mpv-natives/.github/workflows/build-linux.yml

name: build-linux

# Builds a single self-contained libmpv.so for Linux (x86_64) from mpv source
# pinned to a release tag. Every video dependency is built static and linked
# into the one .so; glibc/pthread/dl/m, the system zlib and the system audio
# stack (PipeWire / PulseAudio / ALSA) stay external, mirroring CoreAudio
# (macOS) and WASAPI (Windows), so the OS audio is left dynamic and
# everything else is self contained.
#
# Linux is the easiest of the three platforms: a single native build on an
# ubuntu runner, no cross-compile, no lipo. The only Linux-specific work is the
# font stack: libass (a hard mpv dependency) needs fontconfig (-> expat) where
# macOS/Windows use CoreText/DirectWrite.
#
# Pinned to the mpv tag in ci/versions.env - the version whose client API
# (131077) the jlibmpv JNA bindings are validated against. Bump MPV_REF (and
# the dependency pins) there for a libmpv update. The build recipe
# (dependency versions, static flags) lives in ci/build-libmpv-linux.sh.
#
# Triggers: pull requests (all three build workflows act as the PR check),
# manual workflow_dispatch, and workflow_call from release.yml on tag push.
# A push to main builds nothing on its own.

on:
  pull_request:
  workflow_dispatch:
  workflow_call:
    # A called (reusable) workflow only exposes top-level `workflow_call`
    # outputs to the caller - job outputs are not. release.yml needs the
    # mpv version to name the release assets, so expose it here.
    outputs:
      version:
        description: mpv version the built artifact was compiled from
        value: ${{ jobs.linux.outputs.version }}

env:
  TARGET: x86_64-linux

jobs:
  linux:
    runs-on: ubuntu-24.04
    outputs:
      artifact-name: ${{ steps.artifact.outputs.name }}
      version: ${{ steps.artifact.outputs.version }}
    env:
      CCACHE_BASEDIR: ${{ github.workspace }}
      CCACHE_DIR: ${{ github.workspace }}/.ccache
      CCACHE_MAXSIZE: 500M
    steps:
      - name: Check out mpv-natives (build scripts)
        uses: actions/checkout@v4
        with:
          fetch-depth: 1

      - name: Load pinned versions
        id: versions
        run: |
          source ci/versions.env
          echo "mpv_ref=$MPV_REF" >> "$GITHUB_OUTPUT"

      - name: Check out mpv (pinned tag)
        uses: actions/checkout@v4
        with:
          repository: mpv-player/mpv
          ref: ${{ steps.versions.outputs.mpv_ref }}
          path: mpv
          fetch-depth: 1

      - name: Get time
        id: get_time
        run: echo "timestamp=$(date +%s%N)" >> $GITHUB_OUTPUT

      - name: Restore ccache
        uses: actions/cache/restore@v4
        with:
          path: ${{ env.CCACHE_DIR }}
          key: ${{ env.TARGET }}-${{ steps.get_time.outputs.timestamp }}
          restore-keys: ${{ env.TARGET }}-

      - name: Install dependencies
        run: |
          sudo apt-get update
          sudo apt-get install --no-install-recommends -y \
            ccache nasm ninja-build pkgconf cmake \
            libasound2-dev libpulse-dev libpipewire-0.3-dev
          python3 -m pip install meson

      # Run the vendored build script from inside the mpv source tree, so the
      # native build writes linux_prefix/ and the meson build next to mpv's
      # meson.build and produces the self-contained .so in mpv/artifact/.
      - name: Build self-contained libmpv
        working-directory: mpv
        run: bash "${{ github.workspace }}/ci/build-libmpv-linux.sh"

      - name: Print meson log on failure
        if: failure()
        run: cat mpv/linux_build/meson-logs/meson-log.txt

      - name: Collect artifact
        run: |
          mkdir -p artifact-libmpv
          cp -pv mpv/artifact/libmpv.so artifact-libmpv/
          echo "=== contents ==="
          ls -l artifact-libmpv

      # Verify the artifact is self-contained and portable:
      #   (1) ldd shows only system libs - and among them libasound.so.2,
      #       because audio is left to the OS stack (CoreAudio/WASAPI model),
      #   (2) no .debug sections remain (strip worked, artifact stays small).
      # fontconfig bakes its build prefix into the binary, but that is benign:
      # with no config file at that path it falls back to a built-in config
      # that scans /usr/share/fonts, so we do NOT fail on those strings.
      - name: Verify artifact (ldd, size, alsa is a system lib)
        run: |
          cd artifact-libmpv
          echo "=== dynamic deps (system libs only) ==="
          ldd libmpv.so
          echo "=== debug sections (expect 0) ==="
          readelf -S libmpv.so | grep -c '\.debug' || true
          echo "=== size ==="
          du -h libmpv.so
          echo "=== system audio libs present (pipewire/pulse/alsa, not vendored) ==="
          if ldd libmpv.so | grep -Eq 'libpipewire-0\.3|libpulse\.so|libasound\.so'; then
            echo "OK: at least one system audio lib present, as intended"
          else
            echo "ERROR: libmpv.so links no audio backend (no sound?)"
            exit 1
          fi

      - name: Checksums
        run: |
          cd artifact-libmpv
          sha256sum libmpv.so > checksums.txt
          cat checksums.txt

      - name: Artifact name
        id: artifact
        run: |
          VER=$(cat mpv/MPV_VERSION | tr -d '[:space:]')
          # Intermediate artifact is a per-platform directory (zipped by
          # upload-artifact) containing libmpv.so + checksums.txt. release.yml
          # downloads it and re-uploads the bare .so as the final release asset
          # named <name>-<VER>.so.
          echo "name=mpv-natives-linux-x86_64" >> "$GITHUB_OUTPUT"
          echo "version=$VER" >> "$GITHUB_OUTPUT"

      - name: Upload artifact
        uses: actions/upload-artifact@v4
        with:
          name: ${{ steps.artifact.outputs.name }}
          path: artifact-libmpv

      - name: Save ccache
        uses: actions/cache/save@v4
        if: always()
        with:
          path: ${{ env.CCACHE_DIR }}
          key: ${{ env.TARGET }}-${{ steps.get_time.outputs.timestamp }}