This commit adds numerous improvements to the state of hidden'ility of ReZygisk, and also for compatibility. Recommended to check #111 for more information.
Two counters for module loading and unloading are introduced in the commit a2e83ab348. To remove linker traces of libzygisk.so and Zygisk modules, we should reset them properly.
Reading the file `/proc/self/maps` is detectable by the target process.
Hence, we should cache scanned virtual maps after `libart.so` is loaded for later plt hooks in the target process.
Note that it is impossible to hide injecting trace of virtual memory maps from the hooked target process.
ReZygisk will only focus on removing its trace for approcess that are not hooked by modules.
1. fix typo vsdo -> vdso and allow this symbol to be not found, which is the case for the 32bit linkers on some devices
2. use soinfo_free to fully remove the soinfo record of libzygisk.so
3. set `soinfo.size = 0` to avoid the library being unmapped while removing its soinfo record
4. add more debug logs for troubleshooting
Relying on dlclose to unload libzygisk.so will block us to clean its trace in the solist.
This commit allows us to unmap libzygisk.so without using dlclose.
To call munmap, we use the function pthread_attr_setstacksize instead of pthread_attr_destroy, so that tail-call can still be applied here since it has the same signature as munmap.
In Bionic linker, the `soinfo` structure has a field `next`, which points to the next loaded library in a linked list consisting of all loaded libraries.
Hence, an injected process can easily find all loaded libraries.
Previously in ReZygisk, module library records are hidden by setting the `pathname` field to be empty, which is futile but easier to detect.
Current idea of dropping record can be found in the following commit:
5d635e8c66
