From Android NDK To AOSP
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Bekket McClane gave a presentation on moving from the Android NDK to AOSP. The presentation covered the Android NDK introduction and JNI programming. It provided an overview of AOSP including the zygote process and Binder IPC. An example was shown for controlling the vibrator using C/C++ Binder APIs by accessing libraries from AOSP. The steps included building AOSP libraries, creating an Android.mk file, and interacting with the vibrator service via a fake AIDL interface. Questions were invited via the speaker's online accounts.
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From Android NDK To AOSP
- 1. FROM ANDROID NDK TO AOSP Bekket McClane @SITCON2015
- 2. WHO AM I ?
- 3. WHO AM I ? ⺠民2
- 4. WHO AM I ? BEKKET MCCLANE
- 5. WHO AM I ? MSHOCKWAVE
- 6. DEPARTMENT OF COMPUTER SCIENCE Freshman
- 8. TODAY’S TOPIC • GRAPHIC RENDERING • GAME • SECURITY
- 9. TODAY’S TOPIC • GRAPHIC RENDERING • GAME • SECURITY
- 10. TODAY’S TOPIC • GRAPHIC RENDERING • GAME • SECURITY
- 11. TODAY’S TOPIC • GRAPHIC RENDERING • GAME • SECURITY
- 12. TODAY’S TOPIC • GRAPHIC RENDERING • GAME • SECURITY LEARNING
- 13. • Android NDK Introduction • AOSP Overview • From NDK To AOSP • Example SYLLABUS
- 15. APP JNI Native Library ( .so )
- 18. • Graphic Rendering (Ex. OpenGL) • Multi Media (Ex. OpenMAX) • Game
- 19. JNI PROGRAMMING
- 20. JNI PROGRAMMING
- 22. Android.mk
- 23. 1 LOCAL_PATH := $(call my-dir) 2 include $(CLEAR_VARS) 3 LOCAL_MODULE := foo 4 LOCAL_SRC_FILES := bar.c 5 #LOCAL_CFLAGS += -DDUMMY_FLAG 6 #LOCAL_LDLIBS += -llog 7 include $(BUILD_SHARED_LIBRARY)
- 24. 1 LOCAL_PATH := $(call my-dir) 2 include $(CLEAR_VARS) 3 LOCAL_MODULE := foo 4 LOCAL_SRC_FILES := bar.c 5 #LOCAL_CFLAGS += -DDUMMY_FLAG 6 #LOCAL_LDLIBS += -llog 7 include $(BUILD_SHARED_LIBRARY)
- 25. 1 LOCAL_PATH := $(call my-dir) 2 include $(CLEAR_VARS) 3 LOCAL_MODULE := foo 4 LOCAL_SRC_FILES := bar.c 5 #LOCAL_CFLAGS += -DDUMMY_FLAG 6 #LOCAL_LDLIBS += -llog 7 include $(BUILD_SHARED_LIBRARY) Another makefile
- 26. 1 LOCAL_PATH := $(call my-dir) 2 include $(CLEAR_VARS) 3 LOCAL_MODULE := foo 4 LOCAL_SRC_FILES := bar.c 5 #LOCAL_CFLAGS += -DDUMMY_FLAG 6 #LOCAL_LDLIBS += -llog 7 include $(BUILD_SHARED_LIBRARY) Another makefile
- 27. 1 LOCAL_PATH := $(call my-dir) 2 include $(CLEAR_VARS) 3 LOCAL_MODULE := foo 4 LOCAL_SRC_FILES := bar.c 5 #LOCAL_CFLAGS += -DDUMMY_FLAG 6 #LOCAL_LDLIBS += -llog 7 include $(BUILD_SHARED_LIBRARY) Another makefile Compiler Options
- 28. 1 LOCAL_PATH := $(call my-dir) 2 include $(CLEAR_VARS) 3 LOCAL_MODULE := foo 4 LOCAL_SRC_FILES := bar.c 5 #LOCAL_CFLAGS += -DDUMMY_FLAG 6 #LOCAL_LDLIBS += -llog 7 include $(BUILD_SHARED_LIBRARY) Another makefile Compiler Options
- 29. 1 LOCAL_PATH := $(call my-dir) 2 include $(CLEAR_VARS) 3 LOCAL_MODULE := foo 4 LOCAL_SRC_FILES := bar.c 5 #LOCAL_CFLAGS += -DDUMMY_FLAG 6 #LOCAL_LDLIBS += -llog 7 include $(BUILD_SHARED_LIBRARY) Another makefile Compiler Options The real “builder” makefile
- 30. 1 LOCAL_PATH := $(call my-dir) 2 include $(CLEAR_VARS) 3 LOCAL_MODULE := foo 4 LOCAL_SRC_FILES := bar.c 5 #LOCAL_CFLAGS += -DDUMMY_FLAG 6 #LOCAL_LDLIBS += -llog 7 include $(BUILD_SHARED_LIBRARY) libfoo.so (in this case) Another makefile Compiler Options The real “builder” makefile
- 31. $ ndk-build $ ndk-build -B
- 32. $ ndk-build ($ ndk-build NDK_DEBUG=1) $ ndk-build -B
- 33. AOSP OVERVIEW
- 34. AOSP = Android Open Source Project (vendors’ property libraries)
- 35. AOSP = Android Open Source Project NOT INCLUDED (vendors’ property libraries)
- 36. Zygote
- 39. Zygote ( Java World )
- 40. Zygote Request via Local Socket ( Java World )
- 41. Zygote fork app_01 app_02 app_03 Request via Local Socket ( Java World )
- 42. Zygote fork app_01 app_02 app_03 Shared address space Request via Local Socket ( Java World )
- 43. Pros: Preload Java Classes
- 44. $ adb shell ps | grep -e "u0_" -e "zygote" | awk '{print $1,"t",$2,"t",$3,"t",$9}'
- 45. root 328 1 zygote u0_a24 1051 328 com.android.systemui u0_a8 1151 328 com.asus.launcher u0_a20 1351 328 com.google.process.gapps User PID PPID Process Name . . .
