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12724 update smatch to 0.6.1-rc1-il-5
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--- old/usr/src/tools/smatch/src/smatch_comparison.c
+++ new/usr/src/tools/smatch/src/smatch_comparison.c
1 1 /*
2 2 * Copyright (C) 2012 Oracle.
3 3 *
4 4 * This program is free software; you can redistribute it and/or
5 5 * modify it under the terms of the GNU General Public License
6 6 * as published by the Free Software Foundation; either version 2
7 7 * of the License, or (at your option) any later version.
8 8 *
9 9 * This program is distributed in the hope that it will be useful,
10 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 12 * GNU General Public License for more details.
13 13 *
14 14 * You should have received a copy of the GNU General Public License
15 15 * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
16 16 */
17 17
18 18 /*
19 19 * The point here is to store the relationships between two variables.
20 20 * Ie: y > x.
21 21 * To do that we create a state with the two variables in alphabetical order:
22 22 * ->name = "x vs y" and the state would be "<". On the false path the state
23 23 * would be ">=".
24 24 *
25 25 * Part of the trick of it is that if x or y is modified then we need to reset
26 26 * the state. We need to keep a list of all the states which depend on x and
27 27 * all the states which depend on y. The link_id code handles this.
28 28 *
29 29 */
30 30
31 31 #include "smatch.h"
32 32 #include "smatch_extra.h"
33 33 #include "smatch_slist.h"
34 34
35 35 int comparison_id;
36 36 static int link_id;
37 37 static int inc_dec_id;
38 38 static int inc_dec_link_id;
39 39
40 40 static void add_comparison(struct expression *left, int comparison, struct expression *right);
41 41
42 42 /* for handling for loops */
43 43 STATE(start);
44 44 STATE(incremented);
45 45
46 46 ALLOCATOR(compare_data, "compare data");
47 47
48 48 static struct symbol *vsl_to_sym(struct var_sym_list *vsl)
49 49 {
50 50 struct var_sym *vs;
51 51
52 52 if (!vsl)
53 53 return NULL;
54 54 if (ptr_list_size((struct ptr_list *)vsl) != 1)
55 55 return NULL;
56 56 vs = first_ptr_list((struct ptr_list *)vsl);
57 57 return vs->sym;
58 58 }
59 59
60 60 static const char *show_comparison(int comparison)
61 61 {
62 62 if (comparison == IMPOSSIBLE_COMPARISON)
63 63 return "impossible";
64 64 if (comparison == UNKNOWN_COMPARISON)
65 65 return "unknown";
66 66 return show_special(comparison);
67 67 }
68 68
69 69 struct smatch_state *alloc_compare_state(
70 70 struct expression *left,
71 71 const char *left_var, struct var_sym_list *left_vsl,
72 72 int comparison,
73 73 struct expression *right,
74 74 const char *right_var, struct var_sym_list *right_vsl)
75 75 {
76 76 struct smatch_state *state;
77 77 struct compare_data *data;
78 78
79 79 state = __alloc_smatch_state(0);
80 80 state->name = alloc_sname(show_comparison(comparison));
81 81 data = __alloc_compare_data(0);
82 82 data->left = left;
83 83 data->left_var = alloc_sname(left_var);
84 84 data->left_vsl = clone_var_sym_list(left_vsl);
85 85 data->comparison = comparison;
86 86 data->right = right;
87 87 data->right_var = alloc_sname(right_var);
88 88 data->right_vsl = clone_var_sym_list(right_vsl);
89 89 state->data = data;
90 90 return state;
91 91 }
92 92
93 93 int state_to_comparison(struct smatch_state *state)
94 94 {
95 95 if (!state || !state->data)
96 96 return UNKNOWN_COMPARISON;
97 97 return ((struct compare_data *)state->data)->comparison;
98 98 }
99 99
100 100 /*
101 101 * flip_comparison() reverses the op left and right. So "x >= y" becomes "y <= x".
102 102 */
103 103 int flip_comparison(int op)
104 104 {
105 105 switch (op) {
106 106 case UNKNOWN_COMPARISON:
107 107 return UNKNOWN_COMPARISON;
108 108 case '<':
109 109 return '>';
110 110 case SPECIAL_UNSIGNED_LT:
111 111 return SPECIAL_UNSIGNED_GT;
112 112 case SPECIAL_LTE:
113 113 return SPECIAL_GTE;
114 114 case SPECIAL_UNSIGNED_LTE:
115 115 return SPECIAL_UNSIGNED_GTE;
116 116 case SPECIAL_EQUAL:
117 117 return SPECIAL_EQUAL;
118 118 case SPECIAL_NOTEQUAL:
119 119 return SPECIAL_NOTEQUAL;
120 120 case SPECIAL_GTE:
121 121 return SPECIAL_LTE;
122 122 case SPECIAL_UNSIGNED_GTE:
123 123 return SPECIAL_UNSIGNED_LTE;
124 124 case '>':
125 125 return '<';
126 126 case SPECIAL_UNSIGNED_GT:
127 127 return SPECIAL_UNSIGNED_LT;
128 128 case IMPOSSIBLE_COMPARISON:
129 129 return UNKNOWN_COMPARISON;
130 130 default:
131 131 sm_perror("unhandled comparison %d", op);
132 132 return op;
133 133 }
134 134 }
135 135
136 136 int negate_comparison(int op)
137 137 {
138 138 switch (op) {
139 139 case UNKNOWN_COMPARISON:
140 140 return UNKNOWN_COMPARISON;
141 141 case '<':
142 142 return SPECIAL_GTE;
143 143 case SPECIAL_UNSIGNED_LT:
144 144 return SPECIAL_UNSIGNED_GTE;
145 145 case SPECIAL_LTE:
146 146 return '>';
147 147 case SPECIAL_UNSIGNED_LTE:
148 148 return SPECIAL_UNSIGNED_GT;
149 149 case SPECIAL_EQUAL:
150 150 return SPECIAL_NOTEQUAL;
151 151 case SPECIAL_NOTEQUAL:
152 152 return SPECIAL_EQUAL;
153 153 case SPECIAL_GTE:
154 154 return '<';
155 155 case SPECIAL_UNSIGNED_GTE:
156 156 return SPECIAL_UNSIGNED_LT;
157 157 case '>':
158 158 return SPECIAL_LTE;
159 159 case SPECIAL_UNSIGNED_GT:
160 160 return SPECIAL_UNSIGNED_LTE;
161 161 case IMPOSSIBLE_COMPARISON:
162 162 return UNKNOWN_COMPARISON;
163 163 default:
164 164 sm_perror("unhandled comparison %d", op);
165 165 return op;
166 166 }
167 167 }
168 168
169 169 static int rl_comparison(struct range_list *left_rl, struct range_list *right_rl)
170 170 {
171 171 sval_t left_min, left_max, right_min, right_max;
172 172 struct symbol *type = &int_ctype;
173 173
174 174 if (!left_rl || !right_rl)
175 175 return UNKNOWN_COMPARISON;
176 176
177 177 if (type_positive_bits(rl_type(left_rl)) > type_positive_bits(type))
178 178 type = rl_type(left_rl);
179 179 if (type_positive_bits(rl_type(right_rl)) > type_positive_bits(type))
180 180 type = rl_type(right_rl);
181 181
182 182 left_rl = cast_rl(type, left_rl);
183 183 right_rl = cast_rl(type, right_rl);
184 184
185 185 left_min = rl_min(left_rl);
186 186 left_max = rl_max(left_rl);
187 187 right_min = rl_min(right_rl);
188 188 right_max = rl_max(right_rl);
189 189
190 190 if (left_min.value == left_max.value &&
191 191 right_min.value == right_max.value &&
192 192 left_min.value == right_min.value)
193 193 return SPECIAL_EQUAL;
194 194
195 195 if (sval_cmp(left_max, right_min) < 0)
196 196 return '<';
197 197 if (sval_cmp(left_max, right_min) == 0)
198 198 return SPECIAL_LTE;
199 199 if (sval_cmp(left_min, right_max) > 0)
200 200 return '>';
201 201 if (sval_cmp(left_min, right_max) == 0)
202 202 return SPECIAL_GTE;
203 203
204 204 return UNKNOWN_COMPARISON;
205 205 }
206 206
207 207 static int comparison_from_extra(struct expression *a, struct expression *b)
208 208 {
209 209 struct range_list *left, *right;
210 210
211 211 if (!get_implied_rl(a, &left))
212 212 return UNKNOWN_COMPARISON;
213 213 if (!get_implied_rl(b, &right))
214 214 return UNKNOWN_COMPARISON;
215 215
216 216 return rl_comparison(left, right);
217 217 }
218 218
219 219 static struct range_list *get_orig_rl(struct var_sym_list *vsl)
220 220 {
221 221 struct symbol *sym;
222 222 struct smatch_state *state;
223 223
224 224 if (!vsl)
225 225 return NULL;
226 226 sym = vsl_to_sym(vsl);
227 227 if (!sym || !sym->ident)
228 228 return NULL;
229 229 state = get_orig_estate(sym->ident->name, sym);
230 230 return estate_rl(state);
231 231 }
232 232
233 233 static struct smatch_state *unmatched_comparison(struct sm_state *sm)
234 234 {
235 235 struct compare_data *data = sm->state->data;
236 236 struct range_list *left_rl, *right_rl;
237 237 int op = UNKNOWN_COMPARISON;
238 238
239 239 if (!data)
240 240 return &undefined;
241 241
242 242 if (is_impossible_path()) {
243 243 op = IMPOSSIBLE_COMPARISON;
244 244 goto alloc;
245 245 }
246 246
247 247 if (strstr(data->left_var, " orig"))
248 248 left_rl = get_orig_rl(data->left_vsl);
249 249 else if (!get_implied_rl_var_sym(data->left_var, vsl_to_sym(data->left_vsl), &left_rl))
250 250 goto alloc;
251 251
252 252 if (strstr(data->right_var, " orig"))
253 253 right_rl = get_orig_rl(data->right_vsl);
254 254 else if (!get_implied_rl_var_sym(data->right_var, vsl_to_sym(data->right_vsl), &right_rl))
255 255 goto alloc;
256 256
257 257 op = rl_comparison(left_rl, right_rl);
258 258
259 259 alloc:
260 260 return alloc_compare_state(data->left, data->left_var, data->left_vsl,
261 261 op,
262 262 data->right, data->right_var, data->right_vsl);
263 263 }
264 264
265 265 /* remove_unsigned_from_comparison() is obviously a hack. */
266 266 int remove_unsigned_from_comparison(int op)
267 267 {
268 268 switch (op) {
269 269 case SPECIAL_UNSIGNED_LT:
270 270 return '<';
271 271 case SPECIAL_UNSIGNED_LTE:
272 272 return SPECIAL_LTE;
273 273 case SPECIAL_UNSIGNED_GTE:
274 274 return SPECIAL_GTE;
275 275 case SPECIAL_UNSIGNED_GT:
276 276 return '>';
277 277 default:
278 278 return op;
279 279 }
280 280 }
281 281
282 282 /*
283 283 * This is for when you merge states "a < b" and "a == b", the result is that
284 284 * we can say for sure, "a <= b" after the merge.
285 285 */
286 286 int merge_comparisons(int one, int two)
287 287 {
288 288 int LT, EQ, GT;
289 289
290 290 if (one == UNKNOWN_COMPARISON || two == UNKNOWN_COMPARISON)
291 291 return UNKNOWN_COMPARISON;
292 292
293 293 if (one == IMPOSSIBLE_COMPARISON)
294 294 return two;
295 295 if (two == IMPOSSIBLE_COMPARISON)
296 296 return one;
297 297
298 298 one = remove_unsigned_from_comparison(one);
299 299 two = remove_unsigned_from_comparison(two);
300 300
301 301 if (one == two)
302 302 return one;
303 303
304 304 LT = EQ = GT = 0;
305 305
306 306 switch (one) {
307 307 case '<':
308 308 LT = 1;
309 309 break;
310 310 case SPECIAL_LTE:
311 311 LT = 1;
312 312 EQ = 1;
313 313 break;
314 314 case SPECIAL_EQUAL:
315 315 EQ = 1;
316 316 break;
317 317 case SPECIAL_GTE:
318 318 GT = 1;
319 319 EQ = 1;
320 320 break;
321 321 case '>':
322 322 GT = 1;
323 323 }
324 324
325 325 switch (two) {
326 326 case '<':
327 327 LT = 1;
328 328 break;
329 329 case SPECIAL_LTE:
330 330 LT = 1;
331 331 EQ = 1;
332 332 break;
333 333 case SPECIAL_EQUAL:
334 334 EQ = 1;
335 335 break;
336 336 case SPECIAL_GTE:
337 337 GT = 1;
338 338 EQ = 1;
339 339 break;
340 340 case '>':
341 341 GT = 1;
342 342 }
343 343
344 344 if (LT && EQ && GT)
345 345 return UNKNOWN_COMPARISON;
346 346 if (LT && EQ)
347 347 return SPECIAL_LTE;
348 348 if (LT && GT)
349 349 return SPECIAL_NOTEQUAL;
350 350 if (LT)
351 351 return '<';
352 352 if (EQ && GT)
353 353 return SPECIAL_GTE;
354 354 if (GT)
355 355 return '>';
356 356 return UNKNOWN_COMPARISON;
357 357 }
358 358
359 359 /*
360 360 * This is for if you have "a < b" and "b <= c" and you want to see how "a
361 361 * compares to c". You would call this like get_combined_comparison('<', '<=').
362 362 * The return comparison would be '<'.
