Merge pull request #3794 from Silvertree2010/fix/3572-audit-dxf-import-nested-inserts

Bound DXF import work for nested inserts that produce no nodes

crates/cad/src/import/build.rs

@@ -23,6 +23,8 @@ const PT_PER_MM: f64 = 72.0 / 25.4;
 const THINNEST: f64 = 0.25;
 /// The most objects an import makes.
 const MAX_NODES: usize = 2_000_000;
+/// The most block visits (one per insert copy) an import makes, whatever they produce.
+const MAX_VISITS: usize = 10_000_000;
 /// How far from the origin art may lie (points): the canvas.
 pub(crate) const MAX_EXTENT: f64 = 4.0e6;
 
@@ -63,6 +65,7 @@ pub(crate) struct Build<'d, 'a> {
     /// Lineweights are multiplied by this.
     lw_scale: f64,
     nodes: usize,
+    visits: usize,
     warnings: Vec<String>,
 }
 
@@ -118,6 +121,7 @@ impl<'d, 'a> Build<'d, 'a> {
             symbol_map: Affine::IDENTITY,
             lw_scale: 1.0,
             nodes: 0,
+            visits: 0,
             warnings: vec![],
         }
     }
@@ -557,6 +561,13 @@ impl<'d, 'a> Build<'d, 'a> {
 
     /// The art of block `name` drawn by `map`, as one object.
     fn art(&mut self, name: &str, map: Affine, inh: &Inherit, depth: u32) -> Option<Node> {
+        self.visits += 1;
+        if self.visits > MAX_VISITS {
+            if self.visits == MAX_VISITS + 1 {
+                self.warn(TOO_MANY);
+            }
+            return None;
+        }
         let items = self.block(name)?;
         if !self.enter(name, depth) {
             return None;

crates/cad/src/import/tests.rs

@@ -799,6 +799,24 @@ fn array_inserts_attributes_and_dimensions() {
     assert_eq!(bounds(&leaves(&doc)[0]).width(), 50.0);
 }
 
+#[test]
+fn nested_array_inserts_of_nothing_stop_at_the_work_budget() {
+    let block = |name: &'static str, inner: Option<&'static str>| {
+        let mut b = vec![(0, "BLOCK"), (2, name), (70, "1"), (10, "0"), (20, "0")];
+        if let Some(i) = inner {
+            b.extend([(0, "INSERT"), (2, i), (10, "0"), (20, "0"), (70, "300"), (44, "1")]);
+        }
+        b.push((0, "ENDBLK"));
+        b
+    };
+    let mut blocks = block("*A", Some("*B"));
+    blocks.extend(block("*B", Some("*C")));
+    blocks.extend(block("*C", None));
+    let top = [(0, "INSERT"), (2, "*A"), (10, "0"), (20, "0"), (70, "300"), (44, "1")];
+    let r = open(&drawing(&[], &[], &blocks, &top), &points());
+    assert!(r.warnings.iter().any(|w| w.contains("more than")), "{:?}", r.warnings);
+}
+
 #[test]
 fn blocks_inside_themselves_are_left_out_without_hanging() {
     let blocks = [