Use string startswith() and endswith() methods instead of slicing to check for prefixes and suffixes.

utils/apparmor/aa.py

@@ -2032,7 +2032,7 @@ def parse_profile_data(data, file, do_include, in_preamble):
             aaui.UI_Important(_('Ignoring no longer supported change hat declaration "^%(hat)s," found in file: %(file)s line: %(line)s')
                               % {'hat': matches[0], 'file': file, 'line': lineno + 1})
 
-        elif line[0] == '#':
+        elif line.startswith('#'):
             # Handle initial comments
             if not profile:
                 if line.startswith('# Last Modified:'):

utils/apparmor/aare.py

@@ -89,8 +89,8 @@ class AARE:
 
     def glob_path(self):
         """Glob the given file or directory path"""
-        if self.regex[-1] == '/':
-            if self.regex[-4:] == '/**/' or self.regex[-3:] == '/*/':
+        if self.regex.endswith('/'):
+            if self.regex.endswith(('/**/', '/*/')):
                 # /foo/**/ and /foo/*/ => /**/
                 newpath = re.sub('/[^/]+/\*{1,2}/$', '/**/', self.regex)  # re.sub('/[^/]+/\*{1,2}$/', '/\*\*/', self.regex)
             elif re.search('/[^/]+\*\*[^/]*/$', self.regex):
@@ -102,7 +102,7 @@ class AARE:
             else:
                 newpath = re.sub('/[^/]+/$', '/*/', self.regex)
         else:
-            if self.regex[-3:] == '/**' or self.regex[-2:] == '/*':
+            if self.regex.endswith(('/**', '/*')):
                 # /foo/** and /foo/* => /**
                 newpath = re.sub('/[^/]+/\*{1,2}$', '/**', self.regex)
             elif re.search('/[^/]*\*\*[^/]+$', self.regex):

utils/apparmor/common.py

@@ -182,7 +182,7 @@ def is_skippable_file(path):
 
     basename = os.path.basename(path)
 
-    if not basename or basename[0] == '.' or basename == 'README':
+    if not basename or basename.startswith('.') or basename == 'README':
         return True
 
     skippable_suffix = (
@@ -259,9 +259,9 @@ def convert_regexp(regexp):
     # ?< is the negative lookback operator
     new_reg = new_reg.replace('*', '(((?<=/)[^/\000]+)|((?<!/)[^/\000]*))')
     new_reg = new_reg.replace(multi_glob, '(((?<=/)[^\000]+)|((?<!/)[^\000]*))')
-    if regexp[0] != '^':
+    if not regexp.startswith('^'):
         new_reg = '^' + new_reg
-    if regexp[-1] != '$':
+    if not regexp.endswith('$'):
         new_reg = new_reg + '$'
     return new_reg
 

utils/apparmor/regex.py

@@ -204,7 +204,7 @@ def re_match_include_parse(line, rule_name):
         path = matches.group('quotedpath')
         # LP: 1738880 - parser doesn't handle relative paths everywhere, and
         # neither do we (see aa.py)
-        if rule_name == 'include' and path and path[0] != '/':
+        if rule_name == 'include' and path and not path.startswith('/'):
             raise AppArmorException(_('Syntax error: %s must use quoted path or <...>') % rule_name)
 
     if not path:
@@ -236,14 +236,14 @@ def strip_parenthesis(data):
        The parenthesis must be the first and last char, otherwise they won't be removed.
        Even if no parenthesis get removed, the result will be strip()ped.
     """
-    if data[0] + data[-1] == '()':
+    if data.startswith('(') and data.endswith(')'):
         return data[1:-1].strip()
     else:
         return data.strip()
 
 
 def strip_quotes(data):
-    if len(data) > 1 and data[0] + data[-1] == '""':
+    if len(data) > 1 and data.startswith('"') and data.endswith('"'):
         return data[1:-1]
     else:
         return data

utils/apparmor/rule/file.py

@@ -548,7 +548,7 @@ def split_perms(perm_string, deny):
         if perm_string[0] in file_permissions:
             perms.add(perm_string[0])
             perm_string = perm_string[1:]
-        elif perm_string[0] == 'x':
+        elif perm_string.startswith('x'):
             if not deny:
                 raise AppArmorException(_("'x' must be preceded by an exec qualifier (i, P, C or U)"))
             exec_mode = 'x'

utils/apparmor/severity.py

@@ -97,7 +97,7 @@ class Severity:
         """Returns the rank for the given path"""
         if '@' in path:    # path contains variable
             return self.handle_variable_rank(path, mode)
-        elif path[0] == '/':    # file resource
+        elif path.startswith('/'):    # file resource
             return self.handle_file(path, mode)
         else:
             raise AppArmorException("Unexpected path input: %s" % path)
@@ -175,9 +175,9 @@ class Severity:
             leading = True
         if resource.find(variable + "/") != -1 and resource.find(variable + "//") == -1:
             trailing = True
-        if replacement[0] == '/' and replacement[:2] != '//' and leading:  # finds if the replacement has leading / or not
+        if replacement.startswith('/') and not replacement.startswith('//') and leading:  # finds if the replacement has leading / or not
             replacement = replacement[1:]
-        if replacement[-1] == '/' and replacement[-2:] != '//' and trailing:
+        if replacement.endswith('/') and not replacement.endswith('//') and trailing:
             replacement = replacement[:-1]
         return resource.replace(variable, replacement)