363 363 */
364 364 int combine_comparisons(int left_compare, int right_compare)
365 365 {
366 366 int LT, EQ, GT;
367 367
368 368 left_compare = remove_unsigned_from_comparison(left_compare);
369 369 right_compare = remove_unsigned_from_comparison(right_compare);
370 370
371 371 LT = EQ = GT = 0;
372 372
373 373 switch (left_compare) {
374 374 case '<':
375 375 LT++;
376 376 break;
377 377 case SPECIAL_LTE:
378 378 LT++;
379 379 EQ++;
380 380 break;
381 381 case SPECIAL_EQUAL:
382 382 return right_compare;
383 383 case SPECIAL_GTE:
384 384 GT++;
385 385 EQ++;
386 386 break;
387 387 case '>':
388 388 GT++;
389 389 }
390 390
391 391 switch (right_compare) {
392 392 case '<':
393 393 LT++;
394 394 break;
395 395 case SPECIAL_LTE:
396 396 LT++;
397 397 EQ++;
398 398 break;
399 399 case SPECIAL_EQUAL:
400 400 return left_compare;
401 401 case SPECIAL_GTE:
402 402 GT++;
403 403 EQ++;
404 404 break;
405 405 case '>':
406 406 GT++;
407 407 }
408 408
409 409 if (LT == 2) {
410 410 if (EQ == 2)
411 411 return SPECIAL_LTE;
412 412 return '<';
413 413 }
414 414
415 415 if (GT == 2) {
416 416 if (EQ == 2)
417 417 return SPECIAL_GTE;
418 418 return '>';
419 419 }
420 420 return UNKNOWN_COMPARISON;
421 421 }
422 422
423 423 /*
424 424 * This is mostly used when you know from extra state that a <= b but you
425 425 * know from comparisons that a != b so then if take the intersection then
426 426 * we know that a < b. The name is taken from the fact that the intersection
427 427 * of < and <= is <.
428 428 */
429 429 int comparison_intersection(int left_compare, int right_compare)
430 430 {
431 431 int LT, GT, EQ, NE, total;
432 432
433 433 if (left_compare == IMPOSSIBLE_COMPARISON ||
434 434 right_compare == IMPOSSIBLE_COMPARISON)
435 435 return IMPOSSIBLE_COMPARISON;
436 436
437 437 left_compare = remove_unsigned_from_comparison(left_compare);
438 438 right_compare = remove_unsigned_from_comparison(right_compare);
439 439
440 440 LT = GT = EQ = NE = total = 0;
441 441
442 442 /* Only one side is known. */
443 443 if (!left_compare)
444 444 return right_compare;
445 445 if (!right_compare)
446 446 return left_compare;
447 447
448 448 switch (left_compare) {
449 449 case '<':
450 450 LT++;
451 451 total += 1;
452 452 break;
453 453 case SPECIAL_LTE:
454 454 LT++;
455 455 EQ++;
456 456 total += 2;
457 457 break;
458 458 case SPECIAL_EQUAL:
459 459 EQ++;
460 460 total += 1;
461 461 break;
462 462 case SPECIAL_NOTEQUAL:
463 463 NE++;
464 464 total += 1;
465 465 break;
466 466 case SPECIAL_GTE:
467 467 GT++;
468 468 EQ++;
469 469 total += 2;
470 470 break;
471 471 case '>':
472 472 GT++;
473 473 total += 1;
474 474 break;
475 475 default:
476 476 return UNKNOWN_COMPARISON;
477 477 }
478 478
479 479 switch (right_compare) {
480 480 case '<':
481 481 LT++;
482 482 total += 1;
483 483 break;
484 484 case SPECIAL_LTE:
485 485 LT++;
486 486 EQ++;
487 487 total += 2;
488 488 break;
489 489 case SPECIAL_EQUAL:
490 490 EQ++;
491 491 total += 1;
492 492 break;
493 493 case SPECIAL_NOTEQUAL:
494 494 NE++;
495 495 total += 1;
496 496 break;
497 497 case SPECIAL_GTE:
498 498 GT++;
499 499 EQ++;
500 500 total += 2;
501 501 break;
502 502 case '>':
503 503 GT++;
504 504 total += 1;
505 505 break;
506 506 default:
507 507 return UNKNOWN_COMPARISON;
508 508 }
509 509
510 510 if (LT == 2) {
511 511 if (EQ == 2)
512 512 return SPECIAL_LTE;
513 513 return '<';
514 514 }
515 515
516 516 if (GT == 2) {
517 517 if (EQ == 2)
518 518 return SPECIAL_GTE;
519 519 return '>';
520 520 }
521 521 if (EQ == 2)
522 522 return SPECIAL_EQUAL;
523 523 if (total == 2 && EQ && NE)
524 524 return IMPOSSIBLE_COMPARISON;
525 525 if (GT && LT)
526 526 return IMPOSSIBLE_COMPARISON;
527 527 if (GT && NE)
528 528 return '>';
529 529 if (LT && NE)
530 530 return '<';
531 531 if (NE == 2)
532 532 return SPECIAL_NOTEQUAL;
533 533 if (total == 2 && (LT || GT) && EQ)
534 534 return IMPOSSIBLE_COMPARISON;
535 535
536 536 return UNKNOWN_COMPARISON;
537 537 }
538 538
539 539 static void pre_merge_hook(struct sm_state *cur, struct sm_state *other)
540 540 {
541 541 struct compare_data *data = cur->state->data;
542 542 int extra, new;
543 543 static bool in_recurse;
544 544
545 545 // FIXME. No data is useless
546 546 if (!data)
547 547 return;
548 548
549 549 if (in_recurse)
550 550 return;
551 551 in_recurse = true;
552 552 extra = comparison_from_extra(data->left, data->right);
553 553 in_recurse = false;
554 554 if (!extra)
555 555 return;
556 556 new = comparison_intersection(extra, data->comparison);
557 557 if (new == data->comparison)
558 558 return;
559 559
560 560 // FIXME: we should always preserve implications
561 561 set_state(comparison_id, cur->name, NULL,
562 562 alloc_compare_state(data->left, data->left_var, data->left_vsl,
563 563 new,
564 564 data->right, data->right_var, data->right_vsl));
565 565 }
566 566
567 567 struct smatch_state *merge_compare_states(struct smatch_state *s1, struct smatch_state *s2)
568 568 {
569 569 struct compare_data *data = s1->data;
570 570 int op;
571 571
572 572 if (!data)
573 573 return &undefined;
574 574
575 575 op = merge_comparisons(state_to_comparison(s1), state_to_comparison(s2));
576 576 return alloc_compare_state(
577 577 data->left, data->left_var, data->left_vsl,
578 578 op,
579 579 data->right, data->right_var, data->right_vsl);
580 580 }
581 581
582 582 static struct smatch_state *alloc_link_state(struct string_list *links)
583 583 {
584 584 struct smatch_state *state;
585 585 static char buf[256];
586 586 char *tmp;
587 587 int i;
588 588
589 589 state = __alloc_smatch_state(0);
590 590
591 591 i = 0;
592 592 FOR_EACH_PTR(links, tmp) {
593 593 if (!i++) {
594 594 snprintf(buf, sizeof(buf), "%s", tmp);
595 595 } else {
596 596 append(buf, ", ", sizeof(buf));
597 597 append(buf, tmp, sizeof(buf));
598 598 }
599 599 } END_FOR_EACH_PTR(tmp);
600 600
601 601 state->name = alloc_sname(buf);
602 602 state->data = links;
603 603 return state;
604 604 }
605 605
606 606 static void save_start_states(struct statement *stmt)
607 607 {
608 608 struct symbol *param;
609 609 char orig[64];
610 610 char state_name[128];
611 611 struct smatch_state *state;
612 612 struct string_list *links;
613 613 char *link;
614 614
615 615 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
616 616 struct var_sym_list *left_vsl = NULL;
617 617 struct var_sym_list *right_vsl = NULL;
618 618
619 619 if (!param->ident)
620 620 continue;
621 621 snprintf(orig, sizeof(orig), "%s orig", param->ident->name);
622 622 snprintf(state_name, sizeof(state_name), "%s vs %s", param->ident->name, orig);
623 623 add_var_sym(&left_vsl, param->ident->name, param);
624 624 add_var_sym(&right_vsl, orig, param);
625 625 state = alloc_compare_state(
626 626 NULL, param->ident->name, left_vsl,
627 627 SPECIAL_EQUAL,
628 628 NULL, alloc_sname(orig), right_vsl);
629 629 set_state(comparison_id, state_name, NULL, state);
630 630
631 631 link = alloc_sname(state_name);
632 632 links = NULL;
633 633 insert_string(&links, link);
634 634 state = alloc_link_state(links);
635 635 set_state(link_id, param->ident->name, param, state);
636 636 } END_FOR_EACH_PTR(param);
637 637 }
638 638
639 639 static struct smatch_state *merge_links(struct smatch_state *s1, struct smatch_state *s2)
640 640 {
641 641 struct smatch_state *ret;
642 642 struct string_list *links;
643 643
644 644 links = combine_string_lists(s1->data, s2->data);
645 645 ret = alloc_link_state(links);
646 646 return ret;
647 647 }
648 648
649 649 static void save_link_var_sym(const char *var, struct symbol *sym, const char *link)
650 650 {
651 651 struct smatch_state *old_state, *new_state;
652 652 struct string_list *links;
653 653 char *new;
654 654
655 655 old_state = get_state(link_id, var, sym);
656 656 if (old_state)
657 657 links = clone_str_list(old_state->data);
658 658 else
659 659 links = NULL;
660 660
661 661 new = alloc_sname(link);
662 662 insert_string(&links, new);
663 663
664 664 new_state = alloc_link_state(links);
665 665 set_state(link_id, var, sym, new_state);
666 666 }
667 667
668 668 static void match_inc(struct sm_state *sm, bool preserve)
669 669 {
670 670 struct string_list *links;
671 671 struct smatch_state *state, *new;
672 672 struct compare_data *data;
673 673 char *tmp;
674 674 int flip;
675 675 int op;
676 676
677 677 links = sm->state->data;
678 678
679 679 FOR_EACH_PTR(links, tmp) {
680 680 state = get_state(comparison_id, tmp, NULL);
681 681 if (!state)
682 682 continue;
683 683 data = state->data;
684 684 if (!data)
685 685 continue;
686 686
687 687 flip = 0;
688 688 if (strncmp(sm->name, tmp, strlen(sm->name)) != 0 ||
689 689 tmp[strlen(sm->name)] != ' ')
690 690 flip = 1;
691 691
692 692 op = state_to_comparison(state);
693 693
694 694 switch (flip ? flip_comparison(op) : op) {
695 695 case SPECIAL_EQUAL:
696 696 case SPECIAL_GTE:
697 697 case SPECIAL_UNSIGNED_GTE:
698 698 case '>':
699 699 case SPECIAL_UNSIGNED_GT:
700 700 if (preserve)
701 701 break;
702 702 new = alloc_compare_state(
703 703 data->left, data->left_var, data->left_vsl,
704 704 flip ? '<' : '>',
705 705 data->right, data->right_var, data->right_vsl);
706 706 set_state(comparison_id, tmp, NULL, new);
707 707 break;
708 708 case '<':
709 709 case SPECIAL_UNSIGNED_LT:
710 710 new = alloc_compare_state(
711 711 data->left, data->left_var, data->left_vsl,
712 712 flip ? SPECIAL_GTE : SPECIAL_LTE,
713 713 data->right, data->right_var, data->right_vsl);
714 714 set_state(comparison_id, tmp, NULL, new);
715 715 break;
716 716 default:
717 717 new = alloc_compare_state(
718 718 data->left, data->left_var, data->left_vsl,
719 719 UNKNOWN_COMPARISON,
720 720 data->right, data->right_var, data->right_vsl);
721 721 set_state(comparison_id, tmp, NULL, new);
722 722 }
723 723 } END_FOR_EACH_PTR(tmp);
724 724 }
725 725
726 726 static void match_dec(struct sm_state *sm, bool preserve)
727 727 {
728 728 struct string_list *links;
729 729 struct smatch_state *state;
730 730 char *tmp;
731 731
732 732 links = sm->state->data;
733 733
734 734 FOR_EACH_PTR(links, tmp) {
735 735 struct compare_data *data;
736 736 struct smatch_state *new;
737 737
738 738 state = get_state(comparison_id, tmp, NULL);
739 739 if (!state || !state->data)
740 740 continue;
741 741
742 742 data = state->data;
743 743
744 744 switch (state_to_comparison(state)) {
745 745 case SPECIAL_EQUAL:
746 746 case SPECIAL_LTE:
747 747 case SPECIAL_UNSIGNED_LTE:
748 748 case '<':
749 749 case SPECIAL_UNSIGNED_LT: {
750 750 if (preserve)
751 751 break;
752 752
753 753 new = alloc_compare_state(
754 754 data->left, data->left_var, data->left_vsl,
755 755 '<',
756 756 data->right, data->right_var, data->right_vsl);
757 757 set_state(comparison_id, tmp, NULL, new);
758 758 break;
759 759 }
760 760 default:
761 761 new = alloc_compare_state(
762 762 data->left, data->left_var, data->left_vsl,
763 763 UNKNOWN_COMPARISON,
764 764 data->right, data->right_var, data->right_vsl);
765 765 set_state(comparison_id, tmp, NULL, new);
766 766 }
767 767 } END_FOR_EACH_PTR(tmp);
768 768 }
769 769
770 770 static void reset_sm(struct sm_state *sm)
771 771 {
772 772 struct string_list *links;
773 773 char *tmp;
774 774
775 775 links = sm->state->data;
776 776
777 777 FOR_EACH_PTR(links, tmp) {
778 778 struct smatch_state *old, *new;
779 779
780 780 old = get_state(comparison_id, tmp, NULL);
781 781 if (!old || !old->data) {
782 782 new = &undefined;
783 783 } else {
784 784 struct compare_data *data = old->data;
785 785
786 786 new = alloc_compare_state(
787 787 data->left, data->left_var, data->left_vsl,
788 788 UNKNOWN_COMPARISON,
789 789 data->right, data->right_var, data->right_vsl);
790 790 }
791 791 set_state(comparison_id, tmp, NULL, new);
792 792 } END_FOR_EACH_PTR(tmp);
793 793 set_state(link_id, sm->name, sm->sym, &undefined);
794 794 }
795 795
796 796 static bool match_add_sub_assign(struct sm_state *sm, struct expression *expr)
797 797 {
798 798 struct range_list *rl;
799 799 sval_t zero = { .type = &int_ctype };
800 800
801 801 if (!expr || expr->type != EXPR_ASSIGNMENT)
802 802 return false;
803 803 if (expr->op != SPECIAL_ADD_ASSIGN && expr->op != SPECIAL_SUB_ASSIGN)
804 804 return false;
805 805
806 806 get_absolute_rl(expr->right, &rl);
807 807 if (sval_is_negative(rl_min(rl))) {
808 808 reset_sm(sm);
809 809 return false;
810 810 }
811 811
812 812 if (expr->op == SPECIAL_ADD_ASSIGN)
813 813 match_inc(sm, rl_has_sval(rl, zero));
814 814 else
815 815 match_dec(sm, rl_has_sval(rl, zero));
816 816 return true;
817 817 }
818 818
819 819 static void match_inc_dec(struct sm_state *sm, struct expression *mod_expr)
820 820 {
821 821 /*
822 822 * if (foo > bar) then ++foo is also > bar.
