ci/check-directional-formatting.bash

   1 #!/usr/bin/env bash
   2
   3 # This script verifies that the non-binary files tracked in the Git index do
   4 # not contain any Unicode directional formatting: such formatting could be used
   5 # to deceive reviewers into interpreting code differently from the compiler.
   6 # This is intended to run on an Ubuntu agent in a GitHub workflow.
   7 #
   8 # To allow translated messages to introduce such directional formatting in the
   9 # future, we exclude the `.po` files from this validation.
  10 #
  11 # Neither GNU grep nor `git grep` (not even with `-P`) handle `\u` as a way to
  12 # specify UTF-8.
  13 #
  14 # To work around that, we use `printf` to produce the pattern as a byte
  15 # sequence, and then feed that to `git grep` as a byte sequence (setting
  16 # `LC_CTYPE` to make sure that the arguments are interpreted as intended).
  17 #
  18 # Note: we need to use Bash here because its `printf` interprets `\uNNNN` as
  19 # UTF-8 code points, as desired. Running this script through Ubuntu's `dash`,
  20 # for example, would use a `printf` that does not understand that syntax.
  21
  22 # U+202a..U+2a2e: LRE, RLE, PDF, LRO and RLO
  23 # U+2066..U+2069: LRI, RLI, FSI and PDI
  24 regex='(\u202a|\u202b|\u202c|\u202d|\u202e|\u2066|\u2067|\u2068|\u2069)'
  25
  26 ! LC_CTYPE=C git grep -El "$(LC_CTYPE=C.UTF-8 printf "$regex")" \
  27         -- ':(exclude,attr:binary)' ':(exclude)*.po'