config: Add a nicer error for recursive includes

We can't check recursive includes across "dir/" followed by "../"
because dir may be a symlink, so "dir/../" may resolve to a different
folder. But this is already good within the same folder.

1 files changed, 17 insertions, 0 deletions

diff --git a/niri-config/src/lib.rs b/niri-config/src/lib.rs
index 038d7e5a..ac133c62 100644
--- a/niri-config/src/lib.rs
+++ b/niri-config/src/lib.rs
@@ -114,6 +114,10 @@ struct Recursion(u8);
 struct Includes(Vec<PathBuf>);
 #[derive(Default)]
 struct IncludeErrors(Vec<knuffel::Error>);
+// Used for recursive include detection.
+//
+// We don't *need* it because we have a recursion limit, but it makes for nicer error messages.
+struct IncludeStack(HashSet<PathBuf>);
 
 // Rather than listing all fields and deriving knuffel::Decode, we implement
 // knuffel::DecodeChildren by hand, since we need custom logic for every field anyway: we want to
@@ -294,6 +298,16 @@ where
                     };
                     let base = path.parent().map(Path::to_path_buf).unwrap_or_default();
 
+                    // Check for recursive include for a nicer error message.
+                    let mut include_stack = ctx.get::<IncludeStack>().unwrap().0.clone();
+                    if !include_stack.insert(path.to_path_buf()) {
+                        ctx.emit_error(DecodeError::missing(
+                            node,
+                            "recursive include (file includes itself)",
+                        ));
+                        continue;
+                    }
+
                     // Store even if the include fails to read or parse, so it gets watched.
                     includes.borrow_mut().0.push(path.to_path_buf());
 
@@ -316,6 +330,7 @@ where
                                 ctx.set(Recursion(recursion));
                                 ctx.set(includes.clone());
                                 ctx.set(include_errors.clone());
+                                ctx.set(IncludeStack(include_stack));
                                 ctx.set(config.clone());
                             });
 
@@ -397,6 +412,7 @@ impl Config {
         let config = Rc::new(RefCell::new(Config::default()));
         let includes = Rc::new(RefCell::new(Includes(Vec::new())));
         let include_errors = Rc::new(RefCell::new(IncludeErrors(Vec::new())));
+        let include_stack = HashSet::from([path.to_path_buf()]);
 
         let part = knuffel::parse_with_context::<ConfigPart, knuffel::span::Span, _>(
             filename,
@@ -407,6 +423,7 @@ impl Config {
                 ctx.set(Recursion(0));
                 ctx.set(includes.clone());
                 ctx.set(include_errors.clone());
+                ctx.set(IncludeStack(include_stack));
                 ctx.set(config.clone());
             },
         );