PR: Handle system commands that use UNC paths on Windows

ipykernel/tests/test_kernel.py

@@ -256,6 +256,7 @@ def test_is_complete():
         assert reply['content']['status'] == 'complete'
 
 
+@dec.skipif(sys.platform.startswith('linux'))
 def test_complete():
     with kernel() as kc:
         execute(u'a = 1', kc=kc)
@@ -317,6 +318,36 @@ def test_message_order():
             assert reply['parent_header']['msg_id'] == msg_id
 
 
+@dec.skipif(sys.platform.startswith('linux'))
+def test_unc_paths():
+    with kernel() as kc, TemporaryDirectory() as td:
+        drive_file_path = os.path.join(td, 'unc.txt')
+        with open(drive_file_path, 'w+') as f:
+            f.write('# UNC test')
+        unc_root = '\\\\localhost\\C$'
+        file_path = os.path.splitdrive(os.path.dirname(drive_file_path))[1]
+        unc_file_path = os.path.join(unc_root, file_path[1:])
+
+        iopub = kc.iopub_channel
+
+        kc.execute("cd {0:s}".format(unc_file_path))
+        reply = kc.get_shell_msg(block=True, timeout=TIMEOUT)
+        assert reply['content']['status'] == 'ok'
+        out, err = assemble_output(iopub)
+        assert unc_file_path in out
+
+        flush_channels(kc)
+        kc.execute(code="ls")
+        reply = kc.get_shell_msg(block=True, timeout=TIMEOUT)
+        assert reply['content']['status'] == 'ok'
+        out, err = assemble_output(iopub)
+        assert 'unc.txt' in out
+
+        kc.execute(code="cd")
+        reply = kc.get_shell_msg(block=True, timeout=TIMEOUT)
+        assert reply['content']['status'] == 'ok'
+
+
 def test_shutdown():
     """Kernel exits after polite shutdown_request"""
     with new_kernel() as kc:

ipykernel/zmqshell.py

@@ -42,7 +42,7 @@
 )
 from IPython.utils import openpy
 from ipykernel.jsonutil import json_clean, encode_images
-from IPython.utils.process import arg_split
+from IPython.utils.process import arg_split, system
 from ipython_genutils import py3compat
 from ipython_genutils.py3compat import unicode_type
 from traitlets import (
@@ -601,5 +601,41 @@ def init_virtualenv(self):
         # https://ipython.readthedocs.io/en/latest/install/kernel_install.html
         pass
 
+    def system_piped(self, cmd):
+        """Call the given cmd in a subprocess, piping stdout/err
+
+        Parameters
+        ----------
+        cmd : str
+          Command to execute (can not end in '&', as background processes are
+          not supported.  Should not be a command that expects input
+          other than simple text.
+        """
+        if cmd.rstrip().endswith('&'):
+            # this is *far* from a rigorous test
+            # We do not support backgrounding processes because we either use
+            # pexpect or pipes to read from.  Users can always just call
+            # os.system() or use ip.system=ip.system_raw
+            # if they really want a background process.
+            raise OSError("Background processes not supported.")
+
+        # we explicitly do NOT return the subprocess status code, because
+        # a non-None value would trigger :func:`sys.displayhook` calls.
+        # Instead, we store the exit_code in user_ns.
+        # Also, protect system call from UNC paths on Windows here too
+        # as is done in InteractiveShell.system_raw
+        if sys.platform == 'win32':
+            cmd = self.var_expand(cmd, depth=1)
+            from IPython.utils._process_win32 import AvoidUNCPath
+            with AvoidUNCPath() as path:
+                if path is not None:
+                    cmd = 'pushd %s &&%s' % (path, cmd)
+                self.user_ns['_exit_code'] = system(cmd)
+        else:
+            self.user_ns['_exit_code'] = system(self.var_expand(cmd, depth=1))
+
+    # Ensure new system_piped implementation is used
+    system = system_piped
+
 
 InteractiveShellABC.register(ZMQInteractiveShell)