More robust handling of excluded files

Don't try to enumerate excluded files. List included files, and remove names
from the list if they match an excluded-file pattern.

This resolves the problem that the script could get into an infinite loop
due to the use of recursive globbing. Unfortunately, Python's recursive
globs follows symbolic links to directories, which leads to an infinite loop
if a symbolic link points to an ancestor of the directory that contains it.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

tests/scripts/check_names.py

@@ -44,6 +44,7 @@ error. It must be run from Mbed TLS root.
 
 import abc
 import argparse
+import fnmatch
 import glob
 import textwrap
 import os
@@ -222,8 +223,9 @@ class CodeParser():
         # Memo for storing "glob expression": set(filepaths)
         self.files = {}
 
-        # Globally excluded filenames
-        self.excluded_files = ["**/bn_mul", "**/compat-2.x.h"]
+        # Globally excluded filenames.
+        # Note that "*" can match directory separators in exclude lists.
+        self.excluded_files = ["*/bn_mul", "*/compat-2.x.h"]
 
     @staticmethod
     def check_repo_path():
@@ -302,6 +304,15 @@ class CodeParser():
             "mbed_words": mbed_words
         }
 
+    def is_file_excluded(self, path, exclude_wildcards):
+        """Whether the give file path is excluded."""
+        # exclude_wildcards may be None. Also, consider the global exclusions.
+        exclude_wildcards = (exclude_wildcards or []) + self.excluded_files
+        for pattern in exclude_wildcards:
+            if fnmatch.fnmatch(path, pattern):
+                return True
+        return False
+
     def get_files(self, include_wildcards, exclude_wildcards):
         """
         Get all files that match any of the UNIX-style wildcards. While the
@@ -317,25 +328,11 @@ class CodeParser():
         """
         accumulator = set()
 
-        # exclude_wildcards may be None. Also, consider the global exclusions.
-        exclude_wildcards = (exclude_wildcards or []) + self.excluded_files
-
-        # Internal function to hit the memoisation cache or add to it the result
-        # of a glob operation. Used both for inclusion and exclusion since the
-        # only difference between them is whether they perform set union or
-        # difference on the return value of this function.
-        def hit_cache(wildcard):
-            if wildcard not in self.files:
-                self.files[wildcard] = set(glob.glob(wildcard, recursive=True))
-            return self.files[wildcard]
-
         for include_wildcard in include_wildcards:
-            accumulator = accumulator.union(hit_cache(include_wildcard))
+            accumulator = accumulator.union(glob.iglob(include_wildcard))
 
-        for exclude_wildcard in exclude_wildcards:
-            accumulator = accumulator.difference(hit_cache(exclude_wildcard))
-
-        return list(accumulator)
+        return list(path for path in accumulator
+                    if not self.is_file_excluded(path, exclude_wildcards))
 
     def parse_macros(self, include, exclude=None):
         """