823 823 */
824 824 if (!mod_expr)
825 825 return;
826 826 if (match_add_sub_assign(sm, mod_expr))
827 827 return;
828 828 if (mod_expr->type != EXPR_PREOP && mod_expr->type != EXPR_POSTOP)
829 829 return;
830 830
831 831 if (mod_expr->op == SPECIAL_INCREMENT)
832 832 match_inc(sm, false);
833 833 else if (mod_expr->op == SPECIAL_DECREMENT)
834 834 match_dec(sm, false);
835 835 }
836 836
837 837 static int is_self_assign(struct expression *expr)
838 838 {
839 839 if (!expr || expr->type != EXPR_ASSIGNMENT || expr->op != '=')
840 840 return 0;
841 841 return expr_equiv(expr->left, expr->right);
842 842 }
843 843
844 844 static void match_modify(struct sm_state *sm, struct expression *mod_expr)
845 845 {
846 846 if (mod_expr && is_self_assign(mod_expr))
847 847 return;
848 848
849 849 /* handled by match_inc_dec() */
850 850 if (mod_expr &&
851 851 ((mod_expr->type == EXPR_PREOP || mod_expr->type == EXPR_POSTOP) &&
852 852 (mod_expr->op == SPECIAL_INCREMENT || mod_expr->op == SPECIAL_DECREMENT)))
853 853 return;
854 854 if (mod_expr && mod_expr->type == EXPR_ASSIGNMENT &&
855 855 (mod_expr->op == SPECIAL_ADD_ASSIGN || mod_expr->op == SPECIAL_SUB_ASSIGN))
856 856 return;
857 857
858 858 reset_sm(sm);
859 859 }
860 860
861 861 static void match_preop(struct expression *expr)
862 862 {
863 863 struct expression *parent;
864 864 struct range_list *left, *right;
865 865 int op;
866 866
867 867 /*
868 868 * This is an important special case. Say you have:
869 869 *
870 870 * if (++j == limit)
871 871 *
872 872 * Assume that we know the range of limit is higher than the start
873 873 * value for "j". Then the first thing that we process is the ++j. We
874 874 * have not comparison states set up so it doesn't get caught by the
875 875 * modification hook. But it does get caught by smatch_extra which sets
876 876 * j to unknown then we parse the "j == limit" and sets false to != but
877 877 * really we want false to be <.
878 878 *
879 879 * So what we do is we set j < limit here, then the match_modify catches
880 880 * it and we do a match_inc_dec().
881 881 *
882 882 */
883 883
884 884 if (expr->type != EXPR_PREOP ||
885 885 (expr->op != SPECIAL_INCREMENT && expr->op != SPECIAL_DECREMENT))
886 886 return;
887 887
888 888 parent = expr_get_parent_expr(expr);
889 889 if (!parent)
890 890 return;
891 891 if (parent->type != EXPR_COMPARE || parent->op != SPECIAL_EQUAL)
892 892 return;
893 893 if (parent->left != expr)
894 894 return;
895 895
896 896 if (!get_implied_rl(expr->unop, &left) ||
897 897 !get_implied_rl(parent->right, &right))
898 898 return;
899 899
900 900 op = rl_comparison(left, right);
901 901 if (op == UNKNOWN_COMPARISON)
902 902 return;
903 903
904 904 add_comparison(expr->unop, op, parent->right);
905 905 }
906 906
907 907 static char *chunk_to_var_sym(struct expression *expr, struct symbol **sym)
908 908 {
909 909 expr = strip_expr(expr);
910 910 if (!expr)
911 911 return NULL;
912 912 if (sym)
913 913 *sym = NULL;
914 914
915 915 if (expr->type == EXPR_PREOP &&
916 916 (expr->op == SPECIAL_INCREMENT ||
917 917 expr->op == SPECIAL_DECREMENT))
918 918 expr = strip_expr(expr->unop);
919 919
920 920 if (expr->type == EXPR_CALL) {
921 921 char buf[64];
922 922
923 923 snprintf(buf, sizeof(buf), "return %p", expr);
924 924 return alloc_string(buf);
925 925 }
926 926
927 927 return expr_to_chunk_sym_vsl(expr, sym, NULL);
928 928 }
929 929
930 930 static char *chunk_to_var(struct expression *expr)
931 931 {
932 932 return chunk_to_var_sym(expr, NULL);
933 933 }
934 934
935 935 static struct smatch_state *get_state_chunk(int owner, struct expression *expr)
936 936 {
937 937 char *name;
938 938 struct symbol *sym;
939 939 struct smatch_state *ret;
940 940
941 941 name = chunk_to_var_sym(expr, &sym);
942 942 if (!name)
943 943 return NULL;
944 944
945 945 ret = get_state(owner, name, sym);
946 946 free_string(name);
947 947 return ret;
948 948 }
949 949
950 950 static void save_link(struct expression *expr, char *link)
951 951 {
952 952 char *var;
953 953 struct symbol *sym;
954 954
955 955 expr = strip_expr(expr);
956 956 if (expr->type == EXPR_BINOP) {
957 957 char *chunk;
958 958
959 959 chunk = chunk_to_var(expr);
960 960 if (!chunk)
961 961 return;
962 962
963 963 save_link(expr->left, link);
964 964 save_link(expr->right, link);
965 965 save_link_var_sym(chunk, NULL, link);
966 966 return;
967 967 }
968 968
969 969 var = chunk_to_var_sym(expr, &sym);
970 970 if (!var)
971 971 return;
972 972
973 973 save_link_var_sym(var, sym, link);
974 974 free_string(var);
975 975 }
976 976
977 977 static int get_orig_comparison(struct stree *pre_stree, const char *left, const char *right)
978 978 {
979 979 struct smatch_state *state;
980 980 struct compare_data *data;
981 981 int flip = 0;
982 982 char state_name[256];
983 983
984 984 if (strcmp(left, right) > 0) {
985 985 const char *tmp = right;
986 986
987 987 flip = 1;
988 988 right = left;
989 989 left = tmp;
990 990 }
991 991
992 992 snprintf(state_name, sizeof(state_name), "%s vs %s", left, right);
993 993 state = get_state_stree(pre_stree, comparison_id, state_name, NULL);
994 994 if (!state || !state->data)
995 995 return 0;
996 996 data = state->data;
997 997 if (flip)
998 998 return flip_comparison(data->comparison);
999 999 return data->comparison;
1000 1000
1001 1001 }
1002 1002
1003 1003 static int have_common_var_sym(struct var_sym_list *left_vsl, struct var_sym_list *right_vsl)
1004 1004 {
1005 1005 struct var_sym *tmp;
1006 1006
1007 1007 FOR_EACH_PTR(left_vsl, tmp) {
1008 1008 if (in_var_sym_list(right_vsl, tmp->var, tmp->sym))
1009 1009 return 1;
1010 1010 } END_FOR_EACH_PTR(tmp);
1011 1011
1012 1012 return 0;
1013 1013 }
1014 1014
1015 1015 /*
1016 1016 * The idea here is that we take a comparison "a < b" and then we look at all
1017 1017 * the things which "b" is compared against "b < c" and we say that that implies
1018 1018 * a relationship "a < c".
1019 1019 *
1020 1020 * The names here about because the comparisons are organized like this
1021 1021 * "a < b < c".
1022 1022 *
1023 1023 */
1024 1024 static void update_tf_links(struct stree *pre_stree,
1025 1025 struct expression *left_expr,
1026 1026 const char *left_var, struct var_sym_list *left_vsl,
1027 1027 int left_comparison, int left_false_comparison,
1028 1028 const char *mid_var, struct var_sym_list *mid_vsl,
1029 1029 struct string_list *links)
1030 1030 {
1031 1031 struct smatch_state *state;
1032 1032 struct smatch_state *true_state, *false_state;
1033 1033 struct compare_data *data;
1034 1034 struct expression *right_expr;
1035 1035 const char *right_var;
1036 1036 struct var_sym_list *right_vsl;
1037 1037 int orig_comparison;
1038 1038 int right_comparison;
1039 1039 int true_comparison;
1040 1040 int false_comparison;
1041 1041 char *tmp;
1042 1042 char state_name[256];
1043 1043 struct var_sym *vs;
1044 1044
1045 1045 FOR_EACH_PTR(links, tmp) {
1046 1046 state = get_state_stree(pre_stree, comparison_id, tmp, NULL);
1047 1047 if (!state || !state->data)
1048 1048 continue;
1049 1049 data = state->data;
1050 1050 right_comparison = data->comparison;
1051 1051 right_expr = data->right;
1052 1052 right_var = data->right_var;
1053 1053 right_vsl = data->right_vsl;
1054 1054 if (strcmp(mid_var, right_var) == 0) {
1055 1055 right_expr = data->left;
1056 1056 right_var = data->left_var;
1057 1057 right_vsl = data->left_vsl;
1058 1058 right_comparison = flip_comparison(right_comparison);
1059 1059 }
1060 1060 if (have_common_var_sym(left_vsl, right_vsl))
1061 1061 continue;
1062 1062
1063 1063 orig_comparison = get_orig_comparison(pre_stree, left_var, right_var);
1064 1064
1065 1065 true_comparison = combine_comparisons(left_comparison, right_comparison);
1066 1066 false_comparison = combine_comparisons(left_false_comparison, right_comparison);
1067 1067
1068 1068 true_comparison = comparison_intersection(orig_comparison, true_comparison);
1069 1069 false_comparison = comparison_intersection(orig_comparison, false_comparison);
1070 1070
1071 1071 if (strcmp(left_var, right_var) > 0) {
1072 1072 struct expression *tmp_expr = left_expr;
1073 1073 const char *tmp_var = left_var;
1074 1074 struct var_sym_list *tmp_vsl = left_vsl;
1075 1075
1076 1076 left_expr = right_expr;
1077 1077 left_var = right_var;
1078 1078 left_vsl = right_vsl;
1079 1079 right_expr = tmp_expr;
1080 1080 right_var = tmp_var;
1081 1081 right_vsl = tmp_vsl;
1082 1082 true_comparison = flip_comparison(true_comparison);
1083 1083 false_comparison = flip_comparison(false_comparison);
1084 1084 }
1085 1085
1086 1086 if (!true_comparison && !false_comparison)
1087 1087 continue;
1088 1088
1089 1089 if (true_comparison)
1090 1090 true_state = alloc_compare_state(
1091 1091 left_expr, left_var, left_vsl,
1092 1092 true_comparison,
1093 1093 right_expr, right_var, right_vsl);
1094 1094 else
1095 1095 true_state = NULL;
1096 1096 if (false_comparison)
1097 1097 false_state = alloc_compare_state(
1098 1098 left_expr, left_var, left_vsl,
1099 1099 false_comparison,
1100 1100 right_expr, right_var, right_vsl);
1101 1101 else
1102 1102 false_state = NULL;
1103 1103
1104 1104 snprintf(state_name, sizeof(state_name), "%s vs %s", left_var, right_var);
1105 1105 set_true_false_states(comparison_id, state_name, NULL, true_state, false_state);
1106 1106 FOR_EACH_PTR(left_vsl, vs) {
1107 1107 save_link_var_sym(vs->var, vs->sym, state_name);
1108 1108 } END_FOR_EACH_PTR(vs);
1109 1109 FOR_EACH_PTR(right_vsl, vs) {
1110 1110 save_link_var_sym(vs->var, vs->sym, state_name);
1111 1111 } END_FOR_EACH_PTR(vs);
1112 1112 if (!vsl_to_sym(left_vsl))
1113 1113 save_link_var_sym(left_var, NULL, state_name);
1114 1114 if (!vsl_to_sym(right_vsl))
1115 1115 save_link_var_sym(right_var, NULL, state_name);
1116 1116 } END_FOR_EACH_PTR(tmp);
1117 1117 }
1118 1118
1119 1119 static void update_tf_data(struct stree *pre_stree,
1120 1120 struct expression *left_expr,
1121 1121 const char *left_name, struct var_sym_list *left_vsl,
1122 1122 struct expression *right_expr,
1123 1123 const char *right_name, struct var_sym_list *right_vsl,
1124 1124 int true_comparison, int false_comparison)
1125 1125 {
1126 1126 struct smatch_state *state;
1127 1127
1128 1128 state = get_state_stree(pre_stree, link_id, right_name, vsl_to_sym(right_vsl));
1129 1129 if (state)
