smatch_function_hooks.c

   1 /*
   2  * Copyright (C) 2009 Dan Carpenter.
   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  * There are several types of function hooks:
  20  * add_function_hook()        - For any time a function is called.
  21  * add_function_assign_hook() - foo = the_function().
  22  * add_implied_return_hook()  - Calculates the implied return value.
  23  * add_macro_assign_hook()    - foo = the_macro().
  24  * return_implies_state()     - For when a return value of 1 implies locked
  25  *                              and 0 implies unlocked. etc. etc.
  26  *
  27  */
  28
  29 #include <stdlib.h>
  30 #include <stdio.h>
  31 #include "smatch.h"
  32 #include "smatch_slist.h"
  33 #include "smatch_extra.h"
  34 #include "smatch_function_hashtable.h"
  35
  36 struct fcall_back {
  37         int type;
  38         struct data_range *range;
  39         union {
  40                 func_hook *call_back;
  41                 implication_hook *ranged;
  42                 implied_return_hook *implied_return;
  43         } u;
  44         void *info;
  45 };
  46
  47 ALLOCATOR(fcall_back, "call backs");
  48 DECLARE_PTR_LIST(call_back_list, struct fcall_back);
  49
  50 DEFINE_FUNCTION_HASHTABLE_STATIC(callback, struct fcall_back, struct call_back_list);
  51 static struct hashtable *func_hash;
  52
  53 #define REGULAR_CALL       0
  54 #define RANGED_CALL        1
  55 #define ASSIGN_CALL        2
  56 #define IMPLIED_RETURN     3
  57 #define MACRO_ASSIGN       4
  58 #define MACRO_ASSIGN_EXTRA 5
  59
  60 struct return_implies_callback {
  61         int type;
  62         return_implies_hook *callback;
  63 };
  64 ALLOCATOR(return_implies_callback, "return_implies callbacks");
  65 DECLARE_PTR_LIST(db_implies_list, struct return_implies_callback);
  66 static struct db_implies_list *db_return_states_list;
  67
  68 typedef void (void_fn)(void);
  69 DECLARE_PTR_LIST(void_fn_list, void_fn *);
  70 static struct void_fn_list *return_states_before;
  71 static struct void_fn_list *return_states_after;
  72
  73 static struct fcall_back *alloc_fcall_back(int type, void *call_back,
  74                                            void *info)
  75 {
  76         struct fcall_back *cb;
  77
  78         cb = __alloc_fcall_back(0);
  79         cb->type = type;
  80         cb->u.call_back = call_back;
  81         cb->info = info;
  82         return cb;
  83 }
  84
  85 void add_function_hook(const char *look_for, func_hook *call_back, void *info)
  86 {
  87         struct fcall_back *cb;
  88
  89         cb = alloc_fcall_back(REGULAR_CALL, call_back, info);
  90         add_callback(func_hash, look_for, cb);
  91 }
  92
  93 void add_function_assign_hook(const char *look_for, func_hook *call_back,
  94                               void *info)
  95 {
  96         struct fcall_back *cb;
  97
  98         cb = alloc_fcall_back(ASSIGN_CALL, call_back, info);
  99         add_callback(func_hash, look_for, cb);
 100 }
 101
 102 void add_implied_return_hook(const char *look_for,
 103                              implied_return_hook *call_back,
 104                              void *info)
 105 {
 106         struct fcall_back *cb;
 107
 108         cb = alloc_fcall_back(IMPLIED_RETURN, call_back, info);
 109         add_callback(func_hash, look_for, cb);
 110 }
 111
 112 void add_macro_assign_hook(const char *look_for, func_hook *call_back,
 113                         void *info)
 114 {
 115         struct fcall_back *cb;
 116
 117         cb = alloc_fcall_back(MACRO_ASSIGN, call_back, info);
 118         add_callback(func_hash, look_for, cb);
 119 }
 120
 121 void add_macro_assign_hook_extra(const char *look_for, func_hook *call_back,
 122                         void *info)
 123 {
 124         struct fcall_back *cb;
 125
 126         cb = alloc_fcall_back(MACRO_ASSIGN_EXTRA, call_back, info);
 127         add_callback(func_hash, look_for, cb);
 128 }
 129
 130 void return_implies_state(const char *look_for, long long start, long long end,
 131                          implication_hook *call_back, void *info)
 132 {
 133         struct fcall_back *cb;
 134
 135         cb = alloc_fcall_back(RANGED_CALL, call_back, info);
 136         cb->range = alloc_range_perm(ll_to_sval(start), ll_to_sval(end));
 137         add_callback(func_hash, look_for, cb);
 138 }
 139
 140 void select_return_states_hook(int type, return_implies_hook *callback)
 141 {
 142         struct return_implies_callback *cb = __alloc_return_implies_callback(0);
 143
 144         cb->type = type;
 145         cb->callback = callback;
 146         add_ptr_list(&db_return_states_list, cb);
 147 }
 148
 149 void select_return_states_before(void_fn *fn)
 150 {
 151         void_fn **p = malloc(sizeof(void_fn *));
 152         *p = fn;
 153         add_ptr_list(&return_states_before, p);
 154 }
 155
 156 void select_return_states_after(void_fn *fn)
 157 {
 158         void_fn **p = malloc(sizeof(void_fn *));
 159         *p = fn;
 160         add_ptr_list(&return_states_after, p);
 161 }
 162
 163 static void call_return_states_before_hooks(void)
 164 {
 165         void_fn **fn;
 166
 167         FOR_EACH_PTR(return_states_before, fn) {
 168                 (*fn)();
 169         } END_FOR_EACH_PTR(fn);
 170 }
 171
 172 static void call_return_states_after_hooks(struct expression *expr)
 173 {
 174         void_fn **fn;
 175
 176         FOR_EACH_PTR(return_states_after, fn) {
 177                 (*fn)();
