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use core::ffi::c_void;
use crate::{args::FromBtfArgument, EbpfContext};
pub struct BtfTracePointContext {
ctx: *mut c_void,
}
impl BtfTracePointContext {
pub fn new(ctx: *mut c_void) -> BtfTracePointContext {
BtfTracePointContext { ctx }
}
/// Returns the `n`th argument of the BTF tracepoint, starting from 0.
///
/// You can use the tplist tool provided by bcc to get a list of tracepoints and their
/// arguments. TODO: document this better, possibly add a tplist alternative to aya.
///
/// SAFETY: This function is deeply unsafe, as we are reading raw pointers into kernel memory.
/// In particular, the value of `n` must not exceed the number of function arguments.
/// Luckily, the BPF verifier will catch this for us.
///
/// # Examples
///
/// ```no_run
/// # #![allow(dead_code)]
/// # use aya_ebpf::{programs::BtfTracePointContext, cty::{c_int, c_ulong, c_char}};
/// unsafe fn try_tp_btf_sched_process_fork(ctx: BtfTracePointContext) -> Result<u32, u32> {
/// // Grab arguments
/// let parent_comm: *const c_char = ctx.arg(0);
/// let parent_pid: c_int = ctx.arg(1);
/// let child_comm: *const c_char = ctx.arg(2);
/// let child_pid: c_int = ctx.arg(3);
///
/// // You can then do stuff with parent_pidm parent_comm, child_pid, and
/// // child_comm down here.
///
/// Ok(0)
/// }
/// ```
///
/// [1]: https://elixir.bootlin.com/linux/latest/source/include/linux/lsm_hook_defs.h
pub unsafe fn arg<T: FromBtfArgument>(&self, n: usize) -> T {
T::from_argument(self.ctx as *const _, n)
}
}
impl EbpfContext for BtfTracePointContext {
fn as_ptr(&self) -> *mut c_void {
self.ctx
}
}