From 1ce887b567fd56a65deed1ab09c1dd927f3087bf Mon Sep 17 00:00:00 2001
From: Matthias Beyer <matthias.beyer@ifm.com>
Date: Thu, 18 Aug 2022 14:14:19 +0200
Subject: WIP

---
 Cargo.lock                        |  1 +
 plugins/plugin_lua/Cargo.toml     |  1 +
 plugins/plugin_lua/src/builder.rs | 18 +++++++++++++-----
 plugins/plugin_lua/src/config.rs  |  6 ++++++
 plugins/plugin_lua/src/error.rs   |  5 +++++
 plugins/plugin_lua/src/plugin.rs  | 30 +++++++++++++++++++++++++++---
 6 files changed, 53 insertions(+), 8 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 07e6bd28..fe9e92be 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2518,6 +2518,7 @@ dependencies = [
  "tedge_api",
  "tedge_lib",
  "thiserror",
+ "tokio",
  "toml",
  "tracing",
 ]
diff --git a/plugins/plugin_lua/Cargo.toml b/plugins/plugin_lua/Cargo.toml
index 71f5899e..92c6bbda 100644
--- a/plugins/plugin_lua/Cargo.toml
+++ b/plugins/plugin_lua/Cargo.toml
@@ -14,6 +14,7 @@ serde_with = "1"
 thiserror = "1"
 toml = "0.5"
 tracing = "0.1"
+tokio = { version = "1", features = ["sync"] }
 
 tedge_api = { path = "../../crates/core/tedge_api" }
 tedge_lib = { path = "../../crates/core/tedge_lib" }
diff --git a/plugins/plugin_lua/src/builder.rs b/plugins/plugin_lua/src/builder.rs
index 86f160dd..3e7f8d87 100644
--- a/plugins/plugin_lua/src/builder.rs
+++ b/plugins/plugin_lua/src/builder.rs
@@ -37,10 +37,18 @@ impl<PD: PluginDirectory> PluginBuilder<PD> for LuaPluginBuilder {
     ) -> Result<(), tedge_api::error::PluginError> {
         config
             .clone()
-            .try_into()
-            .map(|_: Config| ())
+            .try_into::<Config>()
             .map_err(crate::error::Error::ConfigParseFailed)
-            .map_err(PluginError::from)
+            .and_then(|config| {
+                if !config.script.exists() {
+                    Err(crate::error::Error::ScriptDoesNotExist(
+                        config.script.clone(),
+                    ))
+                } else {
+                    Ok(())
+                }
+            })
+            .map_err(tedge_api::error::PluginError::from)
     }
 
     async fn instantiate(
@@ -49,11 +57,11 @@ impl<PD: PluginDirectory> PluginBuilder<PD> for LuaPluginBuilder {
         _cancellation_token: CancellationToken,
         _plugin_dir: &PD,
     ) -> Result<BuiltPlugin, PluginError> {
-        let _config = config
+        let config = config
             .try_into::<Config>()
             .map_err(crate::error::Error::ConfigParseFailed)
             .map_err(PluginError::from)?;
 
-        Ok(LuaPlugin::new().finish())
+        Ok(LuaPlugin::new(&config).finish())
     }
 }
diff --git a/plugins/plugin_lua/src/config.rs b/plugins/plugin_lua/src/config.rs
index 46eac953..eb197bd9 100644
--- a/plugins/plugin_lua/src/config.rs
+++ b/plugins/plugin_lua/src/config.rs
@@ -4,4 +4,10 @@ use std::path::PathBuf;
 pub struct Config {
     /// The path to the script to execute
     pub(crate) script: PathBuf,
+
+    /// How much memory the lua virtual machine can allocate
+    ///
+    /// If not specified, no memory limit is set, which means that the lua process can OOM the
+    /// system.
+    pub(crate) memory_limit: Option<tedge_lib::config::ByteSize>,
 }
diff --git a/plugins/plugin_lua/src/error.rs b/plugins/plugin_lua/src/error.rs
index 0c04533b..e7d3f801 100644
--- a/plugins/plugin_lua/src/error.rs
+++ b/plugins/plugin_lua/src/error.rs
@@ -1,6 +1,11 @@
+use std::path::PathBuf;
+
 #[derive(Debug, miette::Diagnostic, thiserror::Error)]
 #[allow(clippy::enum_variant_names)]
 pub(crate) enum Error {
     #[error("Failed to parse configuration")]
     ConfigParseFailed(toml::de::Error),
+
+    #[error("Script does not exist: {0}")]
+    ScriptDoesNotExist(PathBuf),
 }
diff --git a/plugins/plugin_lua/src/plugin.rs b/plugins/plugin_lua/src/plugin.rs
index 7f8e01c4..188b1412 100644
--- a/plugins/plugin_lua/src/plugin.rs
+++ b/plugins/plugin_lua/src/plugin.rs
@@ -1,13 +1,37 @@
+use std::sync::Arc;
+
 use async_trait::async_trait;
+use rlua::Lua;
 use tedge_api::Plugin;
 use tedge_api::PluginError;
+use tokio::sync::RwLock;
+
+use crate::config::Config;
 
 #[derive(Debug)]
-pub struct LuaPlugin;
+pub struct LuaPlugin {
+    lua: RwLock<Lua>,
+}
 
 impl LuaPlugin {
-    pub(crate) fn new() -> Self {
-        LuaPlugin
+    pub(crate) fn new(config: &Config) -> Self {
+        LuaPlugin {
+            lua: {
+                let lua = rlua::Lua::new();
+                let memory_limit = config.memory_limit.map(|bs| {
+                    let bs = bs.into_bytesize().as_u64();
+                    if (usize::MAX as u64) < bs {
+                        usize::MAX
+                    } else {
+                        bs as usize
+                    }
+                });
+
+                lua.set_memory_limit(memory_limit);
+
+                RwLock::new(lua)
+            },
+        }
     }
 }
 
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