 178         } END_FOR_EACH_PTR(fn);
 179         __pass_to_client(expr, FUNCTION_CALL_HOOK_AFTER_DB);
 180 }
 181
 182 static int call_call_backs(struct call_back_list *list, int type,
 183                             const char *fn, struct expression *expr)
 184 {
 185         struct fcall_back *tmp;
 186         int handled = 0;
 187
 188         FOR_EACH_PTR(list, tmp) {
 189                 if (tmp->type == type) {
 190                         (tmp->u.call_back)(fn, expr, tmp->info);
 191                         handled = 1;
 192                 }
 193         } END_FOR_EACH_PTR(tmp);
 194
 195         return handled;
 196 }
 197
 198 static void call_ranged_call_backs(struct call_back_list *list,
 199                                 const char *fn, struct expression *call_expr,
 200                                 struct expression *assign_expr)
 201 {
 202         struct fcall_back *tmp;
 203
 204         FOR_EACH_PTR(list, tmp) {
 205                 (tmp->u.ranged)(fn, call_expr, assign_expr, tmp->info);
 206         } END_FOR_EACH_PTR(tmp);
 207 }
 208
 209 static struct call_back_list *get_same_ranged_call_backs(struct call_back_list *list,
 210                                                 struct data_range *drange)
 211 {
 212         struct call_back_list *ret = NULL;
 213         struct fcall_back *tmp;
 214
 215         FOR_EACH_PTR(list, tmp) {
 216                 if (tmp->type != RANGED_CALL)
 217                         continue;
 218                 if (ranges_equiv(tmp->range, drange))
 219                         add_ptr_list(&ret, tmp);
 220         } END_FOR_EACH_PTR(tmp);
 221         return ret;
 222 }
 223
 224 static int in_list_exact_sval(struct range_list *list, struct data_range *drange)
 225 {
 226         struct data_range *tmp;
 227
 228         FOR_EACH_PTR(list, tmp) {
 229                 if (ranges_equiv(tmp, drange))
 230                         return 1;
 231         } END_FOR_EACH_PTR(tmp);
 232         return 0;
 233 }
 234
 235 static int assign_ranged_funcs(const char *fn, struct expression *expr,
 236                                  struct call_back_list *call_backs)
 237 {
 238         struct fcall_back *tmp;
 239         struct sm_state *sm;
 240         char *var_name;
 241         struct symbol *sym;
 242         struct smatch_state *estate;
 243         struct stree *tmp_stree;
 244         struct stree *final_states = NULL;
 245         struct range_list *handled_ranges = NULL;
 246         struct call_back_list *same_range_call_backs = NULL;
 247         int handled = 0;
 248
 249         if (!call_backs)
 250                 return 0;
 251
 252         var_name = expr_to_var_sym(expr->left, &sym);
 253         if (!var_name || !sym)
 254                 goto free;
 255
 256         FOR_EACH_PTR(call_backs, tmp) {
 257                 if (tmp->type != RANGED_CALL)
 258                         continue;
 259
 260                 if (in_list_exact_sval(handled_ranges, tmp->range))
 261                         continue;
 262                 __push_fake_cur_stree();
 263                 tack_on(&handled_ranges, tmp->range);
 264
 265                 same_range_call_backs = get_same_ranged_call_backs(call_backs, tmp->range);
 266                 call_ranged_call_backs(same_range_call_backs, fn, expr->right, expr);
 267                 __free_ptr_list((struct ptr_list **)&same_range_call_backs);
 268
 269                 estate = alloc_estate_range(tmp->range->min, tmp->range->max);
 270                 set_extra_mod(var_name, sym, estate);
 271
 272                 tmp_stree = __pop_fake_cur_stree();
 273                 merge_fake_stree(&final_states, tmp_stree);
 274                 free_stree(&tmp_stree);
 275                 handled = 1;
 276         } END_FOR_EACH_PTR(tmp);
 277
 278         FOR_EACH_SM(final_states, sm) {
 279                 __set_sm(sm);
 280         } END_FOR_EACH_SM(sm);
 281
 282         free_stree(&final_states);
 283 free:
 284         free_string(var_name);
 285         return handled;
 286 }
 287
 288 static void call_implies_callbacks(int comparison, struct expression *expr, sval_t sval, int left, struct stree **implied_true, struct stree **implied_false)
 289 {
 290         struct call_back_list *call_backs;
 291         struct fcall_back *tmp;
 292         const char *fn;
 293         struct data_range *value_range;
 294         struct stree *true_states = NULL;
 295         struct stree *false_states = NULL;
 296         struct stree *tmp_stree;
 297
 298         *implied_true = NULL;
 299         *implied_false = NULL;
 300         if (expr->fn->type != EXPR_SYMBOL || !expr->fn->symbol)
 301                 return;
 302         fn = expr->fn->symbol->ident->name;
 303         call_backs = search_callback(func_hash, (char *)expr->fn->symbol->ident->name);
 304         if (!call_backs)
 305                 return;
 306         value_range = alloc_range(sval, sval);
 307
 308         /* set true states */
 309         __push_fake_cur_stree();
 310         FOR_EACH_PTR(call_backs, tmp) {
 311                 if (tmp->type != RANGED_CALL)
 312                         continue;
 313                 if (!true_comparison_range_LR(comparison, tmp->range, value_range, left))
 314                         continue;
 315                 (tmp->u.ranged)(fn, expr, NULL, tmp->info);
 316         } END_FOR_EACH_PTR(tmp);
 317         tmp_stree = __pop_fake_cur_stree();
 318         merge_fake_stree(&true_states, tmp_stree);
