Add sample for using C++ dependencies from AARs. (#678)

A sample showing how to import native dependencies from Maven. This
sample uses curl, OpenSSL, and JsonCpp to display a list of the most
recent 10 reviews submitted to AOSP's code review system.

.ci_tools/build_samples.sh

@@ -29,6 +29,7 @@ declare projects=(
     native-codec
     native-media
     native-plasma
+    prefab/curl-ssl
     san-angeles
     sensor-graph
 #    webp
@@ -75,6 +76,7 @@ declare apks=(
   native-codec/app/build/outputs/apk/debug/app-debug.apk
   native-media/app/build/outputs/apk/debug/app-debug.apk
   native-plasma/app/build/outputs/apk/debug/app-debug.apk
+  prefab/curl-ssl/app/build/outputs/apk/debug/app-debug.apk
   sensor-graph/accelerometer/build/outputs/apk/debug/accelerometer-debug.apk
   san-angeles/app/build/outputs/apk/debug/app-armeabi-v7a-debug.apk
   san-angeles/app/build/outputs/apk/debug/app-arm64-v8a-debug.apk

prefab/curl-ssl/.clang-format

@@ -0,0 +1 @@
+BasedOnStyle: Google

prefab/curl-ssl/README.md

@@ -0,0 +1,53 @@
+# curl-ssl
+
+The curl-ssl sample shows how to import native dependencies from Maven. This
+sample uses [curl], [OpenSSL], and [JsonCpp] to display a list of the most
+recent 10 reviews submitted to AOSP's code review system.
+
+[curl]: https://curl.haxx.se/
+[OpenSSL]: https://www.openssl.org/
+[JsonCpp]: https://github.com/open-source-parsers/jsoncpp
+
+## Pre-requisites
+
+* Android Gradle Plugin 4.0+
+* The [Android NDK](https://developer.android.com/ndk/).
+
+## Getting Started
+
+The C++ code in this sample can be built with either CMake (the default for this
+project) or ndk-build. To use ndk-build set the `ndkBuild` project property
+either in your `local.properties` file or on the command line by passing the
+`-PndkBuild` flag when building.
+
+To build with [Android Studio](http://developer.android.com/sdk/index.html):
+
+1. Open this project in Android Studio.
+2. Click *Run/Run 'app'.
+
+To build from the command line:
+
+1. Navigate to this directory in your terminal.
+2. Run `./gradlew installDebug` (or `gradlew.bat installDebug` on Windows).
+
+## CA Certificates
+
+As explained by [this Stack Overflow
+post](https://stackoverflow.com/a/30430033/632035), the root certificates
+presented by Android since ICS are not in the format OpenSSL expects, so we need
+to provide our own certificate file. We do this by downloading curl's cacert.pem
+and storing that in our assets directory, as described in [this Stack Overflow
+post](https://stackoverflow.com/a/31521185/632035).
+
+## Screenshots
+
+![screenshot](screenshot.png)
+
+## Support
+
+If you've found an error in these samples, please [file an
+issue](https://github.com/android/ndk-samples/issues/new).
+
+Patches are encouraged, and may be submitted by submitting a pull request
+through GitHub. Please see [CONTRIBUTING.md](../../CONTRIBUTING.md) for more
+details.

prefab/curl-ssl/app/build.gradle

@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-android-extensions'
+
+android {
+    compileSdkVersion 29
+    defaultConfig {
+        applicationId "com.example.curlssl"
+        minSdkVersion 21
+        targetSdkVersion 29
+        versionCode 1
+        versionName "1.0"
+
+        externalNativeBuild {
+            if (!project.hasProperty("ndkBuild")) {
+                cmake {
+                    arguments "-DANDROID_STL=c++_shared"
+                }
+            }
+        }
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+
+    externalNativeBuild {
+        if (!project.hasProperty("ndkBuild")) {
+            cmake {
+                path "src/main/cpp/CMakeLists.txt"
+            }
+        } else {
+            ndkBuild {
+                path "src/main/cpp/Android.mk"
+            }
+        }
+    }
+}
+
+dependencies {
+    implementation fileTree(dir: 'libs', include: ['*.jar'])
+    implementation"org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+    implementation 'com.android.support:appcompat-v7:29.0.0'
+    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
+    implementation "com.android.ndk.thirdparty:curl:7.68.0-alpha-1"
+    implementation "com.android.ndk.thirdparty:jsoncpp:1.8.4-alpha-1"
+    implementation "com.android.ndk.thirdparty:openssl:1.1.1d-alpha-1"
+}

