xdegaye · Nov 12, 2017 · Oct 28, 2017 · Oct 29, 2017 · Oct 29, 2017 · Oct 29, 2017
diff --git a/Lib/test/support/__init__.py b/Lib/test/support/__init__.py
@@ -32,6 +32,9 @@
 import unittest
 import urllib.error
 import warnings
+import selectors
+from contextlib import ExitStack
+from errno import EIO
 
 try:
     import multiprocessing.process
@@ -105,6 +108,7 @@
     "run_with_locale", "swap_item",
     "swap_attr", "Matcher", "set_memlimit", "SuppressCrashReport", "sortdict",
     "run_with_tz", "PGO", "missing_compiler_executable", "fd_count",
+    "run_pty",
     ]
 
 class Error(Exception):
@@ -2756,6 +2760,60 @@ def fd_count():
 
     return count
 
+def run_pty(script, input=b"dummy input\r", env=None):
+    pty = import_module('pty')
+    output = bytearray()
+    [master, slave] = pty.openpty()
+    if script is None:
+        args = (sys.executable, '-q')
+    else:
+        args = (sys.executable, '-c', script)
+    proc = subprocess.Popen(args, stdin=slave, stdout=slave, stderr=slave, env=env)
+    os.close(slave)
+    with ExitStack() as cleanup:
+        cleanup.enter_context(proc)
+        def terminate(proc):
+            try:
+                proc.kill()
+            except ProcessLookupError:
+                # Workaround for Open/Net BSD bug (Issue 16762)
+                pass
+        cleanup.callback(terminate, proc)
+        cleanup.callback(os.close, master)
+        # Avoid using DefaultSelector and PollSelector. Kqueue() does not
+        # work with pseudo-terminals on OS X < 10.9 (Issue 20365) and Open
+        # BSD (Issue 20667). Poll() does not work with OS X 10.6 or 10.4
+        # either (Issue 20472). Hopefully the file descriptor is low enough
+        # to use with select().
+        sel = cleanup.enter_context(selectors.SelectSelector())
+        os.set_blocking(master, False)
+        sel.register(master, selectors.EVENT_READ | selectors.EVENT_WRITE)
+        while sel.get_map():
+            for [key, events] in sel.select():
+                if events & selectors.EVENT_READ:
+                    try:
+                        chunk = os.read(master, 0x10000)
+                    except OSError as err:
+                        # Linux raises EIO when slave is closed (Issue 5380)
+                        if err.errno != EIO:
+                            raise
+                        chunk = b""
+                    if not chunk:
+                        sel.unregister(key.fileobj)
+                        break
+                    output.extend(chunk)
+                if events & selectors.EVENT_WRITE:
+                    try:
+                        input = input[os.write(master, input):]
+                    except OSError as err:
+                        # Apparently EIO means the slave was closed
+                        if err.errno != EIO:
+                            raise
+                        input = b""  # Stop writing
+                    if not input:
+                        sel.modify(master, selectors.EVENT_READ)
+        proc.wait()
+        return proc.returncode, output
 
 class SaveSignals:
     """

diff --git a/Lib/test/test_readline.py b/Lib/test/test_readline.py
@@ -1,15 +1,11 @@
 """
 Very minimal unittests for parts of the readline module.
 """
-from contextlib import ExitStack
-from errno import EIO
 import os
-import selectors
-import subprocess
-import sys
 import tempfile
 import unittest
-from test.support import import_module, unlink, temp_dir, TESTFN, verbose
+from test.support import (import_module, unlink, temp_dir, TESTFN, verbose,
+                         run_pty)
 from test.support.script_helper import assert_python_ok
 
 # Skip tests if there is no readline module
@@ -145,11 +141,11 @@ def test_init(self):
 """
 
     def test_auto_history_enabled(self):
-        output = run_pty(self.auto_history_script.format(True))
+        rc, output = run_pty(self.auto_history_script.format(True))
         self.assertIn(b"History length: 1\r\n", output)
 
     def test_auto_history_disabled(self):
-        output = run_pty(self.auto_history_script.format(False))
+        rc, output = run_pty(self.auto_history_script.format(False))
         self.assertIn(b"History length: 0\r\n", output)
 
     def test_nonascii(self):
@@ -215,7 +211,7 @@ def display(substitution, matches, longest_match_length):
         input += b"\t\t"  # Display possible completions
         input += b"x\t"  # Complete "t\xEBx" -> "t\xEBxt"
         input += b"\r"
-        output = run_pty(script, input)
+        rc, output = run_pty(script, input)
         self.assertIn(b"text 't\\xeb'\r\n", output)
         self.assertIn(b"line '[\\xefnserted]|t\\xeb[after]'\r\n", output)
         self.assertIn(b"indexes 11 13\r\n", output)
@@ -271,55 +267,5 @@ def test_history_size(self):
             self.assertEqual(lines[-1].strip(), b"last input")
 
