Depending on my first question, I tried to include the fanotify.h header in my application. The application is based on fsmon (a small application to use the fanotify syscall), I changed some code lines for my purpose and created an 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 $(BUILD_EXECUTABLE)
I need to include the linux/inotify.h and the linux/fanotify.h headers.
On executing ndk-build, only the arm64-v8a, mips64 and x86_64 executable files (in libs/xxx) get created cause of following error messages:
fabian@fabian-ubuntu:~/kernel_android_goldfish/fsmon/fsmon/jni$ ndk-build
[arm64-v8a] Compile : fsmon <= inotify.c
[arm64-v8a] Compile : fsmon <= fanotify.c
[arm64-v8a] Compile : fsmon <= util.c
[arm64-v8a] Compile : fsmon <= main.c
[arm64-v8a] Executable : fsmon
[arm64-v8a] Install : 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 <= main.c
[x86_64] Executable : fsmon
[x86_64] Install : fsmon => libs/x86_64/fsmon
[mips64] Compile : fsmon <= inotify.c
[mips64] Compile : fsmon <= fanotify.c
[mips64] Compile : fsmon <= util.c
[mips64] Compile : fsmon <= main.c
[mips64] Executable : fsmon
[mips64] Install : 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
Cause of inotify.c including the signal.h header which re-includes the linux/signal.h and this in turn the platforms/android-9/arch-arm/usr/include/asm/signal.h , where the error appears. (suddenly from android-9).
I can't figure out where the problem is.. I tried to include the include folder from sysroot - but similar errors appear.
Source file: inotify.c fanotify.c
You shouldn't manually point to the NDK headers in LOCAL_C_INCLUDES. This should be added automatically, pointing to the right version. However, nothing actually uses the variables APP_PLATFORM or TARGET_PLATFORM here.
Instead, add APP_PLATFORM := android-23 in the file jni/Application.mk. That should make it build using the right platform headers, for all architectures.