check_frees_param_strict.c

/*
 * Copyright (C) 2014 Oracle.
 *
 * 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
 */

/*
 * This file is sort of like check_dereferences_param.c.  In theory the one
 * difference should be that the param is NULL it should still be counted as a
 * free.  But for now I don't handle that case.
 */

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

static int my_id;

STATE(ignore);

static struct smatch_state *unmatched_state(struct sm_state *sm)
{
	if (parent_is_null_var_sym(sm->name, sm->sym))
		return sm->state;
	return &undefined;
}

static void set_ignore(struct sm_state *sm, struct expression *mod_expr)
{
	if (sm->sym && sm->sym->ident &&
	    strcmp(sm->sym->ident->name, sm->name) == 0)
		return;
	set_state(my_id, sm->name, sm->sym, &ignore);
}

void track_freed_param(struct expression *expr, struct smatch_state *state)
{
	const char *key;
	int param;

	param = get_param_key_from_expr(expr, NULL, &key);
	if (param < 0)
		return;
	if (param_was_set(expr))
		return;

	set_state_expr(my_id, expr, state);
}

void track_freed_param_var_sym(const char *name, struct symbol *sym,
			       struct smatch_state *state)
{
	struct expression *tmp;

	tmp = get_assigned_expr_name_sym(name, sym);
	if (tmp)
		track_freed_param(tmp, state);

	if (get_param_num_from_sym(sym) < 0)
		return;
	/*
	 * FIXME: some unpublished code made this apply to only '$' and I
	 * don't remember why I would do that.  But there was probably
	 * a reason.
	 */
	if (param_was_set_var_sym(name, sym))
		return;

	set_state(my_id, name, sym, state);
}

static int get_freed_type(struct sm_state *sm)
{
	struct sm_state *tmp;

	if (strcmp(sm->state->name, "freed") == 0)
		return PARAM_FREED;

	FOR_EACH_PTR(sm->possible, tmp) {
		if (strcmp(tmp->state->name, "freed") == 0)
			return MAYBE_FREED;
	} END_FOR_EACH_PTR(tmp);

	return 0;
}

static void return_freed_callback(int return_id, char *return_ranges,
				 struct expression *returned_expr,
				 int param,
				 const char *printed_name,
				 struct sm_state *sm)
{
	int type;

	type = get_freed_type(sm);
	if (!type)
		return;

	if (on_atomic_dec_path())
		return;

	sql_insert_return_states(return_id, return_ranges, type,
				 param, printed_name, "");
}

void check_frees_param_strict(int id)
{
	my_id = id;

	add_modification_hook(my_id, &set_ignore);
	add_return_info_callback(my_id, return_freed_callback);
	add_unmatched_state_hook(my_id, &unmatched_state);
}