Dont set the EDITOR env var in child processes

It isnt really needed, since the various kittens dont rely on it
anymore, instead calling get_editor() to get the path to the editor.
Has the nice side-effect of not needing to run the shell at startup
to read its environment. Now the shell is only run if the user calls
the edit config file kitten. Fixes #3426

kitty/boss.py

@@ -866,7 +866,7 @@ class Boss:
         confpath = prepare_config_file_for_editing()
         # On macOS vim fails to handle SIGWINCH if it occurs early, so add a
         # small delay.
-        cmd = [kitty_exe(), '+runpy', 'import os, sys, time; time.sleep(0.05); os.execvp(sys.argv[1], sys.argv[1:])'] + get_editor() + [confpath]
+        cmd = [kitty_exe(), '+runpy', 'import os, sys, time; time.sleep(0.05); os.execvp(sys.argv[1], sys.argv[1:])'] + get_editor(self.opts) + [confpath]
         self.new_os_window(*cmd)
 
     def get_output(self, source_window: Window, num_lines: Optional[int] = 1) -> str:

kitty/cli.py

@@ -852,3 +852,10 @@ def create_opts(args: CLIOptions, debug_config: bool = False, accumulate_bad_lin
             print('Running under:', green('Wayland' if is_wayland(opts) else 'X11'))
         compare_opts(opts)
     return opts
+
+
+def create_default_opts() -> OptionsStub:
+    from .config import load_config
+    config = tuple(resolve_config(SYSTEM_CONF, defconf, ()))
+    opts = load_config(*config)
+    return opts

kitty/main.py

@@ -7,7 +7,7 @@ import os
 import shutil
 import sys
 from contextlib import contextmanager, suppress
-from typing import Dict, Generator, List, Mapping, Optional, Sequence
+from typing import Dict, Generator, List, Optional, Sequence
 
 from .borders import load_borders_program
 from .boss import Boss
@@ -32,8 +32,8 @@ from .os_window_size import initial_window_size_func
 from .session import get_os_window_sizing_data
 from .types import SingleKey
 from .utils import (
-    detach, expandvars, find_exe, log_error, read_shell_environment,
-    single_instance, startup_notification_handler, unix_socket_paths
+    detach, expandvars, log_error, single_instance,
+    startup_notification_handler, unix_socket_paths
 )
 from .window import load_shader_programs
 
@@ -225,39 +225,6 @@ def macos_cmdline(argv_args: List[str]) -> List[str]:
     return ans
 
 
-def resolve_editor_cmd(editor: str, shell_env: Mapping[str, str]) -> Optional[str]:
-    import shlex
-    editor_cmd = shlex.split(editor)
-    editor_exe = (editor_cmd or ('',))[0]
-    if editor_exe and os.path.isabs(editor_exe):
-        return editor
-    if not editor_exe:
-        return None
-
-    def patched(exe: str) -> str:
-        editor_cmd[0] = exe
-        return ' '.join(map(shlex.quote, editor_cmd))
-
-    if shell_env is os.environ:
-        q = find_exe(editor_exe)
-        if q:
-            return patched(q)
-    elif 'PATH' in shell_env:
-        import shlex
-        q = shutil.which(editor_exe, path=shell_env['PATH'])
-        if q:
-            return patched(q)
-
-
-def get_editor_from_env(shell_env: Mapping[str, str]) -> Optional[str]:
-    for var in ('VISUAL', 'EDITOR'):
-        editor = shell_env.get(var)
-        if editor:
-            editor = resolve_editor_cmd(editor, shell_env)
-            if editor:
-                return editor
-
-
 def expand_listen_on(listen_on: str, from_config_file: bool) -> str:
     listen_on = expandvars(listen_on)
     if '{kitty_pid}' not in listen_on and from_config_file:
@@ -275,15 +242,6 @@ def expand_listen_on(listen_on: str, from_config_file: bool) -> str:
 
 
 def setup_environment(opts: OptionsStub, cli_opts: CLIOptions) -> None:
-    if opts.editor == '.':
-        editor = get_editor_from_env(os.environ)
-        if not editor:
-            shell_env = read_shell_environment(opts)
-            editor = get_editor_from_env(shell_env)
-        if editor:
-            os.environ['EDITOR'] = editor
-    else:
-        os.environ['EDITOR'] = opts.editor
     from_config_file = False
     if not cli_opts.listen_on and opts.listen_on.startswith('unix:'):
         cli_opts.listen_on = opts.listen_on

kitty/utils.py

@@ -462,12 +462,49 @@ def natsort_ints(iterable: Iterable[str]) -> List[str]:
     return sorted(iterable, key=alphanum_key)
 
 
-@run_once
-def get_editor() -> List[str]:
+def resolve_editor_cmd(editor: str, shell_env: Mapping[str, str]) -> Optional[str]:
+    import shlex
+    editor_cmd = shlex.split(editor)
+    editor_exe = (editor_cmd or ('',))[0]
+    if editor_exe and os.path.isabs(editor_exe):
+        return editor
+    if not editor_exe:
+        return None
+
+    def patched(exe: str) -> str:
+        editor_cmd[0] = exe
+        return ' '.join(map(shlex.quote, editor_cmd))
+
+    if shell_env is os.environ:
+        q = find_exe(editor_exe)
+        if q:
+            return patched(q)
+    elif 'PATH' in shell_env:
+        import shutil
+        q = shutil.which(editor_exe, path=shell_env['PATH'])
+        if q:
+            return patched(q)
+
+
+def get_editor_from_env(env: Mapping[str, str]) -> Optional[str]:
+    for var in ('VISUAL', 'EDITOR'):
+        editor = env.get(var)
+        if editor:
+            editor = resolve_editor_cmd(editor, env)
+            if editor:
+                return editor
+
+
+def get_editor_from_env_vars(opts: Optional[Options] = None) -> List[str]:
     import shlex
     import shutil
-    for ans in (os.environ.get('VISUAL'), os.environ.get('EDITOR'), 'vim',
-                'nvim', 'vi', 'emacs', 'kak', 'micro', 'nano', 'vis'):
+
+    editor = get_editor_from_env(os.environ)
+    if not editor:
+        shell_env = read_shell_environment(opts)
+        editor = get_editor_from_env(shell_env)
+
+    for ans in (editor, 'vim', 'nvim', 'vi', 'emacs', 'kak', 'micro', 'nano', 'vis'):
         if ans and shutil.which(shlex.split(ans)[0]):
             break
     else:
@@ -475,6 +512,16 @@ def get_editor() -> List[str]:
     return shlex.split(ans)
 
 
+def get_editor(opts: Optional[Options] = None) -> List[str]:
+    if opts is None:
+        from .cli import create_default_opts
+        opts = create_default_opts()
+    if opts.editor == '.':
+        return get_editor_from_env_vars()
+    import shlex
+    return shlex.split(opts.editor)
+
+
 def is_path_in_temp_dir(path: str) -> bool:
     if not path:
         return False