From 8d62df60d8733d0fa9aee14ef746d0009a7a9726 Mon Sep 17 00:00:00 2001
From: Daniel Hillier <daniel.hillier@gmail.com>
Date: Sat, 30 Nov 2019 19:30:47 +1100
Subject: [PATCH] bpo-37523: Raise ValueError for I/O operations on a closed
 zipfile.ZipExtFile. (GH-14658)

Raises ValueError when calling the following on a closed zipfile.ZipExtFile: read, readable, seek, seekable, tell.
---
 Lib/test/test_zipfile.py                           | 14 ++++++++++++++
 Lib/zipfile.py                                     | 10 ++++++++++
 .../2019-10-02-02-55-37.bpo-37523.GguwJ6.rst       |  1 +
 3 files changed, 25 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2019-10-02-02-55-37.bpo-37523.GguwJ6.rst

diff --git a/Lib/test/test_zipfile.py b/Lib/test/test_zipfile.py
index 1e1854be710..66f05ac1f3a 100644
--- a/Lib/test/test_zipfile.py
+++ b/Lib/test/test_zipfile.py
@@ -571,6 +571,20 @@ def test_write_default_name(self):
             with open(TESTFN, "rb") as f:
                 self.assertEqual(zipfp.read(TESTFN), f.read())
 
+    def test_io_on_closed_zipextfile(self):
+        fname = "somefile.txt"
+        with zipfile.ZipFile(TESTFN2, mode="w") as zipfp:
+            zipfp.writestr(fname, "bogus")
+
+        with zipfile.ZipFile(TESTFN2, mode="r") as zipfp:
+            with zipfp.open(fname) as fid:
+                fid.close()
+                self.assertRaises(ValueError, fid.read)
+                self.assertRaises(ValueError, fid.seek, 0)
+                self.assertRaises(ValueError, fid.tell)
+                self.assertRaises(ValueError, fid.readable)
+                self.assertRaises(ValueError, fid.seekable)
+
     def test_write_to_readonly(self):
         """Check that trying to call write() on a readonly ZipFile object
         raises a ValueError."""
diff --git a/Lib/zipfile.py b/Lib/zipfile.py
index b0afb9da942..e1d07f2a523 100644
--- a/Lib/zipfile.py
+++ b/Lib/zipfile.py
@@ -889,12 +889,16 @@ def peek(self, n=1):
         return self._readbuffer[self._offset: self._offset + 512]
 
     def readable(self):
+        if self.closed:
+            raise ValueError("I/O operation on closed file.")
         return True
 
     def read(self, n=-1):
         """Read and return up to n bytes.
         If the argument is omitted, None, or negative, data is read and returned until EOF is reached.
         """
+        if self.closed:
+            raise ValueError("read from closed file.")
         if n is None or n < 0:
             buf = self._readbuffer[self._offset:]
             self._readbuffer = b''
@@ -1031,9 +1035,13 @@ def close(self):
             super().close()
 
     def seekable(self):
+        if self.closed:
+            raise ValueError("I/O operation on closed file.")
         return self._seekable
 
     def seek(self, offset, whence=0):
+        if self.closed:
+            raise ValueError("seek on closed file.")
         if not self._seekable:
             raise io.UnsupportedOperation("underlying stream is not seekable")
         curr_pos = self.tell()
@@ -1082,6 +1090,8 @@ def seek(self, offset, whence=0):
         return self.tell()
 
     def tell(self):
+        if self.closed:
+            raise ValueError("tell on closed file.")
         if not self._seekable:
             raise io.UnsupportedOperation("underlying stream is not seekable")
         filepos = self._orig_file_size - self._left - len(self._readbuffer) + self._offset
diff --git a/Misc/NEWS.d/next/Library/2019-10-02-02-55-37.bpo-37523.GguwJ6.rst b/Misc/NEWS.d/next/Library/2019-10-02-02-55-37.bpo-37523.GguwJ6.rst
new file mode 100644
index 00000000000..5711969ff38
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-10-02-02-55-37.bpo-37523.GguwJ6.rst
@@ -0,0 +1 @@
+Change :class:`zipfile.ZipExtFile` to raise ``ValueError`` when trying to access the underlying file object after it has been closed. This new behavior is consistent with how accessing closed files is handled in other parts of Python.
\ No newline at end of file