[build] add CMake Android NDK support (#9010)

.github/workflows/build.yml

@@ -400,3 +400,33 @@ jobs:
         export PATH=$(brew --prefix m4)/bin:$PATH
         script/check-posix-build
         script/check-simulation-build
+
+  android-ndk:
+    name: android-ndk
+    runs-on: ubuntu-22.04
+    container:
+      image: openthread/environment
+    steps:
+    - name: Harden Runner
+      uses: step-security/harden-runner@6b3083af2869dc3314a0257a42f4af696cc79ba3 # v2.3.1
+      with:
+        egress-policy: audit # TODO: change to 'egress-policy: block' after couple of runs
+
+    - uses: actions/checkout@ac593985615ec2ede58e132d2e21d2b1cbd6127c # v3.3.0
+      with:
+        submodules: true
+    - name: Install unzip
+      run: apt update && apt install -y unzip
+    - name: Setup NDK
+      id: setup-ndk
+      uses: nttld/setup-ndk@v1
+      with:
+        ndk-version: r25c
+        local-cache: true
+
+    - name: Build
+      env:
+        NDK: ${{ steps.setup-ndk.outputs.ndk-path }}
+      run: |
+        rm -rf build/ && OT_CMAKE_NINJA_TARGET="ot-daemon ot-ctl" script/cmake-build android-ndk
+        rm -rf build/ && OT_CMAKE_NINJA_TARGET="ot-cli" script/cmake-build android-ndk

CMakeLists.txt

@@ -175,6 +175,7 @@ list(APPEND OT_PUBLIC_INCLUDES ${PROJECT_SOURCE_DIR}/include)
 
 if(OT_PLATFORM STREQUAL "posix")
     target_include_directories(ot-config INTERFACE ${PROJECT_SOURCE_DIR}/src/posix/platform)
+    target_compile_definitions(ot-config INTERFACE OPENTHREAD_PLATFORM_POSIX=1)
     add_subdirectory("${PROJECT_SOURCE_DIR}/src/posix/platform")
 elseif(OT_PLATFORM STREQUAL "external")
     # skip in this case

etc/cmake/options.cmake

@@ -79,6 +79,7 @@ macro(ot_option name ot_config description)
 endmacro()
 
 ot_option(OT_15_4 OPENTHREAD_CONFIG_RADIO_LINK_IEEE_802_15_4_ENABLE "802.15.4 radio link")
+ot_option(OT_ANDROID_NDK OPENTHREAD_CONFIG_ANDROID_NDK_ENABLE "enable android NDK")
 ot_option(OT_ANYCAST_LOCATOR OPENTHREAD_CONFIG_TMF_ANYCAST_LOCATOR_ENABLE "anycast locator")
 ot_option(OT_ASSERT OPENTHREAD_CONFIG_ASSERT_ENABLE "assert function OT_ASSERT()")
 ot_option(OT_BACKBONE_ROUTER OPENTHREAD_CONFIG_BACKBONE_ROUTER_ENABLE "backbone router functionality")

script/cmake-build

@@ -62,12 +62,12 @@
 
 set -euxo pipefail
 
-OT_CMAKE_NINJA_TARGET=${OT_CMAKE_NINJA_TARGET:-}
+OT_CMAKE_NINJA_TARGET=${OT_CMAKE_NINJA_TARGET-}
 
 OT_SRCDIR="$(cd "$(dirname "$0")"/.. && pwd)"
 readonly OT_SRCDIR
 
-OT_PLATFORMS=(simulation posix)
+OT_PLATFORMS=(simulation posix android-ndk)
 readonly OT_PLATFORMS
 
 OT_POSIX_SIM_COMMON_OPTIONS=(
@@ -152,11 +152,62 @@ main()
     shift
     local local_options=()
     local options=(
-        "-DOT_PLATFORM=${platform}"
         "-DOT_SLAAC=ON"
     )
 
