Support cross-building for ARM64 (#91)

* Support cross-building for Ubuntu 18.04 arm64 (bionic)

* Add linux-arm64

* Update CI script

* Add Debian 9 - arm64

* Add Ubuntu 16.04, 18.10 Dockerfiles

* Reduce dependency graph

Author: qmfrederik

.travis.yml

@@ -35,6 +35,14 @@ matrix:
       env: RID=alpine.3.9-x64
     - os: osx
       env: RID=osx
+    - os: linux
+      dist: trusty
+      sudo: required
+      env: RID=ubuntu.16.04-arm64
+    - os: linux
+      dist: trusty
+      sudo: required
+      env: RID=debian-arm64
 
 branches:
  only:

CMakeLists.arm64.txt

@@ -0,0 +1,6 @@
+SET(CMAKE_SYSTEM_NAME Linux)
+set(CMAKE_SYSTEM_PROCESSOR aarch64)
+set(TARGET_ABI "linux-gnu")
+
+SET(CMAKE_C_COMPILER   ${CMAKE_SYSTEM_PROCESSOR}-${TARGET_ABI}-gcc)
+SET(CMAKE_CXX_COMPILER ${CMAKE_SYSTEM_PROCESSOR}-${TARGET_ABI}-g++)

Dockerfile.debian-arm64

@@ -0,0 +1,12 @@
+FROM debian:9
+WORKDIR /nativebinaries
+COPY . /nativebinaries/
+
+RUN dpkg --add-architecture arm64
+
+RUN apt update \
+&& apt -y install cmake pkg-config \
+   crossbuild-essential-arm64 \
+   libssl-dev:arm64
+
+CMD ["/bin/bash", "-c", "./build.libgit2.sh"]

Dockerfile.ubuntu.16.04-arm64

@@ -0,0 +1,17 @@
+FROM ubuntu:16.04
+
+WORKDIR /nativebinaries
+COPY . /nativebinaries/
+
+RUN dpkg --add-architecture arm64 \
+&& sed -i 's/deb/deb [arch=amd64]/g' /etc/apt/sources.list \
+&& echo "deb [arch=arm64] http://ports.ubuntu.com/ubuntu-ports xenial main universe" > /etc/apt/sources.list.d/arm64.list \
+&& echo "deb [arch=arm64] http://ports.ubuntu.com/ubuntu-ports xenial-updates main universe" > /etc/apt/sources.list.d/arm64-updates.list
+
+RUN apt update \
+&& apt -y install cmake pkg-config \
+   crossbuild-essential-arm64 \
+   pkg-config-aarch64-linux-gnu \
+   libssl-dev:arm64
+
+CMD ["/bin/bash", "-c", "./build.libgit2.sh"]

build.libgit2.sh

@@ -9,13 +9,18 @@ pushd libgit2/build
 
 export _BINPATH=`pwd`
 
+if [[ $RID == *arm64 ]]; then
+	export TOOLCHAIN_FILE=/nativebinaries/CMakeLists.arm64.txt
+fi
+
 cmake -DCMAKE_BUILD_TYPE:STRING=Release \
       -DBUILD_CLAR:BOOL=OFF \
       -DUSE_SSH=OFF \
       -DENABLE_TRACE=ON \
       -DLIBGIT2_FILENAME=git2-$SHORTSHA \
       -DCMAKE_OSX_ARCHITECTURES="i386;x86_64" \
       -DUSE_BUNDLED_ZLIB=ON \
+      -DCMAKE_TOOLCHAIN_FILE=${TOOLCHAIN_FILE} \
       ..
 cmake --build .