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, "==$");
 378         if (!str)
 379                 return;
 380         str += 3;
 381         param = strtoll(str, NULL, 10);
 382         arg = get_argument_from_call_expr(call->args, param);
 383         if (!arg)
 384                 return;
 385         get_absolute_rl(arg, &orig);
 386         rl = rl_intersection(orig, rl);
 387         if (!rl)
 388                 return;
 389         set_extra_expr_nomod(arg, alloc_estate_rl(rl));
 390 }
 391
 392 static int impossible_limit(struct expression *expr, int param, char *key, char *value)
 393 {
 394         struct expression *arg;
 395         struct smatch_state *state;
 396         struct range_list *passed;
 397         struct range_list *limit;
 398         struct symbol *compare_type;
 399
 400         while (expr->type == EXPR_ASSIGNMENT)
 401                 expr = strip_expr(expr->right);
 402         if (expr->type != EXPR_CALL)
 403                 return 0;
 404
 405         arg = get_argument_from_call_expr(expr->args, param);
 406         if (!arg)
 407                 return 0;
 408
 409         if (strcmp(key, "$") == 0) {
 410                 if (!get_implied_rl(arg, &passed))
 411                         return 0;
 412
 413                 compare_type = get_arg_type(expr->fn, param);
 414         } else {
 415                 char *name;
 416                 struct symbol *sym;
 417
 418                 name = get_variable_from_key(arg, key, &sym);
 419                 if (!name || !sym)
 420                         return 0;
 421
 422                 state = get_state(SMATCH_EXTRA, name, sym);
 423                 if (!state) {
 424                         free_string(name);
 425                         return 0;
 426                 }
 427                 passed = estate_rl(state);
 428                 if (!passed || is_whole_rl(passed)) {
 429                         free_string(name);
 430                         return 0;
 431                 }
 432
 433                 compare_type = get_member_type_from_key(arg, key);
 434         }
 435
 436         passed = cast_rl(compare_type, passed);
 437         call_results_to_rl(expr, compare_type, value, &limit);
 438         if (!limit || is_whole_rl(limit))
 439                 return 0;
 440         if (possibly_true_rl(passed, SPECIAL_EQUAL, limit))
 441                 return 0;
 442         if (option_debug || local_debug)
 443                 sm_msg("impossible: %d '%s' limit '%s' == '%s'", param, key, show_rl(passed), value);
 444         return 1;
 445 }
 446
 447 static int is_impossible_data(int type, struct expression *expr, int param, char *key, char *value)
 448 {
 449         if (type == PARAM_LIMIT && impossible_limit(expr, param, key, value))
 450                 return 1;
 451         if (type == COMPARE_LIMIT && param_compare_limit_is_impossible(expr, param, key, value))
 452                 return 1;
 453         return 0;
 454 }
 455
 456 static int db_compare_callback(void *_info, int argc, char **argv, char **azColName)
 457 {
 458         struct db_callback_info *db_info = _info;
 459         struct range_list *var_rl = db_info->rl;
 460         struct range_list *ret_range;
 461         int type, param;
 462         char *key, *value;
 463         struct return_implies_callback *tmp;
 464         struct stree *stree;
 465         int return_id;
 466         int comparison;
 467
 468         if (argc != 6)
 469                 return 0;
 470
 471         return_id = atoi(argv[0]);
 472         type = atoi(argv[2]);
 473         param = atoi(argv[3]);
 474         key = argv[4];
 475         value = argv[5];
 476
 477         if (db_info->prev_return_id != -1 && type == INTERNAL) {
 478                 set_return_state(db_info->var_expr, db_info);
 479                 stree = __pop_fake_cur_stree();
 480
 481                 if (!db_info->cull)
 482                         merge_fake_stree(&db_info->stree, stree);
 483                 free_stree(&stree);
 484                 __push_fake_cur_stree();
 485                 db_info->cull = 0;
 486         }
 487         db_info->prev_return_id = return_id;
 488
 489         if (db_info->cull)
 490                 return 0;
 491         if (type == CULL_PATH) {
 492                 db_info->cull = 1;
 493                 return 0;
 494         }
 495
 496         if (is_impossible_data(type, db_info->expr, param, key, value)) {
 497                 db_info->cull = 1;
 498                 return 0;
 499         }
 500
 501         call_results_to_rl(db_info->expr, get_type(strip_expr(db_info->expr)), argv[1], &ret_range);
 502         ret_range = cast_rl(get_type(db_info->expr), ret_range);
 503         if (!ret_range)
 504                 ret_range = alloc_whole_rl(get_type(db_info->expr));
 505
 506         comparison = db_info->comparison;
 507         if (db_info->left)
 508                 comparison = flip_comparison(comparison);
 509
 510         if (db_info->true_side) {
 511                 if (!possibly_true_rl(var_rl, comparison, ret_range))
 512                         return 0;
 513                 if (type == PARAM_LIMIT)
 514                         param_limit_implications(db_info->expr, param, key, value);
 515                 filter_by_comparison(&var_rl, comparison, ret_range);
 516                 filter_by_comparison(&ret_range, flip_comparison(comparison), var_rl);
 517         } else {
 518                 if (!possibly_false_rl(var_rl, comparison, ret_range))
 519                         return 0;
 520                 if (type == PARAM_LIMIT)
 521                         param_limit_implications(db_info->expr, param, key, value);
 522                 filter_by_comparison(&var_rl, negate_comparison(comparison), ret_range);
 523                 filter_by_comparison(&ret_range, flip_comparison(negate_comparison(comparison)), var_rl);
 524         }
 525
 526         handle_ret_equals_param(argv[1], ret_range, db_info->expr);
 527
 528         if (type == INTERNAL)
 529                 set_state(-1, "unnull_path", NULL, &true_state);
 530
 531         FOR_EACH_PTR(db_info->callbacks, tmp) {
 532                 if (tmp->type == type)
 533                         tmp->callback(db_info->expr, param, key, value);
 534         } END_FOR_EACH_PTR(tmp);
 535
 536         store_return_state(db_info, alloc_estate_rl(clone_rl(var_rl)));
 537         return 0;
 538 }
 539
 540 static void compare_db_return_states_callbacks(struct expression *left, int comparison, struct expression *right, struct stree *implied_true, struct stree *implied_false)
 541 {
 542         struct stree *orig_states;
 543         struct stree *stree;
 544         struct stree *true_states;
 545         struct stree *false_states;
 546         struct sm_state *sm;
 547         struct db_callback_info db_info = {};
 548         struct expression *var_expr;
 549         struct expression *call_expr;
 550         struct range_list *rl;
 551         int call_on_left;
 552
 553         orig_states = clone_stree(__get_cur_stree());
 554
 555         /* legacy cruft.  need to fix call_implies_callbacks(). */
 556         call_on_left = 1;
 557         call_expr = left;
 558         var_expr = right;
 559         if (left->type != EXPR_CALL) {
 560                 call_on_left = 0;
 561                 call_expr = right;
 562                 var_expr = left;
 563         }
 564
 565         get_absolute_rl(var_expr, &rl);
 566
 567         db_info.comparison = comparison;
 568         db_info.expr = call_expr;
 569         db_info.rl = rl;
 570         db_info.left = call_on_left;
 571         db_info.callbacks = db_return_states_list;
 572         db_info.var_expr = var_expr;
 573
 574         call_return_states_before_hooks();
 575
 576         db_info.true_side = 1;
 577         db_info.stree = NULL;
 578         db_info.prev_return_id = -1;
 579         __push_fake_cur_stree();
 580         sql_select_return_states("return_id, return, type, parameter, key, value",
 581                                  call_expr, db_compare_callback, &db_info);
 582         set_return_state(db_info.var_expr, &db_info);
 583         stree = __pop_fake_cur_stree();
 584         if (!db_info.cull) {
 585                 set_return_state(db_info.var_expr, &db_info);
 586                 merge_fake_stree(&db_info.stree, stree);
 587         }
 588         free_stree(&stree);
 589         true_states = db_info.stree;
 590         if (db_info.cull && !true_states) {
 591                 __push_fake_cur_stree();
 592                 set_path_impossible();
 593                 true_states = __pop_fake_cur_stree();
 594         }
 595
 596         nullify_path();
 597         __unnullify_path();
 598         FOR_EACH_SM(orig_states, sm) {
 599                 __set_sm_cur_stree(sm);
 600         } END_FOR_EACH_SM(sm);
 601
 602         db_info.true_side = 0;
 603         db_info.stree = NULL;
 604         db_info.prev_return_id = -1;
 605         db_info.cull = 0;
 606         __push_fake_cur_stree();
 607         sql_select_return_states("return_id, return, type, parameter, key, value", call_expr,
 608                         db_compare_callback, &db_info);
 609         stree = __pop_fake_cur_stree();
 610         if (!db_info.cull) {
 611                 set_return_state(db_info.var_expr, &db_info);
 612                 merge_fake_stree(&db_info.stree, stree);
 613         }
 614         free_stree(&stree);
 615         false_states = db_info.stree;
 616         if (db_info.cull && !false_states) {
 617                 __push_fake_cur_stree();
 618                 set_path_impossible();
 619                 false_states = __pop_fake_cur_stree();
 620         }
 621
 622         nullify_path();
 623         __unnullify_path();
 624         FOR_EACH_SM(orig_states, sm) {
 625                 __set_sm_cur_stree(sm);
 626         } END_FOR_EACH_SM(sm);
 627
 628         free_stree(&orig_states);
 629
 630         FOR_EACH_SM(true_states, sm) {
 631                 __set_true_false_sm(sm, NULL);
 632         } END_FOR_EACH_SM(sm);
 633         FOR_EACH_SM(false_states, sm) {
 634                 __set_true_false_sm(NULL, sm);
 635         } END_FOR_EACH_SM(sm);
 636
 637         free_stree(&true_states);
 638         free_stree(&false_states);
 639
 640         call_return_states_after_hooks(call_expr);
 641
 642         FOR_EACH_SM(implied_true, sm) {
 643                 __set_true_false_sm(sm, NULL);
 644         } END_FOR_EACH_SM(sm);
 645         FOR_EACH_SM(implied_false, sm) {
 646                 __set_true_false_sm(NULL, sm);
 647         } END_FOR_EACH_SM(sm);
 648 }
 649
 650 void function_comparison(struct expression *left, int comparison, struct expression *right)
 651 {
 652         struct expression *var_expr;
 653         struct expression *call_expr;
 654         struct stree *implied_true = NULL;
 655         struct stree *implied_false = NULL;
 656         struct range_list *rl;
 657         sval_t sval;
 658         int call_on_left;
 659
 660         if (unreachable())
 661                 return;
 662
 663         /* legacy cruft.  need to fix call_implies_callbacks(). */
 664         call_on_left = 1;
 665         call_expr = left;
 666         var_expr = right;
 667         if (left->type != EXPR_CALL) {
 668                 call_on_left = 0;
 669                 call_expr = right;
 670                 var_expr = left;
 671         }
 672
 673         get_absolute_rl(var_expr, &rl);
 674
 675         if (rl_to_sval(rl, &sval))
 676                 call_implies_callbacks(comparison, call_expr, sval, call_on_left, &implied_true, &implied_false);
 677
 678         compare_db_return_states_callbacks(left, comparison, right, implied_true, implied_false);
 679         free_stree(&implied_true);
 680         free_stree(&implied_false);
 681 }
 682
 683 static void call_ranged_return_hooks(struct db_callback_info *db_info)
 684 {
 685         struct call_back_list *call_backs;
 686         struct expression *expr;
 687         struct fcall_back *tmp;
 688         char *fn;
 689
 690         expr = strip_expr(db_info->expr);
 691         while (expr->type == EXPR_ASSIGNMENT)
 692                 expr = strip_expr(expr->right);
 693         if (expr->type != EXPR_CALL ||
 694             expr->fn->type != EXPR_SYMBOL)
 695                 return;
 696
 697         fn = expr->fn->symbol_name->name;
 698
 699         call_backs = search_callback(func_hash, fn);
 700         FOR_EACH_PTR(call_backs, tmp) {
 701                 struct range_list *range_rl = NULL;
 702
 703                 if (tmp->type != RANGED_CALL)
 704                         continue;
 705                 add_range(&range_rl, tmp->range->min, tmp->range->max);
 706                 range_rl = cast_rl(estate_type(db_info->ret_state), range_rl);
 707                 if (possibly_true_rl(range_rl, SPECIAL_EQUAL, estate_rl(db_info->ret_state))) {
 708                         if (!possibly_true_rl(rl_invert(range_rl), SPECIAL_EQUAL, estate_rl(db_info->ret_state)))
 709                                 (tmp->u.ranged)(fn, expr, db_info->expr, tmp->info);
 710                         else
 711                                 db_info->handled = -1;
 712                 }
 713         } END_FOR_EACH_PTR(tmp);
 714 }
 715
 716 static int db_assign_return_states_callback(void *_info, int argc, char **argv, char **azColName)
 717 {
 718         struct db_callback_info *db_info = _info;
 719         struct range_list *ret_range;
 720         int type, param;
 721         char *key, *value;
 722         struct return_implies_callback *tmp;
 723         struct stree *stree;
 724         int return_id;
 725
 726         if (argc != 6)
 727                 return 0;
 728
 729         return_id = atoi(argv[0]);
 730         type = atoi(argv[2]);
 731         param = atoi(argv[3]);
 732         key = argv[4];
 733         value = argv[5];
 734
 735         if (db_info->prev_return_id != -1 && type == INTERNAL) {
 736                 call_ranged_return_hooks(db_info);
 737                 set_return_state(db_info->expr->left, db_info);
 738                 stree = __pop_fake_cur_stree();
 739                 if (!db_info->cull)
 740                         merge_fake_stree(&db_info->stree, stree);
 741                 free_stree(&stree);
 742                 __push_fake_cur_stree();
 743                 db_info->cull = 0;
 744         }
 745         db_info->prev_return_id = return_id;
 746
 747         if (db_info->cull)
 748                 return 0;
 749         if (type == CULL_PATH) {
 750                 db_info->cull = 1;
 751                 return 0;
 752         }
 753         if (is_impossible_data(type, db_info->expr, param, key, value)) {
 754                 db_info->cull = 1;
 755                 return 0;
 756         }
 757
 758         if (type == PARAM_LIMIT)
 759                 param_limit_implications(db_info->expr, param, key, value);
 760
 761         db_info->handled = 1;
 762         call_results_to_rl(db_info->expr->right, get_type(strip_expr(db_info->expr->right)), argv[1], &ret_range);
 763         __add_comparison_info(db_info->expr->left, strip_expr(db_info->expr->right), argv[1]);
 764         if (!ret_range)
 765                 ret_range = alloc_whole_rl(get_type(strip_expr(db_info->expr->right)));
 766         ret_range = cast_rl(get_type(db_info->expr->right), ret_range);
 767
 768         if (type == INTERNAL)
 769                 set_state(-1, "unnull_path", NULL, &true_state);
 770
 771         FOR_EACH_PTR(db_return_states_list, tmp) {
 772                 if (tmp->type == type)
 773                         tmp->callback(db_info->expr, param, key, value);
 774         } END_FOR_EACH_PTR(tmp);
 775         store_return_state(db_info, alloc_estate_rl(ret_range));
 776
 777         return 0;
 778 }
 779
 780 static int db_return_states_assign(struct expression *expr)
 781 {
 782         struct expression *right;
 783         struct sm_state *sm;
 784         struct stree *stree;
 785         struct db_callback_info db_info = {};
 786
 787         right = strip_expr(expr->right);
 788
 789         db_info.prev_return_id = -1;
 790         db_info.expr = expr;
 791         db_info.stree = NULL;
 792         db_info.handled = 0;
 793
 794         call_return_states_before_hooks();
 795
 796         __push_fake_cur_stree();
 797         sql_select_return_states("return_id, return, type, parameter, key, value",
 798                         right, db_assign_return_states_callback, &db_info);
 799         if (option_debug) {
 800                 sm_msg("%s return_id %d return_ranges %s",
 801                         db_info.cull ? "culled" : "merging",
 802                         db_info.prev_return_id,
 803                         db_info.ret_state ? db_info.ret_state->name : "'<empty>'");
 804         }
 805         if (db_info.handled)
 806                 call_ranged_return_hooks(&db_info);
 807         set_return_state(db_info.expr->left, &db_info);
 808         stree = __pop_fake_cur_stree();
 809         if (!db_info.cull)
 810                 merge_fake_stree(&db_info.stree, stree);
 811         free_stree(&stree);
 812
 813         if (!db_info.stree && db_info.cull) /* this means we culled everything */
 814                 set_extra_expr_mod(expr->left, alloc_estate_whole(get_type(expr->left)));
 815         FOR_EACH_SM(db_info.stree, sm) {
 816                 __set_sm(sm);
 817         } END_FOR_EACH_SM(sm);
 818
 819         free_stree(&db_info.stree);
 820         call_return_states_after_hooks(right);
 821
 822         return db_info.handled;
 823 }
 824
 825 static int handle_implied_return(struct expression *expr)
 826 {
 827         struct range_list *rl;
 828
 829         if (!get_implied_return(expr->right, &rl))
 830                 return 0;
 831         rl = cast_rl(get_type(expr->left), rl);
 832         set_extra_expr_mod(expr->left, alloc_estate_rl(rl));
 833         return 1;
 834 }
 835
 836 static void match_assign_call(struct expression *expr)
 837 {
 838         struct call_back_list *call_backs;
 839         const char *fn;
 840         struct expression *right;
 841         int handled = 0;
 842         struct range_list *rl;
 843
 844         if (expr->op != '=')
 845                 return;
 846
 847         right = strip_expr(expr->right);
 848         if (right->fn->type != EXPR_SYMBOL || !right->fn->symbol) {
 849                 handled |= db_return_states_assign(expr);
 850                 if (!handled)
 851                         goto assigned_unknown;
 852                 return;
 853         }
 854         if (is_fake_call(right)) {
 855                 set_extra_expr_mod(expr->left, alloc_estate_whole(get_type(expr->left)));
 856                 return;
 857         }
 858
 859         fn = right->fn->symbol->ident->name;
 860         call_backs = search_callback(func_hash, (char *)fn);
 861
 862         /*
 863          * The ordering here is sort of important.
 864          * One example, of how this matters is that when we do:
 865          *
 866          *      len = strlen(str);
 867          *
 868          * That is handled by smatch_common_functions.c and smatch_strlen.c.
 869          * They use implied_return and function_assign_hook respectively.
 870          * We want to get the implied return first before we do the function
 871          * assignment hook otherwise we end up writing the wrong thing for len
 872          * in smatch_extra.c because we assume that it already holds the
 873          * strlen() when we haven't set it yet.
 874          */
 875
 876         if (db_return_states_assign(expr) == 1)
 877                 handled = 1;
 878         else
 879                 handled = assign_ranged_funcs(fn, expr, call_backs);
 880         handled |= handle_implied_return(expr);
 881
 882
 883         call_call_backs(call_backs, ASSIGN_CALL, fn, expr);
 884
 885         if (handled)
 886                 return;
 887
 888 assigned_unknown:
 889         get_absolute_rl(expr->right, &rl);
 890         rl = cast_rl(get_type(expr->left), rl);
 891         set_extra_expr_mod(expr->left, alloc_estate_rl(rl));
 892 }
 893
 894 static int db_return_states_callback(void *_info, int argc, char **argv, char **azColName)
 895 {
 896         struct db_callback_info *db_info = _info;
 897         struct range_list *ret_range;
 898         int type, param;
 899         char *key, *value;
 900         struct return_implies_callback *tmp;
 901         struct stree *stree;
 902         int return_id;
 903         char buf[64];
 904
 905         if (argc != 6)
 906                 return 0;
 907
 908         return_id = atoi(argv[0]);
 909         type = atoi(argv[2]);
 910         param = atoi(argv[3]);
 911         key = argv[4];
 912         value = argv[5];
 913
 914         if (db_info->prev_return_id != -1 && type == INTERNAL) {
 915                 stree = __pop_fake_cur_stree();
 916                 if (!db_info->cull)
 917                         merge_fake_stree(&db_info->stree, stree);
 918                 free_stree(&stree);
 919                 __push_fake_cur_stree();
 920                 __unnullify_path();
 921                 db_info->cull = 0;
 922         }
 923         db_info->prev_return_id = return_id;
 924
 925         if (db_info->cull)
 926                 return 0;
 927         if (type == CULL_PATH) {
 928                 db_info->cull = 1;
 929                 return 0;
 930         }
 931         if (is_impossible_data(type, db_info->expr, param, key, value)) {
 932                 db_info->cull = 1;
 933                 return 0;
 934         }
 935
 936         if (type == PARAM_LIMIT)
 937                 param_limit_implications(db_info->expr, param, key, value);
 938
 939         call_results_to_rl(db_info->expr, get_type(strip_expr(db_info->expr)), argv[1], &ret_range);
 940         ret_range = cast_rl(get_type(db_info->expr), ret_range);
 941
 942         if (type == INTERNAL)
 943                 set_state(-1, "unnull_path", NULL, &true_state);
 944
 945         FOR_EACH_PTR(db_return_states_list, tmp) {
 946                 if (tmp->type == type)
 947                         tmp->callback(db_info->expr, param, key, value);
 948         } END_FOR_EACH_PTR(tmp);
 949
 950         /*
 951          * We want to store the return values so that we can split the strees
 952          * in smatch_db.c.  This uses set_state() directly because it's not a
 953          * real smatch_extra state.
 954          */
 955         snprintf(buf, sizeof(buf), "return %p", db_info->expr);
 956         set_state(SMATCH_EXTRA, buf, NULL, alloc_estate_rl(ret_range));
 957
 958         return 0;
 959 }
 960
 961 static void db_return_states(struct expression *expr)
 962 {
 963         struct sm_state *sm;
 964         struct stree *stree;
 965         struct db_callback_info db_info = {};
 966
 967         if (!__get_cur_stree())  /* no return functions */
 968                 return;
 969
 970         db_info.prev_return_id = -1;
 971         db_info.expr = expr;
 972         db_info.stree = NULL;
 973
 974         call_return_states_before_hooks();
 975
 976         __push_fake_cur_stree();
 977         __unnullify_path();
 978         sql_select_return_states("return_id, return, type, parameter, key, value",
 979                         expr, db_return_states_callback, &db_info);
 980         stree = __pop_fake_cur_stree();
 981         if (!db_info.cull)
 982                 merge_fake_stree(&db_info.stree, stree);
 983         free_stree(&stree);
 984
 985         FOR_EACH_SM(db_info.stree, sm) {
 986                 __set_sm(sm);
 987         } END_FOR_EACH_SM(sm);
 988
 989         free_stree(&db_info.stree);
 990         call_return_states_after_hooks(expr);
 991 }
 992
 993 static int is_condition_call(struct expression *expr)
 994 {
 995         struct expression *tmp;
 996
 997         FOR_EACH_PTR_REVERSE(big_condition_stack, tmp) {
 998                 if (expr == tmp || expr->parent == tmp)
 999                         return 1;
1000                 if (tmp->pos.line < expr->pos.line)
1001                         return 0;
1002         } END_FOR_EACH_PTR_REVERSE(tmp);
1003
1004         return 0;
1005 }
1006
1007 static void db_return_states_call(struct expression *expr)
1008 {
1009         if (unreachable())
1010                 return;
1011
1012         if (is_assigned_call(expr))
1013                 return;
1014         if (is_condition_call(expr))
1015                 return;
1016         db_return_states(expr);
1017 }
1018
1019 static void match_function_call(struct expression *expr)
1020 {
1021         struct call_back_list *call_backs;
1022
1023         if (expr->fn->type == EXPR_SYMBOL && expr->fn->symbol) {
1024                 call_backs = search_callback(func_hash, (char *)expr->fn->symbol->ident->name);
1025                 if (call_backs)
1026                         call_call_backs(call_backs, REGULAR_CALL,
1027                                         expr->fn->symbol->ident->name, expr);
1028         }
1029         db_return_states_call(expr);
1030 }
1031
1032 static void match_macro_assign(struct expression *expr)
1033 {
1034         struct call_back_list *call_backs;
1035         const char *macro;
1036         struct expression *right;
1037
1038         right = strip_expr(expr->right);
1039         macro = get_macro_name(right->pos);
1040         call_backs = search_callback(func_hash, (char *)macro);
1041         if (!call_backs)
1042                 return;
1043         call_call_backs(call_backs, MACRO_ASSIGN, macro, expr);
1044         call_call_backs(call_backs, MACRO_ASSIGN_EXTRA, macro, expr);
1045 }
1046
1047 int get_implied_return(struct expression *expr, struct range_list **rl)
1048 {
1049         struct call_back_list *call_backs;
1050         struct fcall_back *tmp;
1051         int handled = 0;
1052         char *fn;
1053
1054         *rl = NULL;
1055
1056         expr = strip_expr(expr);
1057         fn = expr_to_var(expr->fn);
1058         if (!fn)
1059                 goto out;
1060
1061         call_backs = search_callback(func_hash, fn);
1062
1063         FOR_EACH_PTR(call_backs, tmp) {
1064                 if (tmp->type == IMPLIED_RETURN) {
1065                         (tmp->u.implied_return)(expr, tmp->info, rl);
1066                         handled = 1;
1067                 }
1068         } END_FOR_EACH_PTR(tmp);
1069
1070 out:
1071         free_string(fn);
1072         return handled;
1073 }
1074
1075 void create_function_hook_hash(void)
1076 {
1077         func_hash = create_function_hashtable(5000);
1078 }
1079
1080 void register_function_hooks(int id)
1081 {
1082         add_hook(&match_function_call, CALL_HOOK_AFTER_INLINE);
1083         add_hook(&match_assign_call, CALL_ASSIGNMENT_HOOK);
1084         add_hook(&match_macro_assign, MACRO_ASSIGNMENT_HOOK);
1085 }