bpo-41352: Raise UnsupportedOperation for FileIO.readall() in "w" mode

evanWang1409 · evanWang1409 · commit 75a219e439d6 · 2020-07-20T14:29:48.000-07:00
check self-&gt;readable

added tests for FileIO.read and FileIO.readall
diff --git a/Lib/test/test_fileio.py b/Lib/test/test_fileio.py
@@ -73,6 +73,24 @@ def testBlksize(self):
             blksize = getattr(fst, 'st_blksize', blksize)
         self.assertEqual(self.f._blksize, blksize)
 
+    def testReadWithWritingMode(self):
+        r, w = os.pipe()
+        w = os.fdopen(w, "w")
+        w.write("hello")
+        w.close()
+        with io.FileIO(r, mode="w") as f:
+            with self.assertRaises(_io.UnsupportedOperation):
+                f.read()
+
+    def testReadallWithWritingMode(self):
+        r, w = os.pipe()
+        w = os.fdopen(w, "w")
+        w.write("hello")
+        w.close()
+        with io.FileIO(r, mode="w") as f:
+            with self.assertRaises(_io.UnsupportedOperation):
+                f.readall()
+
     # verify readinto
     def testReadintoByteArray(self):
         self.f.write(bytes([1, 2, 0, 255]))
diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
@@ -699,6 +699,8 @@ _io_FileIO_readall_impl(fileio *self)
 
     if (self->fd < 0)
         return err_closed();
+    if (!self->readable)
+        return err_mode("reading");
 
     Py_BEGIN_ALLOW_THREADS
     _Py_BEGIN_SUPPRESS_IPH
