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 int __in_fake_parameter_assign;
  54
  55 #define REGULAR_CALL       0
  56 #define RANGED_CALL        1
  57 #define ASSIGN_CALL        2
  58 #define IMPLIED_RETURN     3
  59 #define MACRO_ASSIGN       4
  60 #define MACRO_ASSIGN_EXTRA 5
  61
  62 struct return_implies_callback {
  63         int type;
  64         return_implies_hook *callback;
  65 };
  66 ALLOCATOR(return_implies_callback, "return_implies callbacks");
  67 DECLARE_PTR_LIST(db_implies_list, struct return_implies_callback);
  68 static struct db_implies_list *db_return_states_list;
  69
  70 typedef void (void_fn)(void);
  71 DECLARE_PTR_LIST(void_fn_list, void_fn *);
  72 static struct void_fn_list *return_states_before;
  73 static struct void_fn_list *return_states_after;
  74
  75 static struct fcall_back *alloc_fcall_back(int type, void *call_back,
  76                                            void *info)
  77 {
  78         struct fcall_back *cb;
  79
  80         cb = __alloc_fcall_back(0);
  81         cb->type = type;
  82         cb->u.call_back = call_back;
  83         cb->info = info;
  84         return cb;
  85 }
  86
  87 void add_function_hook(const char *look_for, func_hook *call_back, void *info)
  88 {
  89         struct fcall_back *cb;
  90
  91         cb = alloc_fcall_back(REGULAR_CALL, call_back, info);
  92         add_callback(func_hash, look_for, cb);
  93 }
  94
  95 void add_function_assign_hook(const char *look_for, func_hook *call_back,
  96                               void *info)
  97 {
  98         struct fcall_back *cb;
  99
 100         cb = alloc_fcall_back(ASSIGN_CALL, call_back, info);
 101         add_callback(func_hash, look_for, cb);
 102 }
 103
 104 void add_implied_return_hook(const char *look_for,
 105                              implied_return_hook *call_back,
 106                              void *info)
 107 {
 108         struct fcall_back *cb;
 109
 110         cb = alloc_fcall_back(IMPLIED_RETURN, call_back, info);
 111         add_callback(func_hash, look_for, cb);
 112 }
 113
 114 void add_macro_assign_hook(const char *look_for, func_hook *call_back,
 115                         void *info)
 116 {
 117         struct fcall_back *cb;
 118
 119         cb = alloc_fcall_back(MACRO_ASSIGN, call_back, info);
 120         add_callback(func_hash, look_for, cb);
 121 }
 122
 123 void add_macro_assign_hook_extra(const char *look_for, func_hook *call_back,
 124                         void *info)
 125 {
 126         struct fcall_back *cb;
 127
 128         cb = alloc_fcall_back(MACRO_ASSIGN_EXTRA, call_back, info);
 129         add_callback(func_hash, look_for, cb);
 130 }
 131
 132 void return_implies_state(const char *look_for, long long start, long long end,
 133                          implication_hook *call_back, void *info)
 134 {
 135         struct fcall_back *cb;
 136
 137         cb = alloc_fcall_back(RANGED_CALL, call_back, info);
 138         cb->range = alloc_range_perm(ll_to_sval(start), ll_to_sval(end));
 139         add_callback(func_hash, look_for, cb);
 140 }
 141
 142 void select_return_states_hook(int type, return_implies_hook *callback)
 143 {
 144         struct return_implies_callback *cb = __alloc_return_implies_callback(0);
 145
 146         cb->type = type;
 147         cb->callback = callback;
 148         add_ptr_list(&db_return_states_list, cb);
 149 }
 150
 151 void select_return_states_before(void_fn *fn)
 152 {
 153         void_fn **p = malloc(sizeof(void_fn *));
 154         *p = fn;
 155         add_ptr_list(&return_states_before, p);
 156 }
 157
 158 void select_return_states_after(void_fn *fn)
 159 {
 160         void_fn **p = malloc(sizeof(void_fn *));
 161         *p = fn;
 162         add_ptr_list(&return_states_after, p);
 163 }
 164
 165 static void call_return_states_before_hooks(void)
 166 {
 167         void_fn **fn;
 168
 169         FOR_EACH_PTR(return_states_before, fn) {
 170                 (*fn)();
 171         } END_FOR_EACH_PTR(fn);
 172 }
 173
 174 static void call_return_states_after_hooks(struct expression *expr)
 175 {
 176         void_fn **fn;
 177
 178         FOR_EACH_PTR(return_states_after, fn) {
 179                 (*fn)();
 180         } END_FOR_EACH_PTR(fn);
 181         __pass_to_client(expr, FUNCTION_CALL_HOOK_AFTER_DB);
 182 }
 183
 184 static int call_call_backs(struct call_back_list *list, int type,
 185                             const char *fn, struct expression *expr)
 186 {
 187         struct fcall_back *tmp;
 188         int handled = 0;
 189
 190         FOR_EACH_PTR(list, tmp) {
 191                 if (tmp->type == type) {
 192                         (tmp->u.call_back)(fn, expr, tmp->info);
 193                         handled = 1;
 194                 }
 195         } END_FOR_EACH_PTR(tmp);
 196
 197         return handled;
 198 }
 199
 200 static void call_ranged_call_backs(struct call_back_list *list,
 201                                 const char *fn, struct expression *call_expr,
 202                                 struct expression *assign_expr)
 203 {
 204         struct fcall_back *tmp;
 205
 206         FOR_EACH_PTR(list, tmp) {
 207                 (tmp->u.ranged)(fn, call_expr, assign_expr, tmp->info);
 208         } END_FOR_EACH_PTR(tmp);
 209 }
 210
 211 static struct call_back_list *get_same_ranged_call_backs(struct call_back_list *list,
 212                                                 struct data_range *drange)
