Add eprint function

implants/lib/eldritch/src/report/mod.rs

@@ -31,7 +31,6 @@ fn methods(builder: &mut MethodsBuilder) {
         Ok(NoneType{})
     }
 
-
     #[allow(unused_variables)]
     fn process_list(this: &ReportLibrary, starlark_eval: &mut Evaluator<'v, '_>, process_list: UnpackList<SmallMap<String, Value>>) -> anyhow::Result<NoneType> {
         let env = crate::runtime::Environment::from_extra(starlark_eval.extra)?;

implants/lib/eldritch/src/runtime/eprint_impl.rs

@@ -0,0 +1,65 @@
+use crate::runtime::{messages::ReportErrorMessage, Environment};
+use anyhow::Result;
+
+pub fn eprint(env: &Environment, message: String) -> Result<()> {
+    env.send(ReportErrorMessage {
+        id: env.id(),
+        error: message.clone(),
+    })?;
+
+    #[cfg(feature = "print_stdout")]
+    eprintln!("{}", message);
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod test {
+    use crate::runtime::Message;
+    use pb::eldritch::Tome;
+    use std::collections::HashMap;
+
+    macro_rules! test_cases {
+        ($($name:ident: $value:expr,)*) => {
+        $(
+            #[tokio::test]
+            async fn $name() {
+                let tc: TestCase = $value;
+
+                // Run Eldritch (until finished)
+                let mut runtime = crate::start(tc.id, tc.tome).await;
+                runtime.finish().await;
+
+                // Read Messages
+                let mut found = false;
+                for msg in runtime.messages() {
+                    if let Message::ReportError(m) = msg {
+                        assert_eq!(tc.id, m.id);
+                        assert_eq!(tc.want_error, m.error);
+                        found = true;
+                    }
+                }
+                assert!(found);
+            }
+        )*
+        }
+    }
+
+    struct TestCase {
+        pub id: i64,
+        pub tome: Tome,
+        pub want_error: String,
+    }
+
+    test_cases! {
+            one_error: TestCase{
+                id: 123,
+                tome: Tome{
+                    eldritch: String::from(r#"eprint(message="Beep Boop an error occured")"#),
+                    parameters: HashMap::new(),
+                    file_names: Vec::new(),
+                },
+                want_error: String::from("Beep Boop an error occured"),
+            },
+    }
+}

implants/lib/eldritch/src/runtime/eval.rs

@@ -8,6 +8,7 @@ use crate::{
     regex::RegexLibrary,
     report::ReportLibrary,
     runtime::{
+        eprint_impl,
         messages::{reduce, Message, ReportErrorMessage, ReportFinishMessage, ReportStartMessage},
         Environment,
     },
@@ -24,8 +25,7 @@ use starlark::{
     eval::Evaluator,
     starlark_module,
     syntax::{AstModule, Dialect},
-    values::dict::Dict,
-    values::AllocValue,
+    values::{dict::Dict, none::NoneType, AllocValue},
 };
 use std::sync::mpsc::{channel, Receiver};
 use tokio::task::JoinHandle;
@@ -142,6 +142,16 @@ pub struct Runtime {
     rx: Receiver<Message>,
 }
 
+#[starlark_module]
+fn error_handler(builder: &mut GlobalsBuilder) {
+    #[allow(unused_variables)]
+    fn eprint(starlark_eval: &mut Evaluator<'v, '_>, message: String) -> anyhow::Result<NoneType> {
+        let env = crate::runtime::Environment::from_extra(starlark_eval.extra)?;
+        eprint_impl::eprint(env, message)?;
+        Ok(NoneType {})
+    }
+}
+
 impl Runtime {
     /*
      * Globals available to eldritch code.
@@ -177,6 +187,7 @@ impl Runtime {
             LibraryExtension::Typing,
         ])
         .with(eldritch)
+        .with(error_handler)
         .build()
     }
 

implants/lib/eldritch/src/runtime/mod.rs

@@ -1,5 +1,6 @@
 mod drain;
 mod environment;
+mod eprint_impl;
 mod eval;
 pub mod messages;