CI: use evergreen runners; update actions.

GitHub will continue to merrily deprecate and remove old runner
environments, as is their prerogative. However, the simplest way to
produce a library with a low minimum glibc version requirement is to
build in an environment having an old glibc. Not only does Ubuntu 18.04
have a fairly old glibc (v2.27), but the symbol versions our library
links against require only glibc v2.7 (on x86_64; somewhat higher for
some of the other architectures).

Having previously fixed cross-compilation compatibility with GCC 8, we
are no longer able to build with GCC 7-based compilers. Thankfully,
Ubuntu did package GCC 8 on 18.04; it's just not the default.

.github/workflows/build.yml

@@ -6,23 +6,32 @@ on:
 jobs:
  natives-linux-windows:
  name: Linux (x86/ARM/PPC) and Windows native library compilation
- runs-on: ubuntu-18.04
+ runs-on: ubuntu-latest
+ container:
+ image: ubuntu:18.04
+ env:
+ GCC: gcc-8
 
  defaults:
  run:
  working-directory: src/main/c
 
  steps:
  - name: Checkout the target branch
- uses: actions/checkout@v2
+ uses: actions/checkout@v3
  - name: Setup Java
- uses: actions/setup-java@v1
+ uses: actions/setup-java@v3
  with:
+ distribution: temurin
  java-version: 8
+ # Don't need the dependency cache here (or in any of the other native
+ # library compilation steps), because we're not invoking the Java
+ # compiler in this step. We only need the JDK for its headers.
  - name: Install build prerequisites
  run: |
- sudo apt update
- sudo make crosstools
+ apt-get update
+ apt-get --assume-yes install make $GCC
+ make crosstools
 
  - name: Build the Linux and Windows native libraries
  run: |
@@ -33,36 +42,37 @@ jobs:
  # exactly to the directories inside `src/main/c/resources/native`. That
  # way, the Java build job can pull down all artifacts and unpack them
  # into that directory to overwrite the versions in-repo. This is sadly
- # necessary because the actions/download-artifact@v2 action flattens
+ # necessary because the actions/download-artifact@v3 action flattens
  # paths inside artifacts. If it retained full relative paths, we could
  # put Linux and Windows natives inside the same artifact, and we could be
  # flexible with the artifact names. But it doesn't, so we can't, and we
  # can't.
  - name: Upload Linux native libraries
- uses: actions/upload-artifact@v2
+ uses: actions/upload-artifact@v3
  with:
  name: linux
  path: src/main/c/resources/native/linux
  - name: Upload Windows native libraries
- uses: actions/upload-artifact@v2
+ uses: actions/upload-artifact@v3
  with:
  name: windows
  path: src/main/c/resources/native/windows
 
  natives-macos:
  name: macOS native library compilation
- runs-on: macos-10.15
+ runs-on: macos-latest
 
  defaults:
  run:
  working-directory: src/main/c
 
  steps:
  - name: Checkout the target branch
- uses: actions/checkout@v2
+ uses: actions/checkout@v3
  - name: Setup Java
- uses: actions/setup-java@v1
+ uses: actions/setup-java@v3
  with:
+ distribution: temurin
  java-version: 8
 
  - name: Build the macOS native libraries
@@ -71,32 +81,34 @@ jobs:
  make osx
 
  - name: Upload macOS native libraries
- uses: actions/upload-artifact@v2
+ uses: actions/upload-artifact@v3
  with:
  name: osx
  path: src/main/c/resources/native/osx/libNRJavaSerial.jnilib
 
  natives-freebsd:
  name: FreeBSD native library compilation
- runs-on: ubuntu-18.04
+ runs-on: ubuntu-latest
  container:
  image: empterdose/freebsd-cross-build:9.3
- env:
- JAVA_HOME: /usr/lib/jvm/default-jvm
 
  defaults:
  run:
  working-directory: src/main/c
 
  steps:
  - name: Checkout the target branch
- uses: actions/checkout@v2
+ uses: actions/checkout@v3
  - name: Setup Java
+ uses: actions/setup-java@v3
+ with:
+ distribution: temurin
+ java-version: 8
+ - name: Fake the FreeBSD Java headers
  # This feels extremely dirty, but the only native header we care about
  # is `jni_md.h`, and it is exactly identical between Linux and FreeBSD
  # (at least in OpenJDK 8).
  run: |
- apk add openjdk8
  ln -s $JAVA_HOME/include/linux $JAVA_HOME/include/freebsd
 
