Merge branch 'empty-filter-bounds' into 'main'

Fix panic when feTile gets an empty source region

Closes #928

See merge request GNOME/librsvg!787

7 files changed, 59 insertions, 8 deletions

diff --git a/src/filters/flood.rs b/src/filters/flood.rs
index a3f06422..50838207 100644
--- a/src/filters/flood.rs
+++ b/src/filters/flood.rs
@@ -36,9 +36,10 @@ impl Flood {
         bounds_builder: BoundsBuilder,
         ctx: &FilterContext,
         _acquired_nodes: &mut AcquiredNodes<'_>,
-        _draw_ctx: &mut DrawingCtx,
+        draw_ctx: &mut DrawingCtx,
     ) -> Result<FilterOutput, FilterError> {
         let bounds: IRect = bounds_builder.compute(ctx).clipped.into();
+        rsvg_log!(draw_ctx.session(), "(feFlood bounds={:?}", bounds);
 
         let surface = ctx.source_graphic().flood(bounds, self.color)?;
 
diff --git a/src/filters/mod.rs b/src/filters/mod.rs
index c2ec8168..0bd1cefa 100644
--- a/src/filters/mod.rs
+++ b/src/filters/mod.rs
@@ -272,6 +272,12 @@ pub fn render(
         node_bbox,
     )
     .and_then(|mut filter_ctx| {
+        // the message has an unclosed parenthesis; we'll close it below.
+        rsvg_log!(
+            session,
+            "(rendering filter with effects_region={:?}",
+            filter_ctx.effects_region()
+        );
         for user_space_primitive in &filter.primitives {
             let start = Instant::now();
 
@@ -299,6 +305,9 @@ pub fn render(
                         err
                     );
 
+                    // close the opening parenthesis from the message at the start of this function
+                    rsvg_log!(session, ")");
+
                     // Exit early on Cairo errors. Continue rendering otherwise.
                     if let FilterError::CairoError(status) = err {
                         return Err(FilterError::CairoError(status));
@@ -307,6 +316,9 @@ pub fn render(
             }
         }
 
+        // close the opening parenthesis from the message at the start of this function
+        rsvg_log!(session, ")");
+
         Ok(filter_ctx.into_output()?)
     })
     .or_else(|err| match err {
diff --git a/src/filters/offset.rs b/src/filters/offset.rs
index acdbab1a..27698b05 100644
--- a/src/filters/offset.rs
+++ b/src/filters/offset.rs
@@ -76,6 +76,7 @@ impl Offset {
             .compute(ctx)
             .clipped
             .into();
+        rsvg_log!(draw_ctx.session(), "(feOffset bounds={:?}", bounds);
 
         let (dx, dy) = ctx.paffine().transform_distance(self.dx, self.dy);
 
diff --git a/src/filters/tile.rs b/src/filters/tile.rs
index 0bd4417c..e3bf940a 100644
--- a/src/filters/tile.rs
+++ b/src/filters/tile.rs
@@ -64,14 +64,30 @@ impl Tile {
                 surface: input_surface,
                 bounds: input_bounds,
             }) => {
-                let tile_surface = input_surface.tile(input_bounds)?;
+                if input_bounds.is_empty() {
+                    rsvg_log!(
+                        draw_ctx.session(),
+                        "(feTile with empty input_bounds; returning just the input surface)"
+                    );
 
-                ctx.source_graphic().paint_image_tiled(
-                    bounds,
-                    &tile_surface,
-                    input_bounds.x0,
-                    input_bounds.y0,
-                )?
+                    input_surface
+                } else {
+                    rsvg_log!(
+                        draw_ctx.session(),
+                        "(feTile bounds={:?}, input_bounds={:?})",
+                        bounds,
+                        input_bounds
+                    );
+
+                    let tile_surface = input_surface.tile(input_bounds)?;
+
+                    ctx.source_graphic().paint_image_tiled(
+                        bounds,
+                        &tile_surface,
+                        input_bounds.x0,
+                        input_bounds.y0,
+                    )?
+                }
             }
         };
 
diff --git a/src/surface_utils/shared_surface.rs b/src/surface_utils/shared_surface.rs
index 0bd74353..4fdd66c2 100644
--- a/src/surface_utils/shared_surface.rs
+++ b/src/surface_utils/shared_surface.rs
@@ -1079,8 +1079,16 @@ impl ImageSurface<Shared> {
     }
 
     /// Creates a new surface with the size and content specified in `bounds`
+    ///
+    /// # Panics
+    /// Panics if `bounds` is an empty rectangle, since `SharedImageSurface` cannot
+    /// represent zero-sized images.
     #[inline]
     pub fn tile(&self, bounds: IRect) -> Result<SharedImageSurface, cairo::Error> {
+        // Cairo lets us create zero-sized surfaces, but the call to SharedImageSurface::wrap()
+        // below will panic in that case.  So, disallow requesting a zero-sized subregion.
+        assert!(!bounds.is_empty());
+
         let output_surface =
             cairo::ImageSurface::create(cairo::Format::ARgb32, bounds.width(), bounds.height())?;
 
diff --git a/tests/fixtures/render-crash/bug928-empty-feTile-bounds.svg b/tests/fixtures/render-crash/bug928-empty-feTile-bounds.svg
new file mode 100644
index 00000000..9920080f
--- /dev/null
+++ b/tests/fixtures/render-crash/bug928-empty-feTile-bounds.svg
@@ -0,0 +1,12 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="100" height="100">
+  <filter id="filter">
+    <!-- We want to test that feTile gets an empty input region, since
+         the feFlood's bounds are outside the default filter effects
+         region.
+    -->
+    <feFlood flood-color="lime" x="50" y="50" width="10" height="10"/>
+    <feTile/>
+  </filter>
+
+  <rect x="10" y="10" width="10" height="10" filter="url(#filter)"/>
+</svg>
diff --git a/tests/src/render_crash.rs b/tests/src/render_crash.rs
index 311aa38d..da58192a 100644
--- a/tests/src/render_crash.rs
+++ b/tests/src/render_crash.rs
@@ -62,6 +62,7 @@ mod tests {
     t!(bug721_pattern_cycle_from_child_svg,             "bug721-pattern-cycle-from-child.svg");
     t!(bug721_pattern_cycle_from_other_child_svg,       "bug721-pattern-cycle-from-other-child.svg");
     t!(bug777155_zero_sized_pattern_svg,                "bug777155-zero-sized-pattern.svg");
+    t!(bug928_empty_fetile_bounds_svg,                  "bug928-empty-feTile-bounds.svg");
     t!(femerge_color_interpolation_srgb_svg,            "feMerge-color-interpolation-srgb.svg");
     t!(filters_non_invertible_paffine_svg,              "filters-non-invertible-paffine.svg");
     t!(gradient_with_empty_bbox_svg,                    "gradient-with-empty-bbox.svg");