Tweaks and add a Dockerfile to compile for Android

Cargo.toml

@@ -133,3 +133,6 @@ members = [
 	"transaction-pool",
 	"whisper"
 ]
+
+[patch.crates-io]
+ring = { git = "https://github.com/paritytech/ring" }

docker/android/Dockerfile

@@ -0,0 +1,77 @@
+FROM ubuntu:xenial
+LABEL maintainer="Parity Technologies <devops@parity.io>"
+
+RUN apt-get update && \
+    apt-get install -yq sudo curl file build-essential wget git g++ cmake pkg-config bison flex \
+                        unzip lib32stdc++6 lib32z1 python autotools-dev automake autoconf libtool \
+                        gperf xsltproc docbook-xsl
+
+# Rust & Cargo
+RUN curl https://sh.rustup.rs -sSf | sh -s -- -y
+ENV PATH /root/.cargo/bin:$PATH
+RUN rustup toolchain install stable
+RUN rustup target add --toolchain stable arm-linux-androideabi
+RUN rustup target add --toolchain stable armv7-linux-androideabi
+
+# Android NDK and toolchain
+RUN cd /usr/local && \
+    wget -q https://dl.google.com/android/repository/android-ndk-r16b-linux-x86_64.zip && \
+    unzip -q android-ndk-r16b-linux-x86_64.zip && \
+    rm android-ndk-r16b-linux-x86_64.zip
+ENV NDK_HOME /usr/local/android-ndk-r16b
+RUN /usr/local/android-ndk-r16b/build/tools/make-standalone-toolchain.sh \
+    --arch=arm --install-dir=/opt/ndk-standalone --stl=libc++ --platform=android-26
+ENV PATH $PATH:/opt/ndk-standalone/bin
+
+# Compiling OpenSSL for Android
+RUN cd /root && \
+    git clone git://git.openssl.org/openssl.git && \
+    cd openssl && \
+    git checkout OpenSSL_1_1_0-stable
+ENV CROSS_SYSROOT /opt/ndk-standalone/sysroot
+RUN cd /root/openssl && \
+    ./Configure android-armeabi --cross-compile-prefix=arm-linux-androideabi- \
+    -static no-stdio no-ui \
+    -I/usr/local/android-ndk-r16b/sysroot/usr/include \
+    -I/usr/local/android-ndk-r16b/sysroot/usr/include/arm-linux-androideabi \
+    -L/usr/local/android-ndk-r16b/sysroot/usr/lib \
+    --prefix=/opt/ndk-standalone/sysroot/usr
+RUN cd /root/openssl && \
+    make build_libs && \
+    make install_dev
+RUN rm -rf /root/openssl
+
+# Compiling libudev for Android
+# This is the most hacky part of the process, as we need to apply a patch and pass specific
+# options that the compiler environment doesn't define.
+RUN cd /root && \
+    git clone https://github.com/gentoo/eudev.git
+ADD libudev.patch /root
+RUN cd /root/eudev && \
+    git checkout 83d918449f22720d84a341a05e24b6d109e6d3ae && \
+    ./autogen.sh && \
+    ./configure --disable-introspection --disable-programs --disable-hwdb \
+                --host=arm-linux-androideabi --prefix=/opt/ndk-standalone/sysroot/usr/ \
+                --enable-shared=false CC=arm-linux-androideabi-clang \
+                CFLAGS="-D LINE_MAX=2048 -D RLIMIT_NLIMITS=15 -D IPTOS_LOWCOST=2 -std=gnu99" \
+                CXX=arm-linux-androideabi-clang++ && \
+    git apply - < /root/libudev.patch && \
+    make && \
+    make install
+RUN rm -rf /root/eudev
+RUN rm /root/libudev.patch
+
+# Rust-related configuration
+ADD cargo-config.toml /root/.cargo/config
+ENV ARM_LINUX_ANDROIDEABI_OPENSSL_DIR /opt/ndk-standalone/sysroot/usr
+ENV ARMV7_LINUX_ANDROIDEABI_OPENSSL_DIR /opt/ndk-standalone/sysroot/usr
+ENV CC_arm_linux_androideabi arm-linux-androideabi-clang
+ENV CC_armv7_linux_androideabi arm-linux-androideabi-clang
+ENV CXX_arm_linux_androideabi arm-linux-androideabi-clang++
+ENV CXX_armv7_linux_androideabi arm-linux-androideabi-clang++
+ENV AR_arm_linux_androideabi arm-linux-androideabi-ar
+ENV AR_armv7_linux_androideabi arm-linux-androideabi-ar
+ENV CFLAGS_arm_linux_androideabi -std=gnu11 -fPIC -D OS_ANDROID
+ENV CFLAGS_armv7_linux_androideabi -std=gnu11 -fPIC -D OS_ANDROID
+ENV CXXFLAGS_arm_linux_androideabi -std=gnu++11 -fPIC -fexceptions -frtti -static-libstdc++ -D OS_ANDROID
+ENV CXXFLAGS_armv7_linux_androideabi -std=gnu++11 -fPIC -fexceptions -frtti -static-libstdc++ -D OS_ANDROID

docker/android/cargo-config.toml

@@ -0,0 +1,9 @@
+[target.armv7-linux-androideabi]
+linker = "arm-linux-androideabi-clang"
+ar = "arm-linux-androideabi-ar"
+rustflags = ["-C", "link-arg=-lc++_static", "-C", "link-arg=-lc++abi", "-C", "link-arg=-landroid_support"]
+
+[target.arm-linux-androideabi]
+linker = "arm-linux-androideabi-clang"
+ar = "arm-linux-androideabi-ar"
+rustflags = ["-C", "link-arg=-lc++_static", "-C", "link-arg=-lc++abi", "-C", "link-arg=-landroid_support"]