Cmake测试被忽略-在android中用gradle构建cmake项目

Question

我正在尝试将https://github.com/j0r1/JRTPLIB集成到gradle中。关于readme，已经有关于如何将库编译为在Android上安装的教程，但是我需要gradle集成。

下面是我如何将项目添加到我的gradle文件中：

https://github.com/lucaszanella/jscam/blob/ecc99f430b360f7e1aa5bf687633a5e3557c045e/src/jscam/android/app/build.gradle#L118

我收到了一个编译错误，因为我的系统库不支持ifaddrs。然而，该项目的策划者对此有一个测试：

jrtplib_include_test(ifaddrs.h RTP_SUPPORT_IFADDRS "// No ifaddrs support")

，那么，为什么gradle试图构建一些没有通过测试的东西呢？

下面是编译我的应用程序时的错误：

Error while executing '/android-sdk-linux/cmake/3.6.4111459/bin/cmake' with arguments {--build /home/project/src/jscam/android/app/.externalNativeBuild/cmake/debug/x86 --target jrtplib-shared}
  [1/3] Building CXX object src/CMakeFiles/jrtplib-shared.dir/rtpudpv4transmitter.cpp.o
  [2/3] Building CXX object src/CMakeFiles/jrtplib-shared.dir/rtpudpv6transmitter.cpp.o
  FAILED: /android-sdk-linux/ndk-bundle/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++  --target=i686-none-linux-android --gcc-toolchain=/android-sdk-linux/ndk-bundle/toolchains/x86-4.9/prebuilt/linux-x86_64 --sysroot=/android-sdk-linux/ndk-bundle/sysroot  -DJRTPLIB_COMPILING -Djrtplib_shared_EXPORTS -I/home/project/src/jscam/JRTPLIB/src -Isrc -isystem /android-sdk-linux/ndk-bundle/sources/cxx-stl/gnu-libstdc++/4.9/include -isystem /android-sdk-linux/ndk-bundle/sources/cxx-stl/gnu-libstdc++/4.9/libs/x86/include -isystem /android-sdk-linux/ndk-bundle/sources/cxx-stl/gnu-libstdc++/4.9/include/backward-isystem /android-sdk-linux/ndk-bundle/sysroot/usr/include/i686-linux-android -D__ANDROID_API__=16 -g -DANDROID -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -mstackrealign -Wa,--noexecstack -Wformat -Werror=format-security   -O0 -fno-limit-debug-info  -fPIC -MD -MT src/CMakeFiles/jrtplib-shared.dir/rtpudpv6transmitter.cpp.o -MF src/CMakeFiles/jrtplib-shared.dir/rtpudpv6transmitter.cpp.o.d -o src/CMakeFiles/jrtplib-shared.dir/rtpudpv6transmitter.cpp.o -c /home/project/src/jscam/JRTPLIB/src/rtpudpv6transmitter.cpp
  /home/project/src/jscam/JRTPLIB/src/rtpudpv6transmitter.cpp:1575:2: error: use of undeclared identifier 'getifaddrs'
          getifaddrs(&addrs);
          ^
  /home/project/src/jscam/JRTPLIB/src/rtpudpv6transmitter.cpp:1588:2: error: use of undeclared identifier 'freeifaddrs'
          freeifaddrs(addrs);
          ^
  2 errors generated.
  FAILED: /android-sdk-linux/ndk-bundle/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++  --target=i686-none-linux-android --gcc-toolchain=/android-sdk-linux/ndk-bundle/toolchains/x86-4.9/prebuilt/linux-x86_64 --sysroot=/android-sdk-linux/ndk-bundle/sysroot  -DJRTPLIB_COMPILING -Djrtplib_shared_EXPORTS -I/home/project/src/jscam/JRTPLIB/src -Isrc -isystem /android-sdk-linux/ndk-bundle/sources/cxx-stl/gnu-libstdc++/4.9/include -isystem /android-sdk-linux/ndk-bundle/sources/cxx-stl/gnu-libstdc++/4.9/libs/x86/include -isystem /android-sdk-linux/ndk-bundle/sources/cxx-stl/gnu-libstdc++/4.9/include/backward-isystem /android-sdk-linux/ndk-bundle/sysroot/usr/include/i686-linux-android -D__ANDROID_API__=16 -g -DANDROID -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -mstackrealign -Wa,--noexecstack -Wformat -Werror=format-security   -O0 -fno-limit-debug-info  -fPIC -MD -MT src/CMakeFiles/jrtplib-shared.dir/rtpudpv4transmitter.cpp.o -MF src/CMakeFiles/jrtplib-shared.dir/rtpudpv4transmitter.cpp.o.d -o src/CMakeFiles/jrtplib-shared.dir/rtpudpv4transmitter.cpp.o -c /home/project/src/jscam/JRTPLIB/src/rtpudpv4transmitter.cpp
  /home/project/src/jscam/JRTPLIB/src/rtpudpv4transmitter.cpp:1813:2: error: use of undeclared identifier 'getifaddrs'
          getifaddrs(&addrs);
          ^
  /home/project/src/jscam/JRTPLIB/src/rtpudpv4transmitter.cpp:1826:2: error: use of undeclared identifier 'freeifaddrs'
          freeifaddrs(addrs);
          ^
  2 errors generated.
  ninja: build stopped: subcommand failed.

Answer 1

Android为你准备了<ifaddrs.h>。但是缺少的函数，如getifaddrs()，可用于__ANDROID_API__ 24及更高版本，而您的项目则设置为

如果您的库将与低于24的minSdkVersion一起使用，则不能使用这些函数。不幸的是，JRTPLIB似乎没有对ifaddr的如此细粒度的支持，但是如果您选择的话，您可以强制关闭RTP_SUPPORT_IFADDRS。