 
-def run_pty(script, input=b"dummy input\r", env=None):
-    pty = import_module('pty')
-    output = bytearray()
-    [master, slave] = pty.openpty()
-    args = (sys.executable, '-c', script)
-    proc = subprocess.Popen(args, stdin=slave, stdout=slave, stderr=slave, env=env)
-    os.close(slave)
-    with ExitStack() as cleanup:
-        cleanup.enter_context(proc)
-        def terminate(proc):
-            try:
-                proc.terminate()
-            except ProcessLookupError:
-                # Workaround for Open/Net BSD bug (Issue 16762)
-                pass
-        cleanup.callback(terminate, proc)
-        cleanup.callback(os.close, master)
-        # Avoid using DefaultSelector and PollSelector. Kqueue() does not
-        # work with pseudo-terminals on OS X < 10.9 (Issue 20365) and Open
-        # BSD (Issue 20667). Poll() does not work with OS X 10.6 or 10.4
-        # either (Issue 20472). Hopefully the file descriptor is low enough
-        # to use with select().
-        sel = cleanup.enter_context(selectors.SelectSelector())
-        sel.register(master, selectors.EVENT_READ | selectors.EVENT_WRITE)
-        os.set_blocking(master, False)
-        while True:
-            for [_, events] in sel.select():
-                if events & selectors.EVENT_READ:
-                    try:
-                        chunk = os.read(master, 0x10000)
-                    except OSError as err:
-                        # Linux raises EIO when slave is closed (Issue 5380)
-                        if err.errno != EIO:
-                            raise
-                        chunk = b""
-                    if not chunk:
-                        return output
-                    output.extend(chunk)
-                if events & selectors.EVENT_WRITE:
-                    try:
-                        input = input[os.write(master, input):]
-                    except OSError as err:
-                        # Apparently EIO means the slave was closed
-                        if err.errno != EIO:
-                            raise
-                        input = b""  # Stop writing
-                    if not input:
-                        sel.modify(master, selectors.EVENT_READ)
-
-
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_repl.py b/Lib/test/test_repl.py
@@ -0,0 +1,29 @@
+"""Test the interactive interpreter."""
+
+import unittest
+from textwrap import dedent
+from test.support import run_pty, SuppressCrashReport
+
+class TestInteractiveInterpreter(unittest.TestCase):
+
+    def test_no_memory(self):
+        # Issue #30696: Fix the interactive interpreter looping endlessly when
+        # no memory. Check also that the fix does not break the interactive
+        # loop when an exception is raised.
+        user_input = """
+            import sys, _testcapi
+            1/0
+            print('After the exception.')
+            _testcapi.set_nomemory(0)
+            sys.exit(0)
+        """
+        user_input = dedent(user_input)
+        user_input = b'\r'.join(x.encode() for x in user_input.split('\n'))
+        user_input += b'\r'
+        with SuppressCrashReport():
+            rc, output = run_pty(None, input=user_input)
+        self.assertIn(b'After the exception.\r\n>>>', output)
+        self.assertIn(rc, (1, 120))
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/Misc/NEWS.d/next/Core and Builtins/2017-10-28-22-06-03.bpo-30696.lhC3HE.rst b/Misc/NEWS.d/next/Core and Builtins/2017-10-28-22-06-03.bpo-30696.lhC3HE.rst
@@ -0,0 +1 @@
+Fix the interactive interpreter looping endlessly when no memory.
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
@@ -65,6 +65,7 @@ static PyObject *run_pyc_file(FILE *, const char *, PyObject *, PyObject *,
                               PyCompilerFlags *);
 static void err_input(perrdetail *);
 static void err_free(perrdetail *);
+static int PyRun_InteractiveOneObjectEx(FILE *, PyObject *, PyCompilerFlags *);
 
