Issue #10093: ResourceWarnings are now issued when files and sockets are

deallocated without explicit closing.  These warnings are silenced by
default, except in pydebug mode.

4 files changed, 81 insertions, 12 deletions

diff --git a/Lib/socket.py b/Lib/socket.py
index 6af1964..2dc9736 100644
--- a/Lib/socket.py
+++ b/Lib/socket.py
@@ -108,7 +108,7 @@ class socket(_socket.socket):
         if s.startswith("<socket object"):
             s = "<%s.%s%s%s" % (self.__class__.__module__,
                                 self.__class__.__name__,
-                                (self._closed and " [closed] ") or "",
+                                getattr(self, '_closed', False) and " [closed] " or "",
                                 s[7:])
         return s
 
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index 8784e34..7ce9753 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -29,6 +29,7 @@ import weakref
 import abc
 import signal
 import errno
+import warnings
 from itertools import cycle, count
 from collections import deque
 from test import support
@@ -2525,6 +2526,46 @@ class MiscIOTest(unittest.TestCase):
         # baseline "io" module.
         self._check_abc_inheritance(io)
 
+    def _check_warn_on_dealloc(self, *args, **kwargs):
+        f = open(*args, **kwargs)
+        r = repr(f)
+        with self.assertWarns(ResourceWarning) as cm:
+            f = None
+            support.gc_collect()
+        self.assertIn(r, str(cm.warning.args[0]))
+
+    def test_warn_on_dealloc(self):
+        self._check_warn_on_dealloc(support.TESTFN, "wb", buffering=0)
+        self._check_warn_on_dealloc(support.TESTFN, "wb")
+        self._check_warn_on_dealloc(support.TESTFN, "w")
+
+    def _check_warn_on_dealloc_fd(self, *args, **kwargs):
+        fds = []
+        try:
+            r, w = os.pipe()
+            fds += r, w
+            self._check_warn_on_dealloc(r, *args, **kwargs)
+            # When using closefd=False, there's no warning
+            r, w = os.pipe()
+            fds += r, w
+            with warnings.catch_warnings(record=True) as recorded:
+                open(r, *args, closefd=False, **kwargs)
+                support.gc_collect()
+            self.assertEqual(recorded, [])
+        finally:
+            for fd in fds:
+                try:
+                    os.close(fd)
+                except EnvironmentError as e:
+                    if e.errno != errno.EBADF:
+                        raise
+
+    def test_warn_on_dealloc_fd(self):
+        self._check_warn_on_dealloc_fd("rb", buffering=0)
+        self._check_warn_on_dealloc_fd("rb")
+        self._check_warn_on_dealloc_fd("r")
+
+
 class CMiscIOTest(MiscIOTest):
     io = io
 
diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py
index 699efc0..e20364d 100644
--- a/Lib/test/test_socket.py
+++ b/Lib/test/test_socket.py
@@ -706,6 +706,23 @@ class GeneralModuleTests(unittest.TestCase):
     def test_sendall_interrupted_with_timeout(self):
         self.check_sendall_interrupted(True)
 
+    def test_dealloc_warn(self):
+        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        r = repr(sock)
+        with self.assertWarns(ResourceWarning) as cm:
+            sock = None
+            support.gc_collect()
+        self.assertIn(r, str(cm.warning.args[0]))
+        # An open socket file object gets dereferenced after the socket
+        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        f = sock.makefile('rb')
+        r = repr(sock)
+        sock = None
+        support.gc_collect()
+        with self.assertWarns(ResourceWarning):
+            f = None
+            support.gc_collect()
+
 
 @unittest.skipUnless(thread, 'Threading required for this test.')
 class BasicTCPTest(SocketConnectedTest):
diff --git a/Lib/xml/etree/ElementTree.py b/Lib/xml/etree/ElementTree.py
index ecc8ea7..9f5717e 100644
--- a/Lib/xml/etree/ElementTree.py
+++ b/Lib/xml/etree/ElementTree.py
@@ -662,17 +662,23 @@ class ElementTree:
     # @exception ParseError If the parser fails to parse the document.
 
     def parse(self, source, parser=None):
+        close_source = False
         if not hasattr(source, "read"):
             source = open(source, "rb")
-        if not parser:
-            parser = XMLParser(target=TreeBuilder())
-        while 1:
-            data = source.read(65536)
-            if not data:
-                break
-            parser.feed(data)
-        self._root = parser.close()
-        return self._root
+            close_source = True
+        try:
+            if not parser:
+                parser = XMLParser(target=TreeBuilder())
+            while 1:
+                data = source.read(65536)
+                if not data:
+                    break
+                parser.feed(data)
+            self._root = parser.close()
+            return self._root
+        finally:
+            if close_source:
+                source.close()
 
     ##
     # Creates a tree iterator for the root element.  The iterator loops
@@ -1226,16 +1232,19 @@ def parse(source, parser=None):
 # @return A (event, elem) iterator.
 
 def iterparse(source, events=None, parser=None):
+    close_source = False
     if not hasattr(source, "read"):
         source = open(source, "rb")
+        close_source = True
     if not parser:
         parser = XMLParser(target=TreeBuilder())
-    return _IterParseIterator(source, events, parser)
+    return _IterParseIterator(source, events, parser, close_source)
 
 class _IterParseIterator:
 
-    def __init__(self, source, events, parser):
+    def __init__(self, source, events, parser, close_source=False):
         self._file = source
+        self._close_file = close_source
         self._events = []
         self._index = 0
         self.root = self._root = None
@@ -1282,6 +1291,8 @@ class _IterParseIterator:
             except IndexError:
                 if self._parser is None:
                     self.root = self._root
+                    if self._close_file:
+                        self._file.close()
                     raise StopIteration
                 # load event buffer
                 del self._events[:]