bpo-34410: Fix a crash in the tee iterator when re-enter it. (GH-15625)
RuntimeError is now raised in this case.
(cherry picked from commit 526a01467b3277f9fcf7f91e66c23321caa1245d)
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
diff --git a/Modules/itertoolsmodule.c b/Modules/itertoolsmodule.c
index 22c04f2..eba59ba 100644
--- a/Modules/itertoolsmodule.c
+++ b/Modules/itertoolsmodule.c
@@ -443,6 +443,7 @@
PyObject_HEAD
PyObject *it;
int numread; /* 0 <= numread <= LINKCELLS */
+ int running;
PyObject *nextlink;
PyObject *(values[LINKCELLS]);
} teedataobject;
@@ -465,6 +466,7 @@
if (tdo == NULL)
return NULL;
+ tdo->running = 0;
tdo->numread = 0;
tdo->nextlink = NULL;
Py_INCREF(it);
@@ -493,7 +495,14 @@
else {
/* this is the lead iterator, so fetch more data */
assert(i == tdo->numread);
+ if (tdo->running) {
+ PyErr_SetString(PyExc_RuntimeError,
+ "cannot re-enter the tee iterator");
+ return NULL;
+ }
+ tdo->running = 1;
value = PyIter_Next(tdo->it);
+ tdo->running = 0;
if (value == NULL)
return NULL;
tdo->numread++;