- 46. root 328 1 zygote u0_a24 1051 328 com.android.systemui u0_a8 1151 328 com.asus.launcher u0_a20 1351 328 com.google.process.gapps User PID PPID Process Name . . .
- 47. And their friends System Services
- 48. Service Manager Java Services Native Services App
- 49. Service Manager Java Services Native Services App addService
- 50. Service Manager Java Services Native Services App Query addService
- 51. Service Manager Java Services Native Services App Query addService Communicate via IPC
- 52. system 979 328 system_server root 328 1 zygote media 331 1 /system/bin/mediaserver system 316 1 /system/bin/servicemanager
- 53. system 979 328 system_server root 328 1 zygote media 331 1 /system/bin/mediaserver system 316 1 /system/bin/servicemanager Most of the Java services live in here
- 54. system 979 328 system_server root 328 1 zygote media 331 1 /system/bin/mediaserver system 316 1 /system/bin/servicemanager Most of the Java services live in here One of native services
- 55. Binder IPC
- 56. HIGHLIGHT send() / recv()-like APIs
- 57. HIGHLIGHT send() / recv()-like APIs
- 58. • Still need kernel’s help • Heavily object oriented • Put “transmission part” and “logic part” together
- 59. • Still need kernel’s help • Heavily object oriented • Put “transmission part” and “logic part” together (Interface, Inheritance…etc)
- 60. • Still need kernel’s help • Heavily object oriented • Put “transmission part” and “logic part” together (Inheritance) (Interface, Inheritance…etc)
- 61. EX: AIDL PROGRAMMING IMyLight led; led = IMyLight.Stub.asInterface(binder); led.turnOn();
- 62. EX: AIDL PROGRAMMING IMyLight led; led = IMyLight.Stub.asInterface(binder); led.turnOn(); The real “messenger”
- 63. EX: AIDL PROGRAMMING IMyLight led; led = IMyLight.Stub.asInterface(binder); led.turnOn(); The real “messenger”
- 64. EX: AIDL PROGRAMMING IMyLight led; led = IMyLight.Stub.asInterface(binder); led.turnOn(); Interface The real “messenger”
- 65. From NDK To AOSP
- 66. FACT:
- 67. b6beb000 156K r-xp /system/lib/libbinder.so b6b22000 4K r-xp /system/lib/libhardware.so PMAP RESULT
- 68. – NOT Barack Obama “If there is a way, there’s a will”
- 69. “If there is a way, there’s a will” “If there is a LIBRARY in the address space, there are SYMBOLS (we can use)”
- 71. Normal App
- 72. Normal App Place we utilize
- 73. clang -c demo.c clang -o demoExe demo.o -I./include -L./lib —lmyLib COMPILE A PROGRAM
- 74. clang -c demo.c clang -o demoExe demo.o -I./include -L./lib —lmyLib COMPILE A PROGRAM
- 75. clang -c demo.c clang -o demoExe demo.o -I./include -L./lib —lmyLib COMPILE A PROGRAM
- 76. clang -c demo.c clang -o demoExe demo.o -I./include -L./lib —lmyLib COMPILE A PROGRAM Only used for looking up for symbols (shared library)
- 77. Example
- 78. Goal: Control vibrator using C/C++ Binder API Available on Github: https://github.com/mshockwave/android-binder-demo-with-vibrator
- 79. HEADER FILES • frameworks/native/include (binder) • system/core/include (cutils, utils)
- 81. LIBRARIES 1. adb pull /system/lib/libfoo.so 2. Build yourself Options:
- 82. BUILDYOURSELF 1. make -jxx 2. mm / mma
- 83. BUILDYOURSELF 1. make -jxx 2. mm / mma
- 84. mm: Build current modules mmm: Build supplied modules mma: Current modules + dependencies mmma: Supplied modules + dependencies
- 85. mm: Build current modules mmm: Build supplied modules mma: Current modules + dependencies mmma: Supplied modules + dependencies LOCAL_MODULE := myModuleName
- 86. $ cd ${AOSP_ROOT}/frameworks/native/libs/binder $ mma $ ls ${AOSP_ROOT}/out/target/product/${DEVICE} system/lib > libbinder.so libutils.so libcutils.so . . . .
- 87. $ cd ${AOSP_ROOT}/frameworks/native/libs/binder $ mma $ ls ${AOSP_ROOT}/out/target/product/${DEVICE} system/lib > libbinder.so libutils.so libcutils.so . . . . Binder module’s dir
- 88. $ cd ${AOSP_ROOT}/frameworks/native/libs/binder $ mma $ ls ${AOSP_ROOT}/out/target/product/${DEVICE} system/lib > libbinder.so libutils.so libcutils.so . . . . Binder module’s dir Build binder module and its dependencies
- 89. $ cd ${AOSP_ROOT}/frameworks/native/libs/binder $ mma $ ls ${AOSP_ROOT}/out/target/product/${DEVICE} system/lib > libbinder.so libutils.so libcutils.so . . . . Binder module’s dir Build binder module and its dependencies
- 90. $ cd ${AOSP_ROOT}/frameworks/native/libs/binder $ mma $ ls ${AOSP_ROOT}/out/target/product/${DEVICE} system/lib > libbinder.so libutils.so libcutils.so . . . . Binder module’s dir Build binder module and its dependencies Result libraries
- 91. PART OF ANDROID.MK LOCAL_MODULE := myVibrator LOCAL_C_INCLUDES += $(AOSP_INCLUDE) LOCAL_LDLIBS += -L$(AOSP_LIB) LOCAL_LDLIBS += -llog -lbinder -lutils -lcutils
- 92. PART OF ANDROID.MK LOCAL_MODULE := myVibrator LOCAL_C_INCLUDES += $(AOSP_INCLUDE) LOCAL_LDLIBS += -L$(AOSP_LIB) LOCAL_LDLIBS += -llog -lbinder -lutils -lcutils
- 93. PART OF ANDROID.MK LOCAL_MODULE := myVibrator LOCAL_C_INCLUDES += $(AOSP_INCLUDE) LOCAL_LDLIBS += -L$(AOSP_LIB) LOCAL_LDLIBS += -llog -lbinder -lutils -lcutils
- 94. PART OF ANDROID.MK LOCAL_MODULE := myVibrator LOCAL_C_INCLUDES += $(AOSP_INCLUDE) LOCAL_LDLIBS += -L$(AOSP_LIB) LOCAL_LDLIBS += -llog -lbinder -lutils -lcutils
- 97. APP Hardware Related Library Permission Denied Hardware Link system_server
- 98. APP Hardware Related Library Permission Denied Hardware Link system_server (Mostly control via sysfs)
- 99. APP Hardware Related Library Permission Denied Hardware Link system_server Link (Mostly control via sysfs)
- 100. APP Hardware Related Library Permission Denied Hardware Link system_server Link Binder IPC (Mostly control via sysfs)
- 101. APP Hardware Related Library Permission Denied Hardware Link system_server Link Binder IPC Actions (Mostly control via sysfs)
- 102. frameworks/base/core/java/android/os/ IVibratorService.aidl AIDL = Android Interface Definition Language
- 103. WE GONNA FAKE ONE !
- 104. class BpMyVibrator : public BpInterface<IMyVibrator> { virtual bool hasVibrator(void) {…} virtual void vibrate(int32_t, String16&, int64_t, int32_t, sp<IBinder>&) {…} virtual void cancelVibrate(sp<IBinder>& token) {…} (vibratePattern Omitted) } Same interface in IVibratorService.aidl
- 105. About detailed Binder part in this example… http://mshockwave.blogspot.tw/2015/01/using-binder-to-vibrate-android- binder.html http://mshockwave.blogspot.tw/2015/02/using-binder-to-vibrate-android- binder.html
- 106. IN THE PREVIOUS EXAMPLE…
- 108. KER KER I’M ROOT
- 109. Native Services: = HIGHER permission = Able to use MORE libraries
- 112. Native Service Link Libraries Service Manager App Interact via Binder
- 114. • libstagefright.so • libui.so • libhardware.so (libhardware_legacy.so)
- 116. QUESTIONS? E-mail / Google account: [email protected] Github / Bitbucket account name: mshockwave Facebook: www.facebook.com/bekket.mcclane