smatch_function_hooks.c

   1 /*
   2  * Copyright (C) 2009 Dan Carpenter.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
  16  */
  17
  18 /*
  19  * There are several types of function hooks:
  20  * add_function_hook()        - For any time a function is called.
  21  * add_function_assign_hook() - foo = the_function().
  22  * add_implied_return_hook()  - Calculates the implied return value.
  23  * add_macro_assign_hook()    - foo = the_macro().
  24  * return_implies_state()     - For when a return value of 1 implies locked
  25  *                              and 0 implies unlocked. etc. etc.
  26  *
  27  */
  28
  29 #include <stdlib.h>
  30 #include <stdio.h>
  31 #include "smatch.h"
  32 #include "smatch_slist.h"
  33 #include "smatch_extra.h"
  34 #include "smatch_function_hashtable.h"
  35
  36 struct fcall_back {
  37         int type;
  38         struct data_range *range;
  39         union {
  40                 func_hook *call_back;
  41                 implication_hook *ranged;
  42                 implied_return_hook *implied_return;
  43         } u;
  44         void *info;
  45 };
  46
  47 ALLOCATOR(fcall_back, "call backs");
  48 DECLARE_PTR_LIST(call_back_list, struct fcall_back);
  49
  50 DEFINE_FUNCTION_HASHTABLE_STATIC(callback, struct fcall_back, struct call_back_list);
  51 static struct hashtable *func_hash;
  52
  53 #define REGULAR_CALL       0
  54 #define RANGED_CALL        1
  55 #define ASSIGN_CALL        2
  56 #define IMPLIED_RETURN     3
  57 #define MACRO_ASSIGN       4
  58 #define MACRO_ASSIGN_EXTRA 5
  59
  60 struct return_implies_callback {
  61         int type;
  62         return_implies_hook *callback;
  63 };
  64 ALLOCATOR(return_implies_callback, "return_implies callbacks");
  65 DECLARE_PTR_LIST(db_implies_list, struct return_implies_callback);
  66 static struct db_implies_list *db_return_states_list;
  67
  68 typedef void (void_fn)(void);
  69 DECLARE_PTR_LIST(void_fn_list, void_fn *);
  70 static struct void_fn_list *return_states_before;
  71 static struct void_fn_list *return_states_after;
  72
  73 static struct fcall_back *alloc_fcall_back(int type, void *call_back,
  74                                            void *info)
  75 {
  76         struct fcall_back *cb;
  77
  78         cb = __alloc_fcall_back(0);
  79         cb->type = type;
  80         cb->u.call_back = call_back;
  81         cb->info = info;
  82         return cb;
  83 }
  84
  85 void add_function_hook(const char *look_for, func_hook *call_back, void *info)
  86 {
  87         struct fcall_back *cb;
  88
  89         cb = alloc_fcall_back(REGULAR_CALL, call_back, info);
  90         add_callback(func_hash, look_for, cb);
  91 }
  92
  93 void add_function_assign_hook(const char *look_for, func_hook *call_back,
  94                               void *info)
  95 {
  96         struct fcall_back *cb;
  97
  98         cb = alloc_fcall_back(ASSIGN_CALL, call_back, info);
  99         add_callback(func_hash, look_for, cb);
 100 }
 101
 102 void add_implied_return_hook(const char *look_for,
 103                              implied_return_hook *call_back,
 104                              void *info)
 105 {
 106         struct fcall_back *cb;
 107
 108         cb = alloc_fcall_back(IMPLIED_RETURN, call_back, info);
 109         add_callback(func_hash, look_for, cb);
 110 }
 111
 112 void add_macro_assign_hook(const char *look_for, func_hook *call_back,
 113                         void *info)
 114 {
 115         struct fcall_back *cb;
 116
 117         cb = alloc_fcall_back(MACRO_ASSIGN, call_back, info);
 118         add_callback(func_hash, look_for, cb);
 119 }
 120
 121 void add_macro_assign_hook_extra(const char *look_for, func_hook *call_back,
 122                         void *info)
 123 {
 124         struct fcall_back *cb;
 125
 126         cb = alloc_fcall_back(MACRO_ASSIGN_EXTRA, call_back, info);
 127         add_callback(func_hash, look_for, cb);
 128 }
 129
 130 void return_implies_state(const char *look_for, long long start, long long end,
 131                          implication_hook *call_back, void *info)
 132 {
 133         struct fcall_back *cb;
 134
 135         cb = alloc_fcall_back(RANGED_CALL, call_back, info);
 136         cb->range = alloc_range_perm(ll_to_sval(start), ll_to_sval(end));
 137         add_callback(func_hash, look_for, cb);
 138 }
 139
 140 void select_return_states_hook(int type, return_implies_hook *callback)
 141 {
 142         struct return_implies_callback *cb = __alloc_return_implies_callback(0);
 143
 144         cb->type = type;
 145         cb->callback = callback;
 146         add_ptr_list(&db_return_states_list, cb);
 147 }
 148
 149 void select_return_states_before(void_fn *fn)
 150 {
 151         void_fn **p = malloc(sizeof(void_fn *));
 152         *p = fn;
 153         add_ptr_list(&return_states_before, p);
 154 }
 155
 156 void select_return_states_after(void_fn *fn)
 157 {
 158         void_fn **p = malloc(sizeof(void_fn *));
 159         *p = fn;
 160         add_ptr_list(&return_states_after, p);
 161 }