  - name: Build the FreeBSD native libraries
@@ -106,14 +118,14 @@ jobs:
  settarget x86_64-freebsd9 make freebsd64
 
  - name: Upload FreeBSD native libraries
- uses: actions/upload-artifact@v2
+ uses: actions/upload-artifact@v3
  with:
  name: freebsd
  path: src/main/c/resources/native/freebsd
 
  java:
  name: Java compilation
- runs-on: ubuntu-18.04
+ runs-on: ubuntu-latest
 
  needs:
  - natives-linux-windows
@@ -126,18 +138,20 @@ jobs:
  # don't regress formatting when compared with the master branch, we need
  # to have a local copy of the master branch for comparison.
  - name: Checkout the master branch
- uses: actions/checkout@v2
+ uses: actions/checkout@v3
  with:
  ref: master
  - name: Checkout the target branch
- uses: actions/checkout@v2
+ uses: actions/checkout@v3
  - name: Setup Java
- uses: actions/setup-java@v1
+ uses: actions/setup-java@v3
  with:
+ distribution: temurin
  java-version: 8
+ cache: gradle
 
  - name: Download native libraries
- uses: actions/download-artifact@v2
+ uses: actions/download-artifact@v3
  with:
  path: src/main/c/resources/native
 
@@ -146,9 +160,9 @@ jobs:
 
  - name: Determine commit hash for artifact filename
  id: vars
- run: echo "::set-output name=short-rev::$(git rev-parse --short HEAD)"
+ run: echo "short-rev=$(git rev-parse --short HEAD)" >>$GITHUB_OUTPUT
  - name: Upload build artifacts
- uses: actions/upload-artifact@v2
+ uses: actions/upload-artifact@v3
  with:
  name: nrjavaserial-${{steps.vars.outputs.short-rev}}
  path: build/libs/*.jar

src/main/c/Makefile

@@ -58,6 +58,14 @@ include JAVA_HOME.mk
 
 include platform.mk
 
+# Most of the time, GCC is called `gcc` and is installed from a `gcc` package.
+# However, sometimes a distribution packages multiple versions of GCC. In this
+# case, both the binary and package names of non-default versions are suffixed
+# (e.g., `gcc-8`). We can't use the standard CC variable to adapt to this,
+# because each target already overrides that variable with the name of the
+# appropriate cross compiler.
+GCC ?= gcc
+
 # In all cases, we want to include the system JNI headers, our own headers,
 # crank the optimization level, and compile position-independent code so that
 # it will work as a library (dlopen(3) et al. can load it into any memory).
@@ -87,13 +95,13 @@ all:
  $(error $(NO_TARGET_PLATFORM_SPECIFIED))
 
 crosstools:
- apt install --install-recommends \
- gcc-i686-linux-gnu \
- gcc-arm-linux-gnueabi \
- gcc-arm-linux-gnueabihf \
- gcc-aarch64-linux-gnu \
+ apt-get --assume-yes install \
+ $(GCC)-i686-linux-gnu \
+ $(GCC)-arm-linux-gnueabi \
+ $(GCC)-arm-linux-gnueabihf \
+ $(GCC)-aarch64-linux-gnu \
  gcc-mingw-w64 \
- gcc-powerpc-linux-gnu
+ $(GCC)-powerpc-linux-gnu
 
 # Does not include Android, because Android toolchains are large, not commonly
 # available, and the resulting library is not typically desired.
@@ -108,14 +116,15 @@ LINUX_CFLAGS += -U_FORTIFY_SOURCE
 endif
 
 # Requires gcc-i686-linux-gnu.
-linux32: export CC := i686-linux-gnu-gcc
+linux32: export CC := i686-linux-gnu-$(GCC)
 linux32: export CFLAGS += $(LINUX_CFLAGS) -m32
 linux32: export LDFLAGS += -m32
 linux32: export platform := linux/x86_32
 linux32:
  $(MAKE) -f natives.mk
 
 # Requires gcc.
+linux64: export CC := $(GCC)
 linux64: export CFLAGS += $(LINUX_CFLAGS) -m64
 linux64: export platform := linux/x86_64
 linux64:
@@ -127,7 +136,7 @@ arm: arm32v5 \
  arm32v8 arm32v8HF arm64v8
 
