Add android build support

.travis.yml

@@ -74,6 +74,24 @@ matrix:
            DOCKER=alexcrichton/rust-slave-linux-cross:2016-11-11
            SKIP_TESTS=1
 
+    # Android use a local docker image
+    - os: linux
+      env: TARGET=arm-linux-androideabi
+           DOCKER=android
+           SKIP_TESTS=1
+    - os: linux
+      env: TARGET=armv7-linux-androideabi
+           DOCKER=android
+           SKIP_TESTS=1
+    - os: linux
+      env: TARGET=aarch64-linux-android
+           DOCKER=android
+           SKIP_TESTS=1
+    - os: linux
+      env: TARGET=i686-linux-android
+           DOCKER=android
+           SKIP_TESTS=1
+
     # On OSX we want to target 10.7 so we ensure that the appropriate
     # environment variable is set to tell the linker what we want.
     - os: osx
@@ -101,16 +119,7 @@ install:
 script:
   - mkdir target
   - if [ ! -z "$DOCKER" ]; then
-      docker run
-        --entrypoint bash
-        -u `id -u`:`id -g`
-        -v $HOME/rust:/travis-rust:ro
-        -v `pwd`:/buildslave:ro
-        -v `pwd`/target:/buildslave/target
-        -e TARGET=$TARGET
-        -e SKIP_TESTS=$SKIP_TESTS
-        -it $DOCKER
-        ci/run-docker.sh;
+      bash ci/docker.sh "$DOCKER" "$TARGET" "$SKIP_TESTS";
     else
       PATH=$HOME/rust/bin:$PATH sh ci/run.sh;
     fi

ci/docker.sh

@@ -0,0 +1,24 @@
+#!/bin/sh
+
+set -ex
+
+mkdir -p target
+
+DOCKER="$1"
+TARGET="$2"
+SKIP_TESTS="$3"
+
+if [ -f "ci/docker/$DOCKER/Dockerfile" ]; then
+  docker build -t "$DOCKER" "ci/docker/$DOCKER/"
+fi
+
+docker run \
+  --entrypoint bash \
+  -u `id -u`:`id -g` \
+  -v $HOME/rust:/travis-rust:ro \
+  -v `pwd`:/buildslave:ro \
+  -v `pwd`/target:/buildslave/target \
+  -e TARGET=$TARGET \
+  -e SKIP_TESTS=$SKIP_TESTS \
+  -it $DOCKER \
+  ci/run-docker.sh

ci/docker/android/Dockerfile

@@ -0,0 +1,35 @@
+FROM ubuntu:16.04
+
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+    ca-certificates \
+    cmake \
+    curl \
+    gcc \
+    libc6-dev \
+    make \
+    pkg-config
+
+RUN apt-get install -y --no-install-recommends \
+    unzip \
+    python && \
+    curl -O https://dl.google.com/android/repository/android-ndk-r13b-linux-x86_64.zip && \
+    unzip -q android-ndk-r13b-linux-x86_64.zip && \
+    ./android-ndk-r13b/build/tools/make_standalone_toolchain.py \
+        --install-dir /android-ndk/arm \
+        --arch arm \
+        --api 21 && \
+    ./android-ndk-r13b/build/tools/make_standalone_toolchain.py \
+        --install-dir /android-ndk/arm64 \
+        --arch arm64 \
+        --api 21 && \
+    ./android-ndk-r13b/build/tools/make_standalone_toolchain.py \
+        --install-dir /android-ndk/x86 \
+        --arch x86 \
+        --api 21 && \
+    rm -rf ./android-ndk-r13b-linux-x86_64.zip ./android-ndk-r13b && \
+    apt-get purge --auto-remove -y unzip python
+
+ENV PATH=$PATH:/android-ndk/arm/bin:/android-ndk/arm64/bin:/android-ndk/x86/bin
+
+WORKDIR /buildslave

ci/run-docker.sh

@@ -2,6 +2,19 @@
 
 set -ex
 
+# For some unknown reason libz is not found in the android docker image, so we
+# use this workaround
+case $TARGET in
+  arm-linux-androideabi | armv7-linux-androideabi )
+    export DEP_Z_ROOT=/android-ndk/arm/sysroot/usr/;;
+
+  aarch64-linux-android )
+    export DEP_Z_ROOT=/android-ndk/arm64/sysroot/usr/;;
+
+  i686-linux-android )
+    export DEP_Z_ROOT=/android-ndk/x86/sysroot/usr/;;
+esac
+
 upper_target=$(echo $TARGET | tr '[a-z]' '[A-Z]' | tr '-' '_')
 export PATH=/travis-rust/bin:$PATH
 export LD_LIBRARY_PATH=/travis-rust/lib:$LD_LIBRARY_PATH
@@ -34,6 +47,27 @@ case $TARGET in
     OPENSSL_SETARCH='setarch i386'
     OPENSSL_CFLAGS=-m32
     ;;
+  arm-linux-androideabi)
+    OPENSSL_OS=android
+    OPENSSL_CC=arm-linux-androideabi-gcc
+    OPENSSL_AR=arm-linux-androideabi-ar
+    ;;
+  armv7-linux-androideabi)
+    OPENSSL_OS=android-armv7
+    OPENSSL_CC=arm-linux-androideabi-gcc
+    OPENSSL_AR=arm-linux-androideabi-ar
+    ;;
+  aarch64-linux-android)
+    OPENSSL_OS=linux-generic64
+    OPENSSL_CC=aarch64-linux-android-gcc
+    OPENSSL_AR=aarch64-linux-android-ar
+    OPENSSL_CFLAGS="-mandroid -fomit-frame-pointer"
+    ;;
+  i686-linux-android)
+    OPENSSL_OS=android-x86
+    OPENSSL_CC=i686-linux-android-gcc
+    OPENSSL_AR=i686-linux-android-ar
+    ;;
   arm-*-linux-gnueabi)
     OPENSSL_OS=linux-armv4
     OPENSSL_CC=arm-linux-gnueabi-gcc