Squashed 'src/ipc/libmultiprocess/' changes from a4f92969649..1fc65008f7d

1fc65008f7d Merge bitcoin-core/libmultiprocess#237: Made SpawnProcess() behavior safe post fork()
5205a87cd90 test: check SpawnProcess post-fork safety
69652f0edfa Precompute argv before fork in SpawnProcess
30a8681de62 SpawnProcess: avoid fd leak on close failure
d0fc1081d09 Merge bitcoin-core/libmultiprocess#196: ci: Add NetBSD job
7b171f45bfc Merge bitcoin-core/libmultiprocess#234: doc: Fix typos and grammar in documentation and comments
861da39cae9 ci: Add NetBSD job
458745e3940 Fix various typos, spelling mistakes, and grammatical errors in design.md and source code comments.
585decc8561 Merge bitcoin-core/libmultiprocess#236: ci: Install binary package `capnproto` on OpenBSD instead of building it
14e926a3ff3 refactor: extract MakeArgv helper
1ee909393f4 ci: Install binary package `capnproto` on OpenBSD instead of building it
470fc518d4b Merge bitcoin-core/libmultiprocess#230: cmake: add ONLY_CAPNP target_capnp_sources option
2d8886f26c4 Merge bitcoin-core/libmultiprocess#228: Add versions.md and version.h files describing version branches and tags
c1838be565d Merge bitcoin-core/libmultiprocess#225: Improve and document act support
a173f1704ce Merge bitcoin-core/libmultiprocess#223: ci: Replace nix-shell with equivalent nix develop command
625eaca42fb Merge bitcoin-core/libmultiprocess#229: Design Documentation Update
cc234be73a6 Design doc update
81c652687b8 cmake: add ONLY_CAPNP target_capnp_sources option
6e01d2d766e Add versions.md and version.h files describing version branches and tags
4e3f8fa0d2c doc: add instructions for using act
81712ff6bbf ci: disable KVM and sandbox inside act containers
18a2237a8ef ci: Replace nix-shell with equivalent nix develop command

git-subtree-dir: src/ipc/libmultiprocess
git-subtree-split: 1fc65008f7d64161e84c08cbd93109a23dd6a1e9

.github/workflows/ci.yml

@@ -5,6 +5,66 @@ on:
   pull_request:
 
 jobs:
+  build-netbsd:
+    runs-on: ubuntu-latest
+    name: build • netbsd ${{ matrix.release }}
+    defaults:
+      run:
+        shell: netbsd {0}
+    strategy:
+      fail-fast: false
+      matrix:
+        # Test all supported releases.
+        # See https://www.netbsd.org/releases/.
+        include:
+          - release: 9.4
+            capnproto-cppflags: 'CPPFLAGS="-DKJ_NO_EXCEPTIONS=0 -DKJ_USE_KQUEUE=0"'
+          - release: 10.1
+            capnproto-cppflags: 'CPPFLAGS="-DKJ_NO_EXCEPTIONS=0"'
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Start NetBSD VM
+        uses: vmactions/netbsd-vm@v1
+        with:
+          release: ${{ matrix.release }}
+          # The installed compiler version must match the CXX variable
+          # defined in `ci/configs/netbsd.bash`.
+          prepare: |
+            pkg_add cmake ninja-build gcc14
+          # capnproto prerequisites.
+          # See the following "Install capnproto" step.
+          run: |
+            set -e
+            pkg_add digest libtool-base mktools pkgconf cwrappers
+            pkg_admin -K /usr/pkg/pkgdb fetch-pkg-vulnerabilities
+            cd /usr
+            cvs -danoncvs@anoncvs.NetBSD.org:/cvsroot checkout -P \
+              pkgsrc/devel/capnproto \
+              pkgsrc/devel/libtool-base \
+              pkgsrc/devel/pkgconf \
+              pkgsrc/devel/zlib \
+              `# gcc15 is referenced here because the pkgsrc framework requires lang/gcc15/version.mk to exist` \
+              `# during the "make install" step below, even though we compile our project with gcc14.` \
+              pkgsrc/lang/gcc15 \
+              pkgsrc/mk \
+              pkgsrc/pkgtools \
+              pkgsrc/security/openssl \
+              pkgsrc/sysutils/install-sh/files
+          sync: 'rsync'
+          copyback: false
+
+      - name: Install capnproto
+        run: |
+          cd /usr/pkgsrc/devel/capnproto/
+          unset PKG_PATH
+          make ${{ matrix.capnproto-cppflags }} install
+
+      - name: Run CI script
+        run: |
+          cd ${{ github.workspace }}
+          CI_CONFIG="ci/configs/netbsd.bash" bash ci/scripts/ci.sh
+
   build-openbsd:
     runs-on: ubuntu-latest
     name: build • openbsd
@@ -18,17 +78,10 @@ jobs:
         uses: vmactions/openbsd-vm@v1
         with:
           prepare: |
-            pkg_add -v cmake ninja git bash
-          run: |
-            git clone --depth=1 https://codeberg.org/OpenBSD/ports.git /usr/ports
+            pkg_add -v cmake ninja bash capnproto
           sync: 'rsync'
           copyback: false
 
-      - name: Install capnproto
-        run: |
-          cd /usr/ports/devel/capnproto/
-          make install
-
       - name: Run CI script
         run: |
           cd ${{ github.workspace }}
@@ -76,6 +129,11 @@ jobs:
   build:
     runs-on: ubuntu-latest
 
+    env:
+      NIX_EXTRA_CONFIG_ACT: |
+        sandbox = false
+        filter-syscalls = false
+
     strategy:
       fail-fast: false
       matrix:
@@ -90,6 +148,10 @@ jobs:
         uses: cachix/install-nix-action@v31       # 2025-05-27, from https://github.com/cachix/install-nix-action/tags
         with:
           nix_path: nixpkgs=channel:nixos-25.05   # latest release
+          # Act executes inside an unprivileged container (Docker or Podman),
+          # so KVM support isn't available.
+          enable_kvm: "${{ github.actor != 'nektos/act' }}"
+          extra_nix_config: ${{ github.actor == 'nektos/act' && env.NIX_EXTRA_CONFIG_ACT || '' }}
 
       - name: Run CI script
         env: