/*
 * 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"
#include "smatch_slist.h"
#include "smatch_extra.h"

static int my_id;

static void ok_to_use(struct sm_state *sm, struct expression *mod_expr)
{
        set_state(my_id, sm->name, sm->sym, &undefined);
}

static void match_snprintf(const char *fn, struct expression *expr, void *info)
{
        struct expression *call;
        struct expression *arg;
        sval_t buflen;

        call = strip_expr(expr->right);
        arg = get_argument_from_call_expr(call->args, 1);
        if (!get_fuzzy_max(arg, &buflen))
                return;
        set_state_expr(my_id, expr->left, alloc_state_num(buflen.value));
}

static int get_old_buflen(struct sm_state *sm)
{
        struct sm_state *tmp;
        int ret = 0;

        FOR_EACH_PTR(sm->possible, tmp) {
                if (PTR_INT(tmp->state->data) > ret)
                        ret = PTR_INT(tmp->state->data);
        } END_FOR_EACH_PTR(tmp);
        return ret;
}

static void match_call(struct expression *expr)
{
        struct expression *arg;
        struct sm_state *sm;
        int old_buflen;
        sval_t max;

        FOR_EACH_PTR(expr->args, arg) {
                sm = get_sm_state_expr(my_id, arg);
                if (!sm)
                        continue;
                old_buflen = get_old_buflen(sm);
                if (!old_buflen)
                        return;
                if (get_absolute_max(arg, &max) && sval_cmp_val(max, old_buflen) > 0)
                        sm_warning("'%s' returned from snprintf() might be larger than %d",
                                sm->name, old_buflen);
        } END_FOR_EACH_PTR(arg);
}

void check_snprintf(int id)
{
        if (option_project != PROJ_KERNEL)
                return;
        if (!option_spammy)
                return;

        my_id = id;
        set_dynamic_states(my_id);
        add_hook(&match_call, FUNCTION_CALL_HOOK);
        add_function_assign_hook("snprintf", &match_snprintf, NULL);
        add_modification_hook(my_id, &ok_to_use);
}