 319         free_stree(&tmp_stree);
 320
 321         /* set false states */
 322         __push_fake_cur_stree();
 323         FOR_EACH_PTR(call_backs, tmp) {
 324                 if (tmp->type != RANGED_CALL)
 325                         continue;
 326                 if (!false_comparison_range_LR(comparison, tmp->range, value_range, left))
 327                         continue;
 328                 (tmp->u.ranged)(fn, expr, NULL, tmp->info);
 329         } END_FOR_EACH_PTR(tmp);
 330         tmp_stree = __pop_fake_cur_stree();
 331         merge_fake_stree(&false_states, tmp_stree);
 332         free_stree(&tmp_stree);
 333
 334         *implied_true = true_states;
 335         *implied_false = false_states;
 336 }
 337
 338 struct db_callback_info {
 339         int true_side;
 340         int comparison;
 341         struct expression *expr;
 342         struct range_list *rl;
 343         int left;
 344         struct stree *stree;
 345         struct db_implies_list *callbacks;
 346         int prev_return_id;
 347         int cull;
 348         int has_states;
 349         struct smatch_state *ret_state;
 350         struct expression *var_expr;
 351         int handled;
 352 };
 353
 354 static void store_return_state(struct db_callback_info *db_info, struct smatch_state *state)
 355 {
 356         db_info->ret_state = state;
 357 }
 358
 359 static void set_return_state(struct expression *expr, struct db_callback_info *db_info)
 360 {
 361         struct smatch_state *state;
 362
 363         if (!db_info->ret_state)
 364                 return;
 365
 366         state = alloc_estate_rl(cast_rl(get_type(expr), clone_rl(estate_rl(db_info->ret_state))));
 367         set_extra_expr_mod(expr, state);
 368         db_info->ret_state = NULL;
 369 }
 370
 371 static void handle_ret_equals_param(char *ret_string, struct range_list *rl, struct expression *call)
 372 {
 373         char *str;
 374         long long param;
 375         struct expression *arg;
 376         struct range_list *orig;
 377
 378         str = strstr(ret_string, "==$");
 379         if (!str)
 380                 return;
 381         str += 3;
 382         param = strtoll(str, NULL, 10);
 383         arg = get_argument_from_call_expr(call->args, param);
 384         if (!arg)
 385                 return;
 386         get_absolute_rl(arg, &orig);
 387         rl = rl_intersection(orig, rl);
 388         if (!rl)
 389                 return;
 390         set_extra_expr_nomod(arg, alloc_estate_rl(rl));
 391 }
 392
 393 static int impossible_limit(struct expression *expr, int param, char *key, char *value)
 394 {
 395         struct expression *arg;
 396         struct smatch_state *state;
 397         struct range_list *passed;
 398         struct range_list *limit;
 399         struct symbol *compare_type;
 400
 401         while (expr->type == EXPR_ASSIGNMENT)
 402                 expr = strip_expr(expr->right);
 403         if (expr->type != EXPR_CALL)
 404                 return 0;
 405
 406         arg = get_argument_from_call_expr(expr->args, param);
 407         if (!arg)
 408                 return 0;
 409
 410         if (strcmp(key, "$") == 0) {
 411                 if (!get_implied_rl(arg, &passed))
 412                         return 0;
 413
 414                 compare_type = get_arg_type(expr->fn, param);
 415         } else {
 416                 char *name;
 417                 struct symbol *sym;
 418
 419                 name = get_variable_from_key(arg, key, &sym);
 420                 if (!name || !sym)
 421                         return 0;
 422
 423                 state = get_state(SMATCH_EXTRA, name, sym);
 424                 if (!state) {
 425                         free_string(name);
 426                         return 0;
 427                 }
 428                 passed = estate_rl(state);
 429                 if (!passed || is_whole_rl(passed)) {
 430                         free_string(name);
 431                         return 0;
 432                 }
 433
 434                 compare_type = get_member_type_from_key(arg, key);
 435         }
 436
 437         passed = cast_rl(compare_type, passed);
 438         call_results_to_rl(expr, compare_type, value, &limit);
 439         if (!limit || is_whole_rl(limit))
 440                 return 0;
 441         if (possibly_true_rl(passed, SPECIAL_EQUAL, limit))
 442                 return 0;
 443         if (option_debug || local_debug)
 444                 sm_msg("impossible: %d '%s' limit '%s' == '%s'", param, key, show_rl(passed), value);
 445         return 1;
 446 }
 447
 448 static int is_impossible_data(int type, struct expression *expr, int param, char *key, char *value)
 449 {
 450         if (type == PARAM_LIMIT && impossible_limit(expr, param, key, value))
 451                 return 1;
 452         if (type == COMPARE_LIMIT && param_compare_limit_is_impossible(expr, param, key, value))
 453                 return 1;
 454         return 0;
 455 }
 456
 457 static int func_type_mismatch(struct expression *expr, const char *value)
 458 {
 459         struct symbol *type;
 460
 461         /* This makes faking returns easier */
 462         if (!value || value[0] == '\0')
 463                 return 0;
 464
 465         while (expr->type == EXPR_ASSIGNMENT)
 466                 expr = strip_expr(expr->right);
 467
 468         /*
 469          * Short cut:  We only care about function pointers that are struct
 470          * members.