prefab/curl-ssl/app/proguard-rules.pro

@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

prefab/curl-ssl/app/src/main/AndroidManifest.xml

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+          package="com.example.curlssl">
+
+    <uses-permission android:name="android.permission.INTERNET" />
+
+    <application
+            android:allowBackup="true"
+            android:icon="@mipmap/ic_launcher"
+            android:label="@string/app_name"
+            android:roundIcon="@mipmap/ic_launcher_round"
+            android:supportsRtl="true"
+            android:theme="@style/AppTheme">
+        <activity android:name="com.example.curlssl.MainActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN"/>
+
+                <category android:name="android.intent.category.LAUNCHER"/>
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>

prefab/curl-ssl/app/src/main/cpp/Android.mk

@@ -0,0 +1,33 @@
+#
+# Copyright (C) 2019 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+LOCAL_PATH := $(call my-dir)
+
+include $(CLEAR_VARS)
+LOCAL_MODULE := libapp
+LOCAL_SRC_FILES := app.cpp http.cpp logging.cpp
+LOCAL_SHARED_LIBRARIES := jsoncpp curl
+LOCAL_LDLIBS := -llog
+include $(BUILD_SHARED_LIBRARY)
+
+# If you don't need your project to build with NDKs older than r21, you can omit
+# this block.
+ifneq ($(call ndk-major-at-least,21),true)
+    $(call import-add-path,$(NDK_GRADLE_INJECTED_IMPORT_PATH))
+endif
+
+$(call import-module,prefab/curl)
+$(call import-module,prefab/jsoncpp)

prefab/curl-ssl/app/src/main/cpp/Application.mk

@@ -0,0 +1,3 @@
+APP_STL := c++_shared
+APP_CPPFLAGS := -std=c++17
+APP_CFLAGS := -Wall -Werror

prefab/curl-ssl/app/src/main/cpp/CMakeLists.txt

@@ -0,0 +1,26 @@
+#
+# Copyright (C) 2019 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+cmake_minimum_required(VERSION 3.6)
+project(app VERSION 1.0.0 LANGUAGES CXX)
+
+find_package(curl REQUIRED CONFIG)
+find_package(jsoncpp REQUIRED CONFIG)
+
+add_library(app SHARED app.cpp http.cpp logging.cpp)
+set_target_properties(app PROPERTIES CXX_STANDARD 17)
+target_compile_options(app PRIVATE -Wall -Werror)
+target_link_libraries(app ${LIBLOG} curl::curl jsoncpp::jsoncpp)

prefab/curl-ssl/app/src/main/cpp/app.cpp

@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <jni.h>
+
+#include <sstream>
+#include <string>
+
+#include "http.h"
+#include "java_interop.h"
+#include "json/json.h"
+#include "logging.h"
+
+namespace curlssl {
+namespace {
+
+std::vector<std::string> get_change_titles(const std::string& cacert_path) {
+  std::string error;
+  auto result = http::Client(cacert_path)
+                    .get(
+                        "http://android-review.googlesource.com/changes/"
+                        "?q=status:open&n=10",
+                        &error);
+  if (!result) {
+    return {error.c_str()};
+  }
+
+  // Strip XSSI defense prefix:
+  // https://gerrit-review.googlesource.com/Documentation/rest-api.html#output
+  const std::string payload = result.value().substr(5);
+
+  Json::Value root;
+  std::istringstream(payload) >> root;
+  std::vector<std::string> titles;
+  for (const auto& change : root) {
+    titles.push_back(change["subject"].asString());
+  }
+  return titles;
+}
+
+}  // namespace
+
+extern "C" JNIEXPORT jobjectArray JNICALL
+Java_com_example_curlssl_MainActivity_getGerritChanges(JNIEnv* env,
+                                                       jobject /* this */,
+                                                       jstring cacert_java) {
+  if (cacert_java == nullptr) {
+    logging::FatalError(env, "cacert argument cannot be null");
+  }
+
+  const std::string cacert =
+      curlssl::jni::Convert<std::string>::from(env, cacert_java);
+  return jni::Convert<jobjectArray, jstring>::from(env,
+                                                   get_change_titles(cacert));
+}
+
+}  // namespace curlssl

prefab/curl-ssl/app/src/main/cpp/http.cpp

@@ -0,0 +1,109 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "http.h"
+
+#include <memory>
+#include <optional>
+#include <string>
+
+#include "curl/curl.h"
+
+using namespace std::string_literals;
+
+namespace {
+
+size_t write_fn(char* data, size_t size, size_t nmemb, void* user_data) {
+  assert(user_data != nullptr);
+  std::string* buffer = reinterpret_cast<std::string*>(user_data);
+  buffer->append(data, size * nmemb);
+  return size * nmemb;
+}
+
+}  // namespace
+
+namespace curlssl {
+namespace http {
+
+Client::Client(const std::string& cacert_path) : cacert_path(cacert_path) {
+  curl_global_init(CURL_GLOBAL_DEFAULT);
+}
+
+Client::~Client() { curl_global_cleanup(); }
+
+std::optional<std::string> Client::get(const std::string& url,
+                                       std::string* error) const {
+  std::string placeholder;
+  if (error == nullptr) {
+    error = &placeholder;
+  }
+
+  std::unique_ptr<CURL, decltype(&curl_easy_cleanup)> curl(curl_easy_init(),
+                                                           curl_easy_cleanup);
+  if (curl == nullptr) {
+    *error = "Failed to create CURL object";
+    return std::nullopt;
+  }
+
+  CURLcode res = curl_easy_setopt(curl.get(), CURLOPT_URL, url.c_str());
+  if (res != CURLE_OK) {
+    *error = "CURLOPT_URL failed: "s + curl_easy_strerror(res);
+    return std::nullopt;
+  }
+
+  res = curl_easy_setopt(curl.get(), CURLOPT_VERBOSE, 1L);
+  if (res != CURLE_OK) {
+    *error = "CURLOPT_VERBOSE failed: "s + curl_easy_strerror(res);
+    return std::nullopt;
+  }
+
+  res = curl_easy_setopt(curl.get(), CURLOPT_CAINFO, cacert_path.c_str());
+  if (res != CURLE_OK) {
+    *error = "CURLOPT_VERBOSE failed: "s + curl_easy_strerror(res);
+    return std::nullopt;
+  }
+
+  res = curl_easy_setopt(curl.get(), CURLOPT_WRITEFUNCTION, write_fn);
+  if (res != CURLE_OK) {
+    *error = "CURLOPT_WRITEFUNCTION failed: "s + curl_easy_strerror(res);
+    return std::nullopt;
+  }
+
+  std::string buffer;
+  res = curl_easy_setopt(curl.get(), CURLOPT_WRITEDATA,
+                         reinterpret_cast<void*>(&buffer));
+  if (res != CURLE_OK) {
+    *error = "CURLOPT_WRITEDATA failed: "s + curl_easy_strerror(res);
+    return std::nullopt;
+  }
+
+  res = curl_easy_setopt(curl.get(), CURLOPT_FOLLOWLOCATION, 1L);
+  if (res != CURLE_OK) {
+    *error = "CURLOPT_FOLLOWLOCATION failed: "s + curl_easy_strerror(res);
+    return std::nullopt;
+  }
+
+  res = curl_easy_perform(curl.get());
+  if (res != CURLE_OK) {
+    *error = "easy_perform failed: "s + curl_easy_strerror(res);
+    return std::nullopt;
+  }
+
+  return buffer;
+}
+
+}  // namespace http
+}  // namespace curlssl

prefab/curl-ssl/app/src/main/cpp/http.h

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <optional>
+#include <string>
+
+namespace curlssl {
+namespace http {
+
+/**
+ * An HTTP client backed by curl.
+ */
+class Client {
+ public:
+  /**
+   * Constructs an HTTP client.
+   *
+   * @param cacert_path Path to the cacert.pem file for use in verifying SSL
+   * certifactes. See the project's README.md for more information.
+   */
+  explicit Client(const std::string& cacert_path);
+  Client(const Client&) = delete;
+  ~Client();
+
+  void operator=(const Client&) = delete;
+
+  /**
+   * Performs an HTTP GET request.
+   *
+   * @param url The URL to GET.
+   * @param error An out parameter for an error string, if one occurs.
+   * @return A non-empty value containing the body of the response on success,
+   * or an empty result on failure.
+   */
+  std::optional<std::string> get(const std::string& url,
+                                 std::string* error) const;
+
+ private:
+  const std::string cacert_path;
+};
+
+}  // namespace http
+}  // namespace curlssl

prefab/curl-ssl/app/src/main/cpp/java_interop.h

@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <jni.h>
+
+#include <cstdlib>
+#include <string>
+#include <vector>
+
+#include "logging.h"
+
+namespace curlssl {
+namespace jni {
+
+template <typename... ToTypes>
+struct Convert;
+
+template <>
+struct Convert<std::string> {
+  static std::string from(JNIEnv* env, const jstring& value) {
+    typedef std::unique_ptr<const char[], std::function<void(const char*)>>
+        JniString;
+
+    JniString cstr(env->GetStringUTFChars(value, nullptr), [=](const char* p) {
+      env->ReleaseStringUTFChars(value, p);
+    });
+
+    if (cstr == nullptr) {
+      logging::FatalError(env, "%s: GetStringUTFChars failed", __func__);
+    }
+
+    return cstr.get();
+  }
+};
+
+template <>
+struct Convert<jobjectArray, jstring> {
+  static jobjectArray from(JNIEnv* env, const std::vector<std::string>& value) {
+    const char stringClassName[] = "java/lang/String";
+    jclass stringClass = env->FindClass(stringClassName);
+    if (stringClass == nullptr) {
+      logging::FatalError(env, "%s: FindClass(\"%s\") failed", __func__,
+                          stringClassName);
+    }
+
+    jobjectArray array =
+        env->NewObjectArray(value.size(), stringClass, nullptr);
+    if (array == nullptr) {
+      logging::FatalError(env, "%s: NewObjectArray failed", __func__);
+    }
+    for (size_t i = 0; i < value.size(); ++i) {
+      jstring str = env->NewStringUTF(value[i].c_str());
+      if (str == nullptr) {
+        logging::FatalError(env, "%s: NewStringUTF(\"%s\") failed", __func__,
+                            value[i].c_str());
+      }
+      env->SetObjectArrayElement(array, i, str);
+    }
+    return array;
+  }
+};
+
+}  // namespace jni
+}  // namespace curlssl

prefab/curl-ssl/app/src/main/cpp/logging.cpp

@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "logging.h"
+
+#include <jni.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+namespace curlssl {
+namespace logging {
+
+[[noreturn, gnu::format(printf, 2, 3)]] void FatalError(JNIEnv* env,
+                                                        const char* fmt, ...) {
+  va_list ap;
+  va_start(ap, fmt);
+  char* msg = nullptr;
+  vasprintf(&msg, fmt, ap);
+  va_end(ap);
+
+  env->FatalError(msg);
+  // env->FatalError() is specified to not return, but the function is not
+  // annotated with the noreturn attribute. abort() just in case.
+  abort();
+}
+
+}  // namespace logging
+}  // namespace curlssl

prefab/curl-ssl/app/src/main/cpp/logging.h

@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <jni.h>
+
+namespace curlssl {
+namespace logging {
+
+[[noreturn, gnu::format(printf, 2, 3)]] void FatalError(JNIEnv* env,
+                                                        const char* fmt, ...);
+
+}  // namespace logging
+}  // namespace curlssl

prefab/curl-ssl/app/src/main/java/com/example/curlssl/MainActivity.kt

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.curlssl
+
+import android.app.ListActivity
+import android.os.Bundle
+import android.widget.ArrayAdapter
+import java.io.FileOutputStream
+
+class MainActivity : ListActivity() {
+    private val cacert by lazy {
+        val path = cacheDir.resolve("cacert.pem")
+        assets.open("cacert.pem").copyTo(FileOutputStream(path))
+        path
+    }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        listAdapter = ArrayAdapter<String>(
+            this,
+            android.R.layout.simple_list_item_1,
+            getGerritChanges(cacert.path)
+        )
+    }
+
+    private external fun getGerritChanges(cacert: String): Array<String>
+
+    companion object {
+        init {
+            System.loadLibrary("app")
+        }
+    }
+}

prefab/curl-ssl/app/src/main/res/drawable-v24/ic_launcher_foreground.xml

@@ -0,0 +1,34 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:aapt="http://schemas.android.com/aapt"
+        android:width="108dp"
+        android:height="108dp"
+        android:viewportHeight="108"
+        android:viewportWidth="108">
+    <path
+            android:fillType="evenOdd"
+            android:pathData="M32,64C32,64 38.39,52.99 44.13,50.95C51.37,48.37 70.14,49.57 70.14,49.57L108.26,87.69L108,109.01L75.97,107.97L32,64Z"
+            android:strokeColor="#00000000"
+            android:strokeWidth="1">
+        <aapt:attr name="android:fillColor">
+            <gradient
+                    android:endX="78.5885"
+                    android:endY="90.9159"
+                    android:startX="48.7653"
+                    android:startY="61.0927"
+                    android:type="linear">
+                <item
+                        android:color="#44000000"
+                        android:offset="0.0"/>
+                <item
+                        android:color="#00000000"
+                        android:offset="1.0"/>
+            </gradient>
+        </aapt:attr>
+    </path>
+    <path
+            android:fillColor="#FFFFFF"
+            android:fillType="nonZero"
+            android:pathData="M66.94,46.02L66.94,46.02C72.44,50.07 76,56.61 76,64L32,64C32,56.61 35.56,50.11 40.98,46.06L36.18,41.19C35.45,40.45 35.45,39.3 36.18,38.56C36.91,37.81 38.05,37.81 38.78,38.56L44.25,44.05C47.18,42.57 50.48,41.71 54,41.71C57.48,41.71 60.78,42.57 63.68,44.05L69.11,38.56C69.84,37.81 70.98,37.81 71.71,38.56C72.44,39.3 72.44,40.45 71.71,41.19L66.94,46.02ZM62.94,56.92C64.08,56.92 65,56.01 65,54.88C65,53.76 64.08,52.85 62.94,52.85C61.8,52.85 60.88,53.76 60.88,54.88C60.88,56.01 61.8,56.92 62.94,56.92ZM45.06,56.92C46.2,56.92 47.13,56.01 47.13,54.88C47.13,53.76 46.2,52.85 45.06,52.85C43.92,52.85 43,53.76 43,54.88C43,56.01 43.92,56.92 45.06,56.92Z"
+            android:strokeColor="#00000000"
+            android:strokeWidth="1"/>
+</vector>

prefab/curl-ssl/app/src/main/res/drawable/ic_launcher_background.xml

@@ -0,0 +1,74 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector
+        xmlns:android="http://schemas.android.com/apk/res/android"
+        android:height="108dp"
+        android:width="108dp"
+        android:viewportHeight="108"
+        android:viewportWidth="108">
+    <path android:fillColor="#008577"
+          android:pathData="M0,0h108v108h-108z"/>
+    <path android:fillColor="#00000000" android:pathData="M9,0L9,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M19,0L19,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M29,0L29,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M39,0L39,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M49,0L49,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M59,0L59,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M69,0L69,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M79,0L79,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M89,0L89,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M99,0L99,108"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,9L108,9"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,19L108,19"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,29L108,29"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,39L108,39"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,49L108,49"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,59L108,59"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,69L108,69"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,79L108,79"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,89L108,89"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M0,99L108,99"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M19,29L89,29"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M19,39L89,39"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M19,49L89,49"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M19,59L89,59"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M19,69L89,69"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M19,79L89,79"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M29,19L29,89"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M39,19L39,89"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M49,19L49,89"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M59,19L59,89"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M69,19L69,89"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+    <path android:fillColor="#00000000" android:pathData="M79,19L79,89"
+          android:strokeColor="#33FFFFFF" android:strokeWidth="0.8"/>
+</vector>

prefab/curl-ssl/app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_background"/>
+    <foreground android:drawable="@drawable/ic_launcher_foreground"/>
+</adaptive-icon>

prefab/curl-ssl/app/src/main/res/mipmap-anydpi-v26/ic_launcher_round.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_background"/>
+    <foreground android:drawable="@drawable/ic_launcher_foreground"/>
+</adaptive-icon>

