Merge pull request #13768 from osherdp/feature/raise-when-opening-sta…

…ndard-streams

raise an error when user tries to open a standard stream

IPython/core/interactiveshell.py

@@ -270,6 +270,16 @@ def __repr__(self):
         return '<%s object at %x, execution_count=%s error_before_exec=%s error_in_exec=%s info=%s result=%s>' %\
                 (name, id(self), self.execution_count, self.error_before_exec, self.error_in_exec, repr(self.info), repr(self.result))
 
+@functools.wraps(io_open)
+def _modified_open(file, *args, **kwargs):
+    if file in {0, 1, 2}:
+        raise ValueError(
+            f"IPython won't let you open fd={file} by default "
+            "as it is likely to crash IPython. If you know what you are doing, "
+            "you can use builtins' open."
+        )
+
+    return io_open(file, *args, **kwargs)
 
 class InteractiveShell(SingletonConfigurable):
     """An enhanced, interactive shell for Python."""
@@ -1323,6 +1333,7 @@ def init_user_ns(self):
 
         ns['exit'] = self.exiter
         ns['quit'] = self.exiter
+        ns["open"] = _modified_open
 
         # Sync what we've added so far to user_ns_hidden so these aren't seen
         # by %who

IPython/core/tests/test_interactiveshell.py

@@ -103,6 +103,18 @@ def test_syntax_error(self):
         res = ip.run_cell("raise = 3")
         self.assertIsInstance(res.error_before_exec, SyntaxError)
 
+    def test_open_standard_input_stream(self):
+        res = ip.run_cell("open(0)")
+        self.assertIsInstance(res.error_in_exec, ValueError)
+
+    def test_open_standard_output_stream(self):
+        res = ip.run_cell("open(1)")
+        self.assertIsInstance(res.error_in_exec, ValueError)
+
+    def test_open_standard_error_stream(self):
+        res = ip.run_cell("open(2)")
+        self.assertIsInstance(res.error_in_exec, ValueError)
+
     def test_In_variable(self):
         "Verify that In variable grows with user input (GH-284)"
         oldlen = len(ip.user_ns['In'])