 471          *
 472          */
 473         if (expr->fn->type == EXPR_SYMBOL)
 474                 return 0;
 475
 476         type = get_type(expr->fn);
 477         if (!type)
 478                 return 0;
 479         if (type->type == SYM_PTR)
 480                 type = get_real_base_type(type);
 481
 482         if (strcmp(type_to_str(type), value) == 0)
 483                 return 0;
 484
 485         return 1;
 486 }
 487
 488 static int db_compare_callback(void *_info, int argc, char **argv, char **azColName)
 489 {
 490         struct db_callback_info *db_info = _info;
 491         struct range_list *var_rl = db_info->rl;
 492         struct range_list *ret_range;
 493         int type, param;
 494         char *key, *value;
 495         struct return_implies_callback *tmp;
 496         struct stree *stree;
 497         int return_id;
 498         int comparison;
 499
 500         if (argc != 6)
 501                 return 0;
 502
 503         return_id = atoi(argv[0]);
 504         type = atoi(argv[2]);
 505         param = atoi(argv[3]);
 506         key = argv[4];
 507         value = argv[5];
 508
 509         db_info->has_states = 1;
 510         if (db_info->prev_return_id != -1 && type == INTERNAL) {
 511                 set_return_state(db_info->var_expr, db_info);
 512                 stree = __pop_fake_cur_stree();
 513
 514                 if (!db_info->cull)
 515                         merge_fake_stree(&db_info->stree, stree);
 516                 free_stree(&stree);
 517                 __push_fake_cur_stree();
 518                 db_info->cull = 0;
 519         }
 520         db_info->prev_return_id = return_id;
 521
 522         if (type == INTERNAL && func_type_mismatch(db_info->expr, value))
 523                 db_info->cull = 1;
 524         if (db_info->cull)
 525                 return 0;
 526         if (type == CULL_PATH) {
 527                 db_info->cull = 1;
 528                 return 0;
 529         }
 530
 531         if (is_impossible_data(type, db_info->expr, param, key, value)) {
 532                 db_info->cull = 1;
 533                 return 0;
 534         }
 535
 536         call_results_to_rl(db_info->expr, get_type(strip_expr(db_info->expr)), argv[1], &ret_range);
 537         ret_range = cast_rl(get_type(db_info->expr), ret_range);
 538         if (!ret_range)
 539                 ret_range = alloc_whole_rl(get_type(db_info->expr));
 540
 541         comparison = db_info->comparison;
 542         if (db_info->left)
 543                 comparison = flip_comparison(comparison);
 544
 545         if (db_info->true_side) {
 546                 if (!possibly_true_rl(var_rl, comparison, ret_range))
 547                         return 0;
 548                 if (type == PARAM_LIMIT)
 549                         param_limit_implications(db_info->expr, param, key, value);
 550                 filter_by_comparison(&var_rl, comparison, ret_range);
 551                 filter_by_comparison(&ret_range, flip_comparison(comparison), var_rl);
 552         } else {
 553                 if (!possibly_false_rl(var_rl, comparison, ret_range))
 554                         return 0;
 555                 if (type == PARAM_LIMIT)
 556                         param_limit_implications(db_info->expr, param, key, value);
 557                 filter_by_comparison(&var_rl, negate_comparison(comparison), ret_range);
 558                 filter_by_comparison(&ret_range, flip_comparison(negate_comparison(comparison)), var_rl);
 559         }
 560
 561         handle_ret_equals_param(argv[1], ret_range, db_info->expr);
 562
 563         if (type == INTERNAL)
 564                 set_state(-1, "unnull_path", NULL, &true_state);
 565
 566         FOR_EACH_PTR(db_info->callbacks, tmp) {
 567                 if (tmp->type == type)
 568                         tmp->callback(db_info->expr, param, key, value);
 569         } END_FOR_EACH_PTR(tmp);
 570
 571         store_return_state(db_info, alloc_estate_rl(clone_rl(var_rl)));
 572         return 0;
 573 }
 574
 575 static void compare_db_return_states_callbacks(struct expression *left, int comparison, struct expression *right, struct stree *implied_true, struct stree *implied_false)
 576 {
 577         struct stree *orig_states;
 578         struct stree *stree;
 579         struct stree *true_states;
 580         struct stree *false_states;
 581         struct sm_state *sm;
 582         struct db_callback_info db_info = {};
 583         struct expression *var_expr;
 584         struct expression *call_expr;
 585         struct range_list *rl;
 586         int call_on_left;
 587
 588         orig_states = clone_stree(__get_cur_stree());
 589
 590         /* legacy cruft.  need to fix call_implies_callbacks(). */
 591         call_on_left = 1;
 592         call_expr = left;
 593         var_expr = right;
 594         if (left->type != EXPR_CALL) {
 595                 call_on_left = 0;
 596                 call_expr = right;
 597                 var_expr = left;
 598         }
 599
 600         get_absolute_rl(var_expr, &rl);
 601
 602         db_info.comparison = comparison;
