1 /*
2 * Copyright (C) 2016 Oracle.
3 *
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.
8 *
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.
13 *
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
16 */
17
18 /*
19 * The point here is to store the relationships between two variables.
20 * Ie: y > x.
21 * To do that we create a state with the two variables in alphabetical order:
22 * ->name = "x vs y" and the state would be "<". On the false path the state
23 * would be ">=".
24 *
25 * Part of the trick of it is that if x or y is modified then we need to reset
26 * the state. We need to keep a list of all the states which depend on x and
27 * all the states which depend on y. The link_id code handles this.
28 *
29 */
30
31 #include "smatch.h"
32 #include "smatch_extra.h"
33 #include "smatch_slist.h"
34
35 static int compare_id;
36 static int link_id;
37
alloc_link_state(struct string_list * links)38 static struct smatch_state *alloc_link_state(struct string_list *links)
39 {
40 struct smatch_state *state;
41 static char buf[256];
42 char *tmp;
43 int i;
44
45 state = __alloc_smatch_state(0);
46
47 i = 0;
48 FOR_EACH_PTR(links, tmp) {
49 if (!i++) {
50 snprintf(buf, sizeof(buf), "%s", tmp);
51 } else {
52 append(buf, ", ", sizeof(buf));
53 append(buf, tmp, sizeof(buf));
54 }
55 } END_FOR_EACH_PTR(tmp);
56
57 state->name = alloc_sname(buf);
58 state->data = links;
59 return state;
60 }
61
merge_links(struct smatch_state * s1,struct smatch_state * s2)62 static struct smatch_state *merge_links(struct smatch_state *s1, struct smatch_state *s2)
63 {
64 struct smatch_state *ret;
65 struct string_list *links;
66
67 links = combine_string_lists(s1->data, s2->data);
68 ret = alloc_link_state(links);
69 return ret;
70 }
71
save_link_var_sym(const char * var,struct symbol * sym,const char * link)72 static void save_link_var_sym(const char *var, struct symbol *sym, const char *link)
73 {
74 struct smatch_state *old_state, *new_state;
75 struct string_list *links;
76 char *new;
77
78 old_state = get_state(link_id, var, sym);
79 if (old_state)
80 links = clone_str_list(old_state->data);
81 else
82 links = NULL;
83
84 new = alloc_sname(link);
85 insert_string(&links, new);
86
87 new_state = alloc_link_state(links);
88 set_state(link_id, var, sym, new_state);
89 }
90
add_comparison_var_sym(const char * left_name,struct var_sym_list * left_vsl,int comparison,const char * right_name,struct var_sym_list * right_vsl)91 static void add_comparison_var_sym(const char *left_name,
92 struct var_sym_list *left_vsl,
93 int comparison,
94 const char *right_name, struct var_sym_list *right_vsl)
95 {
96 struct smatch_state *state;
97 struct var_sym *vs;
98 char state_name[256];
99
100 if (strcmp(left_name, right_name) > 0) {
101 const char *tmp_name = left_name;
102 struct var_sym_list *tmp_vsl = left_vsl;
103
104 left_name = right_name;
105 left_vsl = right_vsl;
106 right_name = tmp_name;
107 right_vsl = tmp_vsl;
108 comparison = flip_comparison(comparison);
109 }
110 snprintf(state_name, sizeof(state_name), "%s vs %s", left_name, right_name);
111 state = alloc_compare_state(NULL, left_name, left_vsl, comparison, NULL, right_name, right_vsl);
112
113 set_state(compare_id, state_name, NULL, state);
114
115 FOR_EACH_PTR(left_vsl, vs) {
116 save_link_var_sym(vs->var, vs->sym, state_name);
117 } END_FOR_EACH_PTR(vs);
118 FOR_EACH_PTR(right_vsl, vs) {
119 save_link_var_sym(vs->var, vs->sym, state_name);
120 } END_FOR_EACH_PTR(vs);
121 }
122
123 /*
124 * This is quite a bit more limitted, less ambitious, simpler compared to
125 * smatch_camparison.c.
126 */
__compare_param_limit_hook(struct expression * left_expr,struct expression * right_expr,const char * state_name,struct smatch_state * true_state,struct smatch_state * false_state)127 void __compare_param_limit_hook(struct expression *left_expr, struct expression *right_expr,
128 const char *state_name,
129 struct smatch_state *true_state, struct smatch_state *false_state)
130 {
131 char *left_name = NULL;
132 char *right_name = NULL;
133 char *tmp_name = NULL;
134 struct symbol *left_sym, *right_sym, *tmp_sym;
135
136 left_name = expr_to_var_sym(left_expr, &left_sym);
137 if (!left_name || !left_sym)
138 goto free;
139 right_name = expr_to_var_sym(right_expr, &right_sym);
140 if (!right_name || !right_sym)
141 goto free;
142
143 if (get_param_num_from_sym(left_sym) < 0 ||
144 get_param_num_from_sym(right_sym) < 0)
145 return;
146
147 tmp_name = get_other_name_sym(left_name, left_sym, &tmp_sym);
148 if (tmp_name) {
149 free_string(left_name);
150 left_name = tmp_name;
151 left_sym = tmp_sym;
152 }
153
154 tmp_name = get_other_name_sym(right_name, right_sym, &tmp_sym);
155 if (tmp_name) {
156 free_string(right_name);
157 right_name = tmp_name;
158 right_sym = tmp_sym;
159 }
160
161 if (param_was_set_var_sym(left_name, left_sym))
162 return;
163 if (param_was_set_var_sym(right_name, right_sym))
164 return;
165
166 set_true_false_states(compare_id, state_name, NULL, true_state, false_state);
167 save_link_var_sym(left_name, left_sym, state_name);
168 save_link_var_sym(right_name, right_sym, state_name);
169 free:
170 free_string(left_name);
171 free_string(right_name);
172 }
173
print_return_comparison(int return_id,char * return_ranges,struct expression * expr)174 static void print_return_comparison(int return_id, char *return_ranges, struct expression *expr)
175 {
176 struct sm_state *tmp;
177 struct string_list *links;
178 char *link;
179 struct sm_state *sm;
180 struct compare_data *data;
181 struct var_sym *left, *right;
182 int left_param, right_param;
183 static char left_buf[248];
184 static char right_buf[248];
185 static char info_buf[256];
186 const char *tmp_name;
187
188 FOR_EACH_MY_SM(link_id, __get_cur_stree(), tmp) {
189 links = tmp->state->data;
190 FOR_EACH_PTR(links, link) {
191 sm = get_sm_state(compare_id, link, NULL);
192 if (!sm)
193 continue;
194 data = sm->state->data;
195 if (!data || !data->comparison)
196 continue;
197 if (ptr_list_size((struct ptr_list *)data->left_vsl) != 1 ||
198 ptr_list_size((struct ptr_list *)data->right_vsl) != 1)
199 continue;
200 left = first_ptr_list((struct ptr_list *)data->left_vsl);
201 right = first_ptr_list((struct ptr_list *)data->right_vsl);
202 if (left->sym == right->sym &&
203 strcmp(left->var, right->var) == 0)
204 continue;
205 /*
206 * Both parameters link to this comparison so only
207 * record the first one.
208 */
209 if (left->sym != tmp->sym ||
210 strcmp(left->var, tmp->name) != 0)
211 continue;
212
213 left_param = get_param_num_from_sym(left->sym);
214 right_param = get_param_num_from_sym(right->sym);
215 if (left_param < 0 || right_param < 0) /* can't happen hopefully */
216 continue;
217
218 tmp_name = get_param_name_var_sym(left->var, left->sym);
219 if (!tmp_name)
220 continue;
221 snprintf(left_buf, sizeof(left_buf), "%s", tmp_name);
222
223 tmp_name = get_param_name_var_sym(right->var, right->sym);
224 if (!tmp_name || tmp_name[0] != '$')
225 continue;
226 snprintf(right_buf, sizeof(right_buf), "$%d%s", right_param, tmp_name + 1);
227
228 snprintf(info_buf, sizeof(info_buf), "%s %s", show_special(data->comparison), right_buf);
229 sql_insert_return_states(return_id, return_ranges,
230 COMPARE_LIMIT, left_param, left_buf, info_buf);
231 } END_FOR_EACH_PTR(link);
232
233 } END_FOR_EACH_SM(tmp);
234 }
235
parse_comparison(char ** value,int * op)236 static int parse_comparison(char **value, int *op)
237 {
238
239 *op = **value;
240
241 switch (*op) {
242 case '<':
243 (*value)++;
244 if (**value == '=') {
245 (*value)++;
246 *op = SPECIAL_LTE;
247 }
248 break;
249 case '=':
250 (*value)++;
251 (*value)++;
252 *op = SPECIAL_EQUAL;
253 break;
254 case '!':
255 (*value)++;
256 (*value)++;
257 *op = SPECIAL_NOTEQUAL;
258 break;
259 case '>':
260 (*value)++;
261 if (**value == '=') {
262 (*value)++;
263 *op = SPECIAL_GTE;
264 }
265 break;
266 default:
267 return 0;
268 }
269
270 if (**value != ' ') {
271 sm_perror("parsing comparison. %s", *value);
272 return 0;
273 }
274
275 (*value)++;
276 return 1;
277 }
278
split_op_param_key(char * value,int * op,int * param,char ** key)279 static int split_op_param_key(char *value, int *op, int *param, char **key)
280 {
281 static char buf[256];
282 char *p;
283
284 if (!parse_comparison(&value, op))
285 return 0;
286
287 snprintf(buf, sizeof(buf), "%s", value);
288
289 p = buf;
290 if (*p++ != '$')
291 return 0;
292
293 *param = atoi(p);
294 if (*param < 0 || *param > 99)
295 return 0;
296 p++;
297 if (*param > 9)
298 p++;
299 p--;
300 *p = '$';
301 *key = p;
302
303 return 1;
304 }
305
db_return_comparison(struct expression * expr,int left_param,char * key,char * value)306 static void db_return_comparison(struct expression *expr, int left_param, char *key, char *value)
307 {
308 struct expression *left_arg, *right_arg;
309 char *left_name = NULL;
310 struct symbol *left_sym;
311 char *right_name = NULL;
312 struct symbol *right_sym;
313 int op;
314 int right_param;
315 char *right_key;
316 struct var_sym_list *left_vsl = NULL, *right_vsl = NULL;
317
318 while (expr->type == EXPR_ASSIGNMENT)
319 expr = strip_expr(expr->right);
320 if (expr->type != EXPR_CALL)
321 return;
322
323 if (!split_op_param_key(value, &op, &right_param, &right_key))
324 return;
325
326 left_arg = get_argument_from_call_expr(expr->args, left_param);
327 if (!left_arg)
328 return;
329
330 right_arg = get_argument_from_call_expr(expr->args, right_param);
331 if (!right_arg)
332 return;
333
334 left_name = get_variable_from_key(left_arg, key, &left_sym);
335 if (!left_name || !left_sym)
336 goto free;
337 if (get_param_num_from_sym(left_sym) < 0)
338 goto free;
339
340 right_name = get_variable_from_key(right_arg, right_key, &right_sym);
341 if (!right_name || !right_sym)
342 goto free;
343 if (get_param_num_from_sym(right_sym) < 0)
344 goto free;
345
346 add_var_sym(&left_vsl, left_name, left_sym);
347 add_var_sym(&right_vsl, right_name, right_sym);
348
349 add_comparison_var_sym(left_name, left_vsl, op, right_name, right_vsl);
350
351 free:
352 free_string(left_name);
353 free_string(right_name);
354 }
355
register_param_compare_limit(int id)356 void register_param_compare_limit(int id)
357 {
358 compare_id = id;
359
360 set_dynamic_states(compare_id);
361 add_merge_hook(compare_id, &merge_compare_states);
362 add_split_return_callback(&print_return_comparison);
363
364 select_return_states_hook(COMPARE_LIMIT, &db_return_comparison);
365 }
366
register_param_compare_limit_links(int id)367 void register_param_compare_limit_links(int id)
368 {
369 link_id = id;
370
371 set_dynamic_states(link_id);
372 add_merge_hook(link_id, &merge_links);
373 }
374
375