replace hard-coded output path with optional argument --gpg-key-output-path

create-gpg-shadow-key-from-x509-cert-req.py

@@ -5,6 +5,7 @@ import cryptography.hazmat.primitives.serialization
 import cryptography.x509
 import math
 
+DEFAULT_KEY_OUTPUT_PATH = 'gpg-key.sexp'
 DEFAULT_SMARTCARD_APP_ID_HEX = 'D2760001240102010001234567890000'
 
 
@@ -22,7 +23,7 @@ def convert_to_sexp(data):
         return b'(' + b''.join(convert_to_sexp(i) for i in data) + b')'
 
 
-def create_gpg_key(input_path, smartcard_app_id_hex):
+def create_gpg_key(input_path, gpg_key_output_path, smartcard_app_id_hex):
     backend = cryptography.hazmat.backends.default_backend()
     with open(input_path, 'rb') as f:
         req = cryptography.x509.load_pem_x509_csr(f.read(), backend)
@@ -35,7 +36,7 @@ def create_gpg_key(input_path, smartcard_app_id_hex):
         ['shadowed', 't1-v1', [int(smartcard_app_id_hex, 16), 'OPENPGP.1']],
     ]]
     key = convert_to_sexp(key_data)
-    with open('gpg-key.sexp', 'wb') as f:
+    with open(gpg_key_output_path, 'wb') as f:
         f.write(key)
 
 
@@ -49,6 +50,12 @@ def _init_argparser():
         'input_path',
         help='path to PEM-encoded X.509 signing request',
     )
+    argparser.add_argument(
+        '--gpg-key-output-path',
+        dest='gpg_key_output_path',
+        default=DEFAULT_KEY_OUTPUT_PATH,
+        help='path to sexp-encoded shadowed-private-key to be created (default: "%(default)s")',
+    )
     argparser.add_argument(
         '--smartcard-app-id',
         dest='smartcard_app_id_hex',