Android build scripts update for SDK level (#1443)

* Android build scripts: Changed default SDK level to 21; enabled specifying NDK_PLATFORM environment variable for custom SDK level; misc cleanup of Android build scripts

* Update android-aar.sh

I forgot to hit save on the script after making this change locally. The script works either way but by setting this value again in android-build.sh people can more easily build arch specific binaries if they want so the export is unnecessary but also rather meaningless.

dist-build/android-aar.sh

@@ -2,13 +2,20 @@
 
 # Create an AAR with libsodium in all combinations of static | shared | minimal | full.
 #
-# The x86 static library will not work due to text relocation rules, so static x86 versions are limited to shared libraries.
 # To simplify linking, library variants have distinct names: sodium, sodium-static, sodium-minimal and sodium-minimal-static.
 
 SODIUM_VERSION="1.0.21.0"
 NDK_VERSION=$(grep "Pkg.Revision = " <"${ANDROID_NDK_HOME}/source.properties" | cut -f 2 -d '=' | cut -f 2 -d' ' | cut -f 1 -d'.')
 DEST_PATH=$(mktemp -d)
 
+if [ -z "$NDK_PLATFORM" ]; then
+  export NDK_PLATFORM="android-21"
+  echo "Compiling for default platform: [${NDK_PLATFORM}] - That can be changed by setting an NDK_PLATFORM environment variable."
+fi
+
+SDK_VERSION=$( echo "$NDK_PLATFORM" | cut -f2 -d"-" )
+
+
 if which zip >/dev/null; then
   echo "The 'zip' command is installed."
 else
@@ -28,7 +35,7 @@ make_prefab_json() {
 
 make_manifest() {
   echo "<manifest xmlns:android=\"http://schemas.android.com/apk/res/android\" package=\"com.android.ndk.thirdparty.sodium\" android:versionCode=\"1\" android:versionName=\"1.0\">
-        <uses-sdk android:minSdkVersion=\"19\" android:targetSdkVersion=\"21\"/>
+        <uses-sdk android:minSdkVersion=\"$SDK_VERSION\" android:targetSdkVersion=\"$SDK_VERSION\"/>
 </manifest>" >"${1}/AndroidManifest.xml"
 }
 
@@ -60,11 +67,7 @@ make_prefab_structure() {
       mkdir "$DEST_PATH/${variant}/libs/android.${arch}"
       mkdir "$DEST_PATH/${variant}/libs/android.${arch}/include"
       NDK_ARCH="$arch"
-      if [ $arch = "arm64-v8a" ] || [ $arch = "x86_64" ]; then
-        SDK_VERSION="21"
-      else
-        SDK_VERSION="19"
-      fi
+
 
       make_abi_json "$DEST_PATH/${variant}/libs/android.${arch}"
     done
@@ -118,8 +121,13 @@ zip -9 -r "$AAR_PATH" META-INF prefab AndroidManifest.xml
 cd .. || exit
 rm -r "$DEST_PATH"
 
-echo
-echo "Congrats you have built an AAR containing libsodium! To use it with
+
+echo "Congrats you have built an AAR containing libsodium! 
+The build used a min Android SDK of version $SDK_VERSION
+You can build for a different SDK version by specifying NDK_PLATFORM=\"android-{SDK_VERSION}\"
+as an environment variable before running this script but the defaults should be fine.
+
+To use the aar with
 gradle or cmake (as set by default for Android Studio projects):
 
 - Edit the app/build.gradle file to add:

dist-build/android-armv8-a.sh

@@ -2,4 +2,4 @@
 export TARGET_ARCH=armv8-a+crypto
 export CFLAGS="-Os -march=${TARGET_ARCH}"
 export LDFLAGS="-Wl,-z,max-page-size=16384"
-NDK_PLATFORM=android-21 ARCH=arm64 HOST_COMPILER=aarch64-linux-android "$(dirname "$0")/android-build.sh"
+ARCH=arm64 HOST_COMPILER=aarch64-linux-android "$(dirname "$0")/android-build.sh"

dist-build/android-build.sh

@@ -1,9 +1,10 @@
 #! /bin/sh
 
 if [ -z "$NDK_PLATFORM" ]; then
-  export NDK_PLATFORM="android-21"
-  echo "Compiling for default platform: [${NDK_PLATFORM}] - That can be changed by setting an NDK_PLATFORM environment variable."
+  echo "No NDK_PLATFORM specified, set to value such as \"android-{Min_SDK_VERSION}\" or just use android-aar.sh"
+  exit
 fi
+SDK_VERSION=$( echo "$NDK_PLATFORM" | cut -f2 -d"-" )
 export NDK_PLATFORM_COMPAT="${NDK_PLATFORM_COMPAT:-${NDK_PLATFORM}}"
 export NDK_API_VERSION="$(echo "$NDK_PLATFORM" | sed 's/^android-//')"
 export NDK_API_VERSION_COMPAT="$(echo "$NDK_PLATFORM_COMPAT" | sed 's/^android-//')"
@@ -30,8 +31,8 @@ export TOOLCHAIN_DIR="$ANDROID_NDK_HOME/toolchains/llvm/prebuilt/${TOOLCHAIN_OS_
 echo "$ANDROID_NDK_HOME/toolchains/llvm/prebuilt/${TOOLCHAIN_OS_DIR}/${HOST_COMPILER}"
 
 export PATH="${PATH}:${TOOLCHAIN_DIR}/bin"
-SDK_VERSION_NUM=$(echo $NDK_PLATFORM | cut -d'-' -f2)
-export CC=${CC:-"${HOST_COMPILER}${SDK_VERSION_NUM}-clang"}
+
+export CC=${CC:-"${HOST_COMPILER}${SDK_VERSION}-clang"}
 
 echo
 echo "Warnings related to headers being present but not usable are due to functions"
@@ -88,5 +89,5 @@ NPROCESSORS=$(getconf NPROCESSORS_ONLN 2>/dev/null || getconf _NPROCESSORS_ONLN
 PROCESSORS=${NPROCESSORS:-3}
 
 make clean &&
-  make -j${PROCESSORS} install &&
+  make -j"${PROCESSORS}" install &&
   echo "libsodium has been installed into ${PREFIX}"

dist-build/android-x86_64.sh

@@ -2,4 +2,4 @@
 export TARGET_ARCH=westmere
 export CFLAGS="-Os -march=${TARGET_ARCH}"
 export LDFLAGS="-Wl,-z,max-page-size=16384"
-NDK_PLATFORM=android-21 ARCH=x86_64 HOST_COMPILER=x86_64-linux-android "$(dirname "$0")/android-build.sh"
+ARCH=x86_64 HOST_COMPILER=x86_64-linux-android "$(dirname "$0")/android-build.sh"