 213 {
 214         struct call_back_list *ret = NULL;
 215         struct fcall_back *tmp;
 216
 217         FOR_EACH_PTR(list, tmp) {
 218                 if (tmp->type != RANGED_CALL)
 219                         continue;
 220                 if (ranges_equiv(tmp->range, drange))
 221                         add_ptr_list(&ret, tmp);
 222         } END_FOR_EACH_PTR(tmp);
 223         return ret;
 224 }
 225
 226 static int in_list_exact_sval(struct range_list *list, struct data_range *drange)
 227 {
 228         struct data_range *tmp;
 229
 230         FOR_EACH_PTR(list, tmp) {
 231                 if (ranges_equiv(tmp, drange))
 232                         return 1;
 233         } END_FOR_EACH_PTR(tmp);
 234         return 0;
 235 }
 236
 237 static int assign_ranged_funcs(const char *fn, struct expression *expr,
 238                                  struct call_back_list *call_backs)
 239 {
 240         struct fcall_back *tmp;
 241         struct sm_state *sm;
 242         char *var_name;
 243         struct symbol *sym;
 244         struct smatch_state *estate;
 245         struct stree *tmp_stree;
 246         struct stree *final_states = NULL;
 247         struct range_list *handled_ranges = NULL;
 248         struct call_back_list *same_range_call_backs = NULL;
 249         int handled = 0;
 250
 251         if (!call_backs)
 252                 return 0;
 253
 254         var_name = expr_to_var_sym(expr->left, &sym);
 255         if (!var_name || !sym)
 256                 goto free;
 257
 258         FOR_EACH_PTR(call_backs, tmp) {
 259                 if (tmp->type != RANGED_CALL)
 260                         continue;
 261
 262                 if (in_list_exact_sval(handled_ranges, tmp->range))
 263                         continue;
 264                 __push_fake_cur_stree();
 265                 tack_on(&handled_ranges, tmp->range);
 266
 267                 same_range_call_backs = get_same_ranged_call_backs(call_backs, tmp->range);
 268                 call_ranged_call_backs(same_range_call_backs, fn, expr->right, expr);
 269                 __free_ptr_list((struct ptr_list **)&same_range_call_backs);
 270
 271                 estate = alloc_estate_range(tmp->range->min, tmp->range->max);
 272                 set_extra_mod(var_name, sym, expr->left, estate);
 273
 274                 tmp_stree = __pop_fake_cur_stree();
 275                 merge_fake_stree(&final_states, tmp_stree);
 276                 free_stree(&tmp_stree);
 277                 handled = 1;
 278         } END_FOR_EACH_PTR(tmp);
 279
 280         FOR_EACH_SM(final_states, sm) {
 281                 __set_sm(sm);
 282         } END_FOR_EACH_SM(sm);
 283
 284         free_stree(&final_states);
 285 free:
 286         free_string(var_name);
 287         return handled;
 288 }
 289
 290 static void call_implies_callbacks(int comparison, struct expression *expr, sval_t sval, int left, struct stree **implied_true, struct stree **implied_false)
 291 {
 292         struct call_back_list *call_backs;
 293         struct fcall_back *tmp;
 294         const char *fn;
 295         struct data_range *value_range;
 296         struct stree *true_states = NULL;
 297         struct stree *false_states = NULL;
 298         struct stree *tmp_stree;
 299
 300         *implied_true = NULL;
 301         *implied_false = NULL;
 302         if (expr->fn->type != EXPR_SYMBOL || !expr->fn->symbol)
 303                 return;
 304         fn = expr->fn->symbol->ident->name;
 305         call_backs = search_callback(func_hash, (char *)expr->fn->symbol->ident->name);
 306         if (!call_backs)
 307                 return;
 308         value_range = alloc_range(sval, sval);
 309
 310         /* set true states */
 311         __push_fake_cur_stree();
 312         FOR_EACH_PTR(call_backs, tmp) {
 313                 if (tmp->type != RANGED_CALL)
 314                         continue;
 315                 if (!true_comparison_range_LR(comparison, tmp->range, value_range, left))
 316                         continue;
 317                 (tmp->u.ranged)(fn, expr, NULL, tmp->info);
 318         } END_FOR_EACH_PTR(tmp);
 319         tmp_stree = __pop_fake_cur_stree();
 320         merge_fake_stree(&true_states, tmp_stree);
 321         free_stree(&tmp_stree);
 322
 323         /* set false states */
 324         __push_fake_cur_stree();
 325         FOR_EACH_PTR(call_backs, tmp) {
 326                 if (tmp->type != RANGED_CALL)
 327                         continue;
 328                 if (!false_comparison_range_LR(comparison, tmp->range, value_range, left))
 329                         continue;
 330                 (tmp->u.ranged)(fn, expr, NULL, tmp->info);
 331         } END_FOR_EACH_PTR(tmp);
 332         tmp_stree = __pop_fake_cur_stree();
 333         merge_fake_stree(&false_states, tmp_stree);
 334         free_stree(&tmp_stree);
 335
 336         *implied_true = true_states;
 337         *implied_false = false_states;
 338 }
 339
 340 struct db_callback_info {
 341         int true_side;
 342         int comparison;
 343         struct expression *expr;
 344         struct range_list *rl;
 345         int left;
 346         struct stree *stree;
 347         struct db_implies_list *callbacks;
 348         int prev_return_id;
 349         int cull;
 350         int has_states;
 351         char *ret_str;
 352         struct smatch_state *ret_state;
 353         struct expression *var_expr;
