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         struct smatch_state *ret_state;
 349         struct expression *var_expr;
 350         int handled;
 351 };
 352
 353 static void store_return_state(struct db_callback_info *db_info, struct smatch_state *state)
 354 {
 355         db_info->ret_state = state;
 356 }
 357
 358 static void set_return_state(struct expression *expr, struct db_callback_info *db_info)
 359 {
 360         struct smatch_state *state;
 361
 362         if (!db_info->ret_state)
 363                 return;
 364
 365         state = alloc_estate_rl(cast_rl(get_type(expr), clone_rl(estate_rl(db_info->ret_state))));
 366         set_extra_expr_mod(expr, state);
 367         db_info->ret_state = NULL;
 368 }
 369
 370 static void handle_ret_equals_param(char *ret_string, struct range_list *rl, struct expression *call)
 371 {
 372         char *str;
 373         long long param;
 374         struct expression *arg;
 375         struct range_list *orig;
 376
 377         str = strstr(ret_string, "==$");
 378         if (!str)
 379                 return;
 380         str += 3;
 381         param = strtoll(str, NULL, 10);
 382         arg = get_argument_from_call_expr(call->args, param);
 383         if (!arg)
 384                 return;
 385         get_absolute_rl(arg, &orig);
 386         rl = rl_intersection(orig, rl);
 387         if (!rl)
 388                 return;
 389         set_extra_expr_nomod(arg, alloc_estate_rl(rl));
 390 }
 391
 392 static int impossible_limit(struct expression *expr, int param, char *key, char *value)
 393 {
 394         struct expression *arg;
 395         struct range_list *passed;
 396         struct range_list *limit;
 397         struct symbol *compare_type;
 398
 399         if (strcmp(key, "$") != 0)
 400                 return 0;
 401
 402         while (expr->type == EXPR_ASSIGNMENT)
 403                 expr = strip_expr(expr->right);
 404         if (expr->type != EXPR_CALL)
 405                 return 0;
 406
 407         arg = get_argument_from_call_expr(expr->args, param);
 408         if (!arg)
 409                 return 0;
 410         if (!get_implied_rl(arg, &passed))
 411                 return 0;
 412         if (!passed || is_whole_rl(passed))
 413                 return 0;
 414
 415         compare_type = get_arg_type(expr->fn, param);
 416         passed = cast_rl(compare_type, passed);
 417         call_results_to_rl(expr, compare_type, value, &limit);
 418         if (!limit || is_whole_rl(limit))
 419                 return 0;
 420         if (possibly_true_rl(passed, SPECIAL_EQUAL, limit))
 421                 return 0;
 422         if (option_debug || local_debug)
 423                 sm_msg("impossible: %d '%s' limit '%s' == '%s'", param, key, show_rl(passed), value);
 424         return 1;
 425 }
 426
 427 static int is_impossible_data(int type, struct expression *expr, int param, char *key, char *value)
 428 {
 429         if (type == PARAM_LIMIT && impossible_limit(expr, param, key, value))
 430                 return 1;
 431         return 0;
 432 }
 433
 434 static int db_compare_callback(void *_info, int argc, char **argv, char **azColName)
 435 {
 436         struct db_callback_info *db_info = _info;
 437         struct range_list *var_rl = db_info->rl;
 438         struct range_list *ret_range;
 439         int type, param;
 440         char *key, *value;
 441         struct return_implies_callback *tmp;
 442         struct stree *stree;
 443         int return_id;
 444         int comparison;
 445
 446         if (argc != 6)
 447                 return 0;
 448
 449         return_id = atoi(argv[0]);
 450         type = atoi(argv[2]);
 451         param = atoi(argv[3]);
 452         key = argv[4];
 453         value = argv[5];
 454
 455         if (db_info->prev_return_id != -1 && return_id != db_info->prev_return_id) {
 456                 set_return_state(db_info->var_expr, db_info);
 457                 stree = __pop_fake_cur_stree();
 458
 459                 if (!db_info->cull)
 460                         merge_fake_stree(&db_info->stree, stree);
 461                 free_stree(&stree);
 462                 __push_fake_cur_stree();
 463                 db_info->cull = 0;
 464         }
 465         db_info->prev_return_id = return_id;
 466
 467         if (db_info->cull)
 468                 return 0;
 469         if (type == CULL_PATH) {
 470                 db_info->cull = 1;
 471                 return 0;
 472         }
 473
 474         if (is_impossible_data(type, db_info->expr, param, key, value)) {
 475                 db_info->cull = 1;
 476                 return 0;
 477         }
 478
 479         call_results_to_rl(db_info->expr, get_type(strip_expr(db_info->expr)), argv[1], &ret_range);
 480         ret_range = cast_rl(get_type(db_info->expr), ret_range);
 481         if (!ret_range)
 482                 ret_range = alloc_whole_rl(get_type(db_info->expr));
 483
 484         comparison = db_info->comparison;
 485         if (db_info->left)
 486                 comparison = flip_comparison(comparison);
 487
 488         if (db_info->true_side) {
 489                 if (!possibly_true_rl(var_rl, comparison, ret_range))
 490                         return 0;
 491                 if (type == PARAM_LIMIT)
 492                         param_limit_implications(db_info->expr, param, key, value);
 493                 filter_by_comparison(&var_rl, comparison, ret_range);
 494                 filter_by_comparison(&ret_range, flip_comparison(comparison), var_rl);
 495         } else {
 496                 if (!possibly_false_rl(var_rl, comparison, ret_range))
 497                         return 0;
 498                 if (type == PARAM_LIMIT)
 499                         param_limit_implications(db_info->expr, param, key, value);
 500                 filter_by_comparison(&var_rl, negate_comparison(comparison), ret_range);
 501                 filter_by_comparison(&ret_range, flip_comparison(negate_comparison(comparison)), var_rl);
 502         }
 503
 504         handle_ret_equals_param(argv[1], ret_range, db_info->expr);
 505
 506         if (type == INTERNAL)
 507                 set_state(-1, "unnull_path", NULL, &true_state);
 508
 509         FOR_EACH_PTR(db_info->callbacks, tmp) {
 510                 if (tmp->type == type)
 511                         tmp->callback(db_info->expr, param, key, value);
 512         } END_FOR_EACH_PTR(tmp);
 513
 514         store_return_state(db_info, alloc_estate_rl(clone_rl(var_rl)));
 515         return 0;
 516 }
 517
 518 static void compare_db_return_states_callbacks(struct expression *left, int comparison, struct expression *right, struct stree *implied_true, struct stree *implied_false)
 519 {
 520         struct stree *orig_states;
 521         struct stree *stree;
 522         struct stree *true_states;
 523         struct stree *false_states;
 524         struct sm_state *sm;
 525         struct db_callback_info db_info = {};
 526         struct expression *var_expr;
 527         struct expression *call_expr;
 528         struct range_list *rl;
 529         int call_on_left;
 530
 531         orig_states = clone_stree(__get_cur_stree());
 532
 533         /* legacy cruft.  need to fix call_implies_callbacks(). */
 534         call_on_left = 1;
 535         call_expr = left;
 536         var_expr = right;
 537         if (left->type != EXPR_CALL) {
 538                 call_on_left = 0;
 539                 call_expr = right;
 540                 var_expr = left;
 541         }
 542
 543         get_absolute_rl(var_expr, &rl);
 544
 545         db_info.comparison = comparison;
 546         db_info.expr = call_expr;
 547         db_info.rl = rl;
 548         db_info.left = call_on_left;
 549         db_info.callbacks = db_return_states_list;
 550         db_info.var_expr = var_expr;
 551
 552         call_return_states_before_hooks();
 553
 554         db_info.true_side = 1;
 555         db_info.stree = NULL;
 556         db_info.prev_return_id = -1;
 557         __push_fake_cur_stree();
 558         sql_select_return_states("return_id, return, type, parameter, key, value",
 559                                  call_expr, db_compare_callback, &db_info);
 560         set_return_state(db_info.var_expr, &db_info);
 561         stree = __pop_fake_cur_stree();
 562         if (!db_info.cull) {
 563                 set_return_state(db_info.var_expr, &db_info);
 564                 merge_fake_stree(&db_info.stree, stree);
 565         }
 566         free_stree(&stree);
 567         true_states = db_info.stree;
 568         if (db_info.cull && !true_states) {
 569                 __push_fake_cur_stree();
 570                 set_path_impossible();
 571                 true_states = __pop_fake_cur_stree();
 572         }
 573
 574         nullify_path();
 575         __unnullify_path();
 576         FOR_EACH_SM(orig_states, sm) {
 577                 __set_sm_cur_stree(sm);
 578         } END_FOR_EACH_SM(sm);
 579
 580         db_info.true_side = 0;
 581         db_info.stree = NULL;
 582         db_info.prev_return_id = -1;
 583         db_info.cull = 0;
 584         __push_fake_cur_stree();
 585         sql_select_return_states("return_id, return, type, parameter, key, value", call_expr,
 586                         db_compare_callback, &db_info);
 587         stree = __pop_fake_cur_stree();
 588         if (!db_info.cull) {
 589                 set_return_state(db_info.var_expr, &db_info);
 590                 merge_fake_stree(&db_info.stree, stree);
 591         }
 592         free_stree(&stree);
 593         false_states = db_info.stree;
 594         if (db_info.cull && !false_states) {
 595                 __push_fake_cur_stree();
 596                 set_path_impossible();
 597                 false_states = __pop_fake_cur_stree();
 598         }
 599
 600         nullify_path();
 601         __unnullify_path();
 602         FOR_EACH_SM(orig_states, sm) {
 603                 __set_sm_cur_stree(sm);
 604         } END_FOR_EACH_SM(sm);
 605
 606         free_stree(&orig_states);
 607
 608         FOR_EACH_SM(true_states, sm) {
 609                 __set_true_false_sm(sm, NULL);
 610         } END_FOR_EACH_SM(sm);
 611         FOR_EACH_SM(false_states, sm) {
 612                 __set_true_false_sm(NULL, sm);
 613         } END_FOR_EACH_SM(sm);
 614
 615         free_stree(&true_states);
 616         free_stree(&false_states);
 617
 618         call_return_states_after_hooks(call_expr);
 619
 620         FOR_EACH_SM(implied_true, sm) {
 621                 __set_true_false_sm(sm, NULL);
 622         } END_FOR_EACH_SM(sm);
 623         FOR_EACH_SM(implied_false, sm) {
 624                 __set_true_false_sm(NULL, sm);
 625         } END_FOR_EACH_SM(sm);
 626 }
 627
 628 void function_comparison(struct expression *left, int comparison, struct expression *right)
 629 {
 630         struct expression *var_expr;
 631         struct expression *call_expr;
 632         struct stree *implied_true = NULL;
 633         struct stree *implied_false = NULL;
 634         struct range_list *rl;
 635         sval_t sval;
 636         int call_on_left;
 637
 638         if (unreachable())
 639                 return;
 640
 641         /* legacy cruft.  need to fix call_implies_callbacks(). */
 642         call_on_left = 1;
 643         call_expr = left;
 644         var_expr = right;
 645         if (left->type != EXPR_CALL) {
 646                 call_on_left = 0;
 647                 call_expr = right;
 648                 var_expr = left;
 649         }
 650
 651         get_absolute_rl(var_expr, &rl);
 652
 653         if (rl_to_sval(rl, &sval))
 654                 call_implies_callbacks(comparison, call_expr, sval, call_on_left, &implied_true, &implied_false);
 655
 656         compare_db_return_states_callbacks(left, comparison, right, implied_true, implied_false);
 657         free_stree(&implied_true);
 658         free_stree(&implied_false);
 659 }
 660
 661 static void call_ranged_return_hooks(struct db_callback_info *db_info)
 662 {
 663         struct call_back_list *call_backs;
 664         struct expression *expr;
 665         struct fcall_back *tmp;
 666         char *fn;
 667
 668         expr = strip_expr(db_info->expr);
 669         while (expr->type == EXPR_ASSIGNMENT)
 670                 expr = strip_expr(expr->right);
 671         if (expr->type != EXPR_CALL ||
 672             expr->fn->type != EXPR_SYMBOL)
 673                 return;
 674
 675         fn = expr->fn->symbol_name->name;
 676
 677         call_backs = search_callback(func_hash, fn);
 678         FOR_EACH_PTR(call_backs, tmp) {
 679                 struct range_list *range_rl = NULL;
 680
 681                 if (tmp->type != RANGED_CALL)
 682                         continue;
 683                 add_range(&range_rl, tmp->range->min, tmp->range->max);
 684                 range_rl = cast_rl(estate_type(db_info->ret_state), range_rl);
 685                 if (possibly_true_rl(range_rl, SPECIAL_EQUAL, estate_rl(db_info->ret_state))) {
 686                         if (!possibly_true_rl(rl_invert(range_rl), SPECIAL_EQUAL, estate_rl(db_info->ret_state)))
 687                                 (tmp->u.ranged)(fn, expr, db_info->expr, tmp->info);
 688                         else
 689                                 db_info->handled = -1;
 690                 }
 691         } END_FOR_EACH_PTR(tmp);
 692 }
 693
 694 static int db_assign_return_states_callback(void *_info, int argc, char **argv, char **azColName)
 695 {
 696         struct db_callback_info *db_info = _info;
 697         struct range_list *ret_range;
 698         int type, param;
 699         char *key, *value;
 700         struct return_implies_callback *tmp;
 701         struct stree *stree;
 702         int return_id;
 703
 704         if (argc != 6)
 705                 return 0;
 706
 707         return_id = atoi(argv[0]);
 708         type = atoi(argv[2]);
 709         param = atoi(argv[3]);
 710         key = argv[4];
 711         value = argv[5];
 712
 713         if (db_info->prev_return_id != -1 && return_id != db_info->prev_return_id) {
 714                 call_ranged_return_hooks(db_info);
 715                 set_return_state(db_info->expr->left, db_info);
 716                 stree = __pop_fake_cur_stree();
 717                 if (!db_info->cull)
 718                         merge_fake_stree(&db_info->stree, stree);
 719                 free_stree(&stree);
 720                 __push_fake_cur_stree();
 721                 db_info->cull = 0;
 722         }
 723         db_info->prev_return_id = return_id;
 724
 725         if (db_info->cull)
 726                 return 0;
 727         if (type == CULL_PATH) {
 728                 db_info->cull = 1;
 729                 return 0;
 730         }
 731         if (is_impossible_data(type, db_info->expr, param, key, value)) {
 732                 db_info->cull = 1;
 733                 return 0;
 734         }
 735
 736         if (type == PARAM_LIMIT)
 737                 param_limit_implications(db_info->expr, param, key, value);
 738
 739         db_info->handled = 1;
 740         call_results_to_rl(db_info->expr->right, get_type(strip_expr(db_info->expr->right)), argv[1], &ret_range);
 741         __add_comparison_info(db_info->expr->left, strip_expr(db_info->expr->right), argv[1]);
 742         if (!ret_range)
 743                 ret_range = alloc_whole_rl(get_type(strip_expr(db_info->expr->right)));
 744         ret_range = cast_rl(get_type(db_info->expr->right), ret_range);
 745
 746         if (type == INTERNAL)
 747                 set_state(-1, "unnull_path", NULL, &true_state);
 748
 749         FOR_EACH_PTR(db_return_states_list, tmp) {
 750                 if (tmp->type == type)
 751                         tmp->callback(db_info->expr, param, key, value);
 752         } END_FOR_EACH_PTR(tmp);
 753         store_return_state(db_info, alloc_estate_rl(ret_range));
 754
 755         return 0;
 756 }
 757
 758 static int db_return_states_assign(struct expression *expr)
 759 {
 760         struct expression *right;
 761         struct sm_state *sm;
 762         struct stree *stree;
 763         struct db_callback_info db_info = {};
 764
 765         right = strip_expr(expr->right);
 766
 767         db_info.prev_return_id = -1;
 768         db_info.expr = expr;
 769         db_info.stree = NULL;
 770         db_info.handled = 0;
 771
 772         call_return_states_before_hooks();
 773
 774         __push_fake_cur_stree();
 775         sql_select_return_states("return_id, return, type, parameter, key, value",
 776                         right, db_assign_return_states_callback, &db_info);
 777         if (option_debug) {
 778                 sm_msg("%s return_id %d return_ranges %s",
 779                         db_info.cull ? "culled" : "merging",
 780                         db_info.prev_return_id,
 781                         db_info.ret_state ? db_info.ret_state->name : "'<empty>'");
 782         }
 783         if (db_info.handled)
 784                 call_ranged_return_hooks(&db_info);
 785         set_return_state(db_info.expr->left, &db_info);
 786         stree = __pop_fake_cur_stree();
 787         if (!db_info.cull)
 788                 merge_fake_stree(&db_info.stree, stree);
 789         free_stree(&stree);
 790
 791         if (!db_info.stree && db_info.cull) /* this means we culled everything */
 792                 set_extra_expr_mod(expr->left, alloc_estate_whole(get_type(expr->left)));
 793         FOR_EACH_SM(db_info.stree, sm) {
 794                 __set_sm(sm);
 795         } END_FOR_EACH_SM(sm);
 796
 797         free_stree(&db_info.stree);
 798         call_return_states_after_hooks(right);
 799
 800         return db_info.handled;
 801 }
 802
 803 static int handle_implied_return(struct expression *expr)
 804 {
 805         struct range_list *rl;
 806
 807         if (!get_implied_return(expr->right, &rl))
 808                 return 0;
 809         rl = cast_rl(get_type(expr->left), rl);
 810         set_extra_expr_mod(expr->left, alloc_estate_rl(rl));
 811         return 1;
 812 }
 813
 814 static void match_assign_call(struct expression *expr)
 815 {
 816         struct call_back_list *call_backs;
 817         const char *fn;
 818         struct expression *right;
 819         int handled = 0;
 820         struct range_list *rl;
 821
 822         if (expr->op != '=')
 823                 return;
 824
 825         right = strip_expr(expr->right);
 826         if (right->fn->type != EXPR_SYMBOL || !right->fn->symbol) {
 827                 handled |= db_return_states_assign(expr);
 828                 if (!handled)
 829                         goto assigned_unknown;
 830                 return;
 831         }
 832         if (is_fake_call(right)) {
 833                 set_extra_expr_mod(expr->left, alloc_estate_whole(get_type(expr->left)));
 834                 return;
 835         }
 836
 837         fn = right->fn->symbol->ident->name;
 838
 839         /*
 840          * some of these conflict (they try to set smatch extra twice), so we
 841          * call them in order from least important to most important.
 842          */
 843
 844         call_backs = search_callback(func_hash, (char *)fn);
 845         call_call_backs(call_backs, ASSIGN_CALL, fn, expr);
 846
 847         if (db_return_states_assign(expr) == 1)
 848                 handled = 1;
 849         else
 850                 handled = assign_ranged_funcs(fn, expr, call_backs);
 851         handled |= handle_implied_return(expr);
 852
 853         if (handled)
 854                 return;
 855
 856 assigned_unknown:
 857         get_absolute_rl(expr->right, &rl);
 858         rl = cast_rl(get_type(expr->left), rl);
 859         set_extra_expr_mod(expr->left, alloc_estate_rl(rl));
 860 }
 861
 862 static int db_return_states_callback(void *_info, int argc, char **argv, char **azColName)
 863 {
 864         struct db_callback_info *db_info = _info;
 865         struct range_list *ret_range;
 866         int type, param;
 867         char *key, *value;
 868         struct return_implies_callback *tmp;
 869         struct stree *stree;
 870         int return_id;
 871         char buf[64];
 872
 873         if (argc != 6)
 874                 return 0;
 875
 876         return_id = atoi(argv[0]);
 877         type = atoi(argv[2]);
 878         param = atoi(argv[3]);
 879         key = argv[4];
 880         value = argv[5];
 881
 882         if (db_info->prev_return_id != -1 && return_id != db_info->prev_return_id) {
 883                 stree = __pop_fake_cur_stree();
 884                 if (!db_info->cull)
 885                         merge_fake_stree(&db_info->stree, stree);
 886                 free_stree(&stree);
 887                 __push_fake_cur_stree();
 888                 __unnullify_path();
 889                 db_info->cull = 0;
 890         }
 891         db_info->prev_return_id = return_id;
 892
 893         if (db_info->cull)
 894                 return 0;
 895         if (type == CULL_PATH) {
 896                 db_info->cull = 1;
 897                 return 0;
 898         }
 899         if (is_impossible_data(type, db_info->expr, param, key, value)) {
 900                 db_info->cull = 1;
 901                 return 0;
 902         }
 903
 904         if (type == PARAM_LIMIT)
 905                 param_limit_implications(db_info->expr, param, key, value);
 906
 907         call_results_to_rl(db_info->expr, get_type(strip_expr(db_info->expr)), argv[1], &ret_range);
 908         ret_range = cast_rl(get_type(db_info->expr), ret_range);
 909
 910         if (type == INTERNAL)
 911                 set_state(-1, "unnull_path", NULL, &true_state);
 912
 913         FOR_EACH_PTR(db_return_states_list, tmp) {
 914                 if (tmp->type == type)
 915                         tmp->callback(db_info->expr, param, key, value);
 916         } END_FOR_EACH_PTR(tmp);
 917
 918         /*
 919          * We want to store the return values so that we can split the strees
 920          * in smatch_db.c.  This uses set_state() directly because it's not a
 921          * real smatch_extra state.
 922          */
 923         snprintf(buf, sizeof(buf), "return %p", db_info->expr);
 924         set_state(SMATCH_EXTRA, buf, NULL, alloc_estate_rl(ret_range));
 925
 926         return 0;
 927 }
 928
 929 static void db_return_states(struct expression *expr)
 930 {
 931         struct sm_state *sm;
 932         struct stree *stree;
 933         struct db_callback_info db_info = {};
 934
 935         if (!__get_cur_stree())  /* no return functions */
 936                 return;
 937
 938         db_info.prev_return_id = -1;
 939         db_info.expr = expr;
 940         db_info.stree = NULL;
 941
 942         call_return_states_before_hooks();
 943
 944         __push_fake_cur_stree();
 945         __unnullify_path();
 946         sql_select_return_states("return_id, return, type, parameter, key, value",
 947                         expr, db_return_states_callback, &db_info);
 948         stree = __pop_fake_cur_stree();
 949         if (!db_info.cull)
 950                 merge_fake_stree(&db_info.stree, stree);
 951         free_stree(&stree);
 952
 953         FOR_EACH_SM(db_info.stree, sm) {
 954                 __set_sm(sm);
 955         } END_FOR_EACH_SM(sm);
 956
 957         free_stree(&db_info.stree);
 958         call_return_states_after_hooks(expr);
 959 }
 960
 961 static int is_condition_call(struct expression *expr)
 962 {
 963         struct expression *tmp;
 964
 965         FOR_EACH_PTR_REVERSE(big_condition_stack, tmp) {
 966                 if (expr == tmp || expr->parent == tmp)
 967                         return 1;
 968                 if (tmp->pos.line < expr->pos.line)
 969                         return 0;
 970         } END_FOR_EACH_PTR_REVERSE(tmp);
 971
 972         return 0;
 973 }
 974
 975 static void db_return_states_call(struct expression *expr)
 976 {
 977         if (unreachable())
 978                 return;
 979
 980         if (is_assigned_call(expr))
 981                 return;
 982         if (is_condition_call(expr))
 983                 return;
 984         db_return_states(expr);
 985 }
 986
 987 static void match_function_call(struct expression *expr)
 988 {
 989         struct call_back_list *call_backs;
 990
 991         if (expr->fn->type == EXPR_SYMBOL && expr->fn->symbol) {
 992                 call_backs = search_callback(func_hash, (char *)expr->fn->symbol->ident->name);
 993                 if (call_backs)
 994                         call_call_backs(call_backs, REGULAR_CALL,
 995                                         expr->fn->symbol->ident->name, expr);
 996         }
 997         db_return_states_call(expr);
 998 }
 999
1000 static void match_macro_assign(struct expression *expr)
1001 {
1002         struct call_back_list *call_backs;
1003         const char *macro;
1004         struct expression *right;
1005
1006         right = strip_expr(expr->right);
1007         macro = get_macro_name(right->pos);
1008         call_backs = search_callback(func_hash, (char *)macro);
1009         if (!call_backs)
1010                 return;
1011         call_call_backs(call_backs, MACRO_ASSIGN, macro, expr);
1012         call_call_backs(call_backs, MACRO_ASSIGN_EXTRA, macro, expr);
1013 }
1014
1015 int get_implied_return(struct expression *expr, struct range_list **rl)
1016 {
1017         struct call_back_list *call_backs;
1018         struct fcall_back *tmp;
1019         int handled = 0;
1020         char *fn;
1021
1022         *rl = NULL;
1023
1024         expr = strip_expr(expr);
1025         fn = expr_to_var(expr->fn);
1026         if (!fn)
1027                 goto out;
1028
1029         call_backs = search_callback(func_hash, fn);
1030
1031         FOR_EACH_PTR(call_backs, tmp) {
1032                 if (tmp->type == IMPLIED_RETURN) {
1033                         (tmp->u.implied_return)(expr, tmp->info, rl);
1034                         handled = 1;
1035                 }
1036         } END_FOR_EACH_PTR(tmp);
1037
1038 out:
1039         free_string(fn);
1040         return handled;
1041 }
1042
1043 void create_function_hook_hash(void)
1044 {
1045         func_hash = create_function_hashtable(5000);
1046 }
1047
1048 void register_function_hooks(int id)
1049 {
1050         add_hook(&match_function_call, CALL_HOOK_AFTER_INLINE);
1051         add_hook(&match_assign_call, CALL_ASSIGNMENT_HOOK);
1052         add_hook(&match_macro_assign, MACRO_ASSIGNMENT_HOOK);
1053 }