Android平台的动态调试一直以来是个困扰我等Coder的头疼问题，特别是对于本地的动态调试支持，可以说是“弱智”级别的，不知道Google的新版NDK和新出的Android Studio对这块支持如何，让我们拭目以待。
言归正传，我这里采用的是cygwin+ndk-gdb的调试模式，灵感来自于XDA的一篇博文（点击打开链接），平台和原文作者不同：
1、Win7 64
2、NDK r9d x86_64
3、Android 4.2.2
4、cygwin 64
5、IDA pro 6.1
话不多话，开始正题，调试步骤如下：
1、环境搭建这类的各位可以自行Google之，这里就不多说了。
2、首先我们随便找个网站，下载游戏的APK包。Android的APK包的正式发布版本是取消了debug属性的，在调试之前，我们还需要做些准备工作。
3、用apktool解包apk文件，然后修改AndroidManifest.xml，在重新打包，再用signapk签名。
4、为ndk-gdb调试做准备工作，这个上面那篇博文已经写得很详细，这里不再赘述。说明一点：我们调试的目标是.\libs\armeabi\libgame.so，这个so是游戏主库文件。
准备好后的目录结构大致如下：
5、好了，准备工作完毕，开始我们的调试之旅！
首先，安装我们重新打包的apk到手机，然后进入cygwin shell，进入本地的游戏解包后的目录。这里要重点说明一点：由于一些兼容性问题，我们不能直接使用google原来的ndk-gdb调试脚本，需要做一些修改：
我这里直接给DATA_DIR赋值为app目录：/data/data/com.umonistudio.tile。这步骤很重要，否则你会遇到run-as之类的错误，导致无法继续调试！
好了，终于准备完毕了，切换到cygwin shell，开始调试，如果没有问题的话，就会顺利进入gdb提示符，我的输出如下：
$ ndk-gdb --verbose --start --nowait
Android NDK installation path: /cygdrive/e/Tools/android-ndk-r9d-windows-x86_64/ android-ndk-r9d
Using default adb command: /cygdrive/e/Tools/adt-bundle-windows-x86_64-20131030/ adt-bundle-windows-x86_64-20131030/sdk/platform-tools/adb
ADB version found: Android Debug Bridge version 1.0.31
Using ADB flags:
Using JDB command: /cygdrive/e/Tools/Java/jdk1.7.0_15/bin/jdb
Using auto-detected project path: .
Found package name: com.umonistudio.tile
ABIs targetted by application: armeabi
Device API Level: 17
Device CPU ABIs: armeabi-v7a armeabi
Compatible device ABI: armeabi
Using gdb setup init: ./libs/armeabi/gdb.setup
Using toolchain prefix: /cygdrive/e/Tools/android-ndk-r9d-windows-x86_64/android-ndk-r9
Using app out directory: ./obj/local/armeabi
Found debuggable flag: true
Found data directory: '/data/data/com.umonistudio.tile'
Found device gdbserver: /data/data/com.umonistudio.tile/lib/gdbserver
Found first launchable activity: .tile
Launching activity: com.umonistudio.tile/.tile
## COMMAND: adb_cmd shell am start -n com.umonistudio.tile/.tile
Starting: Intent { cmp=com.umonistudio.tile/.tile }
## COMMAND: adb_cmd shell sleep 2
Found running PID: 8706
Launched gdbserver succesfully.
Setup network redirection
## COMMAND: adb_cmd shell run-as com.umonistudio.tile /data/data/com.umonistudio .tile/lib/gdbserver +debug-socket --attach 8706
## COMMAND: adb_cmd forward tcp:5039 localfilesystem:/data/data/com.umonistudio. tile/debug-socket
Attached; pid = 8706
Listening on Unix socket debug-socket
## COMMAND: adb_cmd pull /system/bin/app_process obj/local/armeabi/app_process
2384 KB/s (21980 bytes in 0.009s)
Pulled app_process from device/emulator.
## COMMAND: adb_cmd pull /system/bin/linker obj/local/armeabi/linker
3246 KB/s (63176 bytes in 0.019s)
Pulled linker from device/emulator.
## COMMAND: adb_cmd pull /system/lib/libc.so obj/local/armeabi/libc.so
4186 KB/s (424460 bytes in 0.099s)
Pulled libc.so from device/emulator.
GNU gdb (GDB) 7.3.1-gg2
Copyright (C) 2011 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "--host=x86_64-pc-mingw32msvc --target=arm-linux-android".
For bug reporting instructions, please see:
<http://source.android.com/source/report-bugs.html>.
Warning: E:\works\apktools\biecaibaikuaier_an_debug_sign/system/core/include/cutils: No such file or directory.
Remote debugging from host 0.0.0.0
0x400f44b8 in epoll_wait () from E:/works/apktools/biecaibaikuaier_an_debug_sign/obj/local/armeabi/libc.so
warning: Could not load shared library symbols for 108 libraries, e.g. libstdc++.so.
Use the "info sharedlibrary" command to see the complete listing.
Do you need "set solib-search-path" or "set sysroot"?
warning: Breakpoint address adjusted from 0x400b4ab7 to 0x400b4ab6.
(gdb)
这里需要说明一点，我输入的调试命令：ndk-gdb --verbose --start --nowait，加了一个nowait参数：如果不加nowait会在libgame.so这个目标so加载前，gdb就断下来，导致我们无法调试目标库。
好了，我们在gdb命令号输入：
(gdb) info shared
From To Syms Read Shared Object Library
0x400b2280 0x400bb418 Yes (*) E:/works/apktools/biecaibaikuaie r_an_debug_sign/obj/local/armeabi/linker
0x400df830 0x4012e294 Yes (*) E:/works/apktools/biecaibaikuaie r_an_debug_sign/obj/local/armeabi/libc.so
No libstdc++.so
No libm.so
No liblog.so
No libcutils.so
No libgccdemangle.so
No libcorkscrew.so
No libz.so
No libutils.so
No libbinder.so
No libemoji.so
No libjpeg.so
No libexpat.so
No libm4u.so
No libstlport.so
No libnetutils.so
No libbwc.so
No libhardware.so
No libsync.so
No libui.so
No libGLES_trace.so
No libEGL.so
No libGLESv2.so
No libion.so
No libdpframework_os.so
No libdpframework_plat.so
No libdpframework.so
No libgui.so
No libcamera_client.so
No libcam.utils.so
No libaed.so
No libcameracustom.so
No libcam_camera_exif.so
No libnativehelper.so
No libmatv_cust.so
No libcamdrv.so
No libimageio.so
No libcam.campipe.so
No libGdmaScalerPipe.so
No libSwJpgCodec.so
No libvcodec_oal.so
No libsched.so
No libvcodec_utility.so
No libmp4enc_xa.ca7.so
No libvcodecdrv.so
No libJpgDecPipe.so
No libmhalImageCodec.so
No libalmkdrv.so
No libskia.so
No libtinyxml.so
No libandroidfw.so
No libgabi++.so
No libicuuc.so
No libicui18n.so
No libsqlite.so
No libdvm.so
No libGLESv1_CM.so
No libETC1.so
No libwpa_client.so
No libhardware_legacy.so
No libsonivox.so
No libcrypto.so
No libssl.so
No libstagefright_foundation.so
No libspeexresampler.so
No libaudioutils.so
No libmedia_native.so
No libmedia.so
No libusbhost.so
No libharfbuzz.so
No libhwui.so
No libmtkbtextadpa2dp.so
No libextjsr82.so
No libandroid_runtime.so
No libjavacore.so
No libdrmframework.so
No libdrmmtkwhitelist.so
No libdrmmtkutil.so
No libdrmframework_jni.so
No libstagefright_memutil.so
No libstagefright_omx.so
No libstagefright_yuv.so
No libvorbisidec.so
No libstagefright_enc_common.so
No libstagefright_avc_common.so
No libstagefright.so
No libmtp.so
No libexif.so
No libstagefright_amrnb_common.so
No libmtk_drvb.so
No libamr_wrap.so
No libmedia_jni.so
No libbcinfo.so
No libbcc.so
No libRS.so
No librs_jni.so
No libandroid.so
No libchromium_net.so
No libwebcore.so
0x5dd4a500 0x5dfb591c Yes (*) E:/works/apktools/biecaibaikuaie r_an_debug_sign/obj/local/armeabi/libgame.so
No libsoundpool.so
No libsrv_um.so
No libIMGegl.so
No libEGL_mtk.so
No libusc.so
No libGLESv1_CM_mtk.so
No libGLESv2_mtk.so
No libpvrANDROID_WSEGL.so
No libpvr2d.so
No gralloc.mt6589.so
(*): Shared library is missing debugging information.
可以看到我们的目标库已经成功加载，地址0x5dd5a500---0x5dfb591c，终于可以开始愉快的玩耍了
这里我们打开IDA，查看libgame.so的反汇编，找到GameOver::initscore(int,bool)这个函数：
先说明下这个函数的作用：在游戏结束后，显示当前局的分数！我们看下其函数名导出为：_ZN8GameOver9initScoreEib。好了，我们在GDB输入：
(gdb) br _ZN8GameOver9initScoreEib Breakpoint 1 at 0x5dd4c612 (gdb) info b Num Type Disp Enb Address What 1 breakpoint keep y 0x5dd4c612 <GameOver::initScore(int, bool)+26> (gdb) disas 0x5dd4c612,+20 Dump of assembler code from 0x5dd4c612 to 0x5dd4c626: 0x5dd4c612 <_ZN8GameOver9initScoreEib+26>: cmp r1, #0 0x5dd4c614 <_ZN8GameOver9initScoreEib+28>: beq.n 0x5dd4c61a <_ZN8GameOver9initScoreEib+34> 0x5dd4c616 <_ZN8GameOver9initScoreEib+30>: ldr r3, [pc, #284] ; (0x5dd4c734 <_ZN8GameOver9initScoreEib+316>) 0x5dd4c618 <_ZN8GameOver9initScoreEib+32>: str r3, [sp, #4] 0x5dd4c61a <_ZN8GameOver9initScoreEib+34>: adds r4, r5, #0 0x5dd4c61c <_ZN8GameOver9initScoreEib+36>: adds r4, #252 ; 0xfc 0x5dd4c61e <_ZN8GameOver9initScoreEib+38>: bl 0x5dde73d4 <_ZN7cocos2d13CCUserDefault17sharedUserDefaultEv> 0x5dd4c622 <_ZN8GameOver9initScoreEib+42>: ldr r2, [r4, #32] 0x5dd4c624 <_ZN8GameOver9initScoreEib+44>: ldr r3, [pc, #272] ; (0x5dd4c738 <_ZN8GameOver9initScoreEib+320>) End of assembler dump. (gdb)
对照IDA反汇编，可以看到是断在了函数的内部，当然我们可以调整断点到函数入口，这里主要是为了演示，就不做调整。
好了，断点下好了，我们开始游戏，选择“街机”模式开始游戏，然后点几下，再随便点个白块儿让游戏结束。
看看gdb的输出窗口：
(gdb) c Continuing. [New Thread 8720] [Switching to Thread 8720] Breakpoint 1, 0x5dd4c612 in GameOver::initScore(int, bool) () from E:/works/apktools/biecaibaikuaier_an_debug_sign/obj/local/armeabi/libgame.so (gdb) info registers r0 0x65cf59f8 1708087800 r1 0x0 0 r2 0x6e0aeb37 1846209335 r3 0x4013d1f4 1075040756 r4 0x65cf5af4 1708088052 r5 0x65cf59f8 1708087800 r6 0x7 7 r7 0x5dde3b2d 1574845229 r8 0x5e1c2c70 1578904688 r9 0x5e0c2f3c 1577856828 r10 0x5cdd5a88 1558010504 r11 0x5e1c2c84 1578904708 r12 0x5e088afc 1577618172 sp 0x5e1c2af8 0x5e1c2af8 lr 0x5dd4ca0f 1574226447 pc 0x5dd4c612 0x5dd4c612 <GameOver::initScore(int, bool)+26> cpsr 0x30 48 (gdb)set $r6=99999
YES，成功断下！输入info registers查看当前寄存器状态，注意查看r6寄存器，值为0x7(我刚才点了7个黑块儿)。我们开始个好玩的东西，gdb输入：set $r6=99999，然后让游戏继续，看看有什么
总结一下：
这里主要是演示了下Android平台下，对于无源码的第三方动态库的汇编级调试过程（不针对任何游戏，不用于任何商业目的），目前google官方的调试工具对native调试支持不好，希望后面google能对这块给力些。上面所涉及的内容只用于技术交流之用处，不用于任何商业目的。
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