 603         db_info.expr = call_expr;
 604         db_info.rl = rl;
 605         db_info.left = call_on_left;
 606         db_info.callbacks = db_return_states_list;
 607         db_info.var_expr = var_expr;
 608
 609         call_return_states_before_hooks();
 610
 611         db_info.true_side = 1;
 612         db_info.stree = NULL;
 613         db_info.prev_return_id = -1;
 614         __push_fake_cur_stree();
 615         sql_select_return_states("return_id, return, type, parameter, key, value",
 616                                  call_expr, db_compare_callback, &db_info);
 617         set_return_state(db_info.var_expr, &db_info);
 618         stree = __pop_fake_cur_stree();
 619         if (!db_info.cull) {
 620                 set_return_state(db_info.var_expr, &db_info);
 621                 merge_fake_stree(&db_info.stree, stree);
 622         }
 623         free_stree(&stree);
 624         true_states = db_info.stree;
 625         if (!true_states && db_info.has_states) {
 626                 __push_fake_cur_stree();
 627                 set_path_impossible();
 628                 true_states = __pop_fake_cur_stree();
 629         }
 630
 631         nullify_path();
 632         __unnullify_path();
 633         FOR_EACH_SM(orig_states, sm) {
 634                 __set_sm_cur_stree(sm);
 635         } END_FOR_EACH_SM(sm);
 636
 637         db_info.true_side = 0;
 638         db_info.stree = NULL;
 639         db_info.prev_return_id = -1;
 640         db_info.cull = 0;
 641         __push_fake_cur_stree();
 642         sql_select_return_states("return_id, return, type, parameter, key, value", call_expr,
 643                         db_compare_callback, &db_info);
 644         stree = __pop_fake_cur_stree();
 645         if (!db_info.cull) {
 646                 set_return_state(db_info.var_expr, &db_info);
 647                 merge_fake_stree(&db_info.stree, stree);
 648         }
 649         free_stree(&stree);
 650         false_states = db_info.stree;
 651         if (!false_states && db_info.has_states) {
 652                 __push_fake_cur_stree();
 653                 set_path_impossible();
 654                 false_states = __pop_fake_cur_stree();
 655         }
 656
 657         nullify_path();
 658         __unnullify_path();
 659         FOR_EACH_SM(orig_states, sm) {
 660                 __set_sm_cur_stree(sm);
 661         } END_FOR_EACH_SM(sm);
 662
 663         free_stree(&orig_states);
 664
 665         FOR_EACH_SM(true_states, sm) {
 666                 __set_true_false_sm(sm, NULL);
 667         } END_FOR_EACH_SM(sm);
 668         FOR_EACH_SM(false_states, sm) {
 669                 __set_true_false_sm(NULL, sm);
 670         } END_FOR_EACH_SM(sm);
 671
 672         free_stree(&true_states);
 673         free_stree(&false_states);
 674
 675         call_return_states_after_hooks(call_expr);
 676
 677         FOR_EACH_SM(implied_true, sm) {
 678                 __set_true_false_sm(sm, NULL);
 679         } END_FOR_EACH_SM(sm);
 680         FOR_EACH_SM(implied_false, sm) {
 681                 __set_true_false_sm(NULL, sm);
 682         } END_FOR_EACH_SM(sm);
 683 }
 684
 685 void function_comparison(struct expression *left, int comparison, struct expression *right)
 686 {
 687         struct expression *var_expr;
 688         struct expression *call_expr;
 689         struct stree *implied_true = NULL;
 690         struct stree *implied_false = NULL;
 691         struct range_list *rl;
 692         sval_t sval;
 693         int call_on_left;
 694
 695         if (unreachable())
 696                 return;
 697
 698         /* legacy cruft.  need to fix call_implies_callbacks(). */
 699         call_on_left = 1;
 700         call_expr = left;
 701         var_expr = right;
 702         if (left->type != EXPR_CALL) {
 703                 call_on_left = 0;
 704                 call_expr = right;
 705                 var_expr = left;
 706         }
 707
 708         get_absolute_rl(var_expr, &rl);
 709
 710         if (rl_to_sval(rl, &sval))
 711                 call_implies_callbacks(comparison, call_expr, sval, call_on_left, &implied_true, &implied_false);
 712
 713         compare_db_return_states_callbacks(left, comparison, right, implied_true, implied_false);
 714         free_stree(&implied_true);
 715         free_stree(&implied_false);
 716 }
 717
 718 static void call_ranged_return_hooks(struct db_callback_info *db_info)
 719 {
 720         struct call_back_list *call_backs;
 721         struct expression *expr;
 722         struct fcall_back *tmp;
 723         char *fn;
 724
 725         expr = strip_expr(db_info->expr);
 726         while (expr->type == EXPR_ASSIGNMENT)
 727                 expr = strip_expr(expr->right);
 728         if (expr->type != EXPR_CALL ||
 729             expr->fn->type != EXPR_SYMBOL)
 730                 return;
 731
 732         fn = expr->fn->symbol_name->name;
 733
 734         call_backs = search_callback(func_hash, fn);
 735         FOR_EACH_PTR(call_backs, tmp) {
 736                 struct range_list *range_rl = NULL;
 737
 738                 if (tmp->type != RANGED_CALL)
 739                         continue;