1130 1130 update_tf_links(pre_stree, left_expr, left_name, left_vsl, true_comparison, false_comparison, right_name, right_vsl, state->data);
1131 1131
1132 1132 state = get_state_stree(pre_stree, link_id, left_name, vsl_to_sym(left_vsl));
1133 1133 if (state)
1134 1134 update_tf_links(pre_stree, right_expr, right_name, right_vsl, flip_comparison(true_comparison), flip_comparison(false_comparison), left_name, left_vsl, state->data);
1135 1135 }
1136 1136
1137 1137 static void iter_modify(struct sm_state *sm, struct expression *mod_expr)
1138 1138 {
1139 1139 if (sm->state != &start ||
1140 1140 !mod_expr ||
1141 1141 (mod_expr->type != EXPR_PREOP && mod_expr->type != EXPR_POSTOP) ||
1142 1142 mod_expr->op != SPECIAL_INCREMENT)
1143 1143 set_state(inc_dec_id, sm->name, sm->sym, &undefined);
1144 1144 else
1145 1145 set_state(inc_dec_id, sm->name, sm->sym, &incremented);
1146 1146 }
1147 1147
1148 1148 static void handle_for_loops(struct expression *expr, char *state_name, struct smatch_state *false_state)
1149 1149 {
1150 1150 sval_t sval;
1151 1151 char *iter_name, *cap_name;
1152 1152 struct symbol *iter_sym, *cap_sym;
1153 1153 struct compare_data *data;
1154 1154
1155 1155 if (expr->op != '<' && expr->op != SPECIAL_UNSIGNED_LT)
1156 1156 return;
1157 1157
1158 1158 if (!__cur_stmt || !__prev_stmt)
1159 1159 return;
1160 1160 if (__cur_stmt->type != STMT_ITERATOR)
1161 1161 return;
1162 1162 if (__cur_stmt->iterator_pre_condition != expr)
1163 1163 return;
1164 1164
1165 1165 /* literals are handled in smatch_extra.c */
1166 1166 if (get_value(expr->right, &sval))
1167 1167 return;
1168 1168
1169 1169 /* First time checking the condition */
1170 1170 if (__prev_stmt == __cur_stmt->iterator_pre_statement) {
1171 1171 if (!get_implied_value(expr->left, &sval) ||
1172 1172 sval.value != 0)
1173 1173 return;
1174 1174
1175 1175 iter_name = expr_to_var_sym(expr->left, &iter_sym);
1176 1176 cap_name = expr_to_var_sym(expr->right, &cap_sym);
1177 1177 if (!iter_name || !cap_name || !iter_sym || !cap_sym) {
1178 1178 free_string(iter_name);
1179 1179 free_string(cap_name);
1180 1180 return;
1181 1181 }
1182 1182
1183 1183 set_state(inc_dec_id, iter_name, iter_sym, &start);
1184 1184 store_link(inc_dec_link_id, cap_name, cap_sym, iter_name, iter_sym);
1185 1185
1186 1186 free_string(iter_name);
1187 1187 free_string(cap_name);
1188 1188 return;
1189 1189 }
1190 1190
1191 1191 /* Second time checking the condtion */
1192 1192 if (__prev_stmt != __cur_stmt->iterator_post_statement)
1193 1193 return;
1194 1194
1195 1195 if (get_state_chunk(inc_dec_id, expr->left) != &incremented)
1196 1196 return;
1197 1197
1198 1198 data = false_state->data;
1199 1199 false_state = alloc_compare_state(
1200 1200 data->left, data->left_var, data->left_vsl,
1201 1201 SPECIAL_EQUAL,
1202 1202 data->right, data->right_var, data->right_vsl);
1203 1203
1204 1204 // FIXME: This doesn't handle links correct so it doesn't set "param orig"
1205 1205 set_true_false_states(comparison_id, state_name, NULL, NULL, false_state);
1206 1206 }
1207 1207
1208 1208 static int is_plus_one(struct expression *expr)
1209 1209 {
1210 1210 sval_t sval;
1211 1211
1212 1212 if (expr->type != EXPR_BINOP || expr->op != '+')
1213 1213 return 0;
1214 1214 if (!get_implied_value(expr->right, &sval) || sval.value != 1)
1215 1215 return 0;
1216 1216 return 1;
1217 1217 }
1218 1218
1219 1219 static int is_minus_one(struct expression *expr)
1220 1220 {
1221 1221 sval_t sval;
1222 1222
1223 1223 if (expr->type != EXPR_BINOP || expr->op != '-')
1224 1224 return 0;
1225 1225 if (!get_implied_value(expr->right, &sval) || sval.value != 1)
1226 1226 return 0;
1227 1227 return 1;
1228 1228 }
1229 1229
1230 1230 static void move_plus_to_minus_helper(struct expression **left_p, struct expression **right_p)
1231 1231 {
1232 1232 struct expression *left = *left_p;
1233 1233 struct expression *right = *right_p;
1234 1234
1235 1235 /*
1236 1236 * These two are basically equivalent: "foo + 1 != bar" and
1237 1237 * "foo != bar - 1". There are issues with signedness and integer
1238 1238 * overflows. There are also issues with type as well. But let's
1239 1239 * pretend we can ignore all that stuff for now.
1240 1240 *
1241 1241 */
1242 1242
1243 1243 if (!is_plus_one(left))
1244 1244 return;
1245 1245
1246 1246 *left_p = left->left;
1247 1247 *right_p = binop_expression(right, '-', left->right);
1248 1248 }
1249 1249
1250 1250 static void move_plus_to_minus(struct expression **left_p, struct expression **right_p)
1251 1251 {
1252 1252 if (is_plus_one(*left_p) && is_plus_one(*right_p))
1253 1253 return;
1254 1254
1255 1255 move_plus_to_minus_helper(left_p, right_p);
1256 1256 move_plus_to_minus_helper(right_p, left_p);
1257 1257 }
1258 1258
1259 1259 static void handle_comparison(struct expression *left_expr, int op, struct expression *right_expr, char **_state_name, struct smatch_state **_false_state)
1260 1260 {
1261 1261 char *left = NULL;
1262 1262 char *right = NULL;
1263 1263 struct symbol *left_sym, *right_sym;
1264 1264 struct var_sym_list *left_vsl = NULL;
1265 1265 struct var_sym_list *right_vsl = NULL;
1266 1266 int false_op;
1267 1267 int orig_comparison;
1268 1268 struct smatch_state *true_state, *false_state;
1269 1269 static char state_name[256];
1270 1270 struct stree *pre_stree;
1271 1271 sval_t sval;
1272 1272
1273 1273 if (!left_expr || !right_expr)
1274 1274 return;
1275 1275
1276 1276 left_expr = strip_parens(left_expr);
1277 1277 right_expr = strip_parens(right_expr);
1278 1278
1279 1279 while (left_expr->type == EXPR_ASSIGNMENT)
1280 1280 left_expr = strip_parens(left_expr->left);
1281 1281 while (right_expr->type == EXPR_ASSIGNMENT)
1282 1282 right_expr = strip_parens(right_expr->left);
1283 1283
1284 1284 false_op = negate_comparison(op);
1285 1285
1286 1286 move_plus_to_minus(&left_expr, &right_expr);
1287 1287
1288 1288 if (op == SPECIAL_UNSIGNED_LT &&
1289 1289 get_implied_value(left_expr, &sval) &&
1290 1290 sval.value == 0)
1291 1291 false_op = SPECIAL_EQUAL;
1292 1292
1293 1293 if (op == SPECIAL_UNSIGNED_GT &&
1294 1294 get_implied_value(right_expr, &sval) &&
1295 1295 sval.value == 0)
1296 1296 false_op = SPECIAL_EQUAL;
1297 1297
1298 1298 left = chunk_to_var_sym(left_expr, &left_sym);
1299 1299 if (!left)
1300 1300 goto free;
1301 1301 if (left_sym)
1302 1302 add_var_sym(&left_vsl, left, left_sym);
1303 1303 else
1304 1304 left_vsl = expr_to_vsl(left_expr);
1305 1305 right = chunk_to_var_sym(right_expr, &right_sym);
1306 1306 if (!right)
1307 1307 goto free;
1308 1308 if (right_sym)
1309 1309 add_var_sym(&right_vsl, right, right_sym);
1310 1310 else
1311 1311 right_vsl = expr_to_vsl(right_expr);
1312 1312
1313 1313 if (strcmp(left, right) > 0) {
1314 1314 char *tmp_name = left;
1315 1315 struct var_sym_list *tmp_vsl = left_vsl;
1316 1316 struct expression *tmp_expr = left_expr;
1317 1317
1318 1318 left = right;
1319 1319 left_vsl = right_vsl;
1320 1320 left_expr = right_expr;
1321 1321 right = tmp_name;
1322 1322 right_vsl = tmp_vsl;
1323 1323 right_expr = tmp_expr;
1324 1324 op = flip_comparison(op);
1325 1325 false_op = flip_comparison(false_op);
1326 1326 }
1327 1327
1328 1328 orig_comparison = get_comparison(left_expr, right_expr);
1329 1329 op = comparison_intersection(orig_comparison, op);
1330 1330 false_op = comparison_intersection(orig_comparison, false_op);
1331 1331
1332 1332 snprintf(state_name, sizeof(state_name), "%s vs %s", left, right);
1333 1333 true_state = alloc_compare_state(
1334 1334 left_expr, left, left_vsl,
1335 1335 op,
1336 1336 right_expr, right, right_vsl);
1337 1337 false_state = alloc_compare_state(
1338 1338 left_expr, left, left_vsl,
1339 1339 false_op,
1340 1340 right_expr, right, right_vsl);
1341 1341
1342 1342 pre_stree = clone_stree(__get_cur_stree());
1343 1343 update_tf_data(pre_stree, left_expr, left, left_vsl, right_expr, right, right_vsl, op, false_op);
1344 1344 free_stree(&pre_stree);
1345 1345
1346 1346 set_true_false_states(comparison_id, state_name, NULL, true_state, false_state);
1347 1347 __compare_param_limit_hook(left_expr, right_expr, state_name, true_state, false_state);
1348 1348 save_link(left_expr, state_name);
1349 1349 save_link(right_expr, state_name);
1350 1350
1351 1351 if (_false_state)
1352 1352 *_false_state = false_state;
1353 1353 if (_state_name)
1354 1354 *_state_name = state_name;
1355 1355 free:
1356 1356 free_string(left);
1357 1357 free_string(right);
1358 1358 }
1359 1359
1360 1360 void __comparison_match_condition(struct expression *expr)
1361 1361 {
1362 1362 struct expression *left, *right, *new_left, *new_right, *tmp;
1363 1363 struct smatch_state *false_state = NULL;
1364 1364 char *state_name = NULL;
1365 1365 int redo, count;
1366 1366
1367 1367 if (expr->type != EXPR_COMPARE)
1368 1368 return;
1369 1369
1370 1370 handle_comparison(expr->left, expr->op, expr->right, &state_name, &false_state);
1371 1371 if (false_state && state_name)
1372 1372 handle_for_loops(expr, state_name, false_state);
1373 1373
1374 1374 left = strip_parens(expr->left);
1375 1375 right = strip_parens(expr->right);
1376 1376
1377 1377 if (left->type == EXPR_BINOP && left->op == '+') {
1378 1378 new_left = left->left;
1379 1379 new_right = binop_expression(right, '-', left->right);
1380 1380 handle_comparison(new_left, expr->op, new_right, NULL, NULL);
1381 1381
1382 1382 new_left = left->right;
1383 1383 new_right = binop_expression(right, '-', left->left);
1384 1384 handle_comparison(new_left, expr->op, new_right, NULL, NULL);
1385 1385 }
1386 1386
1387 1387 redo = 0;
1388 1388 left = strip_parens(expr->left);
1389 1389 right = strip_parens(expr->right);
1390 1390 if (get_last_expr_from_expression_stmt(expr->left)) {
1391 1391 left = get_last_expr_from_expression_stmt(expr->left);
1392 1392 redo = 1;
1393 1393 }
1394 1394 if (get_last_expr_from_expression_stmt(expr->right)) {
1395 1395 right = get_last_expr_from_expression_stmt(expr->right);
1396 1396 redo = 1;
1397 1397 }
1398 1398
1399 1399 if (!redo)
1400 1400 return;
1401 1401
1402 1402 count = 0;
1403 1403 while ((tmp = get_assigned_expr(left))) {
1404 1404 if (count++ > 3)
1405 1405 break;
1406 1406 left = strip_expr(tmp);
1407 1407 }
1408 1408 count = 0;
1409 1409 while ((tmp = get_assigned_expr(right))) {
1410 1410 if (count++ > 3)
1411 1411 break;
1412 1412 right = strip_expr(tmp);
1413 1413 }
