626d4140a95bae13a88890e5afc3c2392702c2ad
[smatch.git] / check_template.c
blob626d4140a95bae13a88890e5afc3c2392702c2ad
1 /*
2 * Copyright (C) 20XX Your Name.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
19 * First of all, it's best if you lower your expectations from finding
20 * errors to just finding suspicious code. There tends to be a lot
21 * of false positives so having low expectations helps.
23 * For this test let's look for functions that return a negative value
24 * with a semaphore held.
26 * This is just a template check. It's designed for teaching
27 * only and is deliberately less useful than it could be. check_locking.c
28 * is a better real world test.
30 * The biggest short coming is that it assumes a function isn't supposed
31 * to return negative with a lock held. Also it assumes the function was
32 * called without the lock held. It would be better if it handled the stuff
33 * like this:
34 * ret = -ENOMEM;
35 * return ret;
36 * Another idea would be to test other kinds of locks besides just semaphores.
40 #include "smatch.h"
41 #include "smatch_slist.h"
43 static int my_id;
45 STATE(lock);
46 STATE(unlock);
49 * unmatched_state() deals with the case where code is known to be
50 * locked on one path but not known on the other side of a merge. Here
51 * we assume it's the opposite.
54 static struct smatch_state *unmatched_state(struct sm_state *sm)
56 if (sm->state == &lock)
57 return &unlock;
58 if (sm->state == &unlock)
59 return &lock;
60 return &undefined;
63 static void match_call(struct expression *expr)
65 char *fn_name;
66 struct expression *sem_expr;
67 char *sem_name;
69 fn_name = expr_to_var(expr->fn);
70 if (!fn_name || (strcmp(fn_name, "down") && strcmp(fn_name, "up")))
71 goto free_fn;
73 sem_expr = get_argument_from_call_expr(expr->args, 0);
74 sem_name = expr_to_var(sem_expr);
75 if (!strcmp(fn_name, "down")) {
76 set_state(my_id, sem_name, NULL, &lock);
77 } else {
78 set_state(my_id, sem_name, NULL, &unlock);
80 free_string(sem_name);
81 free_fn:
82 free_string(fn_name);
85 static void match_return(struct expression *ret_value)
87 sval_t ret_val;
88 struct stree *stree;
89 struct sm_state *tmp;
91 if (!get_value(ret_value, &ret_val) || sval_cmp_val(ret_val, 0) >= 0)
92 return;
94 stree = __get_cur_stree();
95 FOR_EACH_MY_SM(my_id, stree, tmp) {
96 if (tmp->state != &unlock)
97 sm_msg("warn: returned negative with %s semaphore held",
98 tmp->name);
99 } END_FOR_EACH_SM(tmp);
102 void check_template(int id)
104 my_id = id;
105 add_unmatched_state_hook(my_id, &unmatched_state);
106 add_hook(&match_call, FUNCTION_CALL_HOOK);
107 add_hook(&match_return, RETURN_HOOK);