 /* Parse input from a file and execute it */
 int
@@ -89,6 +90,7 @@ PyRun_InteractiveLoopFlags(FILE *fp, const char *filename_str, PyCompilerFlags *
     PyObject *filename, *v;
     int ret, err;
     PyCompilerFlags local_flags;
+    static int nomem_count = 0;
 
     filename = PyUnicode_DecodeFSDefault(filename_str);
     if (filename == NULL) {
@@ -110,22 +112,32 @@ PyRun_InteractiveLoopFlags(FILE *fp, const char *filename_str, PyCompilerFlags *
         _PySys_SetObjectId(&PyId_ps2, v = PyUnicode_FromString("... "));
         Py_XDECREF(v);
     }
-    err = -1;
-    for (;;) {
-        ret = PyRun_InteractiveOneObject(fp, filename, flags);
+    err = 0;
+    do {
+        ret = PyRun_InteractiveOneObjectEx(fp, filename, flags);
+        if (ret == -1 && PyErr_Occurred()) {
+            /* Prevent an endless loop after multiple consecutive MemoryErrors
+             * while still allowing an interactive command to fail with a
+             * MemoryError. */
+            if (PyErr_ExceptionMatches(PyExc_MemoryError)) {
+                if (++nomem_count > 16) {
+                    PyErr_Clear();
+                    err = -1;
+                    break;
+                }
+            } else {
+                nomem_count = 0;
+            }
+            PyErr_Print();
+            flush_io();
+        } else {
+            nomem_count = 0;
+        }
 #ifdef Py_REF_DEBUG
         if (_PyDebug_XOptionShowRefCount() == Py_True)
             _PyDebug_PrintTotalRefs();
 #endif
-        if (ret == E_EOF) {
-            err = 0;
-            break;
-        }
-        /*
-        if (ret == E_NOMEM)
-            break;
-        */
-    }
+    } while (ret != E_EOF);
     Py_DECREF(filename);
     return err;
 }
@@ -154,8 +166,9 @@ static int PARSER_FLAGS(PyCompilerFlags *flags)
                    PyPARSE_WITH_IS_KEYWORD : 0)) : 0)
 #endif
 
-int
-PyRun_InteractiveOneObject(FILE *fp, PyObject *filename, PyCompilerFlags *flags)
+static int
+PyRun_InteractiveOneObjectEx(FILE *fp, PyObject *filename,
+                             PyCompilerFlags *flags)
 {
     PyObject *m, *d, *v, *w, *oenc = NULL, *mod_name;
     mod_ty mod;
@@ -167,7 +180,6 @@ PyRun_InteractiveOneObject(FILE *fp, PyObject *filename, PyCompilerFlags *flags)
 
     mod_name = _PyUnicode_FromId(&PyId___main__); /* borrowed */
     if (mod_name == NULL) {
-        PyErr_Print();
         return -1;
     }
 
@@ -227,7 +239,6 @@ PyRun_InteractiveOneObject(FILE *fp, PyObject *filename, PyCompilerFlags *flags)
             PyErr_Clear();
             return E_EOF;
         }
-        PyErr_Print();
         return -1;
     }
     m = PyImport_AddModuleObject(mod_name);
@@ -239,15 +250,26 @@ PyRun_InteractiveOneObject(FILE *fp, PyObject *filename, PyCompilerFlags *flags)
     v = run_mod(mod, filename, d, d, flags, arena);
     PyArena_Free(arena);
     if (v == NULL) {
-        PyErr_Print();
-        flush_io();
         return -1;
     }
     Py_DECREF(v);
     flush_io();
     return 0;
 }
 
+int
+PyRun_InteractiveOneObject(FILE *fp, PyObject *filename, PyCompilerFlags *flags)
+{
+    int res;
+
+    res = PyRun_InteractiveOneObjectEx(fp, filename, flags);
+    if (res == -1) {
+        PyErr_Print();
+        flush_io();
+    }
+    return res;
+}
+
 int
 PyRun_InteractiveOneFlags(FILE *fp, const char *filename_str, PyCompilerFlags *flags)
 {
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Fix the interactive interpreter looping endlessly when no memory.