1414 1414
1415 1415 handle_comparison(left, expr->op, right, NULL, NULL);
1416 1416 }
1417 1417
1418 1418 static void add_comparison_var_sym(
1419 1419 struct expression *left_expr,
1420 1420 const char *left_name, struct var_sym_list *left_vsl,
1421 1421 int comparison,
1422 1422 struct expression *right_expr,
1423 1423 const char *right_name, struct var_sym_list *right_vsl)
1424 1424 {
1425 1425 struct smatch_state *state;
1426 1426 struct var_sym *vs;
1427 1427 char state_name[256];
1428 1428
1429 1429 if (strcmp(left_name, right_name) > 0) {
1430 1430 struct expression *tmp_expr = left_expr;
1431 1431 const char *tmp_name = left_name;
1432 1432 struct var_sym_list *tmp_vsl = left_vsl;
1433 1433
1434 1434 left_expr = right_expr;
1435 1435 left_name = right_name;
1436 1436 left_vsl = right_vsl;
1437 1437 right_expr = tmp_expr;
1438 1438 right_name = tmp_name;
1439 1439 right_vsl = tmp_vsl;
1440 1440 comparison = flip_comparison(comparison);
1441 1441 }
1442 1442 snprintf(state_name, sizeof(state_name), "%s vs %s", left_name, right_name);
1443 1443 state = alloc_compare_state(
1444 1444 left_expr, left_name, left_vsl,
1445 1445 comparison,
1446 1446 right_expr, right_name, right_vsl);
1447 1447
1448 1448 set_state(comparison_id, state_name, NULL, state);
1449 1449
1450 1450 FOR_EACH_PTR(left_vsl, vs) {
1451 1451 save_link_var_sym(vs->var, vs->sym, state_name);
1452 1452 } END_FOR_EACH_PTR(vs);
1453 1453 FOR_EACH_PTR(right_vsl, vs) {
1454 1454 save_link_var_sym(vs->var, vs->sym, state_name);
1455 1455 } END_FOR_EACH_PTR(vs);
1456 1456 }
1457 1457
1458 1458 static void add_comparison(struct expression *left, int comparison, struct expression *right)
1459 1459 {
1460 1460 char *left_name = NULL;
1461 1461 char *right_name = NULL;
1462 1462 struct symbol *left_sym, *right_sym;
1463 1463 struct var_sym_list *left_vsl, *right_vsl;
1464 1464 struct smatch_state *state;
1465 1465 char state_name[256];
1466 1466
1467 1467 left_name = chunk_to_var_sym(left, &left_sym);
1468 1468 if (!left_name)
1469 1469 goto free;
1470 1470 left_vsl = expr_to_vsl(left);
1471 1471 right_name = chunk_to_var_sym(right, &right_sym);
1472 1472 if (!right_name)
1473 1473 goto free;
1474 1474 right_vsl = expr_to_vsl(right);
1475 1475
1476 1476 if (strcmp(left_name, right_name) > 0) {
1477 1477 struct expression *tmp_expr = left;
1478 1478 struct symbol *tmp_sym = left_sym;
1479 1479 char *tmp_name = left_name;
1480 1480 struct var_sym_list *tmp_vsl = left_vsl;
1481 1481
1482 1482 left = right;
1483 1483 left_name = right_name;
1484 1484 left_sym = right_sym;
1485 1485 left_vsl = right_vsl;
1486 1486 right = tmp_expr;
1487 1487 right_name = tmp_name;
1488 1488 right_sym = tmp_sym;
1489 1489 right_vsl = tmp_vsl;
1490 1490 comparison = flip_comparison(comparison);
1491 1491 }
1492 1492 snprintf(state_name, sizeof(state_name), "%s vs %s", left_name, right_name);
1493 1493 state = alloc_compare_state(
1494 1494 left, left_name, left_vsl,
1495 1495 comparison,
1496 1496 right, right_name, right_vsl);
1497 1497
1498 1498 set_state(comparison_id, state_name, NULL, state);
1499 1499 save_link(left, state_name);
1500 1500 save_link(right, state_name);
1501 1501
1502 1502 free:
1503 1503 free_string(left_name);
1504 1504 free_string(right_name);
1505 1505 }
1506 1506
1507 1507 static void match_assign_add(struct expression *expr)
1508 1508 {
1509 1509 struct expression *right;
1510 1510 struct expression *r_left, *r_right;
1511 1511 sval_t left_tmp, right_tmp;
1512 1512
1513 1513 right = strip_expr(expr->right);
1514 1514 r_left = strip_expr(right->left);
1515 1515 r_right = strip_expr(right->right);
1516 1516
1517 1517 get_absolute_min(r_left, &left_tmp);
1518 1518 get_absolute_min(r_right, &right_tmp);
1519 1519
1520 1520 if (left_tmp.value > 0)
1521 1521 add_comparison(expr->left, '>', r_right);
1522 1522 else if (left_tmp.value == 0)
1523 1523 add_comparison(expr->left, SPECIAL_GTE, r_right);
1524 1524
1525 1525 if (right_tmp.value > 0)
1526 1526 add_comparison(expr->left, '>', r_left);
1527 1527 else if (right_tmp.value == 0)
1528 1528 add_comparison(expr->left, SPECIAL_GTE, r_left);
1529 1529 }
1530 1530
1531 1531 static void match_assign_sub(struct expression *expr)
1532 1532 {
1533 1533 struct expression *right;
1534 1534 struct expression *r_left, *r_right;
1535 1535 int comparison;
1536 1536 sval_t min;
1537 1537
1538 1538 right = strip_expr(expr->right);
1539 1539 r_left = strip_expr(right->left);
1540 1540 r_right = strip_expr(right->right);
1541 1541
1542 1542 if (get_absolute_min(r_right, &min) && sval_is_negative(min))
1543 1543 return;
1544 1544
1545 1545 comparison = get_comparison(r_left, r_right);
1546 1546
1547 1547 switch (comparison) {
1548 1548 case '>':
1549 1549 case SPECIAL_GTE:
1550 1550 if (implied_not_equal(r_right, 0))
1551 1551 add_comparison(expr->left, '>', r_left);
1552 1552 else
1553 1553 add_comparison(expr->left, SPECIAL_GTE, r_left);
1554 1554 return;
1555 1555 }
1556 1556 }
1557 1557
1558 1558 static void match_assign_divide(struct expression *expr)
1559 1559 {
1560 1560 struct expression *right;
1561 1561 struct expression *r_left, *r_right;
1562 1562 sval_t min;
1563 1563
1564 1564 right = strip_expr(expr->right);
1565 1565 r_left = strip_expr(right->left);
1566 1566 r_right = strip_expr(right->right);
1567 1567 if (!get_implied_min(r_right, &min) || min.value <= 1)
1568 1568 return;
1569 1569
1570 1570 add_comparison(expr->left, '<', r_left);
1571 1571 }
1572 1572
1573 1573 static void match_binop_assign(struct expression *expr)
1574 1574 {
1575 1575 struct expression *right;
1576 1576
1577 1577 right = strip_expr(expr->right);
1578 1578 if (right->op == '+')
1579 1579 match_assign_add(expr);
1580 1580 if (right->op == '-')
1581 1581 match_assign_sub(expr);
1582 1582 if (right->op == '/')
1583 1583 match_assign_divide(expr);
1584 1584 }
1585 1585
1586 1586 static void copy_comparisons(struct expression *left, struct expression *right)
1587 1587 {
1588 1588 struct string_list *links;
1589 1589 struct smatch_state *state;
1590 1590 struct compare_data *data;
1591 1591 struct symbol *left_sym, *right_sym;
1592 1592 char *left_var = NULL;
1593 1593 char *right_var = NULL;
1594 1594 struct var_sym_list *left_vsl;
1595 1595 struct expression *expr;
1596 1596 const char *var;
1597 1597 struct var_sym_list *vsl;
1598 1598 int comparison;
1599 1599 char *tmp;
1600 1600
1601 1601 left_var = chunk_to_var_sym(left, &left_sym);
1602 1602 if (!left_var)
1603 1603 goto done;
1604 1604 left_vsl = expr_to_vsl(left);
1605 1605 right_var = chunk_to_var_sym(right, &right_sym);
1606 1606 if (!right_var)
1607 1607 goto done;
1608 1608
1609 1609 state = get_state(link_id, right_var, right_sym);
1610 1610 if (!state)
1611 1611 return;
1612 1612 links = state->data;
1613 1613
1614 1614 FOR_EACH_PTR(links, tmp) {
1615 1615 state = get_state(comparison_id, tmp, NULL);
1616 1616 if (!state || !state->data)
1617 1617 continue;
1618 1618 data = state->data;
1619 1619 comparison = data->comparison;
1620 1620 expr = data->right;
1621 1621 var = data->right_var;
1622 1622 vsl = data->right_vsl;
1623 1623 if (strcmp(var, right_var) == 0) {
1624 1624 expr = data->left;
1625 1625 var = data->left_var;
1626 1626 vsl = data->left_vsl;
1627 1627 comparison = flip_comparison(comparison);
1628 1628 }
1629 1629 /* n = copy_from_user(dest, src, n); leads to n <= n which is nonsense */
1630 1630 if (strcmp(left_var, var) == 0)
1631 1631 continue;
1632 1632 add_comparison_var_sym(left, left_var, left_vsl, comparison, expr, var, vsl);
1633 1633 } END_FOR_EACH_PTR(tmp);
1634 1634
1635 1635 done:
1636 1636 free_string(right_var);
1637 1637 }
1638 1638
1639 1639 static void match_assign(struct expression *expr)
1640 1640 {
1641 1641 struct expression *right;
1642 1642
1643 1643 if (expr->op != '=')
1644 1644 return;
1645 1645 if (__in_fake_assign || outside_of_function())
1646 1646 return;
1647 1647
1648 1648 if (is_struct(expr->left))
1649 1649 return;
1650 1650
1651 1651 if (is_self_assign(expr))
1652 1652 return;
1653 1653
1654 1654 copy_comparisons(expr->left, expr->right);
1655 1655 add_comparison(expr->left, SPECIAL_EQUAL, expr->right);
1656 1656
1657 1657 right = strip_expr(expr->right);
1658 1658 if (right->type == EXPR_BINOP)
1659 1659 match_binop_assign(expr);
1660 1660 }
1661 1661
1662 1662 int get_comparison_strings(const char *one, const char *two)
1663 1663 {
1664 1664 char buf[256];
1665 1665 struct smatch_state *state;
1666 1666 int invert = 0;
1667 1667 int ret = 0;
1668 1668
1669 1669 if (!one || !two)
1670 1670 return UNKNOWN_COMPARISON;
1671 1671
1672 1672 if (strcmp(one, two) == 0)
1673 1673 return SPECIAL_EQUAL;
1674 1674
1675 1675 if (strcmp(one, two) > 0) {
1676 1676 const char *tmp = one;
1677 1677
1678 1678 one = two;
1679 1679 two = tmp;
1680 1680 invert = 1;
1681 1681 }
1682 1682
1683 1683 snprintf(buf, sizeof(buf), "%s vs %s", one, two);
1684 1684 state = get_state(comparison_id, buf, NULL);
1685 1685 if (state)
1686 1686 ret = state_to_comparison(state);
1687 1687
1688 1688 if (invert)
1689 1689 ret = flip_comparison(ret);
1690 1690
1691 1691 return ret;
1692 1692 }
1693 1693
1694 1694 static int get_comparison_helper(struct expression *a, struct expression *b, bool use_extra)
1695 1695 {
1696 1696 char *one = NULL;
1697 1697 char *two = NULL;
1698 1698 int ret = UNKNOWN_COMPARISON;
1699 1699 int extra = UNKNOWN_COMPARISON;
1700 1700
1701 1701 if (a == UNKNOWN_COMPARISON ||
1702 1702 b == UNKNOWN_COMPARISON)
1703 1703 return UNKNOWN_COMPARISON;
1704 1704
1705 1705 a = strip_parens(a);
1706 1706 b = strip_parens(b);
1707 1707
1708 1708 move_plus_to_minus(&a, &b);
1709 1709
1710 1710 one = chunk_to_var(a);
1711 1711 if (!one)
1712 1712 goto free;
1713 1713 two = chunk_to_var(b);
1714 1714 if (!two)
1715 1715 goto free;
1716 1716
1717 1717 ret = get_comparison_strings(one, two);
1718 1718 if (ret)
1719 1719 goto free;
1720 1720
1721 1721 if (is_plus_one(a) || is_minus_one(a)) {
1722 1722 free_string(one);
1723 1723 one = chunk_to_var(a->left);
1724 1724 ret = get_comparison_strings(one, two);
1725 1725 } else if (is_plus_one(b) || is_minus_one(b)) {
1726 1726 free_string(two);
1727 1727 two = chunk_to_var(b->left);
1728 1728 ret = get_comparison_strings(one, two);
1729 1729 }
1730 1730
1731 1731 if (ret == UNKNOWN_COMPARISON)
1732 1732 goto free;
1733 1733
