Backport PR #12137: Fix inability to interrupt processes on Windows

IPython/utils/_process_win32.py

@@ -1,191 +1,205 b''
 """Windows-specific implementation of process utilities.
 
 This file is only meant to be imported by process.py, not by end-users.
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2010-2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 # stdlib
 import os
 import sys
 import ctypes
+import time
 
 from ctypes import c_int, POINTER
 from ctypes.wintypes import LPCWSTR, HLOCAL
-from subprocess import STDOUT
+from subprocess import STDOUT, TimeoutExpired
+from threading import Thread
 
 # our own imports
 from ._process_common import read_no_interrupt, process_handler, arg_split as py_arg_split
 from . import py3compat
 from .encoding import DEFAULT_ENCODING
 
 #-----------------------------------------------------------------------------
 # Function definitions
 #-----------------------------------------------------------------------------
 
 class AvoidUNCPath(object):
     """A context manager to protect command execution from UNC paths.
 
     In the Win32 API, commands can't be invoked with the cwd being a UNC path.
     This context manager temporarily changes directory to the 'C:' drive on
     entering, and restores the original working directory on exit.
 
     The context manager returns the starting working directory *if* it made a
     change and None otherwise, so that users can apply the necessary adjustment
     to their system calls in the event of a change.
 
     Examples
     --------
     ::
         cmd = 'dir'
         with AvoidUNCPath() as path:
             if path is not None:
                 cmd = '"pushd %s &&"%s' % (path, cmd)
             os.system(cmd)
     """
     def __enter__(self):
         self.path = os.getcwd()
         self.is_unc_path = self.path.startswith(r"\\")
         if self.is_unc_path:
             # change to c drive (as cmd.exe cannot handle UNC addresses)
             os.chdir("C:")
             return self.path
         else:
             # We return None to signal that there was no change in the working
             # directory
             return None
 
     def __exit__(self, exc_type, exc_value, traceback):
         if self.is_unc_path:
             os.chdir(self.path)
 
 
 def _find_cmd(cmd):
     """Find the full path to a .bat or .exe using the win32api module."""
     try:
         from win32api import SearchPath
     except ImportError:
         raise ImportError('you need to have pywin32 installed for this to work')
     else:
         PATH = os.environ['PATH']
         extensions = ['.exe', '.com', '.bat', '.py']
         path = None
         for ext in extensions:
             try:
                 path = SearchPath(PATH, cmd, ext)[0]
             except:
                 pass
         if path is None:
             raise OSError("command %r not found" % cmd)
         else:
             return path
 
 
 def _system_body(p):
     """Callback for _system."""
     enc = DEFAULT_ENCODING
-    for line in read_no_interrupt(p.stdout).splitlines():
-        line = line.decode(enc, 'replace')
-        print(line, file=sys.stdout)
-    for line in read_no_interrupt(p.stderr).splitlines():
-        line = line.decode(enc, 'replace')
-        print(line, file=sys.stderr)
 
-    # Wait to finish for returncode
-    return p.wait()
+    def stdout_read():
+        for line in read_no_interrupt(p.stdout).splitlines():
+            line = line.decode(enc, 'replace')
+            print(line, file=sys.stdout)
+
+    def stderr_read():
+        for line in read_no_interrupt(p.stderr).splitlines():
+            line = line.decode(enc, 'replace')
+            print(line, file=sys.stderr)
+
+    Thread(target=stdout_read).start()
+    Thread(target=stderr_read).start()
+
+    # Wait to finish for returncode. Unfortunately, Python has a bug where
+    # wait() isn't interruptible (https://bugs.python.org/issue28168) so poll in
+    # a loop instead of just doing `return p.wait()`.
+    while True:
+        result = p.poll()
+        if result is None:
+            time.sleep(0.01)
+        else:
+            return result
 
 
 def system(cmd):
     """Win32 version of os.system() that works with network shares.
 
     Note that this implementation returns None, as meant for use in IPython.
 
     Parameters
     ----------
     cmd : str or list
       A command to be executed in the system shell.
 
