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(void)
 173 {
 174         void_fn **fn;
 175
 176         FOR_EACH_PTR(return_states_after, fn) {
 177                 (*fn)();
 178         } END_FOR_EACH_PTR(fn);
 179 }
 180
 181 static int call_call_backs(struct call_back_list *list, int type,
 182                             const char *fn, struct expression *expr)
 183 {
 184         struct fcall_back *tmp;
 185         int handled = 0;
 186
 187         FOR_EACH_PTR(list, tmp) {
 188                 if (tmp->type == type) {
 189                         (tmp->u.call_back)(fn, expr, tmp->info);
 190                         handled = 1;
 191                 }
 192         } END_FOR_EACH_PTR(tmp);
 193
 194         return handled;
 195 }
 196
 197 static void call_ranged_call_backs(struct call_back_list *list,
 198                                 const char *fn, struct expression *call_expr,
 199                                 struct expression *assign_expr)
 200 {
 201         struct fcall_back *tmp;
 202
 203         FOR_EACH_PTR(list, tmp) {
 204                 (tmp->u.ranged)(fn, call_expr, assign_expr, tmp->info);
 205         } END_FOR_EACH_PTR(tmp);
 206 }
 207
 208 static struct call_back_list *get_same_ranged_call_backs(struct call_back_list *list,
 209                                                 struct data_range *drange)
 210 {
 211         struct call_back_list *ret = NULL;
 212         struct fcall_back *tmp;
 213
 214         FOR_EACH_PTR(list, tmp) {
 215                 if (tmp->type != RANGED_CALL)
 216                         continue;
 217                 if (ranges_equiv(tmp->range, drange))
 218                         add_ptr_list(&ret, tmp);
 219         } END_FOR_EACH_PTR(tmp);
 220         return ret;
 221 }
 222
 223 static int in_list_exact_sval(struct range_list *list, struct data_range *drange)
 224 {
 225         struct data_range *tmp;
 226
 227         FOR_EACH_PTR(list, tmp) {
 228                 if (ranges_equiv(tmp, drange))
 229                         return 1;
 230         } END_FOR_EACH_PTR(tmp);
 231         return 0;
 232 }
 233
 234 static int assign_ranged_funcs(const char *fn, struct expression *expr,
 235                                  struct call_back_list *call_backs)
 236 {
 237         struct fcall_back *tmp;
 238         struct sm_state *sm;
 239         char *var_name;
 240         struct symbol *sym;
 241         struct smatch_state *estate;
 242         struct stree *tmp_stree;
 243         struct stree *final_states = NULL;
 244         struct range_list *handled_ranges = NULL;
 245         struct call_back_list *same_range_call_backs = NULL;
 246         int handled = 0;
 247
 248         if (!call_backs)
 249                 return 0;
 250
 251         var_name = expr_to_var_sym(expr->left, &sym);
 252         if (!var_name || !sym)
 253                 goto free;
 254
 255         FOR_EACH_PTR(call_backs, tmp) {
 256                 if (tmp->type != RANGED_CALL)
 257                         continue;
 258
 259                 if (in_list_exact_sval(handled_ranges, tmp->range))
 260                         continue;
 261                 __push_fake_cur_stree();
 262                 tack_on(&handled_ranges, tmp->range);
 263
 264                 same_range_call_backs = get_same_ranged_call_backs(call_backs, tmp->range);
 265                 call_ranged_call_backs(same_range_call_backs, fn, expr->right, expr);
 266                 __free_ptr_list((struct ptr_list **)&same_range_call_backs);
 267
 268                 estate = alloc_estate_range(tmp->range->min, tmp->range->max);
 269                 set_extra_mod(var_name, sym, estate);
 270
 271                 tmp_stree = __pop_fake_cur_stree();
 272                 merge_fake_stree(&final_states, tmp_stree);
 273                 free_stree(&tmp_stree);
 274                 handled = 1;
 275         } END_FOR_EACH_PTR(tmp);
 276
 277         FOR_EACH_SM(final_states, sm) {
 278                 __set_sm(sm);
 279         } END_FOR_EACH_SM(sm);
 280
 281         free_stree(&final_states);
 282 free:
 283         free_string(var_name);
 284         return handled;
 285 }
 286
 287 static void call_implies_callbacks(int comparison, struct expression *expr, sval_t sval, int left, struct stree **implied_true, struct stree **implied_false)
 288 {
 289         struct call_back_list *call_backs;
 290         struct fcall_back *tmp;
 291         const char *fn;
 292         struct data_range *value_range;
 293         struct stree *true_states = NULL;
 294         struct stree *false_states = NULL;
 295         struct stree *tmp_stree;
 296
 297         *implied_true = NULL;
 298         *implied_false = NULL;
 299         if (expr->fn->type != EXPR_SYMBOL || !expr->fn->symbol)
 300                 return;
 301         fn = expr->fn->symbol->ident->name;
 302         call_backs = search_callback(func_hash, (char *)expr->fn->symbol->ident->name);
 303         if (!call_backs)
 304                 return;
 305         value_range = alloc_range(sval, sval);
 306
 307         /* set true states */
 308         __push_fake_cur_stree();
 309         FOR_EACH_PTR(call_backs, tmp) {
 310                 if (tmp->type != RANGED_CALL)
 311                         continue;
 312                 if (!true_comparison_range_LR(comparison, tmp->range, value_range, left))
 313                         continue;
 314                 (tmp->u.ranged)(fn, expr, NULL, tmp->info);
 315         } END_FOR_EACH_PTR(tmp);
 316         tmp_stree = __pop_fake_cur_stree();
 317         merge_fake_stree(&true_states, tmp_stree);
 318         free_stree(&tmp_stree);
 319
 320         /* set false states */
 321         __push_fake_cur_stree();
 322         FOR_EACH_PTR(call_backs, tmp) {
 323                 if (tmp->type != RANGED_CALL)
 324                         continue;
 325                 if (!false_comparison_range_LR(comparison, tmp->range, value_range, left))
 326                         continue;
 327                 (tmp->u.ranged)(fn, expr, NULL, tmp->info);
 328         } END_FOR_EACH_PTR(tmp);
 329         tmp_stree = __pop_fake_cur_stree();
 330         merge_fake_stree(&false_states, tmp_stree);
 331         free_stree(&tmp_stree);
 332
 333         *implied_true = true_states;
 334         *implied_false = false_states;
 335 }
 336
 337 struct db_callback_info {
 338         int true_side;
 339         int comparison;
 340         struct expression *expr;
 341         struct range_list *rl;
 342         int left;
 343         struct stree *stree;
 344         struct db_implies_list *callbacks;
 345         int prev_return_id;
 346         int cull;
 347         struct smatch_state *ret_state;
 348 };
 349
 350 static void store_return_state(struct db_callback_info *db_info, struct smatch_state *state)
 351 {
 352         db_info->ret_state = state;
 353 }
 354
 355 static void set_return_state(struct db_callback_info *db_info)
 356 {
 357         if (db_info->expr->type != EXPR_ASSIGNMENT) {
 358                 sm_msg("Smatch Internal Error: expected an assignment");
 359                 return;
 360         }
 361         if (!db_info->ret_state)
 362                 return;
 363
 364         set_extra_expr_mod(db_info->expr->left, db_info->ret_state);
 365         db_info->ret_state = NULL;
 366 }
 367
 368 static void handle_ret_equals_param(char *ret_string, struct range_list *rl, struct expression *call)
 369 {
 370         char *str;
 371         long long param;
 372         struct expression *arg;
 373         struct range_list *orig;
 374
 375         str = strstr(ret_string, "==$");
 376         if (!str)
 377                 return;
 378         str += 3;
 379         param = strtoll(str, NULL, 10);
 380         arg = get_argument_from_call_expr(call->args, param);
 381         if (!arg)
 382                 return;
 383         get_absolute_rl(arg, &orig);
 384         rl = rl_intersection(orig, rl);
 385         if (!rl)
 386                 return;
 387         set_extra_expr_nomod(arg, alloc_estate_rl(rl));
 388 }
 389
 390 static int impossible_limit(struct expression *expr, int param, char *key, char *value)
 391 {
 392         struct expression *arg;
 393         struct range_list *passed;
 394         struct range_list *limit;
 395         struct symbol *compare_type;
 396
 397         if (strcmp(key, "$") != 0)
 398                 return 0;
 399
 400         while (expr->type == EXPR_ASSIGNMENT)
 401                 expr = strip_expr(expr->right);
 402         if (expr->type != EXPR_CALL)
 403                 return 0;
 404
 405         arg = get_argument_from_call_expr(expr->args, param);
 406         if (!arg)
 407                 return 0;
 408         if (!get_implied_rl(arg, &passed))
 409                 return 0;
 410         if (!passed || is_whole_rl(passed))
 411                 return 0;
 412
 413         compare_type = get_arg_type(expr->fn, param);
 414         call_results_to_rl(expr, compare_type, value, &limit);
 415         if (!limit || is_whole_rl(limit))
 416                 return 0;
 417         if (possibly_true_rl(passed, SPECIAL_EQUAL, limit))
 418                 return 0;
 419         return 1;
 420 }
 421
 422 static int db_compare_callback(void *_info, int argc, char **argv, char **azColName)
 423 {
 424         struct db_callback_info *db_info = _info;
 425         struct range_list *ret_range;
 426         int type, param;
 427         char *key, *value;
 428         struct return_implies_callback *tmp;
 429         struct stree *stree;
 430         int return_id;
 431         int comparison;
 432
 433         if (argc != 6)
 434                 return 0;
 435
 436         return_id = atoi(argv[0]);
 437         type = atoi(argv[2]);
 438         param = atoi(argv[3]);
 439         key = argv[4];
 440         value = argv[5];
 441
 442         if (db_info->prev_return_id != -1 && return_id != db_info->prev_return_id) {
 443                 stree = __pop_fake_cur_stree();
 444                 if (!db_info->cull)
 445                         merge_fake_stree(&db_info->stree, stree);
 446                 free_stree(&stree);
 447                 __push_fake_cur_stree();
 448                 db_info->cull = 0;
 449         }
 450         db_info->prev_return_id = return_id;
 451
 452         if (type == CULL_PATH)
 453                 db_info->cull = 1;
 454         if (type == LIMITED_VALUE && impossible_limit(db_info->expr, param, key, value))
 455                 db_info->cull = 1;
 456         if (db_info->cull)
 457                 return 0;
 458
 459         call_results_to_rl(db_info->expr, get_type(strip_expr(db_info->expr)), argv[1], &ret_range);
 460         ret_range = cast_rl(get_type(db_info->expr), ret_range);
 461         if (!ret_range)
 462                 ret_range = alloc_whole_rl(get_type(db_info->expr));
 463
 464         comparison = db_info->comparison;
 465         if (!db_info->left)
 466                 comparison = flip_comparison(comparison);
 467
 468         if (db_info->true_side) {
 469                 if (!possibly_true_rl(ret_range, comparison, db_info->rl))
 470                         return 0;
 471                 filter_by_comparison(&ret_range, comparison, db_info->rl);
 472         } else {
 473                 if (!possibly_false_rl(ret_range, comparison, db_info->rl))
 474                         return 0;
 475                 filter_by_comparison(&ret_range, negate_comparison(comparison), db_info->rl);
 476         }
 477
 478         handle_ret_equals_param(argv[1], ret_range, db_info->expr);
 479
 480         FOR_EACH_PTR(db_info->callbacks, tmp) {
 481                 if (tmp->type == type)
 482                         tmp->callback(db_info->expr, param, key, value);
 483         } END_FOR_EACH_PTR(tmp);
 484         return 0;
 485 }
 486
 487 static void compare_db_return_states_callbacks(int comparison, struct expression *expr, sval_t sval, int left, struct stree *implied_true, struct stree *implied_false)
 488 {
 489         struct stree *stree;
 490         struct stree *true_states;
 491         struct stree *false_states;
 492         struct sm_state *sm;
 493         struct db_callback_info db_info = {};
 494
 495         db_info.comparison = comparison;
 496         db_info.expr = expr;
 497         db_info.rl = alloc_rl(sval, sval);
 498         db_info.left = left;
 499         db_info.callbacks = db_return_states_list;
 500
 501         call_return_states_before_hooks();
 502
 503         db_info.true_side = 1;
 504         db_info.stree = NULL;
 505         db_info.prev_return_id = -1;
 506         __push_fake_cur_stree();
 507         sql_select_return_states("return_id, return, type, parameter, key, value", expr,
 508                         db_compare_callback, &db_info);
 509         stree = __pop_fake_cur_stree();
 510         if (!db_info.cull)
 511                 merge_fake_stree(&db_info.stree, stree);
 512         free_stree(&stree);
 513         true_states = db_info.stree;
 514
 515         db_info.true_side = 0;
 516         db_info.stree = NULL;
 517         db_info.prev_return_id = -1;
 518         db_info.cull = 0;
 519         __push_fake_cur_stree();
 520         sql_select_return_states("return_id, return, type, parameter, key, value", expr,
 521                         db_compare_callback, &db_info);
 522         stree = __pop_fake_cur_stree();
 523         if (!db_info.cull)
 524                 merge_fake_stree(&db_info.stree, stree);
 525         free_stree(&stree);
 526         false_states = db_info.stree;
 527
 528         FOR_EACH_SM(true_states, sm) {
 529                 __set_true_false_sm(sm, NULL);
 530         } END_FOR_EACH_SM(sm);
 531         FOR_EACH_SM(false_states, sm) {
 532                 __set_true_false_sm(NULL, sm);
 533         } END_FOR_EACH_SM(sm);
 534
 535         free_stree(&true_states);
 536         free_stree(&false_states);
 537
 538         call_return_states_after_hooks();
 539
 540         FOR_EACH_SM(implied_true, sm) {
 541                 __set_true_false_sm(sm, NULL);
 542         } END_FOR_EACH_SM(sm);
 543         FOR_EACH_SM(implied_false, sm) {
 544                 __set_true_false_sm(NULL, sm);
 545         } END_FOR_EACH_SM(sm);
 546
 547 }
 548
 549 void function_comparison(int comparison, struct expression *expr, sval_t sval, int left)
 550 {
 551         struct stree *implied_true, *implied_false;
 552
 553         call_implies_callbacks(comparison, expr, sval, left, &implied_true, &implied_false);
 554         compare_db_return_states_callbacks(comparison, expr, sval, left, implied_true, implied_false);
 555         free_stree(&implied_true);
 556         free_stree(&implied_false);
 557 }
 558
 559 static int db_assign_return_states_callback(void *_info, int argc, char **argv, char **azColName)
 560 {
 561         struct db_callback_info *db_info = _info;
 562         struct range_list *ret_range;
 563         int type, param;
 564         char *key, *value;
 565         struct return_implies_callback *tmp;
 566         struct stree *stree;
 567         int return_id;
 568
 569         if (argc != 6)
 570                 return 0;
 571
 572         return_id = atoi(argv[0]);
 573         type = atoi(argv[2]);
 574         param = atoi(argv[3]);
 575         key = argv[4];
 576         value = argv[5];
 577
 578         if (db_info->prev_return_id != -1 && return_id != db_info->prev_return_id) {
 579                 set_return_state(db_info);
 580                 stree = __pop_fake_cur_stree();
 581                 if (!db_info->cull)
 582                         merge_fake_stree(&db_info->stree, stree);
 583                 free_stree(&stree);
 584                 __push_fake_cur_stree();
 585                 db_info->cull = 0;
 586         }
 587         db_info->prev_return_id = return_id;
 588
 589         if (type == CULL_PATH)
 590                 db_info->cull = 1;
 591         if (type == LIMITED_VALUE && impossible_limit(db_info->expr, param, key, value))
 592                 db_info->cull = 1;
 593         if (db_info->cull)
 594                 return 0;
 595
 596         call_results_to_rl(db_info->expr->right, get_type(strip_expr(db_info->expr->right)), argv[1], &ret_range);
 597         __add_comparison_info(db_info->expr->left, strip_expr(db_info->expr->right), argv[1]);
 598         if (!ret_range)
 599                 ret_range = alloc_whole_rl(get_type(strip_expr(db_info->expr->right)));
 600         ret_range = cast_rl(get_type(db_info->expr->right), ret_range);
 601
 602         FOR_EACH_PTR(db_return_states_list, tmp) {
 603                 if (tmp->type == type)
 604                         tmp->callback(db_info->expr, param, key, value);
 605         } END_FOR_EACH_PTR(tmp);
 606         ret_range = cast_rl(get_type(db_info->expr->left), ret_range);
 607         store_return_state(db_info, alloc_estate_rl(ret_range));
 608
 609         return 0;
 610 }
 611
 612 static int db_return_states_assign(struct expression *expr)
 613 {
 614         struct expression *right;
 615         struct sm_state *sm;
 616         struct stree *stree;
 617         int handled = 0;
 618         struct db_callback_info db_info = {};
 619
 620         right = strip_expr(expr->right);
 621
 622         db_info.prev_return_id = -1;
 623         db_info.expr = expr;
 624         db_info.stree = NULL;
 625
 626         call_return_states_before_hooks();
 627
 628         __push_fake_cur_stree();
 629         sql_select_return_states("return_id, return, type, parameter, key, value",
 630                         right, db_assign_return_states_callback, &db_info);
 631         set_return_state(&db_info);
 632         stree = __pop_fake_cur_stree();
 633         if (!db_info.cull)
 634                 merge_fake_stree(&db_info.stree, stree);
 635         free_stree(&stree);
 636
 637         FOR_EACH_SM(db_info.stree, sm) {
 638                 __set_sm(sm);
 639                 handled = 1;
 640         } END_FOR_EACH_SM(sm);
 641
 642         free_stree(&db_info.stree);
 643         call_return_states_after_hooks();
 644
 645         return handled;
 646 }
 647
 648 static int handle_implied_return(struct expression *expr)
 649 {
 650         struct range_list *rl;
 651
 652         if (!get_implied_return(expr->right, &rl))
 653                 return 0;
 654         rl = cast_rl(get_type(expr->left), rl);
 655         set_extra_expr_mod(expr->left, alloc_estate_rl(rl));
 656         return 1;
 657 }
 658
 659 static void match_assign_call(struct expression *expr)
 660 {
 661         struct call_back_list *call_backs;
 662         const char *fn;
 663         struct expression *right;
 664         int handled = 0;
 665         struct range_list *rl;
 666
 667         if (expr->op != '=')
 668                 return;
 669
 670         right = strip_expr(expr->right);
 671         if (right->fn->type != EXPR_SYMBOL || !right->fn->symbol) {
 672                 handled |= db_return_states_assign(expr);
 673                 if (!handled)
 674                         goto assigned_unknown;
 675                 return;
 676         }
 677         if (is_fake_call(right)) {
 678                 if (!get_state_expr(SMATCH_EXTRA, expr->left))
 679                         return;
 680                 set_extra_expr_mod(expr->left, alloc_estate_whole(get_type(expr->left)));
 681                 return;
 682         }
 683
 684         fn = right->fn->symbol->ident->name;
 685
 686         /*
 687          * some of these conflict (they try to set smatch extra twice), so we
 688          * call them in order from least important to most important.
 689          */
 690
 691         call_backs = search_callback(func_hash, (char *)fn);
 692         call_call_backs(call_backs, ASSIGN_CALL, fn, expr);
 693
 694         handled |= db_return_states_assign(expr);
 695         handled |= assign_ranged_funcs(fn, expr, call_backs);
 696         handled |= handle_implied_return(expr);
 697
 698         if (handled)
 699                 return;
 700
 701 assigned_unknown:
 702         get_absolute_rl(expr->right, &rl);
 703         rl = cast_rl(get_type(expr->left), rl);
 704         set_extra_expr_mod(expr->left, alloc_estate_rl(rl));
 705 }
 706
 707 static int db_return_states_callback(void *_info, int argc, char **argv, char **azColName)
 708 {
 709         struct db_callback_info *db_info = _info;
 710         struct range_list *ret_range;
 711         int type, param;
 712         char *key, *value;
 713         struct return_implies_callback *tmp;
 714         struct stree *stree;
 715         int return_id;
 716         char buf[64];
 717
 718         if (argc != 6)
 719                 return 0;
 720
 721         return_id = atoi(argv[0]);
 722         type = atoi(argv[2]);
 723         param = atoi(argv[3]);
 724         key = argv[4];
 725         value = argv[5];
 726
 727         if (db_info->prev_return_id != -1 && return_id != db_info->prev_return_id) {
 728                 stree = __pop_fake_cur_stree();
 729                 if (!db_info->cull)
 730                         merge_fake_stree(&db_info->stree, stree);
 731                 free_stree(&stree);
 732                 __push_fake_cur_stree();
 733                 __unnullify_path();
 734                 db_info->cull = 0;
 735         }
 736         db_info->prev_return_id = return_id;
 737
 738         if (type == CULL_PATH)
 739                 db_info->cull = 1;
 740         if (type == LIMITED_VALUE && impossible_limit(db_info->expr, param, key, value))
 741                 db_info->cull = 1;
 742         if (db_info->cull)
 743                 return 0;
 744
 745         call_results_to_rl(db_info->expr, get_type(strip_expr(db_info->expr)), argv[1], &ret_range);
 746         ret_range = cast_rl(get_type(db_info->expr), ret_range);
 747
 748         FOR_EACH_PTR(db_return_states_list, tmp) {
 749                 if (tmp->type == type)
 750                         tmp->callback(db_info->expr, param, key, value);
 751         } END_FOR_EACH_PTR(tmp);
 752
 753         /*
 754          * We want to store the return values so that we can split the strees
 755          * in smatch_db.c.  This uses set_state() directly because it's not a
 756          * real smatch_extra state.
 757          */
 758         snprintf(buf, sizeof(buf), "return %p", db_info->expr);
 759         set_state(SMATCH_EXTRA, buf, NULL, alloc_estate_rl(ret_range));
 760
 761         return 0;
 762 }
 763
 764 static void db_return_states(struct expression *expr)
 765 {
 766         struct sm_state *sm;
 767         struct stree *stree;
 768         struct db_callback_info db_info = {};
 769
 770         if (!__get_cur_stree())  /* no return functions */
 771                 return;
 772
 773         db_info.prev_return_id = -1;
 774         db_info.expr = expr;
 775         db_info.stree = NULL;
 776
 777         call_return_states_before_hooks();
 778
 779         __push_fake_cur_stree();
 780         __unnullify_path();
 781         sql_select_return_states("return_id, return, type, parameter, key, value",
 782                         expr, db_return_states_callback, &db_info);
 783         stree = __pop_fake_cur_stree();
 784         if (!db_info.cull)
 785                 merge_fake_stree(&db_info.stree, stree);
 786         free_stree(&stree);
 787
 788         FOR_EACH_SM(db_info.stree, sm) {
 789                 __set_sm(sm);
 790         } END_FOR_EACH_SM(sm);
 791
 792         free_stree(&db_info.stree);
 793         call_return_states_after_hooks();
 794 }
 795
 796 static void db_return_states_call(struct expression *expr)
 797 {
 798         if (is_assigned_call(expr))
 799                 return;
 800         db_return_states(expr);
 801 }
 802
 803 static void match_function_call(struct expression *expr)
 804 {
 805         struct call_back_list *call_backs;
 806
 807         if (expr->fn->type == EXPR_SYMBOL && expr->fn->symbol) {
 808                 call_backs = search_callback(func_hash, (char *)expr->fn->symbol->ident->name);
 809                 if (call_backs)
 810                         call_call_backs(call_backs, REGULAR_CALL,
 811                                         expr->fn->symbol->ident->name, expr);
 812         }
 813         db_return_states_call(expr);
 814 }
 815
 816 static void match_macro_assign(struct expression *expr)
 817 {
 818         struct call_back_list *call_backs;
 819         const char *macro;
 820         struct expression *right;
 821
 822         right = strip_expr(expr->right);
 823         macro = get_macro_name(right->pos);
 824         call_backs = search_callback(func_hash, (char *)macro);
 825         if (!call_backs)
 826                 return;
 827         call_call_backs(call_backs, MACRO_ASSIGN, macro, expr);
 828         call_call_backs(call_backs, MACRO_ASSIGN_EXTRA, macro, expr);
 829 }
 830
 831 int get_implied_return(struct expression *expr, struct range_list **rl)
 832 {
 833         struct call_back_list *call_backs;
 834         struct fcall_back *tmp;
 835         int handled = 0;
 836         char *fn;
 837
 838         *rl = NULL;
 839
 840         expr = strip_expr(expr);
 841         fn = expr_to_var(expr->fn);
 842         if (!fn)
 843                 goto out;
 844
 845         call_backs = search_callback(func_hash, fn);
 846
 847         FOR_EACH_PTR(call_backs, tmp) {
 848                 if (tmp->type == IMPLIED_RETURN) {
 849                         (tmp->u.implied_return)(expr, tmp->info, rl);
 850                         handled = 1;
 851                 }
 852         } END_FOR_EACH_PTR(tmp);
 853
 854 out:
 855         free_string(fn);
 856         return handled;
 857 }
 858
 859 void create_function_hook_hash(void)
 860 {
 861         func_hash = create_function_hashtable(5000);
 862 }
 863
 864 void register_function_hooks(int id)
 865 {
 866         add_hook(&match_function_call, CALL_HOOK_AFTER_INLINE);
 867         add_hook(&match_assign_call, CALL_ASSIGNMENT_HOOK);
 868         add_hook(&match_macro_assign, MACRO_ASSIGNMENT_HOOK);
 869 }