1734 1734 if ((is_plus_one(a) || is_minus_one(b)) && ret == '<')
1735 1735 ret = SPECIAL_LTE;
1736 1736 else if ((is_minus_one(a) || is_plus_one(b)) && ret == '>')
1737 1737 ret = SPECIAL_GTE;
1738 1738 else
1739 1739 ret = UNKNOWN_COMPARISON;
1740 1740
1741 1741 free:
1742 1742 free_string(one);
1743 1743 free_string(two);
1744 1744
1745 1745 extra = comparison_from_extra(a, b);
1746 1746 return comparison_intersection(ret, extra);
1747 1747 }
1748 1748
1749 1749 int get_comparison(struct expression *a, struct expression *b)
1750 1750 {
1751 1751 return get_comparison_helper(a, b, true);
1752 1752 }
1753 1753
1754 1754 int get_comparison_no_extra(struct expression *a, struct expression *b)
1755 1755 {
1756 1756 return get_comparison_helper(a, b, false);
1757 1757 }
1758 1758
1759 1759 int possible_comparison(struct expression *a, int comparison, struct expression *b)
1760 1760 {
1761 1761 char *one = NULL;
1762 1762 char *two = NULL;
1763 1763 int ret = 0;
1764 1764 char buf[256];
1765 1765 struct sm_state *sm;
1766 1766 int saved;
1767 1767
1768 1768 one = chunk_to_var(a);
1769 1769 if (!one)
1770 1770 goto free;
1771 1771 two = chunk_to_var(b);
1772 1772 if (!two)
1773 1773 goto free;
1774 1774
1775 1775
1776 1776 if (strcmp(one, two) == 0 && comparison == SPECIAL_EQUAL) {
1777 1777 ret = 1;
1778 1778 goto free;
1779 1779 }
1780 1780
1781 1781 if (strcmp(one, two) > 0) {
1782 1782 char *tmp = one;
1783 1783
1784 1784 one = two;
1785 1785 two = tmp;
1786 1786 comparison = flip_comparison(comparison);
1787 1787 }
1788 1788
1789 1789 snprintf(buf, sizeof(buf), "%s vs %s", one, two);
1790 1790 sm = get_sm_state(comparison_id, buf, NULL);
1791 1791 if (!sm)
1792 1792 goto free;
1793 1793
1794 1794 FOR_EACH_PTR(sm->possible, sm) {
1795 1795 if (!sm->state->data)
1796 1796 continue;
1797 1797 saved = ((struct compare_data *)sm->state->data)->comparison;
1798 1798 if (saved == comparison)
1799 1799 ret = 1;
1800 1800 if (comparison == SPECIAL_EQUAL &&
1801 1801 (saved == SPECIAL_LTE ||
1802 1802 saved == SPECIAL_GTE ||
1803 1803 saved == SPECIAL_UNSIGNED_LTE ||
1804 1804 saved == SPECIAL_UNSIGNED_GTE))
1805 1805 ret = 1;
1806 1806 if (ret == 1)
1807 1807 goto free;
1808 1808 } END_FOR_EACH_PTR(sm);
1809 1809
1810 1810 return ret;
1811 1811 free:
1812 1812 free_string(one);
1813 1813 free_string(two);
1814 1814 return ret;
1815 1815 }
1816 1816
1817 1817 struct state_list *get_all_comparisons(struct expression *expr)
1818 1818 {
1819 1819 struct smatch_state *state;
1820 1820 struct string_list *links;
1821 1821 struct state_list *ret = NULL;
1822 1822 struct sm_state *sm;
1823 1823 char *tmp;
1824 1824
1825 1825 state = get_state_chunk(link_id, expr);
1826 1826 if (!state)
1827 1827 return NULL;
1828 1828 links = state->data;
1829 1829
1830 1830 FOR_EACH_PTR(links, tmp) {
1831 1831 sm = get_sm_state(comparison_id, tmp, NULL);
1832 1832 if (!sm)
1833 1833 continue;
1834 1834 // FIXME have to compare name with vsl
1835 1835 add_ptr_list(&ret, sm);
1836 1836 } END_FOR_EACH_PTR(tmp);
1837 1837
1838 1838 return ret;
1839 1839 }
1840 1840
1841 1841 struct state_list *get_all_possible_equal_comparisons(struct expression *expr)
1842 1842 {
1843 1843 struct smatch_state *state;
1844 1844 struct string_list *links;
1845 1845 struct state_list *ret = NULL;
1846 1846 struct sm_state *sm;
1847 1847 char *tmp;
1848 1848
1849 1849 state = get_state_chunk(link_id, expr);
1850 1850 if (!state)
1851 1851 return NULL;
1852 1852 links = state->data;
1853 1853
1854 1854 FOR_EACH_PTR(links, tmp) {
1855 1855 sm = get_sm_state(comparison_id, tmp, NULL);
1856 1856 if (!sm)
1857 1857 continue;
1858 1858 if (!strchr(sm->state->name, '='))
1859 1859 continue;
1860 1860 if (strcmp(sm->state->name, "!=") == 0)
1861 1861 continue;
1862 1862 add_ptr_list(&ret, sm);
1863 1863 } END_FOR_EACH_PTR(tmp);
1864 1864
1865 1865 return ret;
1866 1866 }
1867 1867
1868 1868 struct state_list *get_all_possible_not_equal_comparisons(struct expression *expr)
1869 1869 {
1870 1870 struct smatch_state *state;
1871 1871 struct string_list *links;
1872 1872 struct state_list *ret = NULL;
1873 1873 struct sm_state *sm;
1874 1874 struct sm_state *possible;
1875 1875 char *link;
1876 1876
1877 1877 return NULL;
1878 1878
1879 1879 state = get_state_chunk(link_id, expr);
1880 1880 if (!state)
1881 1881 return NULL;
1882 1882 links = state->data;
1883 1883
1884 1884 FOR_EACH_PTR(links, link) {
1885 1885 sm = get_sm_state(comparison_id, link, NULL);
1886 1886 if (!sm)
1887 1887 continue;
1888 1888 FOR_EACH_PTR(sm->possible, possible) {
1889 1889 if (strcmp(possible->state->name, "!=") != 0)
1890 1890 continue;
1891 1891 add_ptr_list(&ret, sm);
1892 1892 break;
1893 1893 } END_FOR_EACH_PTR(link);
1894 1894 } END_FOR_EACH_PTR(link);
1895 1895
1896 1896 return ret;
1897 1897 }
1898 1898
1899 1899 static void update_links_from_call(struct expression *left,
1900 1900 int left_compare,
1901 1901 struct expression *right)
1902 1902 {
1903 1903 struct string_list *links;
1904 1904 struct smatch_state *state;
1905 1905 struct compare_data *data;
1906 1906 struct symbol *left_sym, *right_sym;
1907 1907 char *left_var = NULL;
1908 1908 char *right_var = NULL;
1909 1909 struct var_sym_list *left_vsl;
1910 1910 struct expression *expr;
1911 1911 const char *var;
1912 1912 struct var_sym_list *vsl;
1913 1913 int comparison;
1914 1914 char *tmp;
1915 1915
1916 1916 left_var = chunk_to_var_sym(left, &left_sym);
1917 1917 if (!left_var)
1918 1918 goto done;
1919 1919 left_vsl = expr_to_vsl(left);
1920 1920 right_var = chunk_to_var_sym(right, &right_sym);
1921 1921 if (!right_var)
1922 1922 goto done;
1923 1923
1924 1924 state = get_state(link_id, right_var, right_sym);
1925 1925 if (!state)
1926 1926 return;
1927 1927 links = state->data;
1928 1928
1929 1929 FOR_EACH_PTR(links, tmp) {
1930 1930 state = get_state(comparison_id, tmp, NULL);
1931 1931 if (!state || !state->data)
1932 1932 continue;
1933 1933 data = state->data;
1934 1934 comparison = data->comparison;
1935 1935 expr = data->right;
1936 1936 var = data->right_var;
1937 1937 vsl = data->right_vsl;
1938 1938 if (strcmp(var, right_var) == 0) {
1939 1939 expr = data->left;
1940 1940 var = data->left_var;
1941 1941 vsl = data->left_vsl;
1942 1942 comparison = flip_comparison(comparison);
1943 1943 }
1944 1944 comparison = combine_comparisons(left_compare, comparison);
1945 1945 if (!comparison)
1946 1946 continue;
1947 1947 add_comparison_var_sym(left, left_var, left_vsl, comparison, expr, var, vsl);
1948 1948 } END_FOR_EACH_PTR(tmp);
1949 1949
1950 1950 done:
1951 1951 free_string(right_var);
1952 1952 }
1953 1953
1954 1954 void __add_return_comparison(struct expression *call, const char *range)
1955 1955 {
1956 1956 struct expression *arg;
1957 1957 int comparison;
1958 1958 char buf[16];
1959 1959
1960 1960 if (!str_to_comparison_arg(range, call, &comparison, &arg))
1961 1961 return;
1962 1962 snprintf(buf, sizeof(buf), "%s", show_comparison(comparison));
1963 1963 update_links_from_call(call, comparison, arg);
1964 1964 add_comparison(call, comparison, arg);
1965 1965 }
1966 1966
1967 1967 void __add_comparison_info(struct expression *expr, struct expression *call, const char *range)
1968 1968 {
1969 1969 copy_comparisons(expr, call);
1970 1970 }
1971 1971
1972 1972 static char *get_mask_comparison(struct expression *expr, int ignore)
1973 1973 {
1974 1974 struct expression *tmp, *right;
1975 1975 int count, param;
1976 1976 char buf[256];
1977 1977
1978 1978 /* The return value for "return foo & param;" is <= param */
1979 1979
1980 1980 count = 0;
1981 1981 while ((tmp = get_assigned_expr(expr))) {
1982 1982 expr = strip_expr(tmp);
1983 1983 if (count++ > 4)
1984 1984 break;
1985 1985 }
1986 1986
1987 1987 if (expr->type != EXPR_BINOP || expr->op != '&')
1988 1988 return NULL;
1989 1989
1990 1990 right = strip_expr(expr->right);
1991 1991 param = get_param_num(right);
1992 1992 if (param < 0 || param == ignore)
1993 1993 return NULL;
1994 1994
1995 1995 snprintf(buf, sizeof(buf), "[<=$%d]", param);
1996 1996 return alloc_sname(buf);
1997 1997 }
1998 1998
1999 1999 static char *range_comparison_to_param_helper(struct expression *expr, char starts_with, int ignore)
2000 2000 {
2001 2001 struct symbol *param;
2002 2002 char *var = NULL;
2003 2003 char buf[256];
2004 2004 char *ret_str = NULL;
2005 2005 int compare;
2006 2006 int i;
2007 2007
2008 2008 if (!expr)
2009 2009 return NULL;
2010 2010
2011 2011 var = chunk_to_var(expr);
2012 2012 if (!var)
2013 2013 goto try_mask;
2014 2014
2015 2015 i = -1;
2016 2016 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
2017 2017 i++;
2018 2018 if (i == ignore)
2019 2019 continue;
2020 2020 if (!param->ident)
2021 2021 continue;
2022 2022 snprintf(buf, sizeof(buf), "%s orig", param->ident->name);
2023 2023 compare = get_comparison_strings(var, buf);
2024 2024 if (compare == UNKNOWN_COMPARISON ||
2025 2025 compare == IMPOSSIBLE_COMPARISON)
2026 2026 continue;
2027 2027 if (show_comparison(compare)[0] != starts_with)
2028 2028 continue;
2029 2029 snprintf(buf, sizeof(buf), "[%s$%d]", show_comparison(compare), i);
2030 2030 ret_str = alloc_sname(buf);
2031 2031 break;
2032 2032 } END_FOR_EACH_PTR(param);
2033 2033
2034 2034 free_string(var);
2035 2035 if (!ret_str)
2036 2036 goto try_mask;
2037 2037
2038 2038 return ret_str;
2039 2039
2040 2040 try_mask:
2041 2041 if (starts_with == '<')
2042 2042 ret_str = get_mask_comparison(expr, ignore);
2043 2043 return ret_str;
2044 2044 }
2045 2045
2046 2046 char *name_sym_to_param_comparison(const char *name, struct symbol *sym)
2047 2047 {
2048 2048 struct symbol *param;
2049 2049 char buf[256];
2050 2050 int compare;
2051 2051 int i;
2052 2052
2053 2053 i = -1;
2054 2054 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
2055 2055 i++;
2056 2056 if (!param->ident)
2057 2057 continue;
2058 2058 snprintf(buf, sizeof(buf), "%s orig", param->ident->name);
2059 2059 compare = get_comparison_strings(name, buf);
2060 2060 if (compare == UNKNOWN_COMPARISON ||
2061 2061 compare == IMPOSSIBLE_COMPARISON)
2062 2062 continue;
2063 2063 snprintf(buf, sizeof(buf), "[%s$%d]", show_comparison(compare), i);
2064 2064 return alloc_sname(buf);
2065 2065 } END_FOR_EACH_PTR(param);
2066 2066
2067 2067 return NULL;
2068 2068 }
2069 2069
2070 2070 char *expr_equal_to_param(struct expression *expr, int ignore)
