Getting vm_map of a ptraced process

[Buganini]

I want to get vm_map of a ptraced process,
but process structure is prerequisite to getting vm_map

How can I get the process structure?

I saw FOREACH_THREAD_IN_PROC in the source,
but this need superuser's power, right?

Is PT_READ from memory a good way? (seems to be dirty)

Or this way? (not bad, I think, but not yet standard)
http://www.e.kth.se/~lha/patches/netbsd/gdb-core/ptrace-patch

any better idea is welcome, thanks

-Buganini