prefab/curl-ssl/app/src/main/res/values/colors.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="colorPrimary">#008577</color>
+    <color name="colorPrimaryDark">#00574B</color>
+    <color name="colorAccent">#D81B60</color>
+</resources>

prefab/curl-ssl/app/src/main/res/values/strings.xml

@@ -0,0 +1,3 @@
+<resources>
+    <string name="app_name">NDK curl-ssl Sample</string>
+</resources>

prefab/curl-ssl/app/src/main/res/values/styles.xml

@@ -0,0 +1,11 @@
+<resources>
+
+    <!-- Base application theme. -->
+    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
+        <!-- Customize your theme here. -->
+        <item name="colorPrimary">@color/colorPrimary</item>
+        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
+        <item name="colorAccent">@color/colorAccent</item>
+    </style>
+
+</resources>

prefab/curl-ssl/build.gradle

@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+buildscript {
+    ext.kotlin_version = '1.3.61'
+    repositories {
+        google()
+        jcenter()
+    }
+    dependencies {
+        classpath 'com.android.tools.build:gradle:4.0.0-alpha09'
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+    }
+}
+
+allprojects {
+    repositories {
+        google()
+        jcenter()
+    }
+}
+
+task clean(type: Delete) {
+    delete rootProject.buildDir
+}

prefab/curl-ssl/gradle.properties

@@ -0,0 +1,28 @@
+# Project-wide Gradle settings.
+# IDE (e.g. Android Studio) users:
+# Gradle settings configured through the IDE *will override*
+# any settings specified in this file.
+# For more details on how to configure your build environment visit
+# http://www.gradle.org/docs/current/userguide/build_environment.html
+# Specifies the JVM arguments used for the daemon process.
+# The setting is particularly useful for tweaking memory settings.
+org.gradle.jvmargs=-Xmx1536m
+# When configured, Gradle will run in incubating parallel mode.
+# This option should only be used with decoupled projects. More details, visit
+# http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
+# org.gradle.parallel=true
+# AndroidX package structure to make it clearer which packages are bundled with the
+# Android operating system, and which are packaged with your app's APK
+# https://developer.android.com/topic/libraries/support-library/androidx-rn
+android.useAndroidX=true
+# Automatically convert third-party libraries to use AndroidX
+android.enableJetifier=true
+# Kotlin code style for this project: "official" or "obsolete":
+kotlin.code.style=official
+android.enablePrefab=true
+# AGP 4.0.0-alpha09 defaulted to prefab 1.0.0-alpha3, which has issues on
+# Windows.
+android.prefabVersion=1.0.0-alpha5
+# Workaround bug in AGP where the prefab dependency is being resolved from a
+# non-Gradle thread when enableParallelJsonGen is enabled.
+android.enableParallelJsonGen=false

prefab/curl-ssl/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,6 @@
+#Tue Jun 04 14:17:52 PDT 2019
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.1.1-bin.zip

prefab/curl-ssl/gradlew

@@ -0,0 +1,172 @@
+#!/usr/bin/env sh
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS=""
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn () {
+    echo "$*"
+}
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=$((i+1))
+    done
+    case $i in
+        (0) set -- ;;
+        (1) set -- "$args0" ;;
+        (2) set -- "$args0" "$args1" ;;
+        (3) set -- "$args0" "$args1" "$args2" ;;
+        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
+}
+APP_ARGS=$(save "$@")
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
+if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
+  cd "$(dirname "$0")"
+fi
+
+exec "$JAVACMD" "$@"

prefab/curl-ssl/gradlew.bat

@@ -0,0 +1,84 @@
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS=
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto init
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto init
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:init
+@rem Get command-line arguments, handling Windows variants
+
+if not "%OS%" == "Windows_NT" goto win9xME_args
+
+:win9xME_args
+@rem Slurp the command line arguments.
+set CMD_LINE_ARGS=
+set _SKIP=2
+
+:win9xME_args_slurp
+if "x%~1" == "x" goto execute
+
+set CMD_LINE_ARGS=%*
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

prefab/curl-ssl/settings.gradle

@@ -0,0 +1,2 @@
+rootProject.name='curl-ssl'
+include ':app'