2071 2071 {
2072 2072 return range_comparison_to_param_helper(expr, '=', ignore);
2073 2073 }
2074 2074
2075 2075 char *expr_lte_to_param(struct expression *expr, int ignore)
2076 2076 {
2077 2077 return range_comparison_to_param_helper(expr, '<', ignore);
2078 2078 }
2079 2079
2080 2080 char *expr_param_comparison(struct expression *expr, int ignore)
2081 2081 {
2082 2082 struct symbol *param;
2083 2083 char *var = NULL;
2084 2084 char buf[256];
2085 2085 char *ret_str = NULL;
2086 2086 int compare;
2087 2087 int i;
2088 2088
2089 2089 var = chunk_to_var(expr);
2090 2090 if (!var)
2091 2091 goto free;
2092 2092
2093 2093 i = -1;
2094 2094 FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, param) {
2095 2095 i++;
2096 2096 if (i == ignore)
2097 2097 continue;
2098 2098 if (!param->ident)
2099 2099 continue;
2100 2100 snprintf(buf, sizeof(buf), "%s orig", param->ident->name);
2101 2101 compare = get_comparison_strings(var, buf);
2102 2102 if (!compare)
2103 2103 continue;
2104 2104 snprintf(buf, sizeof(buf), "[%s$%d]", show_comparison(compare), i);
2105 2105 ret_str = alloc_sname(buf);
2106 2106 break;
2107 2107 } END_FOR_EACH_PTR(param);
2108 2108
2109 2109 free:
2110 2110 free_string(var);
2111 2111 return ret_str;
2112 2112 }
2113 2113
2114 2114 char *get_printed_param_name(struct expression *call, const char *param_name, struct symbol *param_sym)
2115 2115 {
2116 2116 struct expression *arg;
2117 2117 char *name;
2118 2118 struct symbol *sym;
2119 2119 static char buf[256];
2120 2120 int len;
2121 2121 int i;
2122 2122
2123 2123 i = -1;
2124 2124 FOR_EACH_PTR(call->args, arg) {
2125 2125 i++;
2126 2126
2127 2127 name = expr_to_var_sym(arg, &sym);
2128 2128 if (!name || !sym)
2129 2129 continue;
2130 2130 if (sym != param_sym)
2131 2131 continue;
2132 2132
2133 2133 len = strlen(name);
2134 2134 if (strncmp(name, param_name, len) != 0)
2135 2135 continue;
2136 2136 if (param_name[len] == '\0') {
2137 2137 snprintf(buf, sizeof(buf), "$%d", i);
2138 2138 return buf;
2139 2139 }
2140 2140 if (param_name[len] != '-')
2141 2141 continue;
2142 2142 snprintf(buf, sizeof(buf), "$%d%s", i, param_name + len);
2143 2143 return buf;
2144 2144 } END_FOR_EACH_PTR(arg);
2145 2145
2146 2146 return NULL;
2147 2147 }
2148 2148
2149 2149 static void match_call_info(struct expression *expr)
2150 2150 {
2151 2151 struct expression *arg;
2152 2152 struct smatch_state *state;
2153 2153 struct sm_state *sm;
2154 2154 struct compare_data *data;
2155 2155 int comparison;
2156 2156 struct string_list *links;
2157 2157 char *arg_name;
2158 2158 const char *right_name;
2159 2159 char *link;
2160 2160 char info_buf[256];
2161 2161 int i;
2162 2162
2163 2163 i = -1;
2164 2164 FOR_EACH_PTR(expr->args, arg) {
2165 2165 i++;
2166 2166
2167 2167 state = get_state_chunk(link_id, arg);
2168 2168 if (!state)
2169 2169 continue;
2170 2170
2171 2171 links = state->data;
2172 2172 FOR_EACH_PTR(links, link) {
2173 2173 struct var_sym_list *right_vsl;
2174 2174 struct var_sym *right_vs;
2175 2175
2176 2176
2177 2177 if (strstr(link, " orig"))
2178 2178 continue;
2179 2179 sm = get_sm_state(comparison_id, link, NULL);
2180 2180 if (!sm)
2181 2181 continue;
2182 2182 data = sm->state->data;
2183 2183 if (!data ||
2184 2184 data->comparison == UNKNOWN_COMPARISON ||
2185 2185 data->comparison == IMPOSSIBLE_COMPARISON)
2186 2186 continue;
2187 2187 arg_name = expr_to_var(arg);
2188 2188 if (!arg_name)
2189 2189 continue;
2190 2190
2191 2191 right_vsl = NULL;
2192 2192 if (strcmp(data->left_var, arg_name) == 0) {
2193 2193 comparison = data->comparison;
2194 2194 right_name = data->right_var;
2195 2195 right_vsl = data->right_vsl;
2196 2196 } else if (strcmp(data->right_var, arg_name) == 0) {
2197 2197 comparison = flip_comparison(data->comparison);
2198 2198 right_name = data->left_var;
2199 2199 right_vsl = data->left_vsl;
2200 2200 }
2201 2201 if (!right_vsl || ptr_list_size((struct ptr_list *)right_vsl) != 1)
2202 2202 goto free;
2203 2203
2204 2204 right_vs = first_ptr_list((struct ptr_list *)right_vsl);
2205 2205 if (strcmp(right_vs->var, right_name) != 0)
2206 2206 goto free;
2207 2207 right_name = get_printed_param_name(expr, right_vs->var, right_vs->sym);
2208 2208 if (!right_name)
2209 2209 goto free;
2210 2210 snprintf(info_buf, sizeof(info_buf), "%s %s", show_comparison(comparison), right_name);
2211 2211 sql_insert_caller_info(expr, PARAM_COMPARE, i, "$", info_buf);
2212 2212
2213 2213 free:
2214 2214 free_string(arg_name);
2215 2215 } END_FOR_EACH_PTR(link);
2216 2216 } END_FOR_EACH_PTR(arg);
2217 2217 }
2218 2218
2219 2219 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *link_sm)
2220 2220 {
2221 2221 struct sm_state *compare_sm;
2222 2222 struct string_list *links;
2223 2223 char *link;
2224 2224 struct compare_data *data;
2225 2225 struct var_sym *left, *right;
2226 2226 static char info_buf[256];
2227 2227 const char *right_name;
2228 2228
2229 2229 if (strstr(printed_name, " orig"))
2230 2230 return;
2231 2231
2232 2232 links = link_sm->state->data;
2233 2233 FOR_EACH_PTR(links, link) {
2234 2234 compare_sm = get_sm_state(comparison_id, link, NULL);
2235 2235 if (!compare_sm)
2236 2236 continue;
2237 2237 data = compare_sm->state->data;
2238 2238 if (!data || !data->comparison)
2239 2239 continue;
2240 2240
2241 2241 if (ptr_list_size((struct ptr_list *)data->left_vsl) != 1 ||
2242 2242 ptr_list_size((struct ptr_list *)data->right_vsl) != 1)
2243 2243 continue;
2244 2244 left = first_ptr_list((struct ptr_list *)data->left_vsl);
2245 2245 right = first_ptr_list((struct ptr_list *)data->right_vsl);
2246 2246 if (left->sym == right->sym &&
2247 2247 strcmp(left->var, right->var) == 0)
2248 2248 continue;
2249 2249 /*
2250 2250 * Both parameters link to this comparison so only
2251 2251 * record the first one.
2252 2252 */
2253 2253 if (left->sym != link_sm->sym ||
2254 2254 strcmp(left->var, link_sm->name) != 0)
2255 2255 continue;
2256 2256
2257 2257 right_name = get_printed_param_name(call, right->var, right->sym);
2258 2258 if (!right_name)
2259 2259 continue;
2260 2260 snprintf(info_buf, sizeof(info_buf), "%s %s", show_comparison(data->comparison), right_name);
2261 2261 sql_insert_caller_info(call, PARAM_COMPARE, param, printed_name, info_buf);
2262 2262 } END_FOR_EACH_PTR(link);
2263 2263 }
2264 2264
2265 2265 static void print_return_value_comparison(int return_id, char *return_ranges, struct expression *expr)
2266 2266 {
2267 2267 char *name;
2268 2268 const char *tmp_name;
2269 2269 struct symbol *sym;
2270 2270 int param;
2271 2271 char info_buf[256];
2272 2272
2273 2273 /*
2274 2274 * TODO: This only prints == comparisons. That's probably the most
2275 2275 * useful comparison because == max has lots of implications. But it
2276 2276 * would be good to capture the rest as well.
2277 2277 *
2278 2278 * This information is already in the DB but it's in the parameter math
2279 2279 * bits and it's awkward to use it. This is is the simpler, possibly
2280 2280 * cleaner way, but not necessarily the best, I don't know.
2281 2281 */
2282 2282
2283 2283 if (!expr)
2284 2284 return;
2285 2285 name = expr_to_var_sym(expr, &sym);
2286 2286 if (!name || !sym)
2287 2287 goto free;
2288 2288
2289 2289 param = get_param_num_from_sym(sym);
2290 2290 if (param < 0)
2291 2291 goto free;
2292 2292 if (param_was_set_var_sym(name, sym))
2293 2293 goto free;
2294 2294
2295 2295 tmp_name = get_param_name_var_sym(name, sym);
2296 2296 if (!tmp_name)
2297 2297 goto free;
2298 2298
2299 2299 snprintf(info_buf, sizeof(info_buf), "== $%d%s", param, tmp_name + 1);
2300 2300 sql_insert_return_states(return_id, return_ranges,
2301 2301 PARAM_COMPARE, -1, "$", info_buf);
2302 2302 free:
2303 2303 free_string(name);
2304 2304 }
2305 2305
2306 2306 static void print_return_comparison(int return_id, char *return_ranges, struct expression *expr)
2307 2307 {
2308 2308 struct sm_state *tmp;
2309 2309 struct string_list *links;
2310 2310 char *link;
2311 2311 struct sm_state *sm;
2312 2312 struct compare_data *data;
2313 2313 struct var_sym *left, *right;
2314 2314 int left_param, right_param;
2315 2315 char left_buf[256];
2316 2316 char right_buf[256];
2317 2317 char info_buf[258];
2318 2318 const char *tmp_name;
2319 2319
2320 2320 print_return_value_comparison(return_id, return_ranges, expr);
2321 2321
2322 2322 FOR_EACH_MY_SM(link_id, __get_cur_stree(), tmp) {
2323 2323 if (get_param_num_from_sym(tmp->sym) < 0)
2324 2324 continue;
2325 2325 links = tmp->state->data;
2326 2326 FOR_EACH_PTR(links, link) {
2327 2327 sm = get_sm_state(comparison_id, link, NULL);
2328 2328 if (!sm)
2329 2329 continue;
2330 2330 data = sm->state->data;
2331 2331 if (!data ||
2332 2332 data->comparison == UNKNOWN_COMPARISON ||
2333 2333 data->comparison == IMPOSSIBLE_COMPARISON)
2334 2334 continue;
2335 2335 if (ptr_list_size((struct ptr_list *)data->left_vsl) != 1 ||
2336 2336 ptr_list_size((struct ptr_list *)data->right_vsl) != 1)
2337 2337 continue;
2338 2338 left = first_ptr_list((struct ptr_list *)data->left_vsl);
2339 2339 right = first_ptr_list((struct ptr_list *)data->right_vsl);
2340 2340 if (left->sym == right->sym &&
2341 2341 strcmp(left->var, right->var) == 0)
2342 2342 continue;
2343 2343 /*
2344 2344 * Both parameters link to this comparison so only
2345 2345 * record the first one.
2346 2346 */
2347 2347 if (left->sym != tmp->sym ||
2348 2348 strcmp(left->var, tmp->name) != 0)
2349 2349 continue;
2350 2350
2351 2351 if (strstr(right->var, " orig"))
2352 2352 continue;
2353 2353
2354 2354 left_param = get_param_num_from_sym(left->sym);
2355 2355 right_param = get_param_num_from_sym(right->sym);
2356 2356 if (left_param < 0 || right_param < 0)
2357 2357 continue;
2358 2358
2359 2359 tmp_name = get_param_name_var_sym(left->var, left->sym);
2360 2360 if (!tmp_name)
2361 2361 continue;
2362 2362 snprintf(left_buf, sizeof(left_buf), "%s", tmp_name);
2363 2363
2364 2364 tmp_name = get_param_name_var_sym(right->var, right->sym);
2365 2365 if (!tmp_name || tmp_name[0] != '$')
2366 2366 continue;
2367 2367 snprintf(right_buf, sizeof(right_buf), "$%d%s", right_param, tmp_name + 1);
2368 2368
2369 2369 /*
2370 2370 * FIXME: this should reject $ type variables (as
2371 2371 * opposed to $->foo type). Those should come from
2372 2372 * smatch_param_compare_limit.c.
