for source in "$articles_dir"/*/article.html; do
	[ -f "$source" ] || continue
	dir=${source%/*}
	slug=${dir##*/}

	[ ! -L "$dir" ] || die "Refusing symlink article directory: $dir"
	[ ! -L "$source" ] || die "Refusing symlink article: $source"
	safe_name "$slug" || die "Unsafe article directory name: $slug"

	article_line=$(sed -n '/<article /{p;q;}' "$source")
	write_attrs "$article_line" "$attrs_file" \
		class data-title id data-created data-modified
	{
		IFS= read -r article_class
		IFS= read -r title
		IFS= read -r article_id
		IFS= read -r created
		IFS= read -r modified
	} < "$attrs_file"

	case " $article_class " in
		*' article '*) ;;
		*) die "$source article element must include class=\"article\"." ;;
	esac
	[ -n "$title" ] || die "Missing article data-title in $source"
	[ -n "$created" ] || created=$build_day
	[ -n "$modified" ] || modified=$created
	safe_date "$created" || die "Article data-created must begin YYYY-MM-DD: $source"
	safe_date "$modified" || die "Article data-modified must begin YYYY-MM-DD: $source"
	[ "$article_id" = "$slug" ] || die "$source must contain id=\"$slug\" on its article element."
	reserve_anchor "$slug" "$source"

	printf '%s\t%s\t%s\t%s\n' \
		"$slug" "$title" "$modified" "$created" >> "$article_meta"
	read_sections "$source" "$slug"
done