[cairo-path] Check for an empty path in cairo_append_path().

As we now generate empty paths, we must be able to handle empty paths
in the user facing API. cairo_append_path() has an explicit check, and
raises an error, for a NULL path->data, so we need to check the
path->num_data first for empty paths.
(cherry picked from commit ef5f460eb1f86a73e016c1150723ae1e70b3b037)

2 files changed, 18 insertions, 0 deletions

diff --git a/src/cairo.c b/src/cairo.c
index 6859e45b..c6ea8c59 100644
--- a/src/cairo.c
+++ b/src/cairo.c
@@ -3405,6 +3405,9 @@ cairo_append_path (cairo_t		*cr,
 	return;
     }
 
+    if (path->num_data == 0)
+	return;
+
     if (path->data == NULL) {
 	_cairo_set_error (cr, CAIRO_STATUS_NULL_POINTER);
 	return;
diff --git a/test/copy-path.c b/test/copy-path.c
index 256f4612..362bb34d 100644
--- a/test/copy-path.c
+++ b/test/copy-path.c
@@ -141,7 +141,13 @@ draw (cairo_t *cr, int width, int height)
 	cairo_path_destroy (path);
 	return CAIRO_TEST_FAILURE;
     }
+    cairo_append_path (cr, path);
     cairo_path_destroy (path);
+    if (cairo_status (cr) != CAIRO_STATUS_SUCCESS) {
+	cairo_test_log ("Error: cairo_append_path failed with a copy of an empty path, returned status of %s\n",
+			cairo_status_to_string (cairo_status (cr)));
+	return CAIRO_TEST_FAILURE;
+    }
 
     /* We draw in the default black, so paint white first. */
     cairo_save (cr);
@@ -224,6 +230,15 @@ main (void)
     path.num_data = 0;
     path.status = CAIRO_STATUS_SUCCESS;
     cairo_append_path (cr, &path);
+    if (cairo_status (cr) != CAIRO_STATUS_SUCCESS)
+	return 1;
+    cairo_destroy (cr);
+
+    cr = cairo_create (surface);
+    path.data = NULL;
+    path.num_data = 1;
+    path.status = CAIRO_STATUS_SUCCESS;
+    cairo_append_path (cr, &path);
     if (cairo_status (cr) != CAIRO_STATUS_NULL_POINTER)
 	return 1;
     cairo_destroy (cr);