Fix ImagePath coordinate conversion errors

Tests/test_imagedraw.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import os.path
+from decimal import Decimal
 
 import pytest
 
@@ -68,6 +69,12 @@ def test_sanity() -> None:
     draw.rectangle(list(range(4)))
 
 
+def test_line_invalid_coordinate_conversion() -> None:
+    draw = ImageDraw.Draw(Image.new("RGB", (4, 4)))
+    with pytest.raises(ValueError, match="[Cc]annot convert signaling NaN to float"):
+        draw.line([Decimal("sNaN"), 0, 1, 1])  # type: ignore[arg-type]
+
+
 def test_new_color() -> None:
     with Image.open("Tests/images/chi.gif") as im:
         draw = ImageDraw.Draw(im)

Tests/test_imagepath.py

@@ -3,6 +3,7 @@
 import array
 import math
 import struct
+from decimal import Decimal
 
 import pytest
 
@@ -87,13 +88,36 @@ def test_path_list_of_lists(
     assert list(p) == expected
 
 
+def test_path_item_assignment_requires_tuple() -> None:
+    p = ImagePath.Path([(0, 1)])
+
+    with pytest.raises(TypeError):
+        p[0] = [4, 5]
+    assert p[0] == (0.0, 1.0)
+
+    p[0] = (4, 5)
+    assert p[0] == (4.0, 5.0)
+
+
+def test_path_coordinate_conversion_errors() -> None:
+    with pytest.raises(ValueError, match="[Cc]annot convert signaling NaN to float"):
+        ImagePath.Path([Decimal("sNaN"), 0])
+
+    large_int = (1 << 30) + 1
+    assert ImagePath.Path([large_int, 0])[0] == (float(large_int), 0.0)
+
+    with pytest.raises(OverflowError):
+        ImagePath.Path([1 << 1024, 0])
+
+
 @pytest.mark.parametrize(
     "coords, message",
     (
         ([[1, 2, 3]], "coordinate list must contain exactly 2 coordinates"),
         ([[1]], "coordinate list must contain exactly 2 coordinates"),
         ([[[1, 2], [3, 4]]], "coordinate list must contain numbers"),
         ([["a", "b"]], "coordinate list must contain numbers"),
+        ([[Decimal("sNaN"), 0]], "[Cc]annot convert signaling NaN to float"),
     ),
 )
 def test_invalid_list_coords(coords: list[list[object]], message: str) -> None:

src/path.c

@@ -117,9 +117,17 @@ assign_item_to_array(double *xy, Py_ssize_t j, PyObject *op) {
     if (PyFloat_Check(op)) {
         xy[j++] = PyFloat_AS_DOUBLE(op);
     } else if (PyLong_Check(op)) {
-        xy[j++] = (float)PyLong_AsLong(op);
+        double value = PyLong_AsDouble(op);
+        if (value == -1.0 && PyErr_Occurred()) {
+            return -1;
+        }
+        xy[j++] = value;
     } else if (PyNumber_Check(op)) {
-        xy[j++] = PyFloat_AsDouble(op);
+        double value = PyFloat_AsDouble(op);
+        if (value == -1.0 && PyErr_Occurred()) {
+            return -1;
+        }
+        xy[j++] = value;
     } else if (PyList_Check(op)) {
         if (PyList_GET_SIZE(op) != 2) {
             PyErr_SetString(
@@ -139,9 +147,11 @@ assign_item_to_array(double *xy, Py_ssize_t j, PyObject *op) {
             }
             Py_DECREF(op1);
             if (j == -1) {
-                PyErr_SetString(
-                    PyExc_ValueError, "coordinate list must contain numbers"
-                );
+                if (!PyErr_Occurred()) {
+                    PyErr_SetString(
+                        PyExc_ValueError, "coordinate list must contain numbers"
+                    );
+                }
                 return -1;
             }
         }
@@ -488,6 +498,11 @@ path_setitem(PyPathObject *self, Py_ssize_t i, PyObject *op) {
 
     xy = &self->xy[i + i];
 
+    if (!PyTuple_Check(op)) {
+        PyErr_SetString(PyExc_TypeError, "argument must be tuple of length 2");
+        return -1;
+    }
+
     if (!PyArg_ParseTuple(op, "dd", &xy[0], &xy[1])) {
         return -1;
     }