 740                 add_range(&range_rl, tmp->range->min, tmp->range->max);
 741                 range_rl = cast_rl(estate_type(db_info->ret_state), range_rl);
 742                 if (possibly_true_rl(range_rl, SPECIAL_EQUAL, estate_rl(db_info->ret_state))) {
 743                         if (!possibly_true_rl(rl_invert(range_rl), SPECIAL_EQUAL, estate_rl(db_info->ret_state)))
 744                                 (tmp->u.ranged)(fn, expr, db_info->expr, tmp->info);
 745                         else
 746                                 db_info->handled = -1;
 747                 }
 748         } END_FOR_EACH_PTR(tmp);
 749 }
 750
 751 static int db_assign_return_states_callback(void *_info, int argc, char **argv, char **azColName)
 752 {
 753         struct db_callback_info *db_info = _info;
 754         struct range_list *ret_range;
 755         int type, param;
 756         char *key, *value;
 757         struct return_implies_callback *tmp;
 758         struct stree *stree;
 759         int return_id;
 760
 761         if (argc != 6)
 762                 return 0;
 763
 764         return_id = atoi(argv[0]);
 765         type = atoi(argv[2]);
 766         param = atoi(argv[3]);
 767         key = argv[4];
 768         value = argv[5];
 769
 770         if (db_info->prev_return_id != -1 && type == INTERNAL) {
 771                 call_ranged_return_hooks(db_info);
 772                 set_return_state(db_info->expr->left, db_info);
 773                 stree = __pop_fake_cur_stree();
 774                 if (!db_info->cull)
 775                         merge_fake_stree(&db_info->stree, stree);
 776                 free_stree(&stree);
 777                 __push_fake_cur_stree();
 778                 db_info->cull = 0;
 779         }
 780         db_info->prev_return_id = return_id;
 781
 782         if (type == INTERNAL && func_type_mismatch(db_info->expr, value))
 783                 db_info->cull = 1;
 784         if (db_info->cull)
 785                 return 0;
 786         if (type == CULL_PATH) {
 787                 db_info->cull = 1;
 788                 return 0;
 789         }
 790         if (is_impossible_data(type, db_info->expr, param, key, value)) {
 791                 db_info->cull = 1;
 792                 return 0;
 793         }
 794
 795         if (type == PARAM_LIMIT)
 796                 param_limit_implications(db_info->expr, param, key, value);
 797
 798         db_info->handled = 1;
 799         call_results_to_rl(db_info->expr->right, get_type(strip_expr(db_info->expr->right)), argv[1], &ret_range);
 800         if (!ret_range)
 801                 ret_range = alloc_whole_rl(get_type(strip_expr(db_info->expr->right)));
 802         ret_range = cast_rl(get_type(db_info->expr->right), ret_range);
 803
 804         if (type == INTERNAL) {
 805                 set_state(-1, "unnull_path", NULL, &true_state);
 806                 __add_comparison_info(db_info->expr->left, strip_expr(db_info->expr->right), argv[1]);
 807                 __add_return_to_param_mapping(db_info->expr, argv[1]);
 808         }
 809
 810         FOR_EACH_PTR(db_return_states_list, tmp) {
 811                 if (tmp->type == type)
 812                         tmp->callback(db_info->expr, param, key, value);
 813         } END_FOR_EACH_PTR(tmp);
 814         store_return_state(db_info, alloc_estate_rl(ret_range));
 815
 816         return 0;
 817 }
 818
 819 static int db_return_states_assign(struct expression *expr)
 820 {
 821         struct expression *right;
 822         struct sm_state *sm;
 823         struct stree *stree;
 824         struct db_callback_info db_info = {};
 825
 826         right = strip_expr(expr->right);
 827
 828         db_info.prev_return_id = -1;
 829         db_info.expr = expr;
 830         db_info.stree = NULL;
 831         db_info.handled = 0;
 832
 833         call_return_states_before_hooks();
 834
 835         __push_fake_cur_stree();
 836         sql_select_return_states("return_id, return, type, parameter, key, value",
 837                         right, db_assign_return_states_callback, &db_info);
 838         if (option_debug) {
 839                 sm_msg("%s return_id %d return_ranges %s",
 840                         db_info.cull ? "culled" : "merging",
 841                         db_info.prev_return_id,
 842                         db_info.ret_state ? db_info.ret_state->name : "'<empty>'");
 843         }
 844         if (db_info.handled)
 845                 call_ranged_return_hooks(&db_info);
 846         set_return_state(db_info.expr->left, &db_info);
 847         stree = __pop_fake_cur_stree();
 848         if (!db_info.cull)
 849                 merge_fake_stree(&db_info.stree, stree);
 850         free_stree(&stree);
 851
 852         if (!db_info.stree && db_info.cull) /* this means we culled everything */
 853                 set_extra_expr_mod(expr->left, alloc_estate_whole(get_type(expr->left)));
 854         FOR_EACH_SM(db_info.stree, sm) {
 855                 __set_sm(sm);
 856         } END_FOR_EACH_SM(sm);
 857
 858         free_stree(&db_info.stree);
 859         call_return_states_after_hooks(right);
