Jail: type-hint execs

in the process i also found a few instances where we were mutating input
parameters — unnecessarily so.

n.b.: libiocage.lib.Foo is the module, libiocage.lib.Foo.Foo is the
actual class that we want

Author: igalic

libiocage/lib/Jail.py

@@ -63,11 +63,11 @@ class Jail:
     """
 
     def __init__(self,
-                 data: Union[str, dict]={},
-                 zfs: Optional[libzfs.ZFS]=None,
-                 host: Optional[libiocage.lib.Host]=None,
-                 logger: Optional[libiocage.lib.Logger]=None,
-                 new=False) -> None:
+                 data:   Union[str, dict]={},
+                 zfs:    Optional[libzfs.ZFS]=None,
+                 host:   Optional[libiocage.lib.Host.Host]=None,
+                 logger: Optional[libiocage.lib.Logger.Logger]=None,
+                 new:    bool=False) -> None:
         """
         Initializes a Jail
 
@@ -82,7 +82,7 @@ def __init__(self,
             host:
                 Inherit an existing Host instance from ancestor classes
 
-            logger (libiocage.lib.Logger): (optional)
+            logger:
                 Inherit an existing Logger instance from ancestor classes
 
         """
@@ -308,35 +308,32 @@ def create(self, release_name: str) -> None:
         self.config.data["release"] = release.name
         self.config.save()
 
-    def exec(self, command, **kwargs):
+    def exec(self, command: List[str], **kwargs):
         """
         Execute a command in a started jail
 
-        command (list):
+        command:
             A list of command and it's arguments
 
             Example: ["/usr/bin/whoami"]
         """
 
-        command = ["/usr/sbin/jexec", self.identifier] + command
+        jexec_command = ["/usr/sbin/jexec", self.identifier] + command
 
         return libiocage.lib.helpers.exec(
-            command, logger=self.logger, **kwargs
+            jexec_command, logger=self.logger, **kwargs
         )
 
-    def passthru(self, command):
+    def passthru(self, command: List[str]):
         """
         Execute a command in a started jail ans passthrough STDIN and STDOUT
 
-        command (list):
+        command:
             A list of command and it's arguments
 
             Example: ["/bin/sh"]
         """
 
-        if isinstance(command, str):
-            command = [command]
-
         return libiocage.lib.helpers.exec_passthru(
             [
                 "/usr/sbin/jexec",

libiocage/lib/helpers.py

@@ -7,6 +7,8 @@
 import libiocage.lib.Host
 import libiocage.lib.Logger
 
+from typing import List
+
 
 def init_zfs(self, zfs):
     if isinstance(zfs, libzfs.ZFS):
@@ -46,11 +48,10 @@ def init_logger(self, logger=None):
         object.__setattr__(self, 'logger', new_logger)
 
 
-def exec(command, logger=None, ignore_error=False):
-    if isinstance(command, str):
-        command = [command]
+def exec(command, logger=None, ignore_error=False) -> (
+        subprocess.Popen, str, str,):
 
-    command_str = " ".join(command)
+    command_str = " ".join(list([command]))
 
     if logger:
         logger.log(f"Executing: {command_str}", level="spam")
@@ -216,21 +217,16 @@ def to_string(data, true="yes", false="no", none="-"):
     return str(data)
 
 
-def exec_passthru(command, logger=None):
-    if isinstance(command, str):
-        command = [command]
-
+def exec_passthru(command: List[str], logger=None):
     command_str = " ".join(command)
+
     if logger:
         logger.spam(f"Executing (interactive): {command_str}")
 
-    return subprocess.Popen(command).communicate()
-
+    return subprocess.Popen(command_str).communicate()
 
-def exec_raw(command, logger=None, **kwargs):
-    if isinstance(command, str):
-        command = [command]
 
+def exec_raw(command: List[str], logger=None, **kwargs):
     command_str = " ".join(command)
     if logger:
         logger.spam(f"Executing (raw): {command_str}")
@@ -241,7 +237,7 @@ def exec_raw(command, logger=None, **kwargs):
     )
 
 
-def exec_iter(command, logger=None):
+def exec_iter(command: List[str], logger=None):
     process = exec_raw(
         command,
         logger=logger,