Merge bitcoin/bitcoin#28967: build: disable external-signer for Windows

308aec3e5655327d98e0428d8205d246f24d6af5 build: disable external-signer for Windows (fanquake)
35537318a19360ddf1ea8f0c1e6d8ad49e635516 ci: remove --enable-external-signer from win64 job (fanquake)

Pull request description:

  It's come to light that Boost ASIO (a Boost Process sub dep) has in some
  instances, been quietly  initialising our network stack on Windows (see
  PR https://github.com/bitcoin/bitcoin/pull/28486 and discussion in https://github.com/bitcoin/bitcoin/issues/28940).

  This has been shielding a bug in our own code, but the larger issue
  is that Boost Process/ASIO is running code before main, and doing things
  like setting up networking. This undermines our own assumptions about
  how our binary works, happens before we run any sanity checks,
  and before we call our own code to setup networking. Note that ASIO also
  calls WSAStartup with version `2.0`, whereas we call with `2.2`.

  It's also not clear why a feature like external signer would have a
  dependency that would be doing anything network/socket related,
  given it only exists to spawn a local process.

  See also the discussion in https://github.com/bitcoin/bitcoin/issues/24907. Note that the maintaince of Boost Process in general,
  has not really improved. For example, rather than fixing bugs like https://github.com/boostorg/process/issues/111,
  i.e, https://github.com/boostorg/process/pull/317, the maintainer chooses to just wrap exception causing overflows
  in try-catch blocks: https://github.com/boostorg/process/commit/0c42a58eacab6a96b19196e399307bad8a938a27. These changes get merged in large,
  unreviewed PRs, i.e https://github.com/boostorg/process/pull/319.

  This PR disables external-signer on Windows for now. If, in future, someone
  changes how Boost Process works, or replaces it entirely with some
  properly reviewed and maintained code, we could reenable this feature on
  Windows.

ACKs for top commit:
  hebasto:
    re-ACK 308aec3e5655327d98e0428d8205d246f24d6af5.
  TheCharlatan:
    ACK 308aec3e5655327d98e0428d8205d246f24d6af5

Tree-SHA512: 7405f7fc9833eeaacd6836c4e5b1c1a7845a40c1fdd55c1060152f8d8189e4777464fde650e11eb1539556a75dddf49667105987078b1457493ee772945da66e

1 files changed, 13 insertions, 3 deletions

diff --git a/configure.ac b/configure.ac
index 58235d67c6..18b00a2b16 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1505,9 +1505,19 @@ if test "$use_external_signer" != "no"; then
   CXXFLAGS="$TEMP_CXXFLAGS"
   AC_MSG_RESULT([$have_boost_process])
   if test "$have_boost_process" = "yes"; then
-    use_external_signer="yes"
-    AC_DEFINE([ENABLE_EXTERNAL_SIGNER], [1], [Define if external signer support is enabled])
-    AC_DEFINE([BOOST_PROCESS_USE_STD_FS], [1], [Defined to avoid Boost::Process trying to use Boost Filesystem])
+    case $host in
+      dnl Boost Process for Windows uses Boost ASIO. Boost ASIO performs
+      dnl pre-main init of Windows networking libraries, which we do not
+      dnl want.
+      *mingw*)
+        use_external_signer="no"
+      ;;
+      *)
+        use_external_signer="yes"
+        AC_DEFINE([ENABLE_EXTERNAL_SIGNER], [1], [Define if external signer support is enabled])
+        AC_DEFINE([BOOST_PROCESS_USE_STD_FS], [1], [Defined to avoid Boost::Process trying to use Boost Filesystem])
+      ;;
+    esac
   else
     if test "$use_external_signer" = "yes"; then
       AC_MSG_ERROR([External signing is not supported for this Boost version])