/*
 * Copyright (C) 2023 Dan Carpenter.
 *
 * This program 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 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 this program; if not, see http://www.gnu.org/copyleft/gpl.txt
 */

#include "smatch.h"
#include "smatch_slist.h"
#include "smatch_extra.h"

static int my_id;

static struct expression *get_len_expr(struct expression *expr)
{
	struct expression *deref;

	if (expr->type != EXPR_DEREF)
		return NULL;
	deref = strip_expr(expr->deref);

	if (local_debug)
		sm_msg("%s: expr='%s' op='%c'", __func__, expr_to_str(expr), expr->op);

	return gen_expression_from_key(deref, (expr->op == '.') ? "$.len" : "$->len");
}

static void array_check(struct expression *expr)
{
	struct expression *array_expr, *offset, *len;
	char *member, *name;
	int comparison;

	expr = strip_expr(expr);
	array_expr = get_array_base(expr);
	offset = get_array_offset(expr);
	if (!array_expr || !offset)
		return;

	member = get_member_name(array_expr);
	if (!member || strcmp(member, "(struct i2c_msg)->buf") != 0)
		goto free;
	len = get_len_expr(array_expr);
	if (!len)
		goto free;

	comparison = get_comparison(offset, len);
	if (comparison == '<')
		goto free;

	name = expr_to_str(len);
	sm_warning("i2c_msg ->buf not checked '%s'", name);
	free_string(name);

free:
	free_string(member);
}

void check_i2c_msg_buf(int id)
{
	my_id = id;

	if (option_project != PROJ_KERNEL)
		return;

	add_hook(&array_check, OP_HOOK);
}