Build the OpenFX plugin for Linux, where Resolve also runs

Resolve is a Linux application and the OFX plugin has only ever shipped for
macOS and Windows. Nothing in the OFX render is platform-specific -- it is a
CPU pass over a host-supplied buffer -- so what was missing was a way to
configure the project without the FFGL half.

OLDCATHODE_BUILD_FFGL, the option idler already carries, is that way. The FFGL
plugin, the SDK submodule and GLEW are one dependency group; turning it off
leaves the OFX target with no GL loader anywhere in the configure, which
matters because the SDK's own find_package(GLEW REQUIRED) would otherwise fail
at configure time on a machine that needs no GL at all.

The job builds in an AlmaLinux 8 container rather than on the ubuntu image, for
glibc 2.28 against 2.39: Resolve's supported Linux is Rocky 8.6, and a plugin
linked against a newer glibc is refused by the loader there, while anything
newer loads a 2.28 build fine. gcc-toolset-13 supplies the compiler and its
runtime is linked statically, since it is not installed on a stock Rocky 8.
The collect step asserts the glibc floor rather than trusting the image.

Not yet loaded into Resolve on Linux -- this is a build, not a measurement.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: stoatworks-labs

.github/workflows/release.yml

@@ -178,9 +178,98 @@ jobs:
           path: installers/*
           if-no-files-found: warn
 
+  linux-ofx:
+    name: linux-x86_64 (OpenFX)
+    runs-on: ubuntu-latest
+    # AlmaLinux 8 rather than the ubuntu image, for glibc 2.28 against 2.39.
+    # Resolve's supported Linux is Rocky 8.6, and a plugin linked against a
+    # newer glibc is refused by the loader on the distro Blackmagic actually
+    # ships for -- while anything newer than Rocky 8 loads a 2.28 build
+    # perfectly well. This is the widest target, not a concession.
+    #
+    # There is no FFGL half to this job. Resolume has no Linux build, the FFGL
+    # SDK has no Linux path, and the OpenFX plugin is a CPU render that never
+    # makes a GL call.
+    container: almalinux:8
+    steps:
+      # Ahead of checkout on purpose: actions/checkout shells out to git and
+      # the base image has none. gcc-toolset-13 because the stock gcc 8.5
+      # predates parts of the C++17 library this code uses.
+      - name: Toolchain
+        run: |
+          dnf -y install git cmake zip binutils gcc-toolset-13
+          source /opt/rh/gcc-toolset-13/enable
+          gcc --version
+
+      # No submodules: the FFGL SDK is the only one and this job does not build
+      # FFGL. The OpenFX SDK subset is vendored in-tree.
+      - uses: actions/checkout@v7
+
+      # OLDCATHODE_BUILD_FFGL=OFF is what makes the job possible at all. With it
+      # ON, the SDK's own find_package(GLEW REQUIRED) fails at CONFIGURE time,
+      # so the build dies before compiling a line of a plugin that needs no GL
+      # loader.
+      #
+      # Static libstdc++/libgcc because gcc-toolset-13's runtime is not
+      # installed on a stock Rocky or Alma 8 -- a dynamically linked build
+      # would fail to load on precisely the machines this targets.
+      - name: Configure
+        run: |
+          source /opt/rh/gcc-toolset-13/enable
+          cmake -B build \
+            -DCMAKE_BUILD_TYPE=Release \
+            -DOLDCATHODE_BUILD_FFGL=OFF \
+            -DOLDCATHODE_BUILD_TOOLS=OFF \
+            -DCMAKE_CXX_FLAGS="-static-libstdc++ -static-libgcc"
+
+      - name: Build
+        run: |
+          source /opt/rh/gcc-toolset-13/enable
+          cmake --build build --parallel
+
+      - name: Collect artifact
+        run: |
+          so="build/OldCathode.ofx.bundle/Contents/Linux-x86-64/OldCathode.ofx"
+          test -f "$so"
+
+          # `nm ... | grep -q` SIGPIPEs under `bash -eo pipefail` when grep
+          # FINDS its match, failing the release on a correct binary. Captured
+          # and matched with `case` instead, as the macOS job does.
+          __syms=$( nm -D --defined-only "$so" )
+          case "$__syms" in
+            *OfxGetPlugin*) ;;
+            *) echo "expected OfxGetPlugin, got: $__syms"; exit 1 ;;
+          esac
+
+          # The whole reason for the container, asserted rather than assumed:
+          # the highest glibc symbol version the binary asks for must not be
+          # newer than Rocky 8's 2.28. Building in the right image is easy to
+          # get right and impossible to notice getting wrong.
+          __glibc=$( objdump -T "$so" | grep -o 'GLIBC_[0-9.]*' | sort -uV | tail -1 )
+          echo "highest glibc requirement: $__glibc"
+          if [ "$( printf '%s\nGLIBC_2.28\n' "$__glibc" | sort -uV | tail -1 )" != "GLIBC_2.28" ]; then
+            echo "$__glibc is newer than Rocky 8 provides"; exit 1
+          fi
+          readelf -d "$so" | grep NEEDED
+
+          mkdir -p "ofxout/OldCathode.ofx.bundle/Contents/Linux-x86-64"
+          cp "$so" "ofxout/OldCathode.ofx.bundle/Contents/Linux-x86-64/OldCathode.ofx"
+          ls -R ofxout
+
+      - name: Archive (zip)
+        run: |
+          cd ofxout
+          zip -r "../old-cathode-ofx-linux-x86_64.zip" ./*
+
+      - uses: actions/upload-artifact@v7
+        with:
+          name: old-cathode-linux-x86_64
+          path: "*.zip"
+          if-no-files-found: error
+
   release:
     name: Publish release
-    needs: [build, windows-installer]
+    needs: [build, linux-ofx, windows-installer]
     if: startsWith(github.ref, 'refs/tags/v')
     runs-on: ubuntu-latest
     steps:

CMakeLists.txt

@@ -32,6 +32,14 @@ endif()
 
 option(OLDCATHODE_BUILD_TOOLS "Build the offline render harness" ON)
 
+# The FFGL plugin, the FFGL SDK submodule and GLEW are one dependency group,
+# and the OpenFX plugin belongs to none of it. Turning this OFF builds the OFX
+# plugin alone, with no GL loader anywhere in the configure -- which is what
+# the Linux job does, because the FFGL SDK has no Linux path, and GLEW would
+# otherwise have to be installed to build something that never calls it.
+option(OLDCATHODE_BUILD_FFGL "Build the FFGL plugin (needs the FFGL SDK and, off macOS, GLEW)" ON)
+
+if(OLDCATHODE_BUILD_FFGL)
 # ---------------------------------------------------------------------------
 # The Resolume FFGL SDK, as a git submodule under external/.
 # ---------------------------------------------------------------------------
@@ -135,6 +143,8 @@ elseif(APPLE)
         CACHE PATH "" FORCE)
 endif()
 
+endif()  # OLDCATHODE_BUILD_FFGL
+
 # ---------------------------------------------------------------------------
 # The OpenFX build of the same effect, for Resolve/Vegas/Nuke/Natron. CPU
 # render against the vendored OFX SDK subset under external/openfx (C headers
@@ -195,7 +205,9 @@ if(BUILD_OFX)
     endif()
 endif()
 
+if(OLDCATHODE_BUILD_FFGL)
 install(TARGETS OldCathode
     LIBRARY DESTINATION "."
     BUNDLE  DESTINATION "."
 )
+endif()  # OLDCATHODE_BUILD_FFGL