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use wasmer_runtime_core::{
codegen::{Event, EventSink, FunctionMiddleware, InternalEvent},
error::RuntimeError,
module::ModuleInfo,
vm::{Ctx, InternalField},
wasmparser::{Operator, Type as WpType, TypeOrFuncType as WpTypeOrFuncType},
Instance,
};
static INTERNAL_FIELD: InternalField = InternalField::allocate();
pub struct Metering {
limit: u64,
current_block: u64,
}
impl Metering {
pub fn new(limit: u64) -> Metering {
Metering {
limit,
current_block: 0,
}
}
}
#[derive(Copy, Clone, Debug)]
pub struct ExecutionLimitExceededError;
impl FunctionMiddleware for Metering {
type Error = String;
fn feed_event<'a, 'b: 'a>(
&mut self,
op: Event<'a, 'b>,
_module_info: &ModuleInfo,
sink: &mut EventSink<'a, 'b>,
_source_loc: u32,
) -> Result<(), Self::Error> {
match op {
Event::Internal(InternalEvent::FunctionBegin(_)) => {
self.current_block = 0;
}
Event::Wasm(&ref op) | Event::WasmOwned(ref op) => {
self.current_block += 1;
match *op {
Operator::Loop { .. }
| Operator::Block { .. }
| Operator::End
| Operator::If { .. }
| Operator::Else
| Operator::Unreachable
| Operator::Br { .. }
| Operator::BrTable { .. }
| Operator::BrIf { .. }
| Operator::Call { .. }
| Operator::CallIndirect { .. }
| Operator::Return => {
sink.push(Event::Internal(InternalEvent::GetInternal(
INTERNAL_FIELD.index() as _,
)));
sink.push(Event::WasmOwned(Operator::I64Const {
value: self.current_block as i64,
}));
sink.push(Event::WasmOwned(Operator::I64Add));
sink.push(Event::Internal(InternalEvent::SetInternal(
INTERNAL_FIELD.index() as _,
)));
self.current_block = 0;
}
_ => {}
}
match *op {
Operator::Br { .. }
| Operator::BrTable { .. }
| Operator::BrIf { .. }
| Operator::Call { .. }
| Operator::CallIndirect { .. } => {
sink.push(Event::Internal(InternalEvent::GetInternal(
INTERNAL_FIELD.index() as _,
)));
sink.push(Event::WasmOwned(Operator::I64Const {
value: self.limit as i64,
}));
sink.push(Event::WasmOwned(Operator::I64GeU));
sink.push(Event::WasmOwned(Operator::If {
ty: WpTypeOrFuncType::Type(WpType::EmptyBlockType),
}));
sink.push(Event::Internal(InternalEvent::Breakpoint(Box::new(|_| {
Err(RuntimeError::Metering(Box::new(
ExecutionLimitExceededError,
)))
}))));
sink.push(Event::WasmOwned(Operator::End));
}
_ => {}
}
}
_ => {}
}
sink.push(op);
Ok(())
}
}
pub fn get_points_used(instance: &Instance) -> u64 {
instance.get_internal(&INTERNAL_FIELD)
}
pub fn set_points_used(instance: &mut Instance, value: u64) {
instance.set_internal(&INTERNAL_FIELD, value);
}
pub fn get_points_used_ctx(ctx: &Ctx) -> u64 {
ctx.get_internal(&INTERNAL_FIELD)
}
pub fn set_points_used_ctx(ctx: &mut Ctx, value: u64) {
ctx.set_internal(&INTERNAL_FIELD, value);
}