C(++) で実装する必要がある一部のコードでは、AES や 3DES 暗号化/復号化などの暗号化関数が必要です。openssl は Playstore のオプションではなくなったため、別のライブラリを選択する必要がありました。私の選択は libgcrypt でした。今、Android用のlibgpgerrをコンパイルするのに苦労しています。（iOSは問題なく動作しています）
環境:
- Ubuntu 16.04
- Android NDK: 15.1.4119039
- ビルドシステム: cmake を使用したグラドル
- stl:llvm
コンパイラ: クラン
externalNativeBuild { cmake { cppFlags "-std=c++11 -fexceptions" arguments "-DANDROID_ARM_NEON=TRUE", "-DANDROID_STL=c++_shared" } } ndk { // Specifies the ABI configurations of your native // libraries Gradle should build and package with your APK. abiFilters /*'x86', 'x86_64',*/ 'armeabi', 'armeabi-v7a', 'arm64-v8a' /*, 'mips', 'mips64'*/ }
私のlibgcrypt用の（サブ）cmake：
cmake_minimum_required(VERSION 3.6)
include(ExternalProject)
set(CMAKE_CXX_STANDARD 11)
set(LIB_DIR ${CMAKE_CURRENT_LIST_DIR}/../..)
set(LIBGPG_ERROR_DIR ${LIB_DIR}/libgpg-error)
set(LIBGCRYPT_DIR ${LIB_DIR}/libgcrypt)
set(THIS_PREFIX ${CMAKE_CURRENT_BINARY_DIR}/)
message(STATUS "> ****************************** ${CMAKE_SYSTEM_PROCESSOR} >")
get_cmake_property(_variableNames VARIABLES)
foreach (_variableName ${_variableNames})
message(STATUS "${_variableName}=${${_variableName}}")
endforeach()
execute_process(COMMAND "${CMAKE_COMMAND}" "-E" "environment")
message(STATUS "< ****************************** ${CMAKE_SYSTEM_PROCESSOR} <")
if (IS_ANDROID)
# CMAKE_C_IMPLICIT_LINK_DIRECTORIES
set(EXTRA_DIRS "-L/home/user/Android/Sdk/ndk-bundle/sources/cxx-stl/llvm-libc++/libs/armeabi-v7a -L/home/user/Android/Sdk/ndk-bundle/toolchains/llvm/prebuilt/linux-x86_64/lib64/clang/5.0.300080/lib/linux/arm -L/home/user/Android/Sdk/ndk-bundle/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/armv7-a/thumb -L/home/user/Android/Sdk/ndk-bundle/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/arm-linux-androideabi/lib/armv7-a/thumb -L/home/user/Android/Sdk/ndk-bundle/platforms/android-19/arch-arm/usr/lib -I ${CMAKE_C_IMPLICIT_INCLUDE_DIRECTORIES}")
set(MAKE_ENV
export "CFLAGS=${CMAKE_C_FLAGS} ${EXTRA_DIRS} -target ${ANDROID_LLVM_TRIPLE} -v -no-integrated-as -B${ANDROID_TOOLCHAIN_PREFIX}"
&& export "CXXFLAGS=${CMAKE_CXX_FLAGS}"
&& export "LDFLAGS=${ANDROID_LINKER_FLAGS} ${EXTRA_DIRS}"
#CFLAGS= "--sysroot=${}"
#LDFLAGS=
&& export "LD=${CMAKE_LINKER} -v -B${ANDROID_TOOLCHAIN_PREFIX}"
&& export "AS=${ANDROID_ASM_COMPILER}"
&& export "CC=${CMAKE_C_COMPILER} -v ${EXTRA_DIRS} -stdlib=${ANDROID_STL}"
&& export "CXX=${CMAKE_CXX_COMPILER}"
&& export "AR=${CMAKE_AR}"
&& export "RANLIB=${CMAKE_RANLIB}"
&& export "PATH=${ANDROID_LLVM_TOOLCHAIN_PREFIX}:${ANDROID_TOOLCHAIN_ROOT}/bin:${ANDROID_TOOLCHAIN_PREFIX}:$ENV{PATH}"
#GCC_TOOLCHAIN=${ANDROID_TOOLCHAIN_PREFIX}
)
set(HOST ${ANDROID_HEADER_TRIPLE} )
#set(HOST ${ANDROID_LLVM_TRIPLE} )
ExternalProject_Add(
libgpg-error
SOURCE_DIR ${CMAKE_CURRENT_LIST_DIR}/
CONFIGURE_COMMAND ${MAKE_ENV} && ${LIBGPG_ERROR_DIR}/configure --host=${HOST} --prefix=${THIS_PREFIX} --enable-static --disable-shared --disable-doc --disable-languages #--disable-asm
#PREFIX ${THIS_PREFIX}
BUILD_COMMAND ${MAKE_ENV} && make
INSTALL_COMMAND ${MAKE_ENV} && make install
)
# CMAKE_C_COMPILER_TARGET
ExternalProject_Add(
libgcrypt
SOURCE_DIR ${CMAKE_CURRENT_LIST_DIR}/
