# HG changeset patch
# User Kim Alvefur <zash@zash.se>
# Date 1643316013 -3600
# Node ID 056b7920b686f4c102fcad8a531bf9d77cdc60b4
# Parent  25b853e64d833637e138e364fc55f8fa663001b9
util.format: Expand explanation of purpose in comments

diff -r 25b853e64d83 -r 056b7920b686 util/format.lua
--- a/util/format.lua	Thu Jan 27 21:14:22 2022 +0100
+++ b/util/format.lua	Thu Jan 27 21:40:13 2022 +0100
@@ -1,6 +1,9 @@
 --
--- A string.format wrapper that gracefully handles invalid arguments
+-- A string.format wrapper that gracefully handles invalid arguments since
+-- certain format string and argument combinations may casue errors or other
+-- issues like log spoofing
 --
+-- Provides some protection from e.g. CAPEC-135, CWE-117, CWE-134, CWE-93
 
 local tostring = tostring;
 local unpack = table.unpack or unpack; -- luacheck: ignore 113/unpack
@@ -109,6 +112,8 @@
 			if not valid_utf8(arg) then
 				option = "q";
 			elseif option ~= "q" then -- gets fully escaped in the next block
+				-- Prevent funny things with ASCII control characters and ANSI escape codes (CWE-117)
+				-- Also ensure embedded newlines can't look like another log line (CWE-93)
 				args[i] = arg:gsub("[%z\1-\8\11-\31\127]", control_symbols):gsub("\n\t?", "\n\t");
 				return spec;
 			end