From 80f54a7eaa372c89bc12994f9940d55c91fc4361 Mon Sep 17 00:00:00 2001
From: Hennadii Stepanov <32963518+hebasto@users.noreply.github.com>
Date: Mon, 29 Jan 2024 16:18:23 +0000
Subject: [PATCH] cmake: Add external signer support

---
 CMakeLists.txt                      |  6 ++++
 cmake/bitcoin-config.h.in           |  3 ++
 cmake/module/AddBoostIfNeeded.cmake | 49 ++++++++++++++++++++++++++++-
 3 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 915bb321c6cf1e..67dd54de511589 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -69,6 +69,11 @@ tristate_option(WITH_USDT
   "if sys/sdt.h is found."
   AUTO
 )
+tristate_option(WITH_EXTERNAL_SIGNER
+  "Enable external signer support."
+  "if Boost.Process is found."
+  AUTO
+)
 
 option(BUILD_TESTS "Build test_bitcoin executable." ON)
 option(BUILD_BENCH "Build bench_bitcoin executable." ON)
@@ -399,6 +404,7 @@ message("  SQLite, descriptor wallets .......... ${WITH_SQLITE}")
 message("  Berkeley DB, legacy wallets ......... ${WITH_BDB}")
 message("Optional packages:")
 message("  GUI ................................. ${WITH_GUI}")
+message("  external signer ..................... ${WITH_EXTERNAL_SIGNER}")
 message("  NAT-PMP ............................. ${WITH_NATPMP}")
 message("  UPnP ................................ ${WITH_MINIUPNPC}")
 message("  ZeroMQ .............................. ${WITH_ZMQ}")
diff --git a/cmake/bitcoin-config.h.in b/cmake/bitcoin-config.h.in
index ebbb97562cdb01..23033593867043 100644
--- a/cmake/bitcoin-config.h.in
+++ b/cmake/bitcoin-config.h.in
@@ -215,4 +215,7 @@
 /* Define if Berkeley DB (BDB) support should be compiled in. */
 #cmakedefine USE_BDB
 
+/* Define if external signer support is enabled. */
+#cmakedefine ENABLE_EXTERNAL_SIGNER
+
 #endif //BITCOIN_CONFIG_H
diff --git a/cmake/module/AddBoostIfNeeded.cmake b/cmake/module/AddBoostIfNeeded.cmake
index 179887d24bb153..ead1e0b7a25ee2 100644
--- a/cmake/module/AddBoostIfNeeded.cmake
+++ b/cmake/module/AddBoostIfNeeded.cmake
@@ -19,6 +19,7 @@ function(add_boost_if_needed)
 
   set(Boost_NO_BOOST_CMAKE ON)
   find_package(Boost 1.73.0 REQUIRED)
+  mark_as_advanced(Boost_INCLUDE_DIR)
   set_target_properties(Boost::headers PROPERTIES IMPORTED_GLOBAL TRUE)
   target_compile_definitions(Boost::headers INTERFACE
     # We don't use multi_index serialization.
@@ -48,5 +49,51 @@ function(add_boost_if_needed)
     endif()
   endif()
 
-  mark_as_advanced(Boost_INCLUDE_DIR)
+  if(WITH_EXTERNAL_SIGNER)
+    include(CheckCXXSourceCompiles)
+    set(CMAKE_REQUIRED_INCLUDES ${Boost_INCLUDE_DIR})
+    set(CMAKE_REQUIRED_FLAGS "${working_compiler_werror_flag}")
+    # Boost 1.78 requires the following workaround.
+    # See: https://github.com/boostorg/process/issues/235
+    string(APPEND CMAKE_REQUIRED_FLAGS " -Wno-error=narrowing")
+    check_cxx_source_compiles("
+      #define BOOST_PROCESS_USE_STD_FS
+      #include <boost/process.hpp>
+      #include <string>
+
+      int main()
+      {
+        namespace bp = boost::process;
+        bp::opstream stdin_stream;
+        bp::ipstream stdout_stream;
+        bp::child c(\"dummy\", bp::std_out > stdout_stream, bp::std_err > stdout_stream, bp::std_in < stdin_stream);
+        stdin_stream << std::string{\"test\"} << std::endl;
+        if (c.running()) c.terminate();
+        c.wait();
+        c.exit_code();
+      }
+      " HAVE_BOOST_PROCESS
+    )
+    if(HAVE_BOOST_PROCESS)
+      if(WIN32)
+        # Boost Process for Windows uses Boost ASIO. Boost ASIO performs
+        # pre-main init of Windows networking libraries, which we do not
+        # want.
+        set(WITH_EXTERNAL_SIGNER OFF PARENT_SCOPE)
+        set(ENABLE_EXTERNAL_SIGNER OFF PARENT_SCOPE)
+      else()
+        set(WITH_EXTERNAL_SIGNER ON PARENT_SCOPE)
+        set(ENABLE_EXTERNAL_SIGNER ON PARENT_SCOPE)
+        target_compile_definitions(Boost::headers INTERFACE
+          BOOST_PROCESS_USE_STD_FS
+        )
+      endif()
+    elseif(WITH_EXTERNAL_SIGNER STREQUAL "AUTO")
+      set(WITH_EXTERNAL_SIGNER OFF PARENT_SCOPE)
+      set(ENABLE_EXTERNAL_SIGNER OFF PARENT_SCOPE)
+    else()
+      message(FATAL_ERROR "External signing is not supported for this Boost version.")
+    endif()
+  endif()
+
 endfunction()