     case "${platform}" in
+        android-ndk)
+            if [ -z "${NDK-}" ]; then
+                echo "
+The 'NDK' environment variable needs to point to the Android NDK toolchain.
+Please ensure the NDK is downloaded and extracted then try to run this script again
+
+For example:
+    NDK=/opt/android-ndk-r25c ./script/cmake-build-android
+
+You can download the NDK at https://developer.android.com/ndk/downloads
+
+            "
+                exit 1
+            fi
+
+            NDK_CMAKE_TOOLCHAIN_FILE="${NDK?}/build/cmake/android.toolchain.cmake"
+            if [ ! -f "${NDK_CMAKE_TOOLCHAIN_FILE}" ]; then
+                echo "
+Could not fild the Android NDK CMake toolchain file
+- NDK=${NDK}
+- NDK_CMAKE_TOOLCHAIN_FILE=${NDK_CMAKE_TOOLCHAIN_FILE}
+
+            "
+                exit 2
+            fi
+            local_options+=(
+                "-DOT_LOG_OUTPUT=PLATFORM_DEFINED"
+
+                # Add Android NDK flags
+                "-DOT_ANDROID_NDK=1"
+                "-DCMAKE_TOOLCHAIN_FILE=${NDK?}/build/cmake/android.toolchain.cmake"
+
+                # Android API needs to be >= android-24 for `getifsaddrs()`
+                "-DANDROID_PLATFORM=android-24"
+
+                # Store thread settings in the CWD when executing ot-cli or ot-daemon
+                '-DOT_POSIX_SETTINGS_PATH="./thread"'
+            )
+
+            # Rewrite platform to posix
+            platform="posix"
+
+            # Check if OT_DAEMON or OT_APP_CLI flags are needed
+            if [[ ${OT_CMAKE_NINJA_TARGET[*]} =~ "ot-daemon" ]] || [[ ${OT_CMAKE_NINJA_TARGET[*]} =~ "ot-ctl" ]]; then
+                local_options+=("-DOT_DAEMON=ON")
+            elif [[ ${OT_CMAKE_NINJA_TARGET[*]} =~ "ot-cli" ]]; then
+                local_options+=("-DOT_APP_CLI=ON")
+            fi
+
+            options+=("${local_options[@]}")
+            ;;
+
         posix)
             local_options+=(
                 "-DOT_TCP=OFF"
@@ -179,6 +230,9 @@ main()
             ;;
     esac
 
+    options+=(
+        "-DOT_PLATFORM=${platform}"
+    )
     options+=("$@")
     build "${platform}" "${options[@]}"
 }

src/core/api/instance_api.cpp

@@ -43,7 +43,7 @@
 
 #if !defined(OPENTHREAD_BUILD_DATETIME)
 #ifdef __ANDROID__
-#ifdef OPENTHREAD_ENABLE_ANDROID_NDK
+#ifdef OPENTHREAD_CONFIG_ANDROID_NDK_ENABLE
 #include <sys/system_properties.h>
 #else
 #include <cutils/properties.h>
@@ -135,7 +135,7 @@ const char *otGetVersionString(void)
 
 #if !defined(OPENTHREAD_BUILD_DATETIME) && defined(__ANDROID__)
 
-#ifdef OPENTHREAD_ENABLE_ANDROID_NDK
+#ifdef OPENTHREAD_CONFIG_ANDROID_NDK_ENABLE
     static char sVersion[100 + PROP_VALUE_MAX];
     char        dateTime[PROP_VALUE_MAX];
 

src/core/config/openthread-core-config-check.h

@@ -65,6 +65,10 @@
 #error "OPENTHREAD_CONFIG_ENABLE_AUTO_START_SUPPORT was removed."
 #endif
 
+#ifdef OPENTHREAD_ENABLE_ANDROID_NDK
+#error "OPENTHREAD_ENABLE_ANDROID_NDK was replaced by OPENTHREAD_CONFIG_ANDROID_NDK_ENABLE."
+#endif
+
 #ifdef OPENTHREAD_ENABLE_CERT_LOG
 #error "OPENTHREAD_ENABLE_CERT_LOG was replaced by OPENTHREAD_CONFIG_REFERENCE_DEVICE_ENABLE."
 #endif

src/posix/platform/CMakeLists.txt

@@ -97,6 +97,10 @@ endif()
 
 set(CMAKE_EXE_LINKER_FLAGS "-rdynamic ${CMAKE_EXE_LINKER_FLAGS}" PARENT_SCOPE)
 
+if(OT_ANDROID_NDK)
+    target_compile_options(ot-posix-config INTERFACE -Wno-sign-compare)
+endif()
+
 add_library(openthread-posix
     alarm.cpp
     backbone.cpp
@@ -141,7 +145,7 @@ target_link_libraries(openthread-posix
         ot-config-ftd
         ot-config
         ot-posix-config
-        util
+        $<$<NOT:$<BOOL:${OT_ANDROID_NDK}>>:util>
         $<$<STREQUAL:${CMAKE_SYSTEM_NAME},Linux>:rt>
 )