diff -r c0d064521ee0 -r 4e03b0e2a29f tools/linelength.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tools/linelength.py	Tue Jul 27 09:56:06 2021 +0300
@@ -0,0 +1,20 @@
+#!/usr/bin/env python3
+import sys
+def check(filename):
+	with open(filename) as file:
+		for linenumber, line in enumerate(file, 1):
+			if line[-1] == '\n':
+				line = line[:-1]
+			line = str.replace(line, '\t', ' ' * 4)
+			if len(line) > 120:
+				print(str.format(
+					'{filename}:{linenumber}: warning: line length exceeds 120 characters',
+					filename = filename,
+					linenumber = linenumber
+				), file = sys.stderr)
+def main():
+	for filename in sys.argv[1:]:
+		check(filename)
+	return 0
+if __name__ == '__main__':
+	sys.exit(main())