CONFIGURE_COMMAND ${MAKE_ENV} && ${LIBGCRYPT_DIR}/configure --host=${HOST} --prefix=${THIS_PREFIX} --enable-static --disable-shared --with-gpg-error-prefix=${THIS_PREFIX} --disable-doc --disable-languages #--disable-asm
#PREFIX ${THIS_PREFIX}
BUILD_COMMAND ${MAKE_ENV} && make
INSTALL_COMMAND ${MAKE_ENV} && make install
DEPENDS libgpg-error
)
endif()
ログファイルの最後の部分:
clang: warning: argument unused during compilation: '-L/home/user/Android/Sdk/ndk-bundle/platforms/android-19/arch-arm/usr/lib' [-Wunused-command-line-argument]
"/home/user/Android/Sdk/ndk-bundle/toolchains/llvm/prebuilt/linux-x86_64/bin/clang" -cc1 -triple thumbv7-none-linux-android -S -disable-free -disable-llvm-verifier -discard-value-names -main-file-name estream.c -mrelocation-model pic -pic-level 1 -mthread-model posix -mdisable-fp-elim -fmath-errno -masm-verbose -no-integrated-as -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu cortex-a8 -target-feature +soft-float-abi -target-feature -fp-only-sp -target-feature -d16 -target-feature +vfp3 -target-feature -fp16 -target-feature -vfp4 -target-feature -fp-armv8 -target-feature +neon -target-feature -crypto -target-abi aapcs-linux -mfloat-abi soft -target-linker-version 2.24 -v -v -dwarf-column-info -debug-info-kind=limited -dwarf-version=4 -debugger-tuning=gdb -ffunction-sections -coverage-notes-file /home/user/workspace/company/project-android/project/app/.externalNativeBuild/cmake/debug/armeabi-v7a/libgcrypt/libgpg-error-prefix/src/libgpg-error-build/src/estream.gcno -resource-dir /home/user/Android/Sdk/ndk-bundle/toolchains/llvm/prebuilt/linux-x86_64/lib64/clang/5.0.300080 -dependency-file .deps/libgpg_error_la-estream.Tpo -sys-header-deps -MP -MT libgpg_error_la-estream.lo -isystem /home/user/Android/Sdk/ndk-bundle/sysroot/usr/include/arm-linux-androideabi -I /usr/include -D HAVE_CONFIG_H -I . -I /home/user/workspace/company/project-android/project/project-encrypt-lib/shared/lib/cmakeFiles/libgcrypt/../../libgpg-error/src -I .. -D "LOCALEDIR=\"/home/user/workspace/company/project-android/project/app/.externalNativeBuild/cmake/debug/armeabi-v7a/libgcrypt/share/locale\"" -D __ANDROID_API__=19 -D ANDROID -I /usr/include -internal-isystem /usr/local/include -internal-isystem /home/user/Android/Sdk/ndk-bundle/toolchains/llvm/prebuilt/linux-x86_64/lib64/clang/5.0.300080/include -internal-externc-isystem /include -internal-externc-isystem /usr/include -Wformat -Werror=format-security -Wall -Wpointer-arith -fno-dwarf-directory-asm -fdebug-compilation-dir /home/user/workspace/company/project-android/project/app/.externalNativeBuild/cmake/debug/armeabi-v7a/libgcrypt/libgpg-error-prefix/src/libgpg-error-build/src -ferror-limit 19 -fmessage-length 0 -femulated-tls -stack-protector 2 -fallow-half-arguments-and-returns -fno-signed-char -fobjc-runtime=gcc -fdiagnostics-show-option -o /tmp/estream-2a422f.s -x c /home/user/workspace/company/project-android/project/project-encrypt-lib/shared/lib/cmakeFiles/libgcrypt/../../libgpg-error/src/estream.c
clang -cc1 version 5.0.300080 based upon LLVM 5.0.300080 default target x86_64-unknown-linux
ignoring nonexistent directory "/include"
ignoring duplicate directory "/usr/include"
ignoring duplicate directory "/usr/include"
as it is a non-system directory that duplicates a system directory
#include "..." search starts here:
#include <...> search starts here:
.
