Android ndk build无法构建32bit可执行文件
根据我的第一个问题 ，我尝试在我的应用程序中包含fanotify.h标头。 该应用程序基于fsmon （一个使用fanotify系统调用的小应用程序），我为了我的目的更改了一些代码行并创建了一个Android.mk makefile：
APP_PLATFORM := android-23 TARGET_PLATFORM := android-23 LOCAL_PATH := $(call my-dir) include $(CLEAR_VARS) # Enable PIE manually. Will get reset on $(CLEAR_VARS). This # is what enabling PIE translates to behind the scenes. LOCAL_CFLAGS += -fPIE -DHAVE_FANOTIFY=1 -DHAVE_SYS_FANOTIFY=0 LOCAL_LDFLAGS += -fPIE -pie # give module name LOCAL_MODULE := fsmon # include fanotify by api 23: LOCAL_C_INCLUDES := /home/fabian/Android/Sdk/ndk-bundle/platforms/android-23/arch-arm/usr/include # include fanotify by sysroot -> # LOCAL_C_INCLUDES := /home/fabian/Android/Sdk/ndk-bundle/sysroot/usr/include/ # list your C files to compile LOCAL_SRC_FILES := inotify.c fanotify.c util.c main.c # this option will build executables instead of building library for android application. include $(BUILD_EXECUTABLE)
我需要包含linux/inotify.h和linux/fanotify.h头文件。
在执行ndk-build ，只会ndk-build arm64-v8a ， mips64和x86_64可执行文件（在libs / xxx中），导致出现以下错误消息：
fabian@fabian-ubuntu:~/kernel_android_goldfish/fsmon/fsmon/jni$ ndk-build [arm64-v8a] Compile : fsmon <= inotify.c [arm64-v8a] Compile : fsmon <= fanotify.c [arm64-v8a] Compile : fsmon <= util.c [arm64-v8a] Compile : fsmon libs/arm64-v8a/fsmon [x86_64] Compile : fsmon <= inotify.c [x86_64] Compile : fsmon <= fanotify.c [x86_64] Compile : fsmon <= util.c [x86_64] Compile : fsmon libs/x86_64/fsmon [mips64] Compile : fsmon <= inotify.c [mips64] Compile : fsmon <= fanotify.c [mips64] Compile : fsmon <= util.c [mips64] Compile : fsmon libs/mips64/fsmon [armeabi-v7a] Compile thumb : fsmon <= inotify.c In file included from /home/fabian/kernel_android_goldfish/fsmon/fsmon/jni/inotify.c:9: In file included from /home/fabian/Android/Sdk/ndk-bundle/sysroot/usr/include/signal.h:49: In file included from /home/fabian/Android/Sdk/ndk-bundle/sysroot/usr/include/linux/signal.h:21: In file included from /home/fabian/Android/Sdk/ndk-bundle/platforms/android-9/arch-arm/usr/include/asm/signal.h:82: /home/fabian/Android/Sdk/ndk-bundle/sysroot/usr/include/asm-generic/signal.h:92:21: error: use of undeclared identifier '__BITS_PER_LONG' unsigned long sig[_NSIG_WORDS]; ^ /home/fabian/Android/Sdk/ndk-bundle/sysroot/usr/include/asm-generic/signal.h:25:38: note: expanded from macro '_NSIG_WORDS' #define _NSIG_WORDS (_KERNEL__NSIG / _NSIG_BPW) ^ /home/fabian/Android/Sdk/ndk-bundle/sysroot/usr/include/asm-generic/signal.h:24:19: note: expanded from macro '_NSIG_BPW' #define _NSIG_BPW __BITS_PER_LONG ^ /home/fabian/Android/Sdk/ndk-bundle/sysroot/usr/include/asm-generic/signal.h:94:3: error: typedef redefinition with different types ('struct (anonymous struct at /home/fabian/Android/Sdk/ndk-bundle/sysroot/usr/include/asm-generic/signal.h:91:9)' vs 'unsigned long') } sigset_t; ^ /home/fabian/Android/Sdk/ndk-bundle/platforms/android-9/arch-arm/usr/include/asm/signal.h:20:23: note: previous definition is here typedef unsigned long sigset_t; ^ /home/fabian/Android/Sdk/ndk-bundle/platforms/android-9/arch-arm/usr/include/asm/signal.h:84:8: error: redefinition of 'sigaction' struct sigaction { ^ /home/fabian/Android/Sdk/ndk-bundle/sysroot/usr/include/asm-generic/signal.h:101:8: note: previous definition is here struct sigaction { ^ In file included from /home/fabian/kernel_android_goldfish/fsmon/fsmon/jni/inotify.c:9: In file included from /home/fabian/Android/Sdk/ndk-bundle/sysroot/usr/include/signal.h:49: In file included from /home/fabian/Android/Sdk/ndk-bundle/sysroot/usr/include/linux/signal.h:21: /home/fabian/Android/Sdk/ndk-bundle/platforms/android-9/arch-arm/usr/include/asm/signal.h:97:16: error: redefinition of 'sigaltstack' typedef struct sigaltstack { ^ /home/fabian/Android/Sdk/ndk-bundle/sysroot/usr/include/asm-generic/signal.h:111:16: note: previous definition is here typedef struct sigaltstack { ^ In file included from /home/fabian/kernel_android_goldfish/fsmon/fsmon/jni/inotify.c:9: In file included from /home/fabian/Android/Sdk/ndk-bundle/sysroot/usr/include/signal.h:49: In file included from /home/fabian/Android/Sdk/ndk-bundle/sysroot/usr/include/linux/signal.h:21: /home/fabian/Android/Sdk/ndk-bundle/platforms/android-9/arch-arm/usr/include/asm/signal.h:101:3: error: typedef redefinition with different types ('struct (anonymous struct at /home/fabian/Android/Sdk/ndk-bundle/platforms/android-9/arch-arm/usr/include/asm/signal.h:97:16)' vs 'struct sigaltstack') } stack_t; ^ /home/fabian/Android/Sdk/ndk-bundle/sysroot/usr/include/asm-generic/signal.h:116:3: note: previous definition is here } stack_t; ^ In file included from /home/fabian/kernel_android_goldfish/fsmon/fsmon/jni/inotify.c:9: /home/fabian/Android/Sdk/ndk-bundle/sysroot/usr/include/signal.h:71:9: warning: 'NSIG' macro redefined [-Wmacro-redefined] #define NSIG _NSIG ^ /home/fabian/Android/Sdk/ndk-bundle/platforms/android-9/arch-arm/usr/include/asm/signal.h:19:9: note: previous definition is here #define NSIG 32 ^ In file included from /home/fabian/kernel_android_goldfish/fsmon/fsmon/jni/inotify.c:9: /home/fabian/Android/Sdk/ndk-bundle/sysroot/usr/include/signal.h:79:9: warning: 'SIGRTMIN' macro redefined [-Wmacro-redefined] #define SIGRTMIN (__libc_current_sigrtmin()) ^ /home/fabian/Android/Sdk/ndk-bundle/platforms/android-9/arch-arm/usr/include/asm/signal.h:58:9: note: previous definition is here #define SIGRTMIN 32 ^ In file included from /home/fabian/kernel_android_goldfish/fsmon/fsmon/jni/inotify.c:9: /home/fabian/Android/Sdk/ndk-bundle/sysroot/usr/include/signal.h:80:9: warning: 'SIGRTMAX' macro redefined [-Wmacro-redefined] #define SIGRTMAX (__libc_current_sigrtmax()) ^ /home/fabian/Android/Sdk/ndk-bundle/platforms/android-9/arch-arm/usr/include/asm/signal.h:59:9: note: previous definition is here #define SIGRTMAX _NSIG ^ 5 errors generated. make: *** [/home/fabian/kernel_android_goldfish/fsmon/fsmon/obj/local/armeabi-v7a/objs/fsmon/inotify.o] Error 1
inotify.c原因包括signal.h头，它重新包含了linux/signal.h而这又是platforms/android-9/arch-arm/usr/include/asm/signal.h ，其中出现错误。 （突然来自android-9）。
我无法弄清楚问题出在哪里..我试图在sysroot中包含include文件夹 – 但是会出现类似的错误。
源文件： inotify.c fanotify.c
您不应该手动指向LOCAL_C_INCLUDES的NDK标头。 这应该自动添加，指向正确的版本。 但是，这里没有实际使用变量APP_PLATFORM或TARGET_PLATFORM 。
而是在文件jni/Application.mk添加APP_PLATFORM := android-23 。 对于所有体系结构，这应该使用正确的平台标头进行构建。
除了@ mstorsjo的答案，您还可以在NDK r14和更新版本中使用统一标头 。 这些是标头的新forms，它始终是最新的，而不是为每个API级别设置不同的标头集。
这比APP_PLATFORM增加的APP_PLATFORM是你的APP_PLAFORM不能高于你的minSdkVersion （参见我们的常见问题文档 ）。 由于fanotify是在一个相当旧版本的内核中引入的（对于fanotify_init为fanotify_init ），你应该仍然能够用syscall(__NR_fanotify_init)调用它，即使旧版本的libc中不存在该函数。 尽管如此， ENOSYS始终是一种可能性。
默认情况下，在r14中，您仍然可以获得旧标题的forms。 新的“统一标题”包含您正在寻找的标题。 如果要尝试统一标头，请在Application.mk中设置APP_UNIFIED_HEADERS := true （其他构建系统的设置可以在上面的链接中找到）。
在r15（即将推出的第一个测试版）中，默认值已更改为新标题，并且禁用它们的选项已更改（请参阅r15中的相同文档 ）。