Add script for source integrity checking
diff --git a/tests/scripts/check-files.py b/tests/scripts/check-files.py
new file mode 100755
index 0000000..f560d03
--- /dev/null
+++ b/tests/scripts/check-files.py
@@ -0,0 +1,223 @@
+#!/usr/bin/env python3
+"""
+This file is part of Mbed TLS (https://tls.mbed.org)
+
+Copyright (c) 2018, Arm Limited, All Rights Reserved
+
+Purpose
+
+This script checks the current state of the source code for minor issues,
+including incorrect file permissions, presence of tabs, non-Unix line endings,
+trailing whitespace, presence of UTF-8 BOM, and TODO comments.
+Note: requires python 3, must be run from Mbed TLS root.
+"""
+
+import os
+import argparse
+import logging
+import codecs
+import sys
+
+
+class IssueTracker(object):
+    """Base class for issue tracking. Issues should inherit from this and
+    overwrite either issue_with_line if they check the file line by line, or
+    overwrite check_file_for_issue if they check the file as a whole."""
+
+    def __init__(self):
+        self.heading = ""
+        self.files_exemptions = []
+        self.files_with_issues = {}
+
+    def should_check_file(self, filepath):
+        for files_exemption in self.files_exemptions:
+            if filepath.endswith(files_exemption):
+                return False
+        return True
+
+    def issue_with_line(self, line):
+        raise NotImplementedError
+
+    def check_file_for_issue(self, filepath):
+        with open(filepath, "rb") as f:
+            for i, line in enumerate(iter(f.readline, b"")):
+                self.check_file_line(filepath, line, i + 1)
+
+    def check_file_line(self, filepath, line, line_number):
+        if self.issue_with_line(line):
+            if filepath not in self.files_with_issues.keys():
+                self.files_with_issues[filepath] = []
+            self.files_with_issues[filepath].append(line_number)
+
+    def output_file_issues(self, logger):
+        if self.files_with_issues.values():
+            logger.info(self.heading)
+            for filename, lines in sorted(self.files_with_issues.items()):
+                if lines:
+                    logger.info("{}: {}".format(
+                        filename, ", ".join(str(x) for x in lines)
+                    ))
+                else:
+                    logger.info(filename)
+            logger.info("")
+
+
+class PermissionIssueTracker(IssueTracker):
+
+    def __init__(self):
+        super().__init__()
+        self.heading = "Incorrect permissions:"
+
+    def check_file_for_issue(self, filepath):
+        if not (os.access(filepath, os.X_OK) ==
+                filepath.endswith((".sh", ".pl", ".py"))):
+            self.files_with_issues[filepath] = None
+
+
+class EndOfFileNewlineIssueTracker(IssueTracker):
+
+    def __init__(self):
+        super().__init__()
+        self.heading = "Missing newline at end of file:"
+
+    def check_file_for_issue(self, filepath):
+        with open(filepath, "rb") as f:
+            if not f.read().endswith(b"\n"):
+                self.files_with_issues[filepath] = None
+
+
+class Utf8BomIssueTracker(IssueTracker):
+
+    def __init__(self):
+        super().__init__()
+        self.heading = "UTF-8 BOM present:"
+
+    def check_file_for_issue(self, filepath):
+        with open(filepath, "rb") as f:
+            if f.read().startswith(codecs.BOM_UTF8):
+                self.files_with_issues[filepath] = None
+
+
+class LineEndingIssueTracker(IssueTracker):
+
+    def __init__(self):
+        super().__init__()
+        self.heading = "Non Unix line endings:"
+
+    def issue_with_line(self, line):
+        return b"\r" in line
+
+
+class TrailingWhitespaceIssueTracker(IssueTracker):
+
+    def __init__(self):
+        super().__init__()
+        self.heading = "Trailing whitespace:"
+        self.files_exemptions = [".md"]
+
+    def issue_with_line(self, line):
+        return line.rstrip(b"\r\n") != line.rstrip()
+
+
+class TabIssueTracker(IssueTracker):
+
+    def __init__(self):
+        super().__init__()
+        self.heading = "Tabs present:"
+        self.files_exemptions = [
+            "Makefile", "generate_visualc_files.pl"
+        ]
+
+    def issue_with_line(self, line):
+        return b"\t" in line
+
+
+class TodoIssueTracker(IssueTracker):
+
+    def __init__(self):
+        super().__init__()
+        self.heading = "TODO present:"
+        self.files_exemptions = [
+            __file__, "benchmark.c", "pull_request_template.md"
+        ]
+
+    def issue_with_line(self, line):
+        return b"todo" in line.lower()
+
+
+class IntegrityChecker(object):
+
+    def __init__(self, log_file):
+        self.check_repo_path()
+        self.logger = None
+        self.setup_logger(log_file)
+        self.files_to_check = (
+            ".c", ".h", ".sh", ".pl", ".py", ".md", ".function", ".data",
+            "Makefile", "CMakeLists.txt", "ChangeLog"
+        )
+        self.issues_to_check = [
+            PermissionIssueTracker(),
+            EndOfFileNewlineIssueTracker(),
+            Utf8BomIssueTracker(),
+            LineEndingIssueTracker(),
+            TrailingWhitespaceIssueTracker(),
+            TabIssueTracker(),
+            TodoIssueTracker(),
+        ]
+
+    def check_repo_path(self):
+        if not all(os.path.isdir(d) for d in ["include", "library", "tests"]):
+            raise Exception("Must be run from Mbed TLS root")
+
+    def setup_logger(self, log_file, level=logging.INFO):
+        self.logger = logging.getLogger()
+        self.logger.setLevel(level)
+        if log_file:
+            handler = logging.FileHandler(log_file)
+            self.logger.addHandler(handler)
+        else:
+            console = logging.StreamHandler()
+            self.logger.addHandler(console)
+
+    def check_files(self):
+        for root, dirs, files in sorted(os.walk(".")):
+            for filename in sorted(files):
+                filepath = os.path.join(root, filename)
+                if (os.path.join("yotta", "module") in filepath or
+                        not filepath.endswith(self.files_to_check)):
+                    continue
+                for issue_to_check in self.issues_to_check:
+                    if issue_to_check.should_check_file(filepath):
+                        issue_to_check.check_file_for_issue(filepath)
+
+    def output_issues(self):
+        integrity_return_code = 0
+        for issue_to_check in self.issues_to_check:
+            if issue_to_check.files_with_issues:
+                integrity_return_code = 1
+            issue_to_check.output_file_issues(self.logger)
+        return integrity_return_code
+
+
+def run_main():
+    parser = argparse.ArgumentParser(
+        description=(
+            "This script checks the current state of the source code for "
+            "minor issues, including incorrect file permissions, "
+            "presence of tabs, non-Unix line endings, trailing whitespace, "
+            "presence of UTF-8 BOM, and TODO comments. "
+            "Note: requires python 3, must be run from Mbed TLS root."
+        )
+    )
+    parser.add_argument(
+        "-l", "--log_file", type=str, help="path to optional output log",
+    )
+    check_args = parser.parse_args()
+    integrity_check = IntegrityChecker(check_args.log_file)
+    integrity_check.check_files()
+    return_code = integrity_check.output_issues()
+    sys.exit(return_code)
+
+
+if __name__ == "__main__":
+    run_main()