lib.FileContext: Add file methods

Add the following methods, meant to do the obvious:

  unlink(self, path: str) -> None
  erase(self, path: str) -> None
  rename(self, src: str, dst: str) -> None
  mktemp(self, tmpl: str, directory: bool=False) -> None
  chown(self, path: str, owner: str|None=None, group: str|None=None) -> None
  chmod(self, path: str, mode: int) -> None
  stat(self, path: str, follow_symlinks: bool=True) -> StatResult
  file_exists(self, path: str) -> bool
  is_dir(self, path: str) -> bool

All methods are async and call their protected counterpart, which is
designed to be overridden. If possible, default implementations do
something meaningful, if not, they just raise plain
NotImplementedError.

Signed-off-by: Jan Lindemann <jan@janware.com>

src/python/jw/pkg/lib/ec/Local.py

@@ -1,9 +1,9 @@
 # -*- coding: utf-8 -*-
 
-import os, sys, subprocess, asyncio
+import os, sys, subprocess, asyncio, pwd, grp, stat
 
 from ..ExecContext import ExecContext as Base
-from ..base import Result
+from ..base import Result, StatResult
 
 from ..log import *
 from ..util import pretty_cmd
@@ -151,3 +151,32 @@ class Local(Base):
             cmdline.extend(opts)
         cmdline.extend(cmd)
         return await self._run(cmdline, *args, **kwargs)
+
+    async def _unlink(self, path: str) -> None:
+        os.unlink(path)
+
+    async def _erase(self, path: str) -> None:
+        if os.isdir(path):
+            shutil.rmtree(path)
+            return
+        os.unlink(path)
+
+    async def _rename(self, src: str, dst: str) -> None:
+        os.rename(src, dst)
+
+    async def _stat(self, path: str, follow_symlinks: bool) -> StatResult:
+        return StatResult.from_os(os.stat(path, follow_symlinks=follow_symlinks))
+
+    async def _file_exists(self, path: str) -> bool:
+        return os.path.exists(path)
+
+    async def _chown(self, path: str, owner: str|None, group: str|None) -> None:
+        uid = pwd.getpwnam(owner).pw_uid if owner else -1
+        gid = grp.getgrnam(group).gr_gid if group else -1
+        os.chown(path, uid, gid)
+
+    async def _chmod(self, path: str, mode: int) -> None:
+        os.chmod(path, mode)
+
+    async def _is_dir(self, path: str) -> bool:
+        return os.path.isdir(path)