 # Requires gcc-arm-linux-gnueabi.
-arm32v5: export CC := arm-linux-gnueabi-gcc
+arm32v5: export CC := arm-linux-gnueabi-$(GCC)
 arm32v5: export CFLAGS += $(LINUX_CFLAGS) -march=armv5t
 arm32v5: export LDFLAGS += -march=armv5t
 arm32v5: export platform := linux/ARM_32
@@ -136,7 +145,7 @@ arm32v5:
  $(MAKE) -f natives.mk
 
 # Requires gcc-arm-linux-gnueabi.
-arm32v6: export CC := arm-linux-gnueabi-gcc
+arm32v6: export CC := arm-linux-gnueabi-$(GCC)
 arm32v6: export CFLAGS += $(LINUX_CFLAGS) -march=armv6
 arm32v6: export LDFLAGS += -march=armv6
 arm32v6: export platform := linux/ARM_32
@@ -145,7 +154,7 @@ arm32v6:
  $(MAKE) -f natives.mk
 
 # Requires gcc-arm-linux-gnueabihf.
-arm32v6HF: export CC := arm-linux-gnueabihf-gcc
+arm32v6HF: export CC := arm-linux-gnueabihf-$(GCC)
 arm32v6HF: export CFLAGS += $(LINUX_CFLAGS) -march=armv6+fp -marm
 arm32v6HF: export LDFLAGS += -march=armv6+fp -marm
 arm32v6HF: export platform := linux/ARM_32
@@ -154,7 +163,7 @@ arm32v6HF:
  $(MAKE) -f natives.mk
 
 # Requires gcc-arm-linux-gnueabi.
-arm32v7: export CC := arm-linux-gnueabi-gcc
+arm32v7: export CC := arm-linux-gnueabi-$(GCC)
 arm32v7: export CFLAGS += $(LINUX_CFLAGS) -march=armv7-a
 arm32v7: export LDFLAGS += -march=armv7-a
 arm32v7: export platform := linux/ARM_32
@@ -163,7 +172,7 @@ arm32v7:
  $(MAKE) -f natives.mk
 
 # Requires gcc-arm-linux-gnueabihf.
-arm32v7HF: export CC := arm-linux-gnueabihf-gcc
+arm32v7HF: export CC := arm-linux-gnueabihf-$(GCC)
 arm32v7HF: export CFLAGS += $(LINUX_CFLAGS) -march=armv7-a+fp
 arm32v7HF: export LDFLAGS += -march=armv7-a+fp
 arm32v7HF: export platform := linux/ARM_32
@@ -172,7 +181,7 @@ arm32v7HF:
  $(MAKE) -f natives.mk
 
 # Requires gcc-arm-linux-gnueabi.
-arm32v8: export CC := arm-linux-gnueabi-gcc
+arm32v8: export CC := arm-linux-gnueabi-$(GCC)
 arm32v8: export CFLAGS += $(LINUX_CFLAGS) -march=armv8-a
 arm32v8: export LDFLAGS += -march=armv8-a
 arm32v8: export platform := linux/ARM_32
@@ -181,7 +190,7 @@ arm32v8:
  $(MAKE) -f natives.mk
 
 # Requires gcc-arm-linux-gnueabihf.
-arm32v8HF: export CC := arm-linux-gnueabihf-gcc
+arm32v8HF: export CC := arm-linux-gnueabihf-$(GCC)
 arm32v8HF: export CFLAGS += $(LINUX_CFLAGS) -march=armv8-a -mfpu=neon-fp-armv8
 arm32v8HF: export LDFLAGS += -march=armv8-a -mfpu=neon-fp-armv8
 arm32v8HF: export platform := linux/ARM_32
@@ -190,7 +199,7 @@ arm32v8HF:
  $(MAKE) -f natives.mk
 
 # Requires gcc-aarch64-linux-gnu.
-arm64v8: export CC := aarch64-linux-gnu-gcc
+arm64v8: export CC := aarch64-linux-gnu-$(GCC)
 arm64v8: export CFLAGS += $(LINUX_CFLAGS) -march=armv8-a+fp
 arm64v8: export LDFLAGS += -march=armv8-a+fp
 arm64v8: export platform := linux/ARM_64
@@ -208,7 +217,7 @@ android:
  $(MAKE) -f natives.mk
 
 # Requires gcc-powerpc-linux-gnu.
-ppc: export CC := powerpc-linux-gnu-gcc
+ppc: export CC := powerpc-linux-gnu-$(GCC)
 ppc: export CFLAGS += $(LINUX_CFLAGS)
 ppc: export platform := linux/PPC
 ppc: