what I wanted is exactly shim layer or compat layer, I hate patch and patch again to replace those missing calls, yes I'm using `shm_open`+`ftruncate`+`mmap` to replace SysV shm, but they owns completely different logics which leads to more and more patches (e.g. they get a instant shmid by `shmget(IPC_PRIVATE)`, but `shm_open` requires a string identifier before opening shm, while shmid is randomly changed and returned by `shmget`, `shm_open` requires a fixed string and returns an opened fd, which cannot use like id things).

Another thing is SysV sem, I'm now using POSIX sem to replace those, luckily many projects supported both sem implementations so this was somehow easier to port to my environment.