#!/bin/sh
# Check file names in git commits for GNU Emacs.

# Copyright 2014-2022 Free Software Foundation, Inc.

# This file is part of GNU Emacs.

# GNU Emacs is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# GNU Emacs is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.

LC_ALL=C
export LC_ALL

exec >&2

. git-sh-setup

# When doing a two-way merge, ignore problems that came from the other
# side of the merge.
head=HEAD
if test -r "$GIT_DIR"/MERGE_HEAD && test "$GIT_MERGE_CHECK_OTHER" != true; then
  merge_heads=`cat "$GIT_DIR"/MERGE_HEAD` || exit
  for merge_head in $merge_heads; do
    case $head in
      HEAD) head=$merge_head;;
      # For multi-head merges, there's no easy way to ignore merged-in
      # changes.  But if you're doing multi-head merges, presumably
      # you know how to handle any ensuing problems.
      *) head=HEAD; break;;
    esac
  done
fi

git_diff='git diff --cached --name-only --diff-filter=A'

# 'git diff' will backslash escape tabs and newlines, so we don't have
# to worry about word splitting here.
$git_diff $head |
LC_ALL=C grep -E 'ChangeLog|^-|/-|[^-+./_0-9A-Z_a-z]' |
while IFS= read -r new_name; do
  case $new_name in
    -* | */-*)
      echo "$new_name: File name component begins with '-'."
      exit 1;;
    ChangeLog | */ChangeLog)
      echo "$new_name: Please use git commit messages, not ChangeLog files."
      exit 1;;
    *)
      echo "$new_name: File name does not consist of -+./_ or ASCII letters or digits."
      exit 1;;
  esac
done

# The '--check' option of git diff-index makes Git complain if changes
# introduce whitespace errors.  This can be a pain when editing test
# files that deliberately contain lines with trailing whitespace.
# To work around the problem you can run a command like 'git config
# core.whitespace -trailing-space'.  It may be better to revamp the
# tests so that trailing spaces are generated on the fly rather than
# being committed as source.

exec git diff-index --check --cached $head --