/home/user/workspace/company/project-android/project/project-encrypt-lib/shared/lib/cmakeFiles/libgcrypt/../../libgpg-error/src
..
/home/user/Android/Sdk/ndk-bundle/sysroot/usr/include/arm-linux-androideabi
/usr/local/include
/home/user/Android/Sdk/ndk-bundle/toolchains/llvm/prebuilt/linux-x86_64/lib64/clang/5.0.300080/include
/usr/include
End of search list.
/home/user/workspace/company/project-android/project/project-encrypt-lib/shared/lib/cmakeFiles/libgcrypt/../../libgpg-error/src/estream.c:4869:15: error: invalid output constraint '=c' in asm
FD_ZERO (&readfds);
^
/usr/include/sys/select.h:93:26: note: expanded from macro 'FD_ZERO'
#define FD_ZERO(fdsetp) __FD_ZERO (fdsetp)
^
/usr/include/bits/select.h:37:8: note: expanded from macro '__FD_ZERO'
: "=c" (__d0), "=D" (__d1) \
^
/home/user/workspace/company/project-android/project/project-encrypt-lib/shared/lib/cmakeFiles/libgcrypt/../../libgpg-error/src/estream.c:4880:15: error: invalid output constraint '=c' in asm
FD_ZERO (&writefds);
^
/usr/include/sys/select.h:93:26: note: expanded from macro 'FD_ZERO'
#define FD_ZERO(fdsetp) __FD_ZERO (fdsetp)
^
/usr/include/bits/select.h:37:8: note: expanded from macro '__FD_ZERO'
: "=c" (__d0), "=D" (__d1) \
^
/home/user/workspace/company/project-android/project/project-encrypt-lib/shared/lib/cmakeFiles/libgcrypt/../../libgpg-error/src/estream.c:4891:15: error: invalid output constraint '=c' in asm
FD_ZERO (&exceptfds);
^
/usr/include/sys/select.h:93:26: note: expanded from macro 'FD_ZERO'
#define FD_ZERO(fdsetp) __FD_ZERO (fdsetp)
^
/usr/include/bits/select.h:37:8: note: expanded from macro '__FD_ZERO'
: "=c" (__d0), "=D" (__d1) \
^
3 errors generated.
Makefile:876: die Regel für Ziel „libgpg_error_la-estream.lo“ scheiterte
make[3]: *** [libgpg_error_la-estream.lo] Fehler 1
make[3]: Verzeichnis „/home/user/workspace/company/project-android/project/app/.externalNativeBuild/cmake/debug/armeabi-v7a/libgcrypt/libgpg-error-prefix/src/libgpg-error-build/src“ wird verlassen
Makefile:578: die Regel für Ziel „all“ scheiterte
make[2]: *** [all] Fehler 2
make[2]: Verzeichnis „/home/user/workspace/company/project-android/project/app/.externalNativeBuild/cmake/debug/armeabi-v7a/libgcrypt/libgpg-error-prefix/src/libgpg-error-build/src“ wird verlassen
Makefile:474: die Regel für Ziel „all-recursive“ scheiterte
make[1]: *** [all-recursive] Fehler 1
make[1]: Verzeichnis „/home/user/workspace/company/project-android/project/app/.externalNativeBuild/cmake/debug/armeabi-v7a/libgcrypt/libgpg-error-prefix/src/libgpg-error-build“ wird verlassen
Makefile:405: die Regel für Ziel „all“ scheiterte
make: *** [all] Fehler 2
ninja: build stopped: subcommand failed.