     Returns
     -------
-    None : we explicitly do NOT return the subprocess status code, as this
-    utility is meant to be used extensively in IPython, where any return value
-    would trigger :func:`sys.displayhook` calls.
+    int : child process' exit code.
     """
     # The controller provides interactivity with both
     # stdin and stdout
     #import _process_win32_controller
     #_process_win32_controller.system(cmd)
 
     with AvoidUNCPath() as path:
         if path is not None:
             cmd = '"pushd %s &&"%s' % (path, cmd)
         return process_handler(cmd, _system_body)
 
 def getoutput(cmd):
     """Return standard output of executing cmd in a shell.
 
     Accepts the same arguments as os.system().
 
     Parameters
     ----------
     cmd : str or list
       A command to be executed in the system shell.
 
     Returns
     -------
     stdout : str
     """
 
     with AvoidUNCPath() as path:
         if path is not None:
             cmd = '"pushd %s &&"%s' % (path, cmd)
         out = process_handler(cmd, lambda p: p.communicate()[0], STDOUT)
 
     if out is None:
         out = b''
     return py3compat.decode(out)
 
 try:
     CommandLineToArgvW = ctypes.windll.shell32.CommandLineToArgvW
     CommandLineToArgvW.arg_types = [LPCWSTR, POINTER(c_int)]
     CommandLineToArgvW.restype = POINTER(LPCWSTR)
     LocalFree = ctypes.windll.kernel32.LocalFree
     LocalFree.res_type = HLOCAL
     LocalFree.arg_types = [HLOCAL]
     
     def arg_split(commandline, posix=False, strict=True):
         """Split a command line's arguments in a shell-like manner.
 
         This is a special version for windows that use a ctypes call to CommandLineToArgvW
         to do the argv splitting. The posix parameter is ignored.
         
         If strict=False, process_common.arg_split(...strict=False) is used instead.
         """
         #CommandLineToArgvW returns path to executable if called with empty string.
         if commandline.strip() == "":
             return []
         if not strict:
             # not really a cl-arg, fallback on _process_common
             return py_arg_split(commandline, posix=posix, strict=strict)
         argvn = c_int()
         result_pointer = CommandLineToArgvW(py3compat.cast_unicode(commandline.lstrip()), ctypes.byref(argvn))
         result_array_type = LPCWSTR * argvn.value
         result = [arg for arg in result_array_type.from_address(ctypes.addressof(result_pointer.contents))]
         retval = LocalFree(result_pointer)
         return result
 except AttributeError:
     arg_split = py_arg_split
 
 def check_pid(pid):
     # OpenProcess returns 0 if no such process (of ours) exists
     # positive int otherwise
     return bool(ctypes.windll.kernel32.OpenProcess(1,0,pid))

IPython/utils/tests/test_process.py

@@ -1,144 +1,195 b''
 # encoding: utf-8
 """
 Tests for platutils.py
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import sys
+import signal
 import os
+import time
+from _thread import interrupt_main  # Py 3
+import threading
+from unittest import SkipTest
 
 import nose.tools as nt
 
 from IPython.utils.process import (find_cmd, FindCmdError, arg_split,
                                    system, getoutput, getoutputerror,
                                    get_output_error_code)
+from IPython.utils.capture import capture_output
 from IPython.testing import decorators as dec
 from IPython.testing import tools as tt
 
 python = os.path.basename(sys.executable)
 
 #-----------------------------------------------------------------------------
 # Tests
 #-----------------------------------------------------------------------------
 
 
 @dec.skip_win32
 def test_find_cmd_ls():
     """Make sure we can find the full path to ls."""
     path = find_cmd('ls')
     nt.assert_true(path.endswith('ls'))
 
     
 def has_pywin32():
     try:
         import win32api
     except ImportError:
         return False
     return True
 
 
 @dec.onlyif(has_pywin32, "This test requires win32api to run")
 def test_find_cmd_pythonw():
     """Try to find pythonw on Windows."""
     path = find_cmd('pythonw')
     assert path.lower().endswith('pythonw.exe'), path
 
 
 @dec.onlyif(lambda : sys.platform != 'win32' or has_pywin32(),
             "This test runs on posix or in win32 with win32api installed")
 def test_find_cmd_fail():
     """Make sure that FindCmdError is raised if we can't find the cmd."""
     nt.assert_raises(FindCmdError,find_cmd,'asdfasdf')
 
     
 @dec.skip_win32
 def test_arg_split():
     """Ensure that argument lines are correctly split like in a shell."""
     tests = [['hi', ['hi']],
              [u'hi', [u'hi']],
              ['hello there', ['hello', 'there']],
              # \u01ce == \N{LATIN SMALL LETTER A WITH CARON}
              # Do not use \N because the tests crash with syntax error in
              # some cases, for example windows python2.6.
              [u'h\u01cello', [u'h\u01cello']],
              ['something "with quotes"', ['something', '"with quotes"']],
              ]
     for argstr, argv in tests:
         nt.assert_equal(arg_split(argstr), argv)
     
 @dec.skip_if_not_win32
 def test_arg_split_win32():
     """Ensure that argument lines are correctly split like in a shell."""
     tests = [['hi', ['hi']],
              [u'hi', [u'hi']],
              ['hello there', ['hello', 'there']],
              [u'h\u01cello', [u'h\u01cello']],
              ['something "with quotes"', ['something', 'with quotes']],
              ]
     for argstr, argv in tests:
         nt.assert_equal(arg_split(argstr), argv)
 
 
 class SubProcessTestCase(tt.TempFileMixin):
     def setUp(self):
         """Make a valid python temp file."""
         lines = [ "import sys",
                  "print('on stdout', end='', file=sys.stdout)",
                  "print('on stderr', end='', file=sys.stderr)",
                  "sys.stdout.flush()",
                  "sys.stderr.flush()"]
         self.mktmp('\n'.join(lines))
 
     def test_system(self):
         status = system('%s "%s"' % (python, self.fname))
         self.assertEqual(status, 0)
 
     def test_system_quotes(self):
         status = system('%s -c "import sys"' % python)
         self.assertEqual(status, 0)
 
+    def assert_interrupts(self, command):
+        """
+        Interrupt a subprocess after a second.
+        """
+        if threading.main_thread() != threading.current_thread():
+            raise nt.SkipTest("Can't run this test if not in main thread.")
+
+        # Some tests can overwrite SIGINT handler (by using pdb for example),
+        # which then breaks this test, so just make sure it's operating
+        # normally.
+        signal.signal(signal.SIGINT, signal.default_int_handler)
+
+        def interrupt():
+            # Wait for subprocess to start:
+            time.sleep(0.5)
+            interrupt_main()
+
+        threading.Thread(target=interrupt).start()
+        start = time.time()
+        try:
+            result = command()
+        except KeyboardInterrupt:
+            # Success!
+            pass
+        end = time.time()
+        self.assertTrue(
+            end - start < 2, "Process didn't die quickly: %s" % (end - start)
+        )
+        return result
+
+    def test_system_interrupt(self):
+        """
+        When interrupted in the way ipykernel interrupts IPython, the
+        subprocess is interrupted.
+        """
+        def command():
+            return system('%s -c "import time; time.sleep(5)"' % python)
+
+        status = self.assert_interrupts(command)
+        self.assertNotEqual(
+            status, 0, "The process wasn't interrupted. Status: %s" % (status,)
+        )
+
     def test_getoutput(self):
         out = getoutput('%s "%s"' % (python, self.fname))
         # we can't rely on the order the line buffered streams are flushed
         try:
             self.assertEqual(out, 'on stderron stdout')
         except AssertionError:
             self.assertEqual(out, 'on stdouton stderr')
 
     def test_getoutput_quoted(self):
         out = getoutput('%s -c "print (1)"' % python)
         self.assertEqual(out.strip(), '1')
 
     #Invalid quoting on windows
     @dec.skip_win32
     def test_getoutput_quoted2(self):
         out = getoutput("%s -c 'print (1)'" % python)
         self.assertEqual(out.strip(), '1')
         out = getoutput("%s -c 'print (\"1\")'" % python)
         self.assertEqual(out.strip(), '1')
 
     def test_getoutput_error(self):
         out, err = getoutputerror('%s "%s"' % (python, self.fname))
         self.assertEqual(out, 'on stdout')
         self.assertEqual(err, 'on stderr')
-    
+
     def test_get_output_error_code(self):
         quiet_exit = '%s -c "import sys; sys.exit(1)"' % python
         out, err, code = get_output_error_code(quiet_exit)
         self.assertEqual(out, '')
         self.assertEqual(err, '')
         self.assertEqual(code, 1)
         out, err, code = get_output_error_code('%s "%s"' % (python, self.fname))
         self.assertEqual(out, 'on stdout')
         self.assertEqual(err, 'on stderr')
         self.assertEqual(code, 0)
+
+