Merge pull request #57 from BlackFoundryCom/fix56

Reproduce and fix recursion crash

Lib/blackrenderer/font.py

@@ -125,6 +125,7 @@ def drawGlyph(self, glyphName, canvas, *, palette=None, textColor=(0, 0, 0, 1)):
             palette = self.palettes[0]
         self.currentPalette = palette
         self.textColor = textColor
+        self._recursionCheck = set()
 
         glyph = self.colrV1Glyphs.get(glyphName)
         if glyph is not None:
@@ -151,7 +152,13 @@ def _drawGlyphCOLRv0(self, layers, canvas):
             canvas.drawPathSolid(path, self._getColor(layer.colorID, 1))
 
     def _drawGlyphCOLRv1(self, glyph, canvas):
-        self._drawPaint(glyph.Paint, canvas)
+        if glyph.BaseGlyph in self._recursionCheck:
+            raise RecursionError(f"Glyph '{glyph.BaseGlyph}' references itself")
+        self._recursionCheck.add(glyph.BaseGlyph)
+        try:
+            self._drawPaint(glyph.Paint, canvas)
+        finally:
+            self._recursionCheck.remove(glyph.BaseGlyph)
 
     # COLRv1 Paint dispatch
 

Tests/test_glyph_render.py

@@ -26,6 +26,7 @@
     "mutator": dataDir / "MutatorSans.ttf",
     "twemoji": dataDir / "TwemojiMozilla.subset.default.3299.ttf",
     "more_samples": dataDir / "more_samples-glyf_colr_1.ttf",
+    "crash": dataDir / "crash.subset.otf",
 }
 
 
@@ -176,3 +177,16 @@ def test_vectorBackends(backendName, imageSuffix):
     # assert expectedPath.read_bytes() == outputPath.read_bytes()
     diff = compareImages(expectedPath, outputPath)
     assert diff < 0.00012, diff
+
+
+def test_recursive():
+    # https://github.com/BlackFoundryCom/black-renderer/issues/56
+    # https://github.com/justvanrossum/fontgoggles/issues/213
+    glyphName = "hah-ar"
+    font = BlackRendererFont(testFonts["crash"])
+    boundingBox = font.getGlyphBounds(glyphName)
+    surfaceClass = getSurfaceClass("svg", ".svg")
+    surface = surfaceClass()
+    with surface.canvas(boundingBox) as canvas:
+        with pytest.raises(RecursionError):
+            font.drawGlyph(glyphName, canvas)