Change plugin interface to prevent segfaults when unloading plugin (#5210)

Fixes: #3473
Closes: #5193

1 files changed, 153 insertions, 0 deletions

diff --git a/cli/ops/plugin.rs b/cli/ops/plugin.rs
new file mode 100644
index 000000000..cabb3329d
--- /dev/null
+++ b/cli/ops/plugin.rs
@@ -0,0 +1,153 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+use crate::fs::resolve_from_cwd;
+use crate::op_error::OpError;
+use crate::ops::dispatch_json::Deserialize;
+use crate::ops::dispatch_json::JsonOp;
+use crate::ops::dispatch_json::Value;
+use crate::ops::json_op;
+use crate::state::State;
+use deno_core::plugin_api;
+use deno_core::CoreIsolate;
+use deno_core::Op;
+use deno_core::OpAsyncFuture;
+use deno_core::OpId;
+use deno_core::ZeroCopyBuf;
+use dlopen::symbor::Library;
+use futures::prelude::*;
+use std::path::Path;
+use std::pin::Pin;
+use std::rc::Rc;
+use std::task::Context;
+use std::task::Poll;
+
+pub fn init(i: &mut CoreIsolate, s: &State) {
+  i.register_op(
+    "op_open_plugin",
+    s.core_op(json_op(s.stateful_op2(op_open_plugin))),
+  );
+}
+
+#[derive(Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct OpenPluginArgs {
+  filename: String,
+}
+
+pub fn op_open_plugin(
+  isolate: &mut CoreIsolate,
+  state: &State,
+  args: Value,
+  _zero_copy: Option<ZeroCopyBuf>,
+) -> Result<JsonOp, OpError> {
+  state.check_unstable("Deno.openPlugin");
+  let args: OpenPluginArgs = serde_json::from_value(args).unwrap();
+  let filename = resolve_from_cwd(Path::new(&args.filename))?;
+
+  state.check_plugin(&filename)?;
+
+  debug!("Loading Plugin: {:#?}", filename);
+  let plugin_lib = Library::open(filename)
+    .map(Rc::new)
+    .map_err(OpError::from)?;
+  let plugin_resource = PluginResource::new(&plugin_lib);
+
+  let mut resource_table = isolate.resource_table.borrow_mut();
+  let rid = resource_table.add("plugin", Box::new(plugin_resource));
+  let plugin_resource = resource_table.get::<PluginResource>(rid).unwrap();
+
+  let deno_plugin_init = *unsafe {
+    plugin_resource
+      .lib
+      .symbol::<plugin_api::InitFn>("deno_plugin_init")
+  }
+  .unwrap();
+  drop(resource_table);
+
+  let mut interface = PluginInterface::new(isolate, &plugin_lib);
+  deno_plugin_init(&mut interface);
+
+  Ok(JsonOp::Sync(json!(rid)))
+}
+
+struct PluginResource {
+  lib: Rc<Library>,
+}
+
+impl PluginResource {
+  fn new(lib: &Rc<Library>) -> Self {
+    Self { lib: lib.clone() }
+  }
+}
+
+struct PluginInterface<'a> {
+  isolate: &'a mut CoreIsolate,
+  plugin_lib: &'a Rc<Library>,
+}
+
+impl<'a> PluginInterface<'a> {
+  fn new(isolate: &'a mut CoreIsolate, plugin_lib: &'a Rc<Library>) -> Self {
+    Self {
+      isolate,
+      plugin_lib,
+    }
+  }
+}
+
+impl<'a> plugin_api::Interface for PluginInterface<'a> {
+  /// Does the same as `core::Isolate::register_op()`, but additionally makes
+  /// the registered op dispatcher, as well as the op futures created by it,
+  /// keep reference to the plugin `Library` object, so that the plugin doesn't
+  /// get unloaded before all its op registrations and the futures created by
+  /// them are dropped.
+  fn register_op(
+    &mut self,
+    name: &str,
+    dispatch_op_fn: plugin_api::DispatchOpFn,
+  ) -> OpId {
+    let plugin_lib = self.plugin_lib.clone();
+    self.isolate.op_registry.register(
+      name,
+      move |isolate, control, zero_copy| {
+        let mut interface = PluginInterface::new(isolate, &plugin_lib);
+        let op = dispatch_op_fn(&mut interface, control, zero_copy);
+        match op {
+          sync_op @ Op::Sync(..) => sync_op,
+          Op::Async(fut) => {
+            Op::Async(PluginOpAsyncFuture::new(&plugin_lib, fut))
+          }
+          Op::AsyncUnref(fut) => {
+            Op::AsyncUnref(PluginOpAsyncFuture::new(&plugin_lib, fut))
+          }
+        }
+      },
+    )
+  }
+}
+
+struct PluginOpAsyncFuture {
+  fut: Option<OpAsyncFuture>,
+  _plugin_lib: Rc<Library>,
+}
+
+impl PluginOpAsyncFuture {
+  fn new(plugin_lib: &Rc<Library>, fut: OpAsyncFuture) -> Pin<Box<Self>> {
+    let wrapped_fut = Self {
+      fut: Some(fut),
+      _plugin_lib: plugin_lib.clone(),
+    };
+    Box::pin(wrapped_fut)
+  }
+}
+
+impl Future for PluginOpAsyncFuture {
+  type Output = <OpAsyncFuture as Future>::Output;
+  fn poll(mut self: Pin<&mut Self>, ctx: &mut Context) -> Poll<Self::Output> {
+    self.fut.as_mut().unwrap().poll_unpin(ctx)
+  }
+}
+
+impl Drop for PluginOpAsyncFuture {
+  fn drop(&mut self) {
+    self.fut.take();
+  }
+}