gh-87193: Support bytes objects with refcount > 1 in _PyBytes_Resize() (GH-117160)

Create a new bytes object and destroy the old one if it has refcount > 1.

1 files changed, 53 insertions, 0 deletions

diff --git a/Modules/_testcapi/bytes.c b/Modules/_testcapi/bytes.c
new file mode 100644
index 0000000..02294d8
--- /dev/null
+++ b/Modules/_testcapi/bytes.c
@@ -0,0 +1,53 @@
+#include "parts.h"
+#include "util.h"
+
+
+/* Test _PyBytes_Resize() */
+static PyObject *
+bytes_resize(PyObject *Py_UNUSED(module), PyObject *args)
+{
+    PyObject *obj;
+    Py_ssize_t newsize;
+    int new;
+
+    if (!PyArg_ParseTuple(args, "Onp", &obj, &newsize, &new))
+        return NULL;
+
+    NULLABLE(obj);
+    if (new) {
+        assert(obj != NULL);
+        assert(PyBytes_CheckExact(obj));
+        PyObject *newobj = PyBytes_FromStringAndSize(NULL, PyBytes_Size(obj));
+        if (newobj == NULL) {
+            return NULL;
+        }
+        memcpy(PyBytes_AsString(newobj), PyBytes_AsString(obj), PyBytes_Size(obj));
+        obj = newobj;
+    }
+    else {
+        Py_XINCREF(obj);
+    }
+    if (_PyBytes_Resize(&obj, newsize) < 0) {
+        assert(obj == NULL);
+    }
+    else {
+        assert(obj != NULL);
+    }
+    return obj;
+}
+
+
+static PyMethodDef test_methods[] = {
+    {"bytes_resize", bytes_resize, METH_VARARGS},
+    {NULL},
+};
+
+int
+_PyTestCapi_Init_Bytes(PyObject *m)
+{
+    if (PyModule_AddFunctions(m, test_methods) < 0) {
+        return -1;
+    }
+
+    return 0;
+}