 354         int handled;
 355 };
 356
 357 static void store_return_state(struct db_callback_info *db_info, const char *ret_str, struct smatch_state *state)
 358 {
 359         db_info->ret_str = alloc_sname(ret_str),
 360         db_info->ret_state = state;
 361 }
 362
 363 static bool fake_a_param_assignment(struct expression *expr, const char *return_str)
 364 {
 365         struct expression *arg, *left, *right, *fake_assign;
 366         char *p;
 367         int param;
 368         char buf[256];
 369         char *str;
 370
 371         if (expr->type != EXPR_ASSIGNMENT || expr->op != '=')
 372                 return false;
 373         left = expr->left;
 374         right = expr->right;
 375
 376         while (right->type == EXPR_ASSIGNMENT)
 377                 right = strip_expr(right->right);
 378         if (!right || right->type != EXPR_CALL)
 379                 return false;
 380
 381         p = strchr(return_str, '[');
 382         if (!p)
 383                 return false;
 384
 385         p++;
 386         if (p[0] == '=' && p[1] == '=')
 387                 p += 2;
 388         if (p[0] != '$')
 389                 return false;
 390
 391         snprintf(buf, sizeof(buf), "%s", p);
 392
 393         p = buf;
 394         p += 1;
 395         param = strtol(p, &p, 10);
 396
 397         p = strchr(p, ']');
 398         if (!p || *p != ']')
 399                 return false;
 400         *p = '\0';
 401
 402         arg = get_argument_from_call_expr(right->args, param);
 403         if (!arg)
 404                 return false;
 405         /*
 406          * This is a sanity check to prevent side effects from evaluating stuff
 407          * twice.
 408          */
 409         str = expr_to_chunk_sym_vsl(arg, NULL, NULL);
 410         if (!str)
 411                 return false;
 412         free_string(str);
 413
 414         right = gen_expression_from_key(arg, buf);
 415         if (!right)  /* Mostly fails for binops like [$0 + 4032] */
 416                 return false;
 417         fake_assign = assign_expression(left, '=', right);
 418         __in_fake_parameter_assign++;
 419         __split_expr(fake_assign);
 420         __in_fake_parameter_assign--;
 421         return true;
 422 }
 423
 424 static void set_return_state(struct expression *expr, struct db_callback_info *db_info)
 425 {
 426         struct smatch_state *state;
 427
 428         if (!db_info->ret_state)
 429                 return;
 430
 431         state = alloc_estate_rl(cast_rl(get_type(expr), clone_rl(estate_rl(db_info->ret_state))));
 432         set_extra_expr_mod(expr, state);
 433         db_info->ret_state = NULL;
 434         fake_a_param_assignment(db_info->expr, db_info->ret_str);
 435         db_info->ret_str = NULL;
 436 }
 437
 438 static void handle_ret_equals_param(char *ret_string, struct range_list *rl, struct expression *call)
 439 {
 440         char *str;
 441         long long param;
 442         struct expression *arg;
 443         struct range_list *orig;
 444
 445         str = strstr(ret_string, "==$");
 446         if (!str)
 447                 return;
 448         str += 3;
 449         param = strtoll(str, NULL, 10);
 450         arg = get_argument_from_call_expr(call->args, param);
 451         if (!arg)
 452                 return;
 453         get_absolute_rl(arg, &orig);
 454         rl = rl_intersection(orig, rl);
 455         if (!rl)
 456                 return;
 457         set_extra_expr_nomod(arg, alloc_estate_rl(rl));
 458 }
 459
 460 static int impossible_limit(struct expression *expr, int param, char *key, char *value)
 461 {
 462         struct expression *arg;
 463         struct smatch_state *state;
 464         struct range_list *passed;
 465         struct range_list *limit;
 466         struct symbol *compare_type;
 467
 468         while (expr->type == EXPR_ASSIGNMENT)
 469                 expr = strip_expr(expr->right);
 470         if (expr->type != EXPR_CALL)
 471                 return 0;
 472
 473         arg = get_argument_from_call_expr(expr->args, param);
 474         if (!arg)
 475                 return 0;
 476
 477         if (strcmp(key, "$") == 0) {
 478                 if (!get_implied_rl(arg, &passed))
 479                         return 0;
 480
 481                 compare_type = get_arg_type(expr->fn, param);
 482         } else {
 483                 char *name;
 484                 struct symbol *sym;
 485
 486                 name = get_variable_from_key(arg, key, &sym);
 487                 if (!name || !sym)
 488                         return 0;
 489
 490                 state = get_state(SMATCH_EXTRA, name, sym);
 491                 if (!state) {
 492                         free_string(name);
 493                         return 0;
 494                 }
 495                 passed = estate_rl(state);
 496                 if (!passed || is_whole_rl(passed)) {
 497                         free_string(name);
 498                         return 0;
 499                 }
 500
 501                 compare_type = get_member_type_from_key(arg, key);
 502         }
 503
 504         passed = cast_rl(compare_type, passed);
 505         call_results_to_rl(expr, compare_type, value, &limit);
 506         if (!limit || is_whole_rl(limit))
 507                 return 0;
 508         if (possibly_true_rl(passed, SPECIAL_EQUAL, limit))
 509                 return 0;
 510         if (option_debug || local_debug)