 162
 163 static void call_return_states_before_hooks(void)
 164 {
 165         void_fn **fn;
 166
 167         FOR_EACH_PTR(return_states_before, fn) {
 168                 (*fn)();
 169         } END_FOR_EACH_PTR(fn);
 170 }
 171
 172 static void call_return_states_after_hooks(struct expression *expr)
 173 {
 174         void_fn **fn;
 175
 176         FOR_EACH_PTR(return_states_after, fn) {
 177                 (*fn)();
 178         } END_FOR_EACH_PTR(fn);
 179         __pass_to_client(expr, FUNCTION_CALL_HOOK_AFTER_DB);
 180 }
 181
 182 static int call_call_backs(struct call_back_list *list, int type,
 183                             const char *fn, struct expression *expr)
 184 {
 185         struct fcall_back *tmp;
 186         int handled = 0;
 187
 188         FOR_EACH_PTR(list, tmp) {
 189                 if (tmp->type == type) {
 190                         (tmp->u.call_back)(fn, expr, tmp->info);
 191                         handled = 1;
 192                 }
 193         } END_FOR_EACH_PTR(tmp);
 194
 195         return handled;
 196 }
 197
 198 static void call_ranged_call_backs(struct call_back_list *list,
 199                                 const char *fn, struct expression *call_expr,
 200                                 struct expression *assign_expr)
 201 {
 202         struct fcall_back *tmp;
 203
 204         FOR_EACH_PTR(list, tmp) {
 205                 (tmp->u.ranged)(fn, call_expr, assign_expr, tmp->info);
 206         } END_FOR_EACH_PTR(tmp);
 207 }
 208
 209 static struct call_back_list *get_same_ranged_call_backs(struct call_back_list *list,
 210                                                 struct data_range *drange)
 211 {
 212         struct call_back_list *ret = NULL;
 213         struct fcall_back *tmp;
 214
 215         FOR_EACH_PTR(list, tmp) {
 216                 if (tmp->type != RANGED_CALL)
 217                         continue;
 218                 if (ranges_equiv(tmp->range, drange))
 219                         add_ptr_list(&ret, tmp);
 220         } END_FOR_EACH_PTR(tmp);
 221         return ret;
 222 }
 223
 224 static int in_list_exact_sval(struct range_list *list, struct data_range *drange)
 225 {
 226         struct data_range *tmp;
 227
 228         FOR_EACH_PTR(list, tmp) {
 229                 if (ranges_equiv(tmp, drange))
 230                         return 1;
 231         } END_FOR_EACH_PTR(tmp);
 232         return 0;
 233 }
 234
 235 static int assign_ranged_funcs(const char *fn, struct expression *expr,
 236                                  struct call_back_list *call_backs)
 237 {
 238         struct fcall_back *tmp;
 239         struct sm_state *sm;
 240         char *var_name;
 241         struct symbol *sym;
 242         struct smatch_state *estate;
 243         struct stree *tmp_stree;
 244         struct stree *final_states = NULL;
 245         struct range_list *handled_ranges = NULL;
 246         struct call_back_list *same_range_call_backs = NULL;
 247         int handled = 0;
 248
 249         if (!call_backs)
 250                 return 0;
 251
 252         var_name = expr_to_var_sym(expr->left, &sym);
 253         if (!var_name || !sym)
 254                 goto free;
 255
 256         FOR_EACH_PTR(call_backs, tmp) {
 257                 if (tmp->type != RANGED_CALL)
 258                         continue;
 259
 260                 if (in_list_exact_sval(handled_ranges, tmp->range))
 261                         continue;
 262                 __push_fake_cur_stree();
 263                 tack_on(&handled_ranges, tmp->range);
 264
 265                 same_range_call_backs = get_same_ranged_call_backs(call_backs, tmp->range);
 266                 call_ranged_call_backs(same_range_call_backs, fn, expr->right, expr);
 267                 __free_ptr_list((struct ptr_list **)&same_range_call_backs);
 268
 269                 estate = alloc_estate_range(tmp->range->min, tmp->range->max);
 270                 set_extra_mod(var_name, sym, estate);
 271
 272                 tmp_stree = __pop_fake_cur_stree();
 273                 merge_fake_stree(&final_states, tmp_stree);
 274                 free_stree(&tmp_stree);
 275                 handled = 1;
 276         } END_FOR_EACH_PTR(tmp);
 277
 278         FOR_EACH_SM(final_states, sm) {
 279                 __set_sm(sm);
 280         } END_FOR_EACH_SM(sm);
 281
 282         free_stree(&final_states);
 283 free:
 284         free_string(var_name);
 285         return handled;
 286 }
 287
 288 static void call_implies_callbacks(int comparison, struct expression *expr, sval_t sval, int left, struct stree **implied_true, struct stree **implied_false)
 289 {
 290         struct call_back_list *call_backs;
 291         struct fcall_back *tmp;
 292         const char *fn;
 293         struct data_range *value_range;
 294         struct stree *true_states = NULL;
 295         struct stree *false_states = NULL;
 296         struct stree *tmp_stree;
 297
 298         *implied_true = NULL;
 299         *implied_false = NULL;
 300         if (expr->fn->type != EXPR_SYMBOL || !expr->fn->symbol)