 860
 861         return db_info.handled;
 862 }
 863
 864 static int handle_implied_return(struct expression *expr)
 865 {
 866         struct range_list *rl;
 867
 868         if (!get_implied_return(expr->right, &rl))
 869                 return 0;
 870         rl = cast_rl(get_type(expr->left), rl);
 871         set_extra_expr_mod(expr->left, alloc_estate_rl(rl));
 872         return 1;
 873 }
 874
 875 static void match_assign_call(struct expression *expr)
 876 {
 877         struct call_back_list *call_backs;
 878         const char *fn;
 879         struct expression *right;
 880         int handled = 0;
 881         struct range_list *rl;
 882
 883         if (expr->op != '=')
 884                 return;
 885
 886         right = strip_expr(expr->right);
 887         if (right->fn->type != EXPR_SYMBOL || !right->fn->symbol) {
 888                 handled |= db_return_states_assign(expr);
 889                 if (!handled)
 890                         goto assigned_unknown;
 891                 return;
 892         }
 893         if (is_fake_call(right)) {
 894                 set_extra_expr_mod(expr->left, alloc_estate_whole(get_type(expr->left)));
 895                 return;
 896         }
 897
 898         fn = right->fn->symbol->ident->name;
 899         call_backs = search_callback(func_hash, (char *)fn);
 900
 901         /*
 902          * The ordering here is sort of important.
 903          * One example, of how this matters is that when we do:
 904          *
 905          *      len = strlen(str);
 906          *
 907          * That is handled by smatch_common_functions.c and smatch_strlen.c.
 908          * They use implied_return and function_assign_hook respectively.
 909          * We want to get the implied return first before we do the function
 910          * assignment hook otherwise we end up writing the wrong thing for len
 911          * in smatch_extra.c because we assume that it already holds the
 912          * strlen() when we haven't set it yet.
 913          */
 914
 915         if (db_return_states_assign(expr) == 1)
 916                 handled = 1;
 917         else
 918                 handled = assign_ranged_funcs(fn, expr, call_backs);
 919         handled |= handle_implied_return(expr);
 920
 921
 922         call_call_backs(call_backs, ASSIGN_CALL, fn, expr);
 923
 924         if (handled)
 925                 return;
 926
 927 assigned_unknown:
 928         get_absolute_rl(expr->right, &rl);
 929         rl = cast_rl(get_type(expr->left), rl);
 930         set_extra_expr_mod(expr->left, alloc_estate_rl(rl));
 931 }
 932
 933 static int db_return_states_callback(void *_info, int argc, char **argv, char **azColName)
 934 {
 935         struct db_callback_info *db_info = _info;
 936         struct range_list *ret_range;
 937         int type, param;
 938         char *key, *value;
 939         struct return_implies_callback *tmp;
 940         struct stree *stree;
 941         int return_id;
 942         char buf[64];
 943
 944         if (argc != 6)
 945                 return 0;
 946
 947         return_id = atoi(argv[0]);
 948         type = atoi(argv[2]);
 949         param = atoi(argv[3]);
 950         key = argv[4];
 951         value = argv[5];
 952
 953         if (db_info->prev_return_id != -1 && type == INTERNAL) {
 954                 stree = __pop_fake_cur_stree();
 955                 if (!db_info->cull)
 956                         merge_fake_stree(&db_info->stree, stree);
 957                 free_stree(&stree);
 958                 __push_fake_cur_stree();
 959                 __unnullify_path();
 960                 db_info->cull = 0;
 961         }
 962         db_info->prev_return_id = return_id;
 963
 964         if (type == INTERNAL && func_type_mismatch(db_info->expr, value))
 965                 db_info->cull = 1;
 966         if (db_info->cull)
 967                 return 0;
 968         if (type == CULL_PATH) {
 969                 db_info->cull = 1;
 970                 return 0;
 971         }
 972         if (is_impossible_data(type, db_info->expr, param, key, value)) {
 973                 db_info->cull = 1;
 974                 return 0;
 975         }
 976
 977         if (type == PARAM_LIMIT)
 978                 param_limit_implications(db_info->expr, param, key, value);
 979
 980         call_results_to_rl(db_info->expr, get_type(strip_expr(db_info->expr)), argv[1], &ret_range);
 981         ret_range = cast_rl(get_type(db_info->expr), ret_range);
 982
 983         if (type == INTERNAL) {
 984                 set_state(-1, "unnull_path", NULL, &true_state);
 985                 __add_return_to_param_mapping(db_info->expr, argv[1]);
 986         }
 987
 988
 989         FOR_EACH_PTR(db_return_states_list, tmp) {
 990                 if (tmp->type == type)
 991                         tmp->callback(db_info->expr, param, key, value);
 992         } END_FOR_EACH_PTR(tmp);
 993
 994         /*
 995          * We want to store the return values so that we can split the strees
 996          * in smatch_db.c.  This uses set_state() directly because it's not a
 997          * real smatch_extra state.