2373 2373 */
2374 2374
2375 2375 snprintf(info_buf, sizeof(info_buf), "%s %s", show_comparison(data->comparison), right_buf);
2376 2376 sql_insert_return_states(return_id, return_ranges,
2377 2377 PARAM_COMPARE, left_param, left_buf, info_buf);
2378 2378 } END_FOR_EACH_PTR(link);
2379 2379
2380 2380 } END_FOR_EACH_SM(tmp);
2381 2381 }
2382 2382
2383 2383 static int parse_comparison(char **value, int *op)
2384 2384 {
2385 2385
2386 2386 *op = **value;
2387 2387
2388 2388 switch (*op) {
2389 2389 case '<':
2390 2390 (*value)++;
2391 2391 if (**value == '=') {
2392 2392 (*value)++;
2393 2393 *op = SPECIAL_LTE;
2394 2394 }
2395 2395 break;
2396 2396 case '=':
2397 2397 (*value)++;
2398 2398 (*value)++;
2399 2399 *op = SPECIAL_EQUAL;
2400 2400 break;
2401 2401 case '!':
2402 2402 (*value)++;
2403 2403 (*value)++;
2404 2404 *op = SPECIAL_NOTEQUAL;
2405 2405 break;
2406 2406 case '>':
2407 2407 (*value)++;
2408 2408 if (**value == '=') {
2409 2409 (*value)++;
2410 2410 *op = SPECIAL_GTE;
2411 2411 }
2412 2412 break;
2413 2413 default:
2414 2414 return 0;
2415 2415 }
2416 2416
2417 2417 if (**value != ' ') {
2418 2418 sm_perror("parsing comparison. %s", *value);
2419 2419 return 0;
2420 2420 }
2421 2421
2422 2422 (*value)++;
2423 2423 return 1;
2424 2424 }
2425 2425
2426 2426 static int split_op_param_key(char *value, int *op, int *param, char **key)
2427 2427 {
2428 2428 static char buf[256];
2429 2429 char *p;
2430 2430
2431 2431 if (!parse_comparison(&value, op))
2432 2432 return 0;
2433 2433
2434 2434 snprintf(buf, sizeof(buf), "%s", value);
2435 2435
2436 2436 p = buf;
2437 2437 if (*p++ != '$')
2438 2438 return 0;
2439 2439
2440 2440 *param = atoi(p);
2441 2441 if (*param < 0 || *param > 99)
2442 2442 return 0;
2443 2443 p++;
2444 2444 if (*param > 9)
2445 2445 p++;
2446 2446 p--;
2447 2447 *p = '$';
2448 2448 *key = p;
2449 2449
2450 2450 return 1;
2451 2451 }
2452 2452
2453 2453 static void db_return_comparison(struct expression *expr, int left_param, char *key, char *value)
2454 2454 {
2455 2455 struct expression *left_arg, *right_arg;
2456 2456 char *left_name = NULL;
2457 2457 struct symbol *left_sym;
2458 2458 char *right_name = NULL;
2459 2459 struct symbol *right_sym;
2460 2460 int op;
2461 2461 int right_param;
2462 2462 char *right_key;
2463 2463 struct var_sym_list *left_vsl = NULL, *right_vsl = NULL;
2464 2464
2465 2465 if (left_param == -1) {
2466 2466 if (expr->type != EXPR_ASSIGNMENT)
2467 2467 return;
2468 2468 left_arg = strip_expr(expr->left);
2469 2469
2470 2470 while (expr->type == EXPR_ASSIGNMENT)
2471 2471 expr = strip_expr(expr->right);
2472 2472 if (expr->type != EXPR_CALL)
2473 2473 return;
2474 2474 } else {
2475 2475 while (expr->type == EXPR_ASSIGNMENT)
2476 2476 expr = strip_expr(expr->right);
2477 2477 if (expr->type != EXPR_CALL)
2478 2478 return;
2479 2479
2480 2480 left_arg = get_argument_from_call_expr(expr->args, left_param);
2481 2481 if (!left_arg)
2482 2482 return;
2483 2483 }
2484 2484
2485 2485 if (!split_op_param_key(value, &op, &right_param, &right_key))
2486 2486 return;
2487 2487
2488 2488 right_arg = get_argument_from_call_expr(expr->args, right_param);
2489 2489 if (!right_arg)
2490 2490 return;
2491 2491
2492 2492 left_name = get_variable_from_key(left_arg, key, &left_sym);
2493 2493 if (!left_name || !left_sym)
2494 2494 goto free;
2495 2495
2496 2496 right_name = get_variable_from_key(right_arg, right_key, &right_sym);
2497 2497 if (!right_name || !right_sym)
2498 2498 goto free;
2499 2499
2500 2500 add_var_sym(&left_vsl, left_name, left_sym);
2501 2501 add_var_sym(&right_vsl, right_name, right_sym);
2502 2502
2503 2503 add_comparison_var_sym(NULL, left_name, left_vsl, op, NULL, right_name, right_vsl);
2504 2504
2505 2505 free:
2506 2506 free_string(left_name);
2507 2507 free_string(right_name);
2508 2508 }
2509 2509
2510 2510 int param_compare_limit_is_impossible(struct expression *expr, int left_param, char *left_key, char *value)
2511 2511 {
2512 2512 struct smatch_state *state;
2513 2513 char *left_name = NULL;
2514 2514 char *right_name = NULL;
2515 2515 struct symbol *left_sym, *right_sym;
2516 2516 struct expression *left_arg, *right_arg;
2517 2517 int op, state_op;
2518 2518 int right_param;
2519 2519 char *right_key;
2520 2520 int ret = 0;
2521 2521 char buf[256];
2522 2522
2523 2523 while (expr->type == EXPR_ASSIGNMENT)
2524 2524 expr = strip_expr(expr->right);
2525 2525 if (expr->type != EXPR_CALL)
2526 2526 return 0;
2527 2527
2528 2528 if (!split_op_param_key(value, &op, &right_param, &right_key))
2529 2529 return 0;
2530 2530
2531 2531 left_arg = get_argument_from_call_expr(expr->args, left_param);
2532 2532 if (!left_arg)
2533 2533 return 0;
2534 2534
2535 2535 right_arg = get_argument_from_call_expr(expr->args, right_param);
2536 2536 if (!right_arg)
2537 2537 return 0;
2538 2538
2539 2539 left_name = get_variable_from_key(left_arg, left_key, &left_sym);
2540 2540 right_name = get_variable_from_key(right_arg, right_key, &right_sym);
2541 2541 if (!left_name || !right_name)
2542 2542 goto free;
2543 2543
2544 2544 snprintf(buf, sizeof(buf), "%s vs %s", left_name, right_name);
2545 2545 state = get_state(comparison_id, buf, NULL);
2546 2546 if (!state)
2547 2547 goto free;
2548 2548 state_op = state_to_comparison(state);
2549 2549 if (!state_op)
2550 2550 goto free;
2551 2551
2552 2552 if (!comparison_intersection(remove_unsigned_from_comparison(state_op), op))
2553 2553 ret = 1;
2554 2554 free:
2555 2555 free_string(left_name);
2556 2556 free_string(right_name);
2557 2557 return ret;
2558 2558 }
2559 2559
2560 2560 int impossibly_high_comparison(struct expression *expr)
2561 2561 {
2562 2562 struct smatch_state *link_state;
2563 2563 struct sm_state *sm;
2564 2564 struct string_list *links;
2565 2565 char *link;
2566 2566 struct compare_data *data;
2567 2567
2568 2568 link_state = get_state_expr(link_id, expr);
2569 2569 if (!link_state) {
2570 2570 if (expr->type == EXPR_BINOP &&
2571 2571 (impossibly_high_comparison(expr->left) ||
2572 2572 impossibly_high_comparison(expr->right)))
2573 2573 return 1;
2574 2574 return 0;
2575 2575 }
2576 2576
2577 2577 links = link_state->data;
2578 2578 FOR_EACH_PTR(links, link) {
2579 2579 sm = get_sm_state(comparison_id, link, NULL);
2580 2580 if (!sm)
2581 2581 continue;
2582 2582 data = sm->state->data;
2583 2583 if (!data)
2584 2584 continue;
2585 2585 if (!possibly_true(data->left, data->comparison, data->right))
2586 2586 return 1;
2587 2587 } END_FOR_EACH_PTR(link);
2588 2588
2589 2589 return 0;
2590 2590 }
2591 2591
2592 2592 static void free_data(struct symbol *sym)
2593 2593 {
2594 2594 if (__inline_fn)
2595 2595 return;
2596 2596 clear_compare_data_alloc();
2597 2597 }
2598 2598
2599 2599 void register_comparison(int id)
2600 2600 {
2601 2601 comparison_id = id;
2602 2602 set_dynamic_states(comparison_id);
2603 2603 add_hook(&save_start_states, AFTER_DEF_HOOK);
2604 2604 add_unmatched_state_hook(comparison_id, unmatched_comparison);
2605 2605 add_pre_merge_hook(comparison_id, &pre_merge_hook);
2606 2606 add_merge_hook(comparison_id, &merge_compare_states);
2607 2607 add_hook(&free_data, AFTER_FUNC_HOOK);
2608 2608 add_hook(&match_call_info, FUNCTION_CALL_HOOK);
2609 2609 add_split_return_callback(&print_return_comparison);
2610 2610
2611 2611 select_return_states_hook(PARAM_COMPARE, &db_return_comparison);
2612 2612 add_hook(&match_preop, OP_HOOK);
2613 2613 }
2614 2614
2615 2615 void register_comparison_late(int id)
2616 2616 {
2617 2617 add_hook(&match_assign, ASSIGNMENT_HOOK);
2618 2618 }
2619 2619
2620 2620 void register_comparison_links(int id)
2621 2621 {
2622 2622 link_id = id;
2623 2623 db_ignore_states(link_id);
2624 2624 set_dynamic_states(link_id);
2625 2625 add_merge_hook(link_id, &merge_links);
2626 2626 add_modification_hook(link_id, &match_modify);
2627 2627 add_modification_hook_late(link_id, match_inc_dec);
2628 2628
2629 2629 add_member_info_callback(link_id, struct_member_callback);
2630 2630 }
2631 2631
2632 2632 void register_comparison_inc_dec(int id)
2633 2633 {
2634 2634 inc_dec_id = id;
2635 2635 add_modification_hook_late(inc_dec_id, &iter_modify);
2636 2636 }
2637 2637
2638 2638 void register_comparison_inc_dec_links(int id)
2639 2639 {
2640 2640 inc_dec_link_id = id;
2641 2641 set_dynamic_states(inc_dec_link_id);
2642 2642 set_up_link_functions(inc_dec_id, inc_dec_link_id);
2643 2643 }
2644 2644
2645 2645 static struct sm_state *clone_partial_sm(struct sm_state *sm, int comparison)
2646 2646 {
2647 2647 struct compare_data *data;
2648 2648 struct sm_state *clone;
2649 2649 struct stree *stree;
2650 2650
2651 2651 data = sm->state->data;
2652 2652
2653 2653 clone = clone_sm(sm);
2654 2654 clone->state = alloc_compare_state(data->left, data->left_var, data->left_vsl,
2655 2655 comparison,
2656 2656 data->right, data->right_var, data->right_vsl);
2657 2657 free_slist(&clone->possible);
2658 2658 add_possible_sm(clone, clone);
2659 2659
2660 2660 stree = clone_stree(sm->pool);
2661 2661 overwrite_sm_state_stree(&stree, clone);
2662 2662 clone->pool = stree;
2663 2663
2664 2664 return clone;
2665 2665 }
2666 2666
2667 2667 static void create_fake_history(struct sm_state *sm, int op,
2668 2668 struct state_list **true_stack,
2669 2669 struct state_list **false_stack)
2670 2670 {
2671 2671 struct sm_state *true_sm, *false_sm;
2672 2672 struct compare_data *data;
2673 2673 int true_comparison;
2674 2674 int false_comparison;
2675 2675
2676 2676 data = sm->state->data;
2677 2677
2678 2678 if (is_merged(sm) || sm->left || sm->right)
2679 2679 return;
2680 2680
2681 2681 true_comparison = comparison_intersection(data->comparison, op);
2682 2682 false_comparison = comparison_intersection(data->comparison, negate_comparison(op));
2683 2683
2684 2684 true_sm = clone_partial_sm(sm, true_comparison);
2685 2685 false_sm = clone_partial_sm(sm, false_comparison);
2686 2686
2687 2687 sm->merged = 1;
2688 2688 sm->left = true_sm;
2689 2689 sm->right = false_sm;
2690 2690
2691 2691 add_ptr_list(true_stack, true_sm);
2692 2692 add_ptr_list(false_stack, false_sm);
2693 2693 }
2694 2694
2695 2695 static void filter_by_sm(struct sm_state *sm, int op,
2696 2696 struct state_list **true_stack,
2697 2697 struct state_list **false_stack,
2698 2698 bool *useful)
2699 2699 {
2700 2700 struct compare_data *data;
2701 2701 int is_true = 0;
2702 2702 int is_false = 0;
2703 2703
2704 2704 if (!sm)
2705 2705 return;
2706 2706 data = sm->state->data;
2707 2707 if (!data)
2708 2708 goto split;
2709 2709 if (data->comparison == IMPOSSIBLE_COMPARISON)
2710 2710 return;
2711 2711
2712 2712 /*
2713 2713 * We want to check that "data->comparison" is totally inside "op". So
2714 2714 * if data->comparison is < and op is <= then that's true. Or if
2715 2715 * data->comparison is == and op is <= then that's true. But if
2716 2716 * data->comparison is <= and op is < than that's neither true nor
2717 2717 * false.
2718 2718 */
2719 2719 if (data->comparison == comparison_intersection(data->comparison, op))
2720 2720 is_true = 1;
2721 2721 if (data->comparison == comparison_intersection(data->comparison, negate_comparison(op)))
2722 2722 is_false = 1;
2723 2723
2724 2724 if (!is_true && !is_false && !is_merged(sm)) {
2725 2725 create_fake_history(sm, op, true_stack, false_stack);
2726 2726 return;
2727 2727 }
2728 2728
2729 2729 if (debug_implied()) {
2730 2730 sm_msg("%s: %s: op = '%s' negated '%s'. true_intersect = '%s' false_insersect = '%s' sm = '%s'",
2731 2731 __func__,
2732 2732 sm->state->name,
2733 2733 alloc_sname(show_comparison(op)),
2734 2734 alloc_sname(show_comparison(negate_comparison(op))),
2735 2735 alloc_sname(show_comparison(comparison_intersection(data->comparison, op))),
2736 2736 alloc_sname(show_comparison(comparison_intersection(data->comparison, negate_comparison(op)))),
2737 2737 show_sm(sm));
2738 2738 }
2739 2739
2740 2740 *useful = true;
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2741 2741 if (is_true)
2742 2742 add_ptr_list(true_stack, sm);
2743 2743 if (is_false)
2744 2744 add_ptr_list(false_stack, sm);
2745 2745 split:
2746 2746 filter_by_sm(sm->left, op, true_stack, false_stack, useful);
2747 2747 filter_by_sm(sm->right, op, true_stack, false_stack, useful);
2748 2748 }
2749 2749
2750 2750 struct sm_state *comparison_implication_hook(struct expression *expr,
2751 - struct state_list **true_stack,
2752 - struct state_list **false_stack)
2751 + struct state_list **true_stack,
2752 + struct state_list **false_stack)
2753 2753 {
2754 2754 struct sm_state *sm;
2755 2755 char *left, *right;
2756 2756 int op;
2757 2757 static char buf[256];
2758 2758 bool useful = false;
2759 2759
2760 2760 if (expr->type != EXPR_COMPARE)
2761 2761 return NULL;
2762 2762
2763 2763 op = expr->op;
2764 2764
2765 2765 left = expr_to_var(expr->left);
2766 2766 right = expr_to_var(expr->right);
2767 2767 if (!left || !right) {
2768 2768 free_string(left);
2769 2769 free_string(right);
2770 2770 return NULL;
2771 2771 }
2772 2772
2773 2773 if (strcmp(left, right) > 0) {
2774 2774 char *tmp = left;
2775 2775
2776 2776 left = right;
2777 2777 right = tmp;
2778 2778 op = flip_comparison(op);
2779 2779 }
2780 2780
2781 2781 snprintf(buf, sizeof(buf), "%s vs %s", left, right);
2782 2782 sm = get_sm_state(comparison_id, buf, NULL);
2783 2783 if (!sm)
2784 2784 return NULL;
2785 2785 if (!sm->merged)
2786 2786 return NULL;
2787 2787
2788 2788 filter_by_sm(sm, op, true_stack, false_stack, &useful);
2789 2789 if (!useful)
2790 2790 return NULL;
2791 2791
2792 2792 if (debug_implied())
2793 2793 sm_msg("implications from comparison: (%s)", show_sm(sm));
2794 2794
2795 2795 return sm;
2796 2796 }
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