Add option -m/--max

README.rst

@@ -71,6 +71,8 @@ Once installed, use ``--help`` to list all available options::
     --no-caps             Turn off capitalization.
     -s NUM, --specials NUM
                           Insert NUM special chars into generated word.
+    -m NUM, --max NUM
+                          Truncate to NUM length.
     -d DELIMITER, --delimiter DELIMITER
                           Separate words by DELIMITER. Empty string by default.
     -r SOURCE, --randomsource SOURCE

diceware/__init__.py

@@ -104,6 +104,9 @@ def handle_options(args):
     parser.add_argument(
         '-s', '--specials', default=0, type=int, metavar='NUM',
         help="Insert NUM special chars into generated word.")
+    parser.add_argument(
+        '-m', '--max', default=0, type=int, metavar='NUM',
+        help="Truncate to NUM length.")        
     parser.add_argument(
         '-d', '--delimiter', default='',
         help="Separate words by DELIMITER. Empty string by default.")
@@ -193,6 +196,8 @@ def get_passphrase(options=None):
     result = options.delimiter.join(words)
     for _ in range(options.specials):
         result = insert_special_char(result, rnd=rnd)
+    if options.max > 0:
+        result = result[:options.max]
     return result
 
 

diceware/config.py

@@ -30,6 +30,7 @@
     num=6,
     caps=True,
     specials=0,
+    max=0,
     delimiter="",
     randomsource="system",
     verbose=0,

tests/sample_dot_diceware.ini

@@ -3,6 +3,7 @@ num = 6
 caps = on
 specials = 0
 delimiter = ""
+max = 0
 randomsource = "system"
 verbose = 0
 wordlist = "en_securedrop"

tests/test_diceware.py

@@ -45,6 +45,7 @@ def test_handle_options_defaults(self):
         assert options.randomsource == "system"
         assert options.wordlist == "en_eff"
         assert options.verbose == 0
+        assert options.max == 0
 
     def test_handle_options_infile(self, tmpdir):
         # we can give an infile
@@ -69,6 +70,14 @@ def test_handle_options_caps(self):
         assert options.caps is True
         options = handle_options(['--no-caps', ])
         assert options.caps is False
+
+    def test_handle_options_max(self):
+        options = handle_options([])
+        assert options.max == 0 
+        options = handle_options(['-m', '0'])
+        assert options.max == 0 
+        options = handle_options(['--max', '0'])
+        assert options.max == 0
 
     def test_handle_options_caps_conflicting_raises_exc(self):
         # conflicting caps-settings raise an exception
@@ -243,6 +252,12 @@ def test_get_passphrase_delimiters(self):
         options.delimiter = " "
         phrase = get_passphrase(options)
         assert " " in phrase
+
+    def test_get_passphrase_max(self):
+        options = handle_options(args=[])
+        options.max = 15
+        phrase = get_passphrase(options)
+        assert len(phrase) == 15
 
     def test_print_version(self, capsys):
         # we can print version infos
@@ -362,4 +377,4 @@ def test_main_wordlist(self, argv_handler, capsys, wordlists_dir):
         sys.argv = ['diceware', '-w', 'foo']
         main()
         out, err = capsys.readouterr()
-        assert out == 'FooFooFooFooFooFoo\n'
+        assert out == 'FooFooFooFooFooFoo\n'