Porting edencli config.py

Summary: Fixed the code that was complaining while running "eden clone". There is still more work to get everything working, like we need to implement the config file locking (replacement for flock on Windows).

Reviewed By: chadaustin

Differential Revision: D15996454

fbshipit-source-id: 6ba51eb04b6ca1fddbd2016a88b86c7aca7acf0b

eden/cli/config.py

@@ -9,7 +9,6 @@ import binascii
 import collections
 import datetime
 import errno
-import fcntl
 import json
 import os
 import shutil
@@ -28,6 +27,12 @@ from . import configinterpolator, configutil, util
 from .util import EdenStartError, HealthStatus, print_stderr, readlink_retry_estale
 
 
+# On Linux we import fcntl for flock. The Windows LockFileEx is not semantically
+# same as flock. We will need to make some changes for LockFileEx to work.
+if os.name != "nt":
+    import fcntl
+
+
 if typing.TYPE_CHECKING:
     from eden.cli.redirect import RedirectionType  # noqa: F401
 
@@ -181,12 +186,20 @@ class EdenInstance:
 
     @property
     def _config_variables(self) -> Dict[str, str]:
+        if os.name == "nt":
+            # We don't have user ids on Windows right now.
+            # We should update this code if and when we add user id support.
+            user_id = 0
+            user_name = "USERNAME"
+        else:
+            user_id = os.getuid()
+            user_name = "USER"
         return (
             self._interpolate_dict
             if self._interpolate_dict is not None
             else {
-                "USER": os.environ.get("USER", ""),
-                "USER_ID": str(os.getuid()),
+                "USER": os.environ.get(user_name, ""),
+                "USER_ID": str(user_id),
                 "HOME": str(self._home_dir),
             }
         )
@@ -449,7 +462,8 @@ Do you want to run `eden mount %s` instead?"""
         if help_contents is not None:
             with help_path.open("w") as f:
                 f.write(help_contents)
-                os.fchmod(f.fileno(), 0o444)
+                if os.name != "nt":
+                    os.fchmod(f.fileno(), 0o444)
 
     def _create_client_dir_for_path(self, clients_dir: Path, path: str) -> Path:
         """Tries to create a new subdirectory of clients_dir based on the
@@ -850,6 +864,14 @@ class ConfigUpdater(object):
         self.config[key] = value
 
     def _acquire_lock(self) -> None:
+        # Skipping locks on Windows for two reasons:
+        # First, locking the config file is not a strict requirement even on
+        # POSIX. Plus we don't have a similar flock implementation on Windows.
+        # We could make a locking scheme with LockFileEx(), but it would
+        # have different symentics than flock (For one, we can't unlink a
+        # locked file).
+        if os.name == "nt":
+            return
         while True:
             self._lock_file = typing.cast(typing.TextIO, open(self._lock_path, "w+"))
             fcntl.flock(self._lock_file.fileno(), fcntl.LOCK_EX)
@@ -869,6 +891,8 @@ class ConfigUpdater(object):
             continue
 
     def _unlock(self) -> None:
+        if os.name == "nt":
+            return
         assert self._lock_file is not None
         # Remove the file on disk before we unlock it.
         # This way processes currently waiting in _acquire_lock() that already