octal-values: Prevent detection of 8 and 9 as octal values

tests/rules/test_octal_values.py

@@ -50,6 +50,8 @@ class OctalValuesTestCase(RuleTestCase):
                    '  - 0.10\n'
                    '  - .01\n'
                    '  - 0e3\n', conf)
+        self.check('with-decimal-digits: 012345678', conf)
+        self.check('with-decimal-digits: 012345679', conf)
 
     def test_explicit_octal_values(self):
         conf = ('octal-values:\n'
@@ -74,3 +76,5 @@ class OctalValuesTestCase(RuleTestCase):
                    '  - .01\n'
                    '  - 0e3\n', conf)
         self.check('user-city: "010"', conf)
+        self.check('with-decimal-digits: 0o012345678', conf)
+        self.check('with-decimal-digits: 0o012345679', conf)

yamllint/rules/octal_values.py

@@ -71,6 +71,8 @@ converted to ``8``.
       city-code: 0o10
 """
 
+import re
+
 import yaml
 
 from yamllint.linter import LintProblem
@@ -84,6 +86,10 @@ DEFAULT = {'forbid-implicit-octal': True,
            'forbid-explicit-octal': True}
 
 
+def _is_octal_number(string):
+    return re.match(r'^[0-7]+$', string) is not None
+
+
 def check(conf, token, prev, next, nextnext, context):
     if prev and isinstance(prev, yaml.tokens.TagToken):
         return
@@ -92,7 +98,8 @@ def check(conf, token, prev, next, nextnext, context):
         if isinstance(token, yaml.tokens.ScalarToken):
             if not token.style:
                 val = token.value
-                if val.isdigit() and len(val) > 1 and val[0] == '0':
+                if (val.isdigit() and len(val) > 1 and val[0] == '0' and
+                        _is_octal_number(val[1:])):
                     yield LintProblem(
                         token.start_mark.line + 1, token.end_mark.column + 1,
                         'forbidden implicit octal value "%s"' %
@@ -102,7 +109,8 @@ def check(conf, token, prev, next, nextnext, context):
         if isinstance(token, yaml.tokens.ScalarToken):
             if not token.style:
                 val = token.value
-                if len(val) > 2 and val[:2] == '0o' and val[2:].isdigit():
+                if (len(val) > 2 and val[:2] == '0o' and
+                        _is_octal_number(val[2:])):
                     yield LintProblem(
                         token.start_mark.line + 1, token.end_mark.column + 1,
                         'forbidden explicit octal value "%s"' %