 301                 return;
 302         fn = expr->fn->symbol->ident->name;
 303         call_backs = search_callback(func_hash, (char *)expr->fn->symbol->ident->name);
 304         if (!call_backs)
 305                 return;
 306         value_range = alloc_range(sval, sval);
 307
 308         /* set true states */
 309         __push_fake_cur_stree();
 310         FOR_EACH_PTR(call_backs, tmp) {
 311                 if (tmp->type != RANGED_CALL)
 312                         continue;
 313                 if (!true_comparison_range_LR(comparison, tmp->range, value_range, left))
 314                         continue;
 315                 (tmp->u.ranged)(fn, expr, NULL, tmp->info);
 316         } END_FOR_EACH_PTR(tmp);
 317         tmp_stree = __pop_fake_cur_stree();
 318         merge_fake_stree(&true_states, tmp_stree);
 319         free_stree(&tmp_stree);
 320
 321         /* set false states */
 322         __push_fake_cur_stree();
 323         FOR_EACH_PTR(call_backs, tmp) {
 324                 if (tmp->type != RANGED_CALL)
 325                         continue;
 326                 if (!false_comparison_range_LR(comparison, tmp->range, value_range, left))
 327                         continue;
 328                 (tmp->u.ranged)(fn, expr, NULL, tmp->info);
 329         } END_FOR_EACH_PTR(tmp);
 330         tmp_stree = __pop_fake_cur_stree();
 331         merge_fake_stree(&false_states, tmp_stree);
 332         free_stree(&tmp_stree);
 333
 334         *implied_true = true_states;
 335         *implied_false = false_states;
 336 }
 337
 338 struct db_callback_info {
 339         int true_side;
 340         int comparison;
 341         struct expression *expr;
 342         struct range_list *rl;
 343         int left;
 344         struct stree *stree;
 345         struct db_implies_list *callbacks;
 346         int prev_return_id;
 347         int cull;
 348         int has_states;
 349         struct smatch_state *ret_state;
 350         struct expression *var_expr;
 351         int handled;
 352 };
 353
 354 static void store_return_state(struct db_callback_info *db_info, struct smatch_state *state)
 355 {
 356         db_info->ret_state = state;
 357 }
 358
 359 static void set_return_state(struct expression *expr, struct db_callback_info *db_info)
 360 {
 361         struct smatch_state *state;
 362
 363         if (!db_info->ret_state)
 364                 return;
 365
 366         state = alloc_estate_rl(cast_rl(get_type(expr), clone_rl(estate_rl(db_info->ret_state))));
 367         set_extra_expr_mod(expr, state);
 368         db_info->ret_state = NULL;
 369 }
 370
 371 static void handle_ret_equals_param(char *ret_string, struct range_list *rl, struct expression *call)
 372 {
 373         char *str;
 374         long long param;
 375         struct expression *arg;
 376         struct range_list *orig;
 377
 378         str = strstr(ret_string, "==$");
 379         if (!str)
 380                 return;
 381         str += 3;
 382         param = strtoll(str, NULL, 10);
 383         arg = get_argument_from_call_expr(call->args, param);
 384         if (!arg)
 385                 return;
 386         get_absolute_rl(arg, &orig);
 387         rl = rl_intersection(orig, rl);
 388         if (!rl)
 389                 return;
 390         set_extra_expr_nomod(arg, alloc_estate_rl(rl));
 391 }
 392
 393 static int impossible_limit(struct expression *expr, int param, char *key, char *value)
 394 {
 395         struct expression *arg;
 396         struct smatch_state *state;
 397         struct range_list *passed;
 398         struct range_list *limit;
 399         struct symbol *compare_type;
 400
 401         while (expr->type == EXPR_ASSIGNMENT)
 402                 expr = strip_expr(expr->right);
 403         if (expr->type != EXPR_CALL)
 404                 return 0;
 405
 406         arg = get_argument_from_call_expr(expr->args, param);
 407         if (!arg)
 408                 return 0;
 409
 410         if (strcmp(key, "$") == 0) {
 411                 if (!get_implied_rl(arg, &passed))
 412                         return 0;
 413
 414                 compare_type = get_arg_type(expr->fn, param);
 415         } else {
 416                 char *name;
 417                 struct symbol *sym;
 418
 419                 name = get_variable_from_key(arg, key, &sym);
 420                 if (!name || !sym)
 421                         return 0;
 422
 423                 state = get_state(SMATCH_EXTRA, name, sym);
 424                 if (!state) {
 425                         free_string(name);
 426                         return 0;
 427                 }
 428                 passed = estate_rl(state);
 429                 if (!passed || is_whole_rl(passed)) {
 430                         free_string(name);
 431                         return 0;
 432                 }
 433
 434                 compare_type = get_member_type_from_key(arg, key);
 435         }
 436
 437         passed = cast_rl(compare_type, passed);
 438         call_results_to_rl(expr, compare_type, value, &limit);
 439         if (!limit || is_whole_rl(limit))
 440                 return 0;
 441         if (possibly_true_rl(passed, SPECIAL_EQUAL, limit))
 442                 return 0;
 443         if (option_debug || local_debug)
 444                 sm_msg("impossible: %d '%s' limit '%s' == '%s'", param, key, show_rl(passed), value);
 445         return 1;
 446 }
 447
 448 static int is_impossible_data(int type, struct expression *expr, int param, char *key, char *value)
 449 {
 450         if (type == PARAM_LIMIT && impossible_limit(expr, param, key, value))
 451                 return 1;
 452         if (type == COMPARE_LIMIT && param_compare_limit_is_impossible(expr, param, key, value))
 453                 return 1;
 454         return 0;
 455 }
 456
 457 static int db_compare_callback(void *_info, int argc, char **argv, char **azColName)
 458 {
 459         struct db_callback_info *db_info = _info;
 460         struct range_list *var_rl = db_info->rl;
 461         struct range_list *ret_range;
 462         int type, param;
 463         char *key, *value;
 464         struct return_implies_callback *tmp;
 465         struct stree *stree;
 466         int return_id;
 467         int comparison;
 468
 469         if (argc != 6)
 470                 return 0;
 471
 472         return_id = atoi(argv[0]);
 473         type = atoi(argv[2]);
 474         param = atoi(argv[3]);
 475         key = argv[4];
 476         value = argv[5];
 477
 478         db_info->has_states = 1;
 479         if (db_info->prev_return_id != -1 && type == INTERNAL) {
 480                 set_return_state(db_info->var_expr, db_info);
 481                 stree = __pop_fake_cur_stree();
 482
 483                 if (!db_info->cull)
 484                         merge_fake_stree(&db_info->stree, stree);
 485                 free_stree(&stree);
 486                 __push_fake_cur_stree();
 487                 db_info->cull = 0;
 488         }
 489         db_info->prev_return_id = return_id;
 490
 491         if (db_info->cull)
 492                 return 0;
 493         if (type == CULL_PATH) {
 494                 db_info->cull = 1;
 495                 return 0;
 496         }
 497
 498         if (is_impossible_data(type, db_info->expr, param, key, value)) {
 499                 db_info->cull = 1;
 500                 return 0;
 501         }
 502
 503         call_results_to_rl(db_info->expr, get_type(strip_expr(db_info->expr)), argv[1], &ret_range);
 504         ret_range = cast_rl(get_type(db_info->expr), ret_range);
 505         if (!ret_range)
 506                 ret_range = alloc_whole_rl(get_type(db_info->expr));
 507
 508         comparison = db_info->comparison;
 509         if (db_info->left)
 510                 comparison = flip_comparison(comparison);
 511
 512         if (db_info->true_side) {
 513                 if (!possibly_true_rl(var_rl, comparison, ret_range))
 514                         return 0;
 515                 if (type == PARAM_LIMIT)
 516                         param_limit_implications(db_info->expr, param, key, value);
 517                 filter_by_comparison(&var_rl, comparison, ret_range);
 518                 filter_by_comparison(&ret_range, flip_comparison(comparison), var_rl);
 519         } else {
 520                 if (!possibly_false_rl(var_rl, comparison, ret_range))
 521                         return 0;
 522                 if (type == PARAM_LIMIT)
 523                         param_limit_implications(db_info->expr, param, key, value);
 524                 filter_by_comparison(&var_rl, negate_comparison(comparison), ret_range);
 525                 filter_by_comparison(&ret_range, flip_comparison(negate_comparison(comparison)), var_rl);
 526         }
 527
 528         handle_ret_equals_param(argv[1], ret_range, db_info->expr);
 529
 530         if (type == INTERNAL)
 531                 set_state(-1, "unnull_path", NULL, &true_state);
 532
 533         FOR_EACH_PTR(db_info->callbacks, tmp) {
 534                 if (tmp->type == type)
 535                         tmp->callback(db_info->expr, param, key, value);
 536         } END_FOR_EACH_PTR(tmp);
 537
 538         store_return_state(db_info, alloc_estate_rl(clone_rl(var_rl)));
 539         return 0;
 540 }
 541
 542 static void compare_db_return_states_callbacks(struct expression *left, int comparison, struct expression *right, struct stree *implied_true, struct stree *implied_false)
 543 {
 544         struct stree *orig_states;
 545         struct stree *stree;
 546         struct stree *true_states;
 547         struct stree *false_states;
 548         struct sm_state *sm;
 549         struct db_callback_info db_info = {};
 550         struct expression *var_expr;
 551         struct expression *call_expr;
 552         struct range_list *rl;
 553         int call_on_left;
 554
 555         orig_states = clone_stree(__get_cur_stree());
 556
 557         /* legacy cruft.  need to fix call_implies_callbacks(). */
 558         call_on_left = 1;
 559         call_expr = left;
 560         var_expr = right;
 561         if (left->type != EXPR_CALL) {
 562                 call_on_left = 0;
 563                 call_expr = right;
 564                 var_expr = left;
 565         }
 566
 567         get_absolute_rl(var_expr, &rl);
 568
 569         db_info.comparison = comparison;
 570         db_info.expr = call_expr;
 571         db_info.rl = rl;
 572         db_info.left = call_on_left;
 573         db_info.callbacks = db_return_states_list;
 574         db_info.var_expr = var_expr;
 575
 576         call_return_states_before_hooks();
 577
 578         db_info.true_side = 1;
 579         db_info.stree = NULL;
 580         db_info.prev_return_id = -1;
 581         __push_fake_cur_stree();
 582         sql_select_return_states("return_id, return, type, parameter, key, value",
 583                                  call_expr, db_compare_callback, &db_info);
 584         set_return_state(db_info.var_expr, &db_info);
 585         stree = __pop_fake_cur_stree();
 586         if (!db_info.cull) {
 587                 set_return_state(db_info.var_expr, &db_info);
 588                 merge_fake_stree(&db_info.stree, stree);
 589         }
 590         free_stree(&stree);
 591         true_states = db_info.stree;
 592         if (!true_states && db_info.has_states) {
 593                 __push_fake_cur_stree();
 594                 set_path_impossible();
 595                 true_states = __pop_fake_cur_stree();
 596         }
 597
 598         nullify_path();
 599         __unnullify_path();
 600         FOR_EACH_SM(orig_states, sm) {
 601                 __set_sm_cur_stree(sm);
 602         } END_FOR_EACH_SM(sm);
 603
 604         db_info.true_side = 0;
 605         db_info.stree = NULL;
 606         db_info.prev_return_id = -1;
 607         db_info.cull = 0;
 608         __push_fake_cur_stree();
 609         sql_select_return_states("return_id, return, type, parameter, key, value", call_expr,
 610                         db_compare_callback, &db_info);
 611         stree = __pop_fake_cur_stree();
 612         if (!db_info.cull) {
 613                 set_return_state(db_info.var_expr, &db_info);
 614                 merge_fake_stree(&db_info.stree, stree);
 615         }
 616         free_stree(&stree);
 617         false_states = db_info.stree;
 618         if (!false_states && db_info.has_states) {
 619                 __push_fake_cur_stree();
 620                 set_path_impossible();
 621                 false_states = __pop_fake_cur_stree();
 622         }
 623
 624         nullify_path();
 625         __unnullify_path();
 626         FOR_EACH_SM(orig_states, sm) {
 627                 __set_sm_cur_stree(sm);
 628         } END_FOR_EACH_SM(sm);
 629
 630         free_stree(&orig_states);
 631
 632         FOR_EACH_SM(true_states, sm) {
 633                 __set_true_false_sm(sm, NULL);
 634         } END_FOR_EACH_SM(sm);
 635         FOR_EACH_SM(false_states, sm) {
 636                 __set_true_false_sm(NULL, sm);
 637         } END_FOR_EACH_SM(sm);
 638
 639         free_stree(&true_states);
 640         free_stree(&false_states);
 641
 642         call_return_states_after_hooks(call_expr);
 643
 644         FOR_EACH_SM(implied_true, sm) {
 645                 __set_true_false_sm(sm, NULL);
 646         } END_FOR_EACH_SM(sm);
 647         FOR_EACH_SM(implied_false, sm) {
 648                 __set_true_false_sm(NULL, sm);
 649         } END_FOR_EACH_SM(sm);
 650 }
 651
 652 void function_comparison(struct expression *left, int comparison, struct expression *right)
 653 {
 654         struct expression *var_expr;
 655         struct expression *call_expr;
 656         struct stree *implied_true = NULL;
 657         struct stree *implied_false = NULL;
 658         struct range_list *rl;
 659         sval_t sval;
 660         int call_on_left;
 661
 662         if (unreachable())
 663                 return;
 664
 665         /* legacy cruft.  need to fix call_implies_callbacks(). */
 666         call_on_left = 1;
 667         call_expr = left;
 668         var_expr = right;
 669         if (left->type != EXPR_CALL) {
 670                 call_on_left = 0;
 671                 call_expr = right;
 672                 var_expr = left;
 673         }
 674
 675         get_absolute_rl(var_expr, &rl);
 676
 677         if (rl_to_sval(rl, &sval))
 678                 call_implies_callbacks(comparison, call_expr, sval, call_on_left, &implied_true, &implied_false);
 679
 680         compare_db_return_states_callbacks(left, comparison, right, implied_true, implied_false);
 681         free_stree(&implied_true);
 682         free_stree(&implied_false);
 683 }
 684
 685 static void call_ranged_return_hooks(struct db_callback_info *db_info)
 686 {
 687         struct call_back_list *call_backs;
 688         struct expression *expr;
 689         struct fcall_back *tmp;
 690         char *fn;
 691
 692         expr = strip_expr(db_info->expr);
 693         while (expr->type == EXPR_ASSIGNMENT)
 694                 expr = strip_expr(expr->right);
 695         if (expr->type != EXPR_CALL ||
 696             expr->fn->type != EXPR_SYMBOL)
 697                 return;
 698
 699         fn = expr->fn->symbol_name->name;
 700
 701         call_backs = search_callback(func_hash, fn);
 702         FOR_EACH_PTR(call_backs, tmp) {
 703                 struct range_list *range_rl = NULL;
 704
 705                 if (tmp->type != RANGED_CALL)
 706                         continue;
 707                 add_range(&range_rl, tmp->range->min, tmp->range->max);
 708                 range_rl = cast_rl(estate_type(db_info->ret_state), range_rl);
 709                 if (possibly_true_rl(range_rl, SPECIAL_EQUAL, estate_rl(db_info->ret_state))) {
 710                         if (!possibly_true_rl(rl_invert(range_rl), SPECIAL_EQUAL, estate_rl(db_info->ret_state)))
 711                                 (tmp->u.ranged)(fn, expr, db_info->expr, tmp->info);
 712                         else
 713                                 db_info->handled = -1;
 714                 }
 715         } END_FOR_EACH_PTR(tmp);
 716 }
 717
 718 static int db_assign_return_states_callback(void *_info, int argc, char **argv, char **azColName)
 719 {
 720         struct db_callback_info *db_info = _info;
 721         struct range_list *ret_range;
 722         int type, param;
 723         char *key, *value;
 724         struct return_implies_callback *tmp;
 725         struct stree *stree;
 726         int return_id;
 727
 728         if (argc != 6)
 729                 return 0;
 730
 731         return_id = atoi(argv[0]);
 732         type = atoi(argv[2]);
 733         param = atoi(argv[3]);
 734         key = argv[4];
 735         value = argv[5];
 736
 737         if (db_info->prev_return_id != -1 && type == INTERNAL) {
 738                 call_ranged_return_hooks(db_info);
 739                 set_return_state(db_info->expr->left, db_info);
 740                 stree = __pop_fake_cur_stree();
 741                 if (!db_info->cull)
 742                         merge_fake_stree(&db_info->stree, stree);
 743                 free_stree(&stree);
 744                 __push_fake_cur_stree();
 745                 db_info->cull = 0;
 746         }
 747         db_info->prev_return_id = return_id;
 748
 749         if (db_info->cull)
 750                 return 0;
 751         if (type == CULL_PATH) {
 752                 db_info->cull = 1;
 753                 return 0;
 754         }
 755         if (is_impossible_data(type, db_info->expr, param, key, value)) {
 756                 db_info->cull = 1;
 757                 return 0;
 758         }
 759
 760         if (type == PARAM_LIMIT)
 761                 param_limit_implications(db_info->expr, param, key, value);
 762
 763         db_info->handled = 1;
 764         call_results_to_rl(db_info->expr->right, get_type(strip_expr(db_info->expr->right)), argv[1], &ret_range);
 765         __add_comparison_info(db_info->expr->left, strip_expr(db_info->expr->right), argv[1]);
 766         if (!ret_range)
 767                 ret_range = alloc_whole_rl(get_type(strip_expr(db_info->expr->right)));
 768         ret_range = cast_rl(get_type(db_info->expr->right), ret_range);
 769
 770         if (type == INTERNAL)
 771                 set_state(-1, "unnull_path", NULL, &true_state);
 772
 773         FOR_EACH_PTR(db_return_states_list, tmp) {
 774                 if (tmp->type == type)
 775                         tmp->callback(db_info->expr, param, key, value);
 776         } END_FOR_EACH_PTR(tmp);
 777         store_return_state(db_info, alloc_estate_rl(ret_range));
 778
 779         return 0;
 780 }
 781
 782 static int db_return_states_assign(struct expression *expr)
 783 {
 784         struct expression *right;
 785         struct sm_state *sm;
 786         struct stree *stree;
 787         struct db_callback_info db_info = {};
 788
 789         right = strip_expr(expr->right);
 790
 791         db_info.prev_return_id = -1;
 792         db_info.expr = expr;
 793         db_info.stree = NULL;
 794         db_info.handled = 0;
 795
 796         call_return_states_before_hooks();
 797
 798         __push_fake_cur_stree();
 799         sql_select_return_states("return_id, return, type, parameter, key, value",
 800                         right, db_assign_return_states_callback, &db_info);
 801         if (option_debug) {
 802                 sm_msg("%s return_id %d return_ranges %s",
 803                         db_info.cull ? "culled" : "merging",
 804                         db_info.prev_return_id,
 805                         db_info.ret_state ? db_info.ret_state->name : "'<empty>'");
 806         }
 807         if (db_info.handled)
 808                 call_ranged_return_hooks(&db_info);
 809         set_return_state(db_info.expr->left, &db_info);
 810         stree = __pop_fake_cur_stree();
 811         if (!db_info.cull)
 812                 merge_fake_stree(&db_info.stree, stree);
 813         free_stree(&stree);
 814
 815         if (!db_info.stree && db_info.cull) /* this means we culled everything */
 816                 set_extra_expr_mod(expr->left, alloc_estate_whole(get_type(expr->left)));
 817         FOR_EACH_SM(db_info.stree, sm) {
 818                 __set_sm(sm);
 819         } END_FOR_EACH_SM(sm);
 820
 821         free_stree(&db_info.stree);
 822         call_return_states_after_hooks(right);
 823
 824         return db_info.handled;
 825 }
 826
 827 static int handle_implied_return(struct expression *expr)
 828 {
 829         struct range_list *rl;
 830
 831         if (!get_implied_return(expr->right, &rl))
 832                 return 0;
 833         rl = cast_rl(get_type(expr->left), rl);
 834         set_extra_expr_mod(expr->left, alloc_estate_rl(rl));
 835         return 1;
 836 }
 837
 838 static void match_assign_call(struct expression *expr)
 839 {
 840         struct call_back_list *call_backs;
 841         const char *fn;
 842         struct expression *right;
 843         int handled = 0;
 844         struct range_list *rl;
 845
 846         if (expr->op != '=')
 847                 return;
 848
 849         right = strip_expr(expr->right);
 850         if (right->fn->type != EXPR_SYMBOL || !right->fn->symbol) {
 851                 handled |= db_return_states_assign(expr);
 852                 if (!handled)
 853                         goto assigned_unknown;
 854                 return;
 855         }
 856         if (is_fake_call(right)) {
 857                 set_extra_expr_mod(expr->left, alloc_estate_whole(get_type(expr->left)));
 858                 return;
 859         }
 860
 861         fn = right->fn->symbol->ident->name;
 862         call_backs = search_callback(func_hash, (char *)fn);
 863
 864         /*
 865          * The ordering here is sort of important.
 866          * One example, of how this matters is that when we do:
 867          *
 868          *      len = strlen(str);
 869          *
 870          * That is handled by smatch_common_functions.c and smatch_strlen.c.
 871          * They use implied_return and function_assign_hook respectively.
 872          * We want to get the implied return first before we do the function
 873          * assignment hook otherwise we end up writing the wrong thing for len
 874          * in smatch_extra.c because we assume that it already holds the
 875          * strlen() when we haven't set it yet.
 876          */
 877
 878         if (db_return_states_assign(expr) == 1)
 879                 handled = 1;
 880         else
 881                 handled = assign_ranged_funcs(fn, expr, call_backs);
 882         handled |= handle_implied_return(expr);
 883
 884
 885         call_call_backs(call_backs, ASSIGN_CALL, fn, expr);
 886
 887         if (handled)
 888                 return;
 889
 890 assigned_unknown:
 891         get_absolute_rl(expr->right, &rl);
 892         rl = cast_rl(get_type(expr->left), rl);
 893         set_extra_expr_mod(expr->left, alloc_estate_rl(rl));
 894 }
 895
 896 static int db_return_states_callback(void *_info, int argc, char **argv, char **azColName)
 897 {
 898         struct db_callback_info *db_info = _info;
 899         struct range_list *ret_range;
 900         int type, param;
 901         char *key, *value;
 902         struct return_implies_callback *tmp;
 903         struct stree *stree;
 904         int return_id;
 905         char buf[64];
 906
 907         if (argc != 6)
 908                 return 0;
 909
 910         return_id = atoi(argv[0]);
 911         type = atoi(argv[2]);
 912         param = atoi(argv[3]);
 913         key = argv[4];
 914         value = argv[5];
 915
 916         if (db_info->prev_return_id != -1 && type == INTERNAL) {
 917                 stree = __pop_fake_cur_stree();
 918                 if (!db_info->cull)
 919                         merge_fake_stree(&db_info->stree, stree);
 920                 free_stree(&stree);
 921                 __push_fake_cur_stree();
 922                 __unnullify_path();
 923                 db_info->cull = 0;
 924         }
 925         db_info->prev_return_id = return_id;
 926
 927         if (db_info->cull)
 928                 return 0;
 929         if (type == CULL_PATH) {
 930                 db_info->cull = 1;
 931                 return 0;
 932         }
 933         if (is_impossible_data(type, db_info->expr, param, key, value)) {
 934                 db_info->cull = 1;
 935                 return 0;
 936         }
 937
 938         if (type == PARAM_LIMIT)
 939                 param_limit_implications(db_info->expr, param, key, value);
 940
 941         call_results_to_rl(db_info->expr, get_type(strip_expr(db_info->expr)), argv[1], &ret_range);
 942         ret_range = cast_rl(get_type(db_info->expr), ret_range);
 943
 944         if (type == INTERNAL)
 945                 set_state(-1, "unnull_path", NULL, &true_state);
 946
 947         FOR_EACH_PTR(db_return_states_list, tmp) {
 948                 if (tmp->type == type)
 949                         tmp->callback(db_info->expr, param, key, value);
 950         } END_FOR_EACH_PTR(tmp);
 951
 952         /*
 953          * We want to store the return values so that we can split the strees
 954          * in smatch_db.c.  This uses set_state() directly because it's not a
 955          * real smatch_extra state.
 956          */
 957         snprintf(buf, sizeof(buf), "return %p", db_info->expr);
 958         set_state(SMATCH_EXTRA, buf, NULL, alloc_estate_rl(ret_range));
 959
 960         return 0;
 961 }
 962
 963 static void db_return_states(struct expression *expr)
 964 {
 965         struct sm_state *sm;
 966         struct stree *stree;
 967         struct db_callback_info db_info = {};
 968
 969         if (!__get_cur_stree())  /* no return functions */
 970                 return;
 971
 972         db_info.prev_return_id = -1;
 973         db_info.expr = expr;
 974         db_info.stree = NULL;
 975
 976         call_return_states_before_hooks();
 977
 978         __push_fake_cur_stree();
 979         __unnullify_path();
 980         sql_select_return_states("return_id, return, type, parameter, key, value",
 981                         expr, db_return_states_callback, &db_info);
 982         stree = __pop_fake_cur_stree();
 983         if (!db_info.cull)
 984                 merge_fake_stree(&db_info.stree, stree);
 985         free_stree(&stree);
 986
 987         FOR_EACH_SM(db_info.stree, sm) {
 988                 __set_sm(sm);
 989         } END_FOR_EACH_SM(sm);
 990
 991         free_stree(&db_info.stree);
 992         call_return_states_after_hooks(expr);
 993 }
 994
 995 static int is_condition_call(struct expression *expr)
 996 {
 997         struct expression *tmp;
 998
 999         FOR_EACH_PTR_REVERSE(big_condition_stack, tmp) {
1000                 if (expr == tmp || expr->parent == tmp)
1001                         return 1;
1002                 if (tmp->pos.line < expr->pos.line)
1003                         return 0;
1004         } END_FOR_EACH_PTR_REVERSE(tmp);
1005
1006         return 0;
1007 }
1008
1009 static void db_return_states_call(struct expression *expr)
1010 {
1011         if (unreachable())
1012                 return;
1013
1014         if (is_assigned_call(expr))
1015                 return;
1016         if (is_condition_call(expr))
1017                 return;
1018         db_return_states(expr);
1019 }
1020
1021 static void match_function_call(struct expression *expr)
1022 {
1023         struct call_back_list *call_backs;
1024
1025         if (expr->fn->type == EXPR_SYMBOL && expr->fn->symbol) {
1026                 call_backs = search_callback(func_hash, (char *)expr->fn->symbol->ident->name);
1027                 if (call_backs)
1028                         call_call_backs(call_backs, REGULAR_CALL,
1029                                         expr->fn->symbol->ident->name, expr);
1030         }
1031         db_return_states_call(expr);
1032 }
1033
1034 static void match_macro_assign(struct expression *expr)
1035 {
1036         struct call_back_list *call_backs;
1037         const char *macro;
1038         struct expression *right;
1039
1040         right = strip_expr(expr->right);
1041         macro = get_macro_name(right->pos);
1042         call_backs = search_callback(func_hash, (char *)macro);
1043         if (!call_backs)
1044                 return;
1045         call_call_backs(call_backs, MACRO_ASSIGN, macro, expr);
1046         call_call_backs(call_backs, MACRO_ASSIGN_EXTRA, macro, expr);
1047 }
1048
1049 int get_implied_return(struct expression *expr, struct range_list **rl)
1050 {
1051         struct call_back_list *call_backs;
1052         struct fcall_back *tmp;
1053         int handled = 0;
1054         char *fn;
1055
1056         *rl = NULL;
1057
1058         expr = strip_expr(expr);
1059         fn = expr_to_var(expr->fn);
1060         if (!fn)
1061                 goto out;
1062
1063         call_backs = search_callback(func_hash, fn);
1064
1065         FOR_EACH_PTR(call_backs, tmp) {
1066                 if (tmp->type == IMPLIED_RETURN) {
1067                         (tmp->u.implied_return)(expr, tmp->info, rl);
1068                         handled = 1;
1069                 }
1070         } END_FOR_EACH_PTR(tmp);
1071
1072 out:
1073         free_string(fn);
1074         return handled;
1075 }
1076
1077 void create_function_hook_hash(void)
1078 {
1079         func_hash = create_function_hashtable(5000);
1080 }
1081
1082 void register_function_hooks(int id)
1083 {
1084         add_hook(&match_function_call, CALL_HOOK_AFTER_INLINE);
1085         add_hook(&match_assign_call, CALL_ASSIGNMENT_HOOK);
1086         add_hook(&match_macro_assign, MACRO_ASSIGNMENT_HOOK);
1087 }