 511                 sm_msg("impossible: %d '%s' limit '%s' == '%s'", param, key, show_rl(passed), value);
 512         return 1;
 513 }
 514
 515 static int is_impossible_data(int type, struct expression *expr, int param, char *key, char *value)
 516 {
 517         if (type == PARAM_LIMIT && impossible_limit(expr, param, key, value))
 518                 return 1;
 519         if (type == COMPARE_LIMIT && param_compare_limit_is_impossible(expr, param, key, value)) {
 520                 if (local_debug)
 521                         sm_msg("param_compare_limit_is_impossible: %d %s %s", param, key, value);
 522                 return 1;
 523         }
 524         return 0;
 525 }
 526
 527 static int func_type_mismatch(struct expression *expr, const char *value)
 528 {
 529         struct symbol *type;
 530
 531         /* This makes faking returns easier */
 532         if (!value || value[0] == '\0')
 533                 return 0;
 534
 535         while (expr->type == EXPR_ASSIGNMENT)
 536                 expr = strip_expr(expr->right);
 537
 538         /*
 539          * Short cut:  We only care about function pointers that are struct
 540          * members.
 541          *
 542          */
 543         if (expr->fn->type == EXPR_SYMBOL)
 544                 return 0;
 545
 546         type = get_type(expr->fn);
 547         if (!type)
 548                 return 0;
 549         if (type->type == SYM_PTR)
 550                 type = get_real_base_type(type);
 551
 552         if (strcmp(type_to_str(type), value) == 0)
 553                 return 0;
 554
 555         return 1;
 556 }
 557
 558 static int db_compare_callback(void *_info, int argc, char **argv, char **azColName)
 559 {
 560         struct db_callback_info *db_info = _info;
 561         struct range_list *var_rl = db_info->rl;
 562         struct range_list *ret_range;
 563         int type, param;
 564         char *key, *value;
 565         struct return_implies_callback *tmp;
 566         struct stree *stree;
 567         int return_id;
 568         int comparison;
 569
 570         if (argc != 6)
 571                 return 0;
 572
 573         return_id = atoi(argv[0]);
 574         type = atoi(argv[2]);
 575         param = atoi(argv[3]);
 576         key = argv[4];
 577         value = argv[5];
 578
 579         db_info->has_states = 1;
 580         if (db_info->prev_return_id != -1 && type == INTERNAL) {
 581                 set_return_state(db_info->var_expr, db_info);
 582                 stree = __pop_fake_cur_stree();
 583
 584                 if (!db_info->cull)
 585                         merge_fake_stree(&db_info->stree, stree);
 586                 free_stree(&stree);
 587                 __push_fake_cur_stree();
 588                 db_info->cull = 0;
 589         }
 590         db_info->prev_return_id = return_id;
 591
 592         if (type == INTERNAL && func_type_mismatch(db_info->expr, value))
 593                 db_info->cull = 1;
 594         if (db_info->cull)
 595                 return 0;
 596         if (type == CULL_PATH) {
 597                 db_info->cull = 1;
 598                 return 0;
 599         }
 600
 601         if (is_impossible_data(type, db_info->expr, param, key, value)) {
 602                 db_info->cull = 1;
 603                 return 0;
 604         }
 605
 606         call_results_to_rl(db_info->expr, get_type(strip_expr(db_info->expr)), argv[1], &ret_range);
 607         ret_range = cast_rl(get_type(db_info->expr), ret_range);
 608         if (!ret_range)
 609                 ret_range = alloc_whole_rl(get_type(db_info->expr));
 610
 611         comparison = db_info->comparison;
 612         if (db_info->left)
 613                 comparison = flip_comparison(comparison);
 614
 615         if (db_info->true_side) {
 616                 if (!possibly_true_rl(var_rl, comparison, ret_range))
 617                         return 0;
 618                 if (type == PARAM_LIMIT)
 619                         param_limit_implications(db_info->expr, param, key, value);
 620                 filter_by_comparison(&var_rl, comparison, ret_range);
 621                 filter_by_comparison(&ret_range, flip_comparison(comparison), var_rl);
 622         } else {
 623                 if (!possibly_false_rl(var_rl, comparison, ret_range))
 624                         return 0;
 625                 if (type == PARAM_LIMIT)
 626                         param_limit_implications(db_info->expr, param, key, value);
 627                 filter_by_comparison(&var_rl, negate_comparison(comparison), ret_range);
 628                 filter_by_comparison(&ret_range, flip_comparison(negate_comparison(comparison)), var_rl);
 629         }
 630
 631         handle_ret_equals_param(argv[1], ret_range, db_info->expr);
 632
 633         if (type == INTERNAL) {
 634                 set_state(-1, "unnull_path", NULL, &true_state);
 635                 __add_return_comparison(strip_expr(db_info->expr), argv[1]);
 636                 __add_return_to_param_mapping(db_info->expr, argv[1]);
 637                 store_return_state(db_info, argv[1], alloc_estate_rl(clone_rl(var_rl)));
 638         }
 639
 640         FOR_EACH_PTR(db_info->callbacks, tmp) {
 641                 if (tmp->type == type)
 642                         tmp->callback(db_info->expr, param, key, value);
 643         } END_FOR_EACH_PTR(tmp);
 644
 645         return 0;
 646 }
 647
 648 static void compare_db_return_states_callbacks(struct expression *left, int comparison, struct expression *right, struct stree *implied_true, struct stree *implied_false)
 649 {
 650         struct stree *orig_states;
 651         struct stree *stree;
 652         struct stree *true_states;
 653         struct stree *false_states;
 654         struct sm_state *sm;
 655         struct db_callback_info db_info = {};
 656         struct expression *var_expr;
 657         struct expression *call_expr;
 658         struct range_list *rl;
 659         int call_on_left;
 660
 661         orig_states = clone_stree(__get_cur_stree());
 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         db_info.comparison = comparison;
 676         db_info.expr = call_expr;
 677         db_info.rl = rl;
 678         db_info.left = call_on_left;
 679         db_info.callbacks = db_return_states_list;
 680         db_info.var_expr = var_expr;
 681
 682         call_return_states_before_hooks();
 683
 684         db_info.true_side = 1;
 685         db_info.stree = NULL;
 686         db_info.prev_return_id = -1;
 687         __push_fake_cur_stree();
 688         sql_select_return_states("return_id, return, type, parameter, key, value",
 689                                  call_expr, db_compare_callback, &db_info);
 690         set_return_state(db_info.var_expr, &db_info);
 691         stree = __pop_fake_cur_stree();
 692         if (!db_info.cull) {
 693                 set_return_state(db_info.var_expr, &db_info);
 694                 merge_fake_stree(&db_info.stree, stree);
 695         }
 696         free_stree(&stree);
 697         true_states = db_info.stree;
 698         if (!true_states && db_info.has_states) {
 699                 __push_fake_cur_stree();
 700                 set_path_impossible();
 701                 true_states = __pop_fake_cur_stree();
 702         }
 703
 704         nullify_path();
 705         __unnullify_path();
 706         FOR_EACH_SM(orig_states, sm) {
 707                 __set_sm_cur_stree(sm);
 708         } END_FOR_EACH_SM(sm);
 709
 710         db_info.true_side = 0;
 711         db_info.stree = NULL;
 712         db_info.prev_return_id = -1;
 713         db_info.cull = 0;
 714         __push_fake_cur_stree();
 715         sql_select_return_states("return_id, return, type, parameter, key, value", call_expr,
 716                         db_compare_callback, &db_info);
 717         stree = __pop_fake_cur_stree();
 718         if (!db_info.cull) {
 719                 set_return_state(db_info.var_expr, &db_info);
 720                 merge_fake_stree(&db_info.stree, stree);
 721         }
 722         free_stree(&stree);
 723         false_states = db_info.stree;
 724         if (!false_states && db_info.has_states) {
 725                 __push_fake_cur_stree();
 726                 set_path_impossible();
 727                 false_states = __pop_fake_cur_stree();
 728         }
 729
 730         nullify_path();
 731         __unnullify_path();
 732         FOR_EACH_SM(orig_states, sm) {
 733                 __set_sm_cur_stree(sm);
 734         } END_FOR_EACH_SM(sm);
 735
 736         free_stree(&orig_states);
 737
 738         FOR_EACH_SM(true_states, sm) {
 739                 __set_true_false_sm(sm, NULL);
 740         } END_FOR_EACH_SM(sm);
 741         FOR_EACH_SM(false_states, sm) {
 742                 __set_true_false_sm(NULL, sm);
 743         } END_FOR_EACH_SM(sm);
 744
 745         free_stree(&true_states);
 746         free_stree(&false_states);
 747
 748         call_return_states_after_hooks(call_expr);
 749
 750         FOR_EACH_SM(implied_true, sm) {
 751                 __set_true_false_sm(sm, NULL);
 752         } END_FOR_EACH_SM(sm);
 753         FOR_EACH_SM(implied_false, sm) {
 754                 __set_true_false_sm(NULL, sm);
 755         } END_FOR_EACH_SM(sm);
 756 }
 757
 758 void function_comparison(struct expression *left, int comparison, struct expression *right)
 759 {
 760         struct expression *var_expr;
 761         struct expression *call_expr;
 762         struct stree *implied_true = NULL;
 763         struct stree *implied_false = NULL;
 764         struct range_list *rl;
 765         sval_t sval;
 766         int call_on_left;
 767
 768         if (unreachable())
 769                 return;
 770
 771         /* legacy cruft.  need to fix call_implies_callbacks(). */
 772         call_on_left = 1;
 773         call_expr = left;
 774         var_expr = right;
 775         if (left->type != EXPR_CALL) {
 776                 call_on_left = 0;
 777                 call_expr = right;
 778                 var_expr = left;
 779         }
 780
 781         get_absolute_rl(var_expr, &rl);
 782
 783         if (rl_to_sval(rl, &sval))
 784                 call_implies_callbacks(comparison, call_expr, sval, call_on_left, &implied_true, &implied_false);
 785
 786         compare_db_return_states_callbacks(left, comparison, right, implied_true, implied_false);
 787         free_stree(&implied_true);
 788         free_stree(&implied_false);
 789 }
 790
 791 static void call_ranged_return_hooks(struct db_callback_info *db_info)
 792 {
 793         struct call_back_list *call_backs;
 794         struct expression *expr;
 795         struct fcall_back *tmp;
 796         char *fn;
 797
 798         expr = strip_expr(db_info->expr);
 799         while (expr->type == EXPR_ASSIGNMENT)
 800                 expr = strip_expr(expr->right);
 801         if (expr->type != EXPR_CALL ||
 802             expr->fn->type != EXPR_SYMBOL)
 803                 return;
 804
 805         fn = expr->fn->symbol_name->name;
 806
 807         call_backs = search_callback(func_hash, fn);
 808         FOR_EACH_PTR(call_backs, tmp) {
 809                 struct range_list *range_rl = NULL;
 810
 811                 if (tmp->type != RANGED_CALL)
 812                         continue;
 813                 add_range(&range_rl, tmp->range->min, tmp->range->max);
 814                 range_rl = cast_rl(estate_type(db_info->ret_state), range_rl);
 815                 if (possibly_true_rl(range_rl, SPECIAL_EQUAL, estate_rl(db_info->ret_state))) {
 816                         if (!possibly_true_rl(rl_invert(range_rl), SPECIAL_EQUAL, estate_rl(db_info->ret_state)))
 817                                 (tmp->u.ranged)(fn, expr, db_info->expr, tmp->info);
 818                         else
 819                                 db_info->handled = -1;
 820                 }
 821         } END_FOR_EACH_PTR(tmp);
 822 }
 823
 824 static int db_assign_return_states_callback(void *_info, int argc, char **argv, char **azColName)
 825 {
 826         struct db_callback_info *db_info = _info;
 827         struct range_list *ret_range;
 828         int type, param;
 829         char *key, *value;
 830         struct return_implies_callback *tmp;
 831         struct stree *stree;
 832         int return_id;
 833
 834         if (argc != 6)
 835                 return 0;
 836
 837         return_id = atoi(argv[0]);
 838         type = atoi(argv[2]);
 839         param = atoi(argv[3]);
 840         key = argv[4];
 841         value = argv[5];
 842
 843         if (db_info->prev_return_id != -1 && type == INTERNAL) {
 844                 call_ranged_return_hooks(db_info);
 845                 set_return_state(db_info->expr->left, db_info);
 846                 stree = __pop_fake_cur_stree();
 847                 if (!db_info->cull)
 848                         merge_fake_stree(&db_info->stree, stree);
 849                 free_stree(&stree);
 850                 __push_fake_cur_stree();
 851                 db_info->cull = 0;
 852         }
 853         db_info->prev_return_id = return_id;
 854
 855         if (type == INTERNAL && func_type_mismatch(db_info->expr, value))
 856                 db_info->cull = 1;
 857         if (db_info->cull)
 858                 return 0;
 859         if (type == CULL_PATH) {
 860                 db_info->cull = 1;
 861                 return 0;
 862         }
 863         if (is_impossible_data(type, db_info->expr, param, key, value)) {
 864                 db_info->cull = 1;
 865                 return 0;
 866         }
 867
 868         if (type == PARAM_LIMIT)
 869                 param_limit_implications(db_info->expr, param, key, value);
 870
 871         db_info->handled = 1;
 872         call_results_to_rl(db_info->expr->right, get_type(strip_expr(db_info->expr->right)), argv[1], &ret_range);
 873         if (!ret_range)
 874                 ret_range = alloc_whole_rl(get_type(strip_expr(db_info->expr->right)));
 875         ret_range = cast_rl(get_type(db_info->expr->right), ret_range);
 876
 877         if (type == INTERNAL) {
 878                 set_state(-1, "unnull_path", NULL, &true_state);
 879                 __add_return_comparison(strip_expr(db_info->expr->right), argv[1]);
 880                 __add_comparison_info(db_info->expr->left, strip_expr(db_info->expr->right), argv[1]);
 881                 __add_return_to_param_mapping(db_info->expr, argv[1]);
 882                 store_return_state(db_info, argv[1], alloc_estate_rl(ret_range));
 883         }
 884
 885         FOR_EACH_PTR(db_return_states_list, tmp) {
 886                 if (tmp->type == type)
 887                         tmp->callback(db_info->expr, param, key, value);
 888         } END_FOR_EACH_PTR(tmp);
 889
 890         return 0;
 891 }
 892
 893 static int db_return_states_assign(struct expression *expr)
 894 {
 895         struct expression *right;
 896         struct sm_state *sm;
 897         struct stree *stree;
 898         struct db_callback_info db_info = {};
 899
 900         right = strip_expr(expr->right);
 901
 902         db_info.prev_return_id = -1;
 903         db_info.expr = expr;
 904         db_info.stree = NULL;
 905         db_info.handled = 0;
 906
 907         call_return_states_before_hooks();
 908
 909         __push_fake_cur_stree();
 910         sql_select_return_states("return_id, return, type, parameter, key, value",
 911                         right, db_assign_return_states_callback, &db_info);
 912         if (option_debug) {
 913                 sm_msg("%s return_id %d return_ranges %s",
 914                         db_info.cull ? "culled" : "merging",
 915                         db_info.prev_return_id,
 916                         db_info.ret_state ? db_info.ret_state->name : "'<empty>'");
 917         }
 918         if (db_info.handled)
 919                 call_ranged_return_hooks(&db_info);
 920         set_return_state(db_info.expr->left, &db_info);
 921         stree = __pop_fake_cur_stree();
 922         if (!db_info.cull)
 923                 merge_fake_stree(&db_info.stree, stree);
 924         free_stree(&stree);
 925
 926         if (!db_info.stree && db_info.cull) { /* this means we culled everything */
 927                 set_extra_expr_mod(expr->left, alloc_estate_whole(get_type(expr->left)));
 928                 set_path_impossible();
 929         }
 930         FOR_EACH_SM(db_info.stree, sm) {
 931                 __set_sm(sm);
 932         } END_FOR_EACH_SM(sm);
 933
 934         free_stree(&db_info.stree);
 935         call_return_states_after_hooks(right);
 936
 937         return db_info.handled;
 938 }
 939
 940 static int handle_implied_return(struct expression *expr)
 941 {
 942         struct range_list *rl;
 943
 944         if (!get_implied_return(expr->right, &rl))
 945                 return 0;
 946         rl = cast_rl(get_type(expr->left), rl);
 947         set_extra_expr_mod(expr->left, alloc_estate_rl(rl));
 948         return 1;
 949 }
 950
 951 static void match_assign_call(struct expression *expr)
 952 {
 953         struct call_back_list *call_backs;
 954         const char *fn;
 955         struct expression *right;
 956         int handled = 0;
 957         struct range_list *rl;
 958
 959         if (expr->op != '=')
 960                 return;
 961
 962         right = strip_expr(expr->right);
 963         if (right->fn->type != EXPR_SYMBOL || !right->fn->symbol) {
 964                 handled |= db_return_states_assign(expr);
 965                 if (!handled)
 966                         goto assigned_unknown;
 967                 return;
 968         }
 969         if (is_fake_call(right)) {
 970                 set_extra_expr_mod(expr->left, alloc_estate_whole(get_type(expr->left)));
 971                 return;
 972         }
 973
 974         fn = right->fn->symbol->ident->name;
 975         call_backs = search_callback(func_hash, (char *)fn);
 976
 977         /*
 978          * The ordering here is sort of important.
 979          * One example, of how this matters is that when we do:
 980          *
 981          *      len = strlen(str);
 982          *
 983          * That is handled by smatch_common_functions.c and smatch_strlen.c.
 984          * They use implied_return and function_assign_hook respectively.
 985          * We want to get the implied return first before we do the function
 986          * assignment hook otherwise we end up writing the wrong thing for len
 987          * in smatch_extra.c because we assume that it already holds the
 988          * strlen() when we haven't set it yet.
 989          */
 990
 991         if (db_return_states_assign(expr) == 1)
 992                 handled = 1;
 993         else
 994                 handled = assign_ranged_funcs(fn, expr, call_backs);
 995         handled |= handle_implied_return(expr);
 996
 997
 998         call_call_backs(call_backs, ASSIGN_CALL, fn, expr);
 999
1000         if (handled)
1001                 return;
1002
1003 assigned_unknown:
1004         get_absolute_rl(expr->right, &rl);
1005         rl = cast_rl(get_type(expr->left), rl);
1006         set_extra_expr_mod(expr->left, alloc_estate_rl(rl));
1007 }
1008
1009 static int db_return_states_callback(void *_info, int argc, char **argv, char **azColName)
1010 {
1011         struct db_callback_info *db_info = _info;
1012         struct range_list *ret_range;
1013         int type, param;
1014         char *key, *value;
1015         struct return_implies_callback *tmp;
1016         struct stree *stree;
1017         int return_id;
1018         char buf[64];
1019
1020         if (argc != 6)
1021                 return 0;
1022
1023         return_id = atoi(argv[0]);
1024         type = atoi(argv[2]);
1025         param = atoi(argv[3]);
1026         key = argv[4];
1027         value = argv[5];
1028
1029         if (db_info->prev_return_id != -1 && type == INTERNAL) {
1030                 stree = __pop_fake_cur_stree();
1031                 if (!db_info->cull)
1032                         merge_fake_stree(&db_info->stree, stree);
1033                 free_stree(&stree);
1034                 __push_fake_cur_stree();
1035                 __unnullify_path();
1036                 db_info->cull = 0;
1037         }
1038         db_info->prev_return_id = return_id;
1039
1040         if (type == INTERNAL && func_type_mismatch(db_info->expr, value))
1041                 db_info->cull = 1;
1042         if (db_info->cull)
1043                 return 0;
1044         if (type == CULL_PATH) {
1045                 db_info->cull = 1;
1046                 return 0;
1047         }
1048         if (is_impossible_data(type, db_info->expr, param, key, value)) {
1049                 db_info->cull = 1;
1050                 return 0;
1051         }
1052
1053         if (type == PARAM_LIMIT)
1054                 param_limit_implications(db_info->expr, param, key, value);
1055
1056         call_results_to_rl(db_info->expr, get_type(strip_expr(db_info->expr)), argv[1], &ret_range);
1057         ret_range = cast_rl(get_type(db_info->expr), ret_range);
1058
1059         if (type == INTERNAL) {
1060                 set_state(-1, "unnull_path", NULL, &true_state);
1061                 __add_return_comparison(strip_expr(db_info->expr), argv[1]);
1062                 __add_return_to_param_mapping(db_info->expr, argv[1]);
1063         }
1064
1065
1066         FOR_EACH_PTR(db_return_states_list, tmp) {
1067                 if (tmp->type == type)
1068                         tmp->callback(db_info->expr, param, key, value);
1069         } END_FOR_EACH_PTR(tmp);
1070
1071         /*
1072          * We want to store the return values so that we can split the strees
1073          * in smatch_db.c.  This uses set_state() directly because it's not a
1074          * real smatch_extra state.
1075          */
1076         snprintf(buf, sizeof(buf), "return %p", db_info->expr);
1077         set_state(SMATCH_EXTRA, buf, NULL, alloc_estate_rl(ret_range));
1078
1079         return 0;
1080 }
1081
1082 static void db_return_states(struct expression *expr)
1083 {
1084         struct sm_state *sm;
1085         struct stree *stree;
1086         struct db_callback_info db_info = {};
1087
1088         if (!__get_cur_stree())  /* no return functions */
1089                 return;
1090
1091         db_info.prev_return_id = -1;
1092         db_info.expr = expr;
1093         db_info.stree = NULL;
1094
1095         call_return_states_before_hooks();
1096
1097         __push_fake_cur_stree();
1098         __unnullify_path();
1099         sql_select_return_states("return_id, return, type, parameter, key, value",
1100                         expr, db_return_states_callback, &db_info);
1101         stree = __pop_fake_cur_stree();
1102         if (!db_info.cull)
1103                 merge_fake_stree(&db_info.stree, stree);
1104         free_stree(&stree);
1105
1106         FOR_EACH_SM(db_info.stree, sm) {
1107                 __set_sm(sm);
1108         } END_FOR_EACH_SM(sm);
1109
1110         free_stree(&db_info.stree);
1111         call_return_states_after_hooks(expr);
1112 }
1113
1114 static int is_condition_call(struct expression *expr)
1115 {
1116         struct expression *tmp;
1117
1118         FOR_EACH_PTR_REVERSE(big_condition_stack, tmp) {
1119                 if (expr == tmp || expr_get_parent_expr(expr) == tmp)
1120                         return 1;
1121                 if (tmp->pos.line < expr->pos.line)
1122                         return 0;
1123         } END_FOR_EACH_PTR_REVERSE(tmp);
1124
1125         return 0;
1126 }
1127
1128 static void db_return_states_call(struct expression *expr)
1129 {
1130         if (unreachable())
1131                 return;
1132
1133         if (is_assigned_call(expr))
1134                 return;
1135         if (is_condition_call(expr))
1136                 return;
1137         db_return_states(expr);
1138 }
1139
1140 static void match_function_call(struct expression *expr)
1141 {
1142         struct call_back_list *call_backs;
1143
1144         if (expr->fn->type == EXPR_SYMBOL && expr->fn->symbol) {
1145                 call_backs = search_callback(func_hash, (char *)expr->fn->symbol->ident->name);
1146                 if (call_backs)
1147                         call_call_backs(call_backs, REGULAR_CALL,
1148                                         expr->fn->symbol->ident->name, expr);
1149         }
1150         db_return_states_call(expr);
1151 }
1152
1153 static void match_macro_assign(struct expression *expr)
1154 {
1155         struct call_back_list *call_backs;
1156         const char *macro;
1157         struct expression *right;
1158
1159         right = strip_expr(expr->right);
1160         macro = get_macro_name(right->pos);
1161         call_backs = search_callback(func_hash, (char *)macro);
1162         if (!call_backs)
1163                 return;
1164         call_call_backs(call_backs, MACRO_ASSIGN, macro, expr);
1165         call_call_backs(call_backs, MACRO_ASSIGN_EXTRA, macro, expr);
1166 }
1167
1168 int get_implied_return(struct expression *expr, struct range_list **rl)
1169 {
1170         struct call_back_list *call_backs;
1171         struct fcall_back *tmp;
1172         int handled = 0;
1173         char *fn;
1174
1175         *rl = NULL;
1176
1177         expr = strip_expr(expr);
1178         fn = expr_to_var(expr->fn);
1179         if (!fn)
1180                 goto out;
1181
1182         call_backs = search_callback(func_hash, fn);
1183
1184         FOR_EACH_PTR(call_backs, tmp) {
1185                 if (tmp->type == IMPLIED_RETURN) {
1186                         (tmp->u.implied_return)(expr, tmp->info, rl);
1187                         handled = 1;
1188                 }
1189         } END_FOR_EACH_PTR(tmp);
1190
1191 out:
1192         free_string(fn);
1193         return handled;
1194 }
1195
1196 void create_function_hook_hash(void)
1197 {
1198         func_hash = create_function_hashtable(5000);
1199 }
1200
1201 void register_function_hooks(int id)
1202 {
1203         add_hook(&match_function_call, CALL_HOOK_AFTER_INLINE);
1204         add_hook(&match_assign_call, CALL_ASSIGNMENT_HOOK);
1205         add_hook(&match_macro_assign, MACRO_ASSIGNMENT_HOOK);
1206 }