bpo-43292: Fix file leak in `ET.iterparse()` when not exhausted (GH-31696)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
(cherry picked from commit 496c428de3318c9c5770937491b71dc3d3f18a6a)

Co-authored-by: Jacob Walls <jacobtylerwalls@gmail.com>

1 files changed, 9 insertions, 7 deletions

diff --git a/Lib/xml/etree/ElementTree.py b/Lib/xml/etree/ElementTree.py
index e9409fd29a..07be8609b8 100644
--- a/Lib/xml/etree/ElementTree.py
+++ b/Lib/xml/etree/ElementTree.py
@@ -1248,8 +1248,14 @@ def iterparse(source, events=None, parser=None):
     # Use the internal, undocumented _parser argument for now; When the
     # parser argument of iterparse is removed, this can be killed.
     pullparser = XMLPullParser(events=events, _parser=parser)
-    def iterator():
+
+    def iterator(source):
+        close_source = False
         try:
+            if not hasattr(source, "read"):
+                source = open(source, "rb")
+                close_source = True
+            yield None
             while True:
                 yield from pullparser.read_events()
                 # load event buffer
@@ -1265,16 +1271,12 @@ def iterparse(source, events=None, parser=None):
                 source.close()
 
     class IterParseIterator(collections.abc.Iterator):
-        __next__ = iterator().__next__
+        __next__ = iterator(source).__next__
     it = IterParseIterator()
     it.root = None
     del iterator, IterParseIterator
 
-    close_source = False
-    if not hasattr(source, "read"):
-        source = open(source, "rb")
-        close_source = True
-
+    next(it)
     return it