/*
 * Copyright (C) 2010 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"

static void match_snprintf(const char *fn, struct expression *expr, void *unused)
{
        struct expression *dest;
        struct expression *dest_size_expr;
        struct expression *format_string;
        struct expression *data;
        char *data_name = NULL;
        int dest_size;
        sval_t limit_size;
        char *format;
        int data_size;

        dest = get_argument_from_call_expr(expr->args, 0);
        dest_size_expr = get_argument_from_call_expr(expr->args, 1);
        format_string = get_argument_from_call_expr(expr->args, 2);
        data = get_argument_from_call_expr(expr->args, 3);

        dest_size = get_array_size_bytes(dest);
        if (!get_implied_value(dest_size_expr, &limit_size))
                return;
        if (dest_size > 1 && dest_size < limit_size.value)
                sm_error("snprintf() is printing too much %s vs %d",
                         sval_to_str(limit_size), dest_size);
        format = expr_to_var(format_string);
        if (!format)
                return;
        if (strcmp(format, "\"%s\""))
                goto free;
        data_name = expr_to_str(data);
        data_size = get_size_from_strlen(data);
        if (!data_size)
                data_size = get_array_size_bytes(data);
        if (limit_size.value < data_size)
                sm_error("snprintf() chops off the last chars of '%s': %d vs %s",
                       data_name, data_size, sval_to_str(limit_size));
free:
        free_string(data_name);
        free_string(format);
}

void check_snprintf_overflow(int id)
{
        add_function_hook("snprintf", &match_snprintf, NULL);
}