[转]IOS热更新研究

http://blog.csdn.net/yy405145590/article/details/41282669

主要思路是替换掉在mono里image.c的mono_image_open_from_data_with_name函数，HOOK掉加载DLL的地方，实现读取自定义的DLL文件。


检查发现在Xcode工程里的libiPhone-lib.a里存在mono的库文件，在libiPhone-lib.a下有两个CPU架构的库

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lipo -info libiPhone-lib.a 
 
Architectures in the fat file: libiPhone-lib.a are: armv7 i386 

使用
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lipo libiPhone-lib.a -thin armv7 -output libiPhone-lib.arm 

解压出armv7的库文件
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ar -t libiPhone-lib.arm 
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filterscpuimplvectordata.o 
filterscpuimplwarp.o 
filterscpumipmaps.o 
filterscpupassvectordata.o 
filterscpupvrtc.o 
filterscpufxmapsbuffer.o 
filterscpufxmapsmain.o 
filterscpufxmapsdrawjob.o 
filterscpufxmapsdrawqueue.o 
filterscpufxmapsjob.o 
filterscpufxmapspool.o 
filterscpufxmapsthread.o 
parsebitmap.o 
parseblend.o 
parseblur.o 
parsechannelsshuffle.o 
parsecommon.o 
parsecontext.o 
parsedata.o 
parsedirectionalmotionblur.o 
parsedirectionalwarp.o 
parseemboss.o 
parsefxmaps.o 
parsefxmapssetcell.o 
parsegradientmap.o 
parsegrayscaleconversion.o 
parsehsl.o 
parselevels.o 
parsemotionblur.o 
parsenormal.o 
parsesharpen.o 
parsetransformation2d.o 
parseuniformcolor.o 
parsevectorgraphicsdata.o 
parsewarp.o 
apicontext.o 
apihandle.o 
apiversion.o 
libCrashReporter-iphoneos.a-armv7-master.o 

[html] view plaincopy在CODE上查看代码片派生到我的代码片
ar -t libiPhone-lib.arm | grep image.o 
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image.o 
可以看到armv7下确实有image.o的模块


解压出image.o模块

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ar -x libiPhone-lib.arm image.o 
用十六进制工具搜索

[cpp] view plaincopy在CODE上查看代码片派生到我的代码片
mono_image_open_from_data_with_name  替换成  mono_image_open_from_data_with_xxxx 

自己编译一个imagehook.c的文件生成imagehook.o，内容如下

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#include <stdio.h> 
 
extern int * 
mono_image_open_from_data_with_xxxx( 
                                    char *data, unsigned int data_len, 
                                    int  need_copy, 
                                    int *status, 
                                    int only, const char *name); 
 
 
int * 
mono_image_open_from_data_with_name( 
                                    char *data, unsigned int data_len, 
                                    int  need_copy, 
                                    int *status, 
                                    int only, const char *name) 
{ 
    printf("call mono_image_open_from_data_with_name 0x%x 0x%x 0x%x 0x%x 0x%x %s", (int)data, (int)data_len, need_copy, (int)status, only, name); 
    return mono_image_open_from_data_with_xxxx(data, data_len, need_copy, status, only, name); 
} 

将image.o 和 imagehook.o重新打包进libiPhone-lib.arm
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ar -r libiPhone-lib.arm image.o 
ar -q libiPhone-lib.arm imagehook.o 

重新生成libiPhone-lib.a
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lipo libiPhone-lib.a -replace armv7 libiPhone-lib.arm -output libiPhone-lib.a_01 

这样用新生成的libiPhone-lib.a去链接应用程序会发现调用到了我们自己的函数。

但是你会发现都是没用的，因为mono在IOS下是FULL AOT模式编译的，每个脚本dll会生成对应的.s汇编代码直接连接到可执行文件里面.