 998          */
 999         snprintf(buf, sizeof(buf), "return %p", db_info->expr);
1000         set_state(SMATCH_EXTRA, buf, NULL, alloc_estate_rl(ret_range));
1001
1002         return 0;
1003 }
1004
1005 static void db_return_states(struct expression *expr)
1006 {
1007         struct sm_state *sm;
1008         struct stree *stree;
1009         struct db_callback_info db_info = {};
1010
1011         if (!__get_cur_stree())  /* no return functions */
1012                 return;
1013
1014         db_info.prev_return_id = -1;
1015         db_info.expr = expr;
1016         db_info.stree = NULL;
1017
1018         call_return_states_before_hooks();
1019
1020         __push_fake_cur_stree();
1021         __unnullify_path();
1022         sql_select_return_states("return_id, return, type, parameter, key, value",
1023                         expr, db_return_states_callback, &db_info);
1024         stree = __pop_fake_cur_stree();
1025         if (!db_info.cull)
1026                 merge_fake_stree(&db_info.stree, stree);
1027         free_stree(&stree);
1028
1029         FOR_EACH_SM(db_info.stree, sm) {
1030                 __set_sm(sm);
1031         } END_FOR_EACH_SM(sm);
1032
1033         free_stree(&db_info.stree);
1034         call_return_states_after_hooks(expr);
1035 }
1036
1037 static int is_condition_call(struct expression *expr)
1038 {
1039         struct expression *tmp;
1040
1041         FOR_EACH_PTR_REVERSE(big_condition_stack, tmp) {
1042                 if (expr == tmp || expr_get_parent_expr(expr) == tmp)
1043                         return 1;
1044                 if (tmp->pos.line < expr->pos.line)
1045                         return 0;
1046         } END_FOR_EACH_PTR_REVERSE(tmp);
1047
1048         return 0;
1049 }
1050
1051 static void db_return_states_call(struct expression *expr)
1052 {
1053         if (unreachable())
1054                 return;
1055
1056         if (is_assigned_call(expr))
1057                 return;
1058         if (is_condition_call(expr))
1059                 return;
1060         db_return_states(expr);
1061 }
1062
1063 static void match_function_call(struct expression *expr)
1064 {
1065         struct call_back_list *call_backs;
1066
1067         if (expr->fn->type == EXPR_SYMBOL && expr->fn->symbol) {
1068                 call_backs = search_callback(func_hash, (char *)expr->fn->symbol->ident->name);
1069                 if (call_backs)
1070                         call_call_backs(call_backs, REGULAR_CALL,
1071                                         expr->fn->symbol->ident->name, expr);
1072         }
1073         db_return_states_call(expr);
1074 }
1075
1076 static void match_macro_assign(struct expression *expr)
1077 {
1078         struct call_back_list *call_backs;
1079         const char *macro;
1080         struct expression *right;
1081
1082         right = strip_expr(expr->right);
1083         macro = get_macro_name(right->pos);
1084         call_backs = search_callback(func_hash, (char *)macro);
1085         if (!call_backs)
1086                 return;
1087         call_call_backs(call_backs, MACRO_ASSIGN, macro, expr);
1088         call_call_backs(call_backs, MACRO_ASSIGN_EXTRA, macro, expr);
1089 }
1090
1091 int get_implied_return(struct expression *expr, struct range_list **rl)
1092 {
1093         struct call_back_list *call_backs;
1094         struct fcall_back *tmp;
1095         int handled = 0;
1096         char *fn;
1097
1098         *rl = NULL;
1099
1100         expr = strip_expr(expr);
1101         fn = expr_to_var(expr->fn);
1102         if (!fn)
1103                 goto out;
1104
1105         call_backs = search_callback(func_hash, fn);
1106
1107         FOR_EACH_PTR(call_backs, tmp) {
1108                 if (tmp->type == IMPLIED_RETURN) {
1109                         (tmp->u.implied_return)(expr, tmp->info, rl);
1110                         handled = 1;
1111                 }
1112         } END_FOR_EACH_PTR(tmp);
1113
1114 out:
1115         free_string(fn);
1116         return handled;
1117 }
1118
1119 void create_function_hook_hash(void)
1120 {
1121         func_hash = create_function_hashtable(5000);
1122 }
1123
1124 void register_function_hooks(int id)
1125 {
1126         add_hook(&match_function_call, CALL_HOOK_AFTER_INLINE);
1127         add_hook(&match_assign_call, CALL_ASSIGNMENT_HOOK);
1128         add_hook(&match_macro_assign, MACRO_ASSIGNMENT_HOOK);
1129 }