm)