A basic example of Userland Statically Defined Tracing in Rust using native C.
Inspired by rust-libprobe but that is Linux focused and uses asm! which is currently only available in nightly.
It's based on the sample given in the dtrace.org website
% uname -a
FreeBSD 11.1-RELEASE FreeBSD 11.1-RELEASE #0: Sun Dec 31 13:23:21 UTC 2017 root@:/usr/obj/usr/src/sys/FIFOKERNEL amd64
% pkg install rust
% rustc -V
rustc 1.23.0
% cc --version
FreeBSD clang version 4.0.0 (tags/RELEASE_400/final 297347) (based on LLVM 4.0.0)
Target: x86_64-unknown-freebsd11.1
Thread model: posix
InstalledDir: /usr/bin
This should "Just Work"™
% cargo run
As root run the dtrace script to see the probes
# dtrace -l | grep myserv
73093 myserv3361 rust-usdt-helloworld sayhello query-receive
Now run a dtrace script to consume the probe.
# dtrace -s tools/probe.d
sayhello Fired 3
sayhello Fired 4
sayhello Fired 5
...
The trick here is in the build.rs where the trace provider object is generated using the .d script and the "mungled" hello object
% dtrace -G -s trace_hello.d libhello.o