`qmk new-keymap`: validate keymap name (#23420)

lib/python/qmk/cli/new/keymap.py

@@ -1,5 +1,6 @@
 """This script automates the copying of the default keymap into your own keymap.
 """
+import re
 import shutil
 
 from milc import cli
@@ -13,6 +14,13 @@ from qmk.keyboard import keyboard_completer, keyboard_folder
 from qmk.userspace import UserspaceDefs
 
 
+def validate_keymap_name(name):
+    """Returns True if the given keymap name contains only a-z, 0-9 and underscore characters.
+    """
+    regex = re.compile(r'^[a-zA-Z0-9][a-zA-Z0-9_]+$')
+    return bool(regex.match(name))
+
+
 def prompt_keyboard():
     prompt = """{fg_yellow}Select Keyboard{style_reset_all}
 If you`re unsure you can view a full list of supported keyboards with {fg_yellow}qmk list-keyboards{style_reset_all}.
@@ -60,6 +68,10 @@ def new_keymap(cli):
         cli.log.error(f'Default keymap {{fg_cyan}}{keymap_path_default}{{fg_reset}} does not exist!')
         return False
 
+    if not validate_keymap_name(user_name):
+        cli.log.error('Keymap names must contain only {fg_cyan}a-z{fg_reset}, {fg_cyan}0-9{fg_reset} and {fg_cyan}_{fg_reset}! Please choose a different name.')
+        return False
+
     if keymap_path_new.exists():
         cli.log.error(f'Keymap {{fg_cyan}}{user_name}{{fg_reset}} already exists! Please choose a different name.')
         return False