[librsvg: 4/16] Do the limits check in acquire_node()

[Federico Mena Quintero <federico src gnome org>]

commit d0cbdbf59da582a4b0ae9142001b56779306ad9b
Author: Federico Mena Quintero <federico gnome org>
Date:   Thu Oct 10 15:46:22 2019 -0500

    Do the limits check in acquire_node()
    
    This lets us remove the single-purpose
    increase_num_elements_rendered_through_use().

 rsvg_internals/src/drawing_ctx.rs | 24 +++++++++---------------
 rsvg_internals/src/structure.rs   |  2 --
 2 files changed, 9 insertions(+), 17 deletions(-)
---
diff --git a/rsvg_internals/src/drawing_ctx.rs b/rsvg_internals/src/drawing_ctx.rs
index ec8f4db2..51b44a77 100644
--- a/rsvg_internals/src/drawing_ctx.rs
+++ b/rsvg_internals/src/drawing_ctx.rs
@@ -337,10 +337,16 @@ impl DrawingCtx {
     // acquire it again.  If you acquire a node "#foo" and don't release it before
     // trying to acquire "foo" again, you will obtain a None the second time.
     pub fn acquire_node(
-        &self,
+        &mut self,
         fragment: &Fragment,
         node_types: &[NodeType]
     ) -> Result<AcquiredNode, AcquireError> {
+        self.num_elements_acquired += 1;
+
+        if self.num_elements_acquired > limits::MAX_REFERENCED_ELEMENTS {
+            return Err(AcquireError::MaxReferencesExceeded);
+        }
+
         self.acquired_nodes.acquire(fragment, node_types)
     }
 
@@ -612,7 +618,7 @@ impl DrawingCtx {
         );
     }
 
-    fn acquire_paint_server(&self, fragment: &Fragment) -> Result<AcquiredNode, AcquireError> {
+    fn acquire_paint_server(&mut self, fragment: &Fragment) -> Result<AcquiredNode, AcquireError> {
         self.acquire_node(
             fragment,
             &[
@@ -857,7 +863,7 @@ impl DrawingCtx {
             self.drawsub_stack.push(top);
         }
 
-        res.and_then(|bbox| self.check_limits().and_then(|_| Ok(bbox)))
+        res
     }
 
     pub fn add_node_and_ancestors_to_stack(&mut self, node: &RsvgNode) {
@@ -866,18 +872,6 @@ impl DrawingCtx {
             self.add_node_and_ancestors_to_stack(parent);
         }
     }
-
-    pub fn increase_num_elements_rendered_through_use(&mut self, n: usize) {
-        self.num_elements_acquired += n;
-    }
-
-    fn check_limits(&self) -> Result<(), RenderingError> {
-        if self.num_elements_acquired > limits::MAX_REFERENCED_ELEMENTS {
-            Err(RenderingError::InstancingLimit)
-        } else {
-            Ok(())
-        }
-    }
 }
 
 #[derive(Debug)]
diff --git a/rsvg_internals/src/structure.rs b/rsvg_internals/src/structure.rs
index 8771100d..de27c194 100644
--- a/rsvg_internals/src/structure.rs
+++ b/rsvg_internals/src/structure.rs
@@ -330,8 +330,6 @@ impl NodeTrait for NodeUse {
             return Err(RenderingError::CircularReference);
         }
 
-        draw_ctx.increase_num_elements_rendered_through_use(1);
-
         let params = draw_ctx.get_view_params();
 
         let nx = self.x.normalize(values, &params);