I want to transform/instrument Dex files. The goals of transformation include measuring code coverage. Note that the source files are not available. So instrumenting Dex is the only option.
I am wondering if there are any existing code base that I could look at as examples to write a tool to achieve my goal.
I know about the Smali project and a host of other projects that build on Smali. However, none of these projects are good examples for my purpose.
I am looking for code that automatically transforms smali code or the dexlib representation, from which smali is generated. The later option is preferred for my purpose because the overhead of generating smali can be avoided.
In some cases smali itself does a small amount of instruction rewriting while re-assembling a dex file. Things like replacing a const-string with a const-string/jumbo, or a goto instruction with a “larger” one, if the target is out of range. This involves replacing instructions in the instruction list with potentially larger ones, and the corresponding fixing up of offsets.
CodeItem.fixInstructions is the method responsible for this.
Additionally, there is the asmdex library. I’m not all that familiar with it, but it sounds like it might be relevant to what you’re wanting to do.