如何使用 NDK 19 在 OSX Darwin 上交叉编译适用于 64 位 Android 的 OpenSSL

Question

我之前在这里问过基本上相同的问题（不同的 NDK），并认为我正确构建了 openssl，但是当我尝试将其链接到我的应用程序时，我发现我没有正确构建它。

1. 如果我在这里桥接@AlexCohn 的答案，我会从脚本开始setenv_android.sh。

2. 我修改脚本以设置THE_ARCH=arm64-v8a尝试针对 64 位 android 架构。

3. 当我运行脚本时，它找不到一些东西：

   ERROR: Failed to find Android cpp. Please edit this script.
   ERROR: Failed to find Android gcc. Please edit this script.
   ERROR: Failed to find Android g++. Please edit this script.
   ERROR: AOSP_STL_INC is not valid. Please edit this script.
   ERROR: AOSP_STL_LIB is not valid. Please edit this script.
   ANDROID_NDK_ROOT: /Users/spartygw/android-ndk-r19/
   AOSP_TOOLCHAIN_PATH: /Users/spartygw/android-ndk-r19//toolchains/aarch64-linux-android-4.9/prebuilt/darwin-x86_64/bin
   AOSP_ABI: arm64-v8a
   AOSP_API: android-21
   AOSP_SYSROOT: /Users/spartygw/android-ndk-r19//platforms/android-21/arch-arm64
   AOSP_FLAGS: -funwind-tables -fexceptions -frtti
   AOSP_STL_INC: /Users/spartygw/android-ndk-r19//sources/cxx-stl/stlport/stlport/
   AOSP_STL_LIB: /Users/spartygw/android-ndk-r19//sources/cxx-stl/stlport/libs/arm64-v8a/libstlport_shared.so
   

4. 当我查看时/Users/spartygw/android-ndk-r19//toolchains/aarch64-linux-android-4.9/prebuilt/darwin-x86_64/bin，没有aarch64-linux-android-cpp或-gcc或-g++正如脚本输出所示：

   $ ls -1 ~/android-ndk-r19//toolchains/aarch64-linux-android-4.9/prebuilt/darwin-x86_64/bin
   ./
   ../
   aarch64-linux-android-addr2line
   aarch64-linux-android-ar
   aarch64-linux-android-as
   aarch64-linux-android-c++filt
   aarch64-linux-android-dwp
   aarch64-linux-android-elfedit
   aarch64-linux-android-gprof
   aarch64-linux-android-ld
   aarch64-linux-android-ld.bfd
   aarch64-linux-android-ld.gold
   aarch64-linux-android-nm
   aarch64-linux-android-objcopy
   aarch64-linux-android-objdump
   aarch64-linux-android-ranlib
   aarch64-linux-android-readelf
   aarch64-linux-android-size
   aarch64-linux-android-strings
   aarch64-linux-android-strip
   

我想这就是我上次遇到麻烦的地方。我开始修改脚本以获得一些似乎有效的东西，但我确信我现在所做的事情是错误的。

我真的不明白这个过程，所以我希望得到帮助。有人成功构建了arm64-v8a版本的OpenSLL吗？

Answer 1

我能够使用 NDK r19 为 android arm64 构建、链接和运行 openssl。但我必须使用 android-ndk-r19 生成的独立工具链。

$ cd /path/to/android-ndk-r19
$ ./build/tools/make-standalone-toolchain.sh               \
            --toolchain=aarch64-linux-android

这将在您的 tmp 目录中生成一个名为 aarch64-linux-android 的目录，将其 bin 目录放入您的路径中。另外，将您的 ANDROID_NDK_HOME 设置为此位置。

$ export PATH=/path/to/aarch64-linux-android/bin:${PATH}
$ export ANDROID_NDK_HOME=/path/to/aarch64-linux-android

然后只需运行 openssl 的配置和制作。

$ cd /path/to/openssl1.1.1
$ ./Configure android-arm64
$ make

./Configure 的输出如下：

$ ./Configure android-arm64
Configuring OpenSSL version 1.1.1b-dev (0x10101020L) for android-arm64
Using os-specific seed configuration
Creating configdata.pm
Creating Makefile

**********************************************************************
***                                                                ***
***   OpenSSL has been successfully configured                     ***
***                                                                ***
***   If you encounter a problem while building, please open an    ***
***   issue on GitHub <https://github.com/openssl/openssl/issues>  ***
***   and include the output from the following command:           ***
***                                                                ***
***       perl configdata.pm --dump                                ***
***                                                                ***
***   (If you are new to OpenSSL, you might want to consult the    ***
***   'Troubleshooting' section in the INSTALL file first)         ***
***                                                                ***
**********************************************************************
$ 

最后，我创建了一个新的 Android Studio 项目，其中包含 c++11、异常和 rtti 支持（通过新项目向导），并在构建的输出中链接了一个对 Android 创建的项目稍加修改的 CMakeLists.txt工作室：

cmake_minimum_required(VERSION 3.4.1)

# Creates and names a library, sets it as either STATIC
# or SHARED, and provides the relative paths to its source code.
# You can define multiple libraries, and CMake builds them for you.
# Gradle automatically packages shared libraries with your APK.

add_library( # Sets the name of the library.
             native-lib

             # Sets the library as a shared library.
             SHARED

             # Provides a relative path to your source file(s).
             src/main/cpp/native-lib.cpp )

# Searches for a specified prebuilt library and stores the path as a
# variable. Because CMake includes system libraries in the search path by
# default, you only need to specify the name of the public NDK library
# you want to add. CMake verifies that the library exists before
# completing its build.

find_library( # Sets the name of the path variable.
              log-lib

              # Specifies the name of the NDK library that
              # you want CMake to locate.
              log )

# HERE ARE THE PARTS I EDITED:
# NOTE FOR THE COMMANDS ABOVE, THIS IS JUST THE OPENSSL SOURCE DIR.
set (SSL_PATH /path/to/ssl/build/outputs/)
include_directories(${SSL_PATH}/include)
set (open-ssl-libs ${SSL_PATH}/libssl.a ${SSL_PATH}/libcrypto.a)


# Specifies libraries CMake should link to your target library. You
# can link multiple libraries, such as libraries you define in this
# build script, prebuilt third-party libraries, or system libraries.

target_link_libraries( # Specifies the target library.
                       native-lib
                       # LINK SSL AND CRYPTO HERE:
                        ${open-ssl-libs}
                       # Links the target library to the log library
                       # included in the NDK.
                       ${log-lib} )

这足以表明它是链接的，但我在 Android Studio 生成的样板 C++ 代码中添加了一个对 libssl.a 的小引用：

#include <jni.h>
#include <string>
#include <openssl/ssl.h>

extern "C" JNIEXPORT jstring JNICALL
Java_com_vernier_android_test_1ssl_MainActivity_stringFromJNI(
        JNIEnv* env,
        jobject /* this */) {

    SSL* ssl = SSL_new(nullptr);
    std::string hello = "Hello from C++";
    return env->NewStringUTF(hello.c_str());
}

我成功运行了该应用程序。