smatch_function_hooks.c

   1 /*
   2  * Copyright (C) 2009 Dan Carpenter.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
  16  */
  17
  18 /*
  19  * There are several types of function hooks:
  20  * add_function_hook()        - For any time a function is called.
  21  * add_function_assign_hook() - foo = the_function().
  22  * add_implied_return_hook()  - Calculates the implied return value.
  23  * add_macro_assign_hook()    - foo = the_macro().
  24  * return_implies_state()     - For when a return value of 1 implies locked
  25  *                              and 0 implies unlocked. etc. etc.
  26  *
  27  */
  28
  29 #include <stdlib.h>
  30 #include <stdio.h>
  31 #include "smatch.h"
  32 #include "smatch_slist.h"
  33 #include "smatch_extra.h"
  34 #include "smatch_function_hashtable.h"
  35
  36 struct fcall_back {
  37         int type;
  38         struct data_range *range;
  39         union {
  40                 func_hook *call_back;
  41                 implication_hook *ranged;
  42                 implied_return_hook *implied_return;
  43         } u;
  44         void *info;
  45 };
  46
  47 ALLOCATOR(fcall_back, "call backs");
  48 DECLARE_PTR_LIST(call_back_list, struct fcall_back);
  49
  50 DEFINE_FUNCTION_HASHTABLE_STATIC(callback, struct fcall_back, struct call_back_list);
  51 static struct hashtable *func_hash;
  52
  53 #define REGULAR_CALL       0
  54 #define RANGED_CALL        1
  55 #define ASSIGN_CALL        2
  56 #define IMPLIED_RETURN     3
  57 #define MACRO_ASSIGN       4
  58 #define MACRO_ASSIGN_EXTRA 5
  59
  60 struct return_implies_callback {
  61         int type;
  62         return_implies_hook *callback;
  63 };
  64 ALLOCATOR(return_implies_callback, "return_implies callbacks");
  65 DECLARE_PTR_LIST(db_implies_list, struct return_implies_callback);
  66 static struct db_implies_list *db_return_states_list;
  67
  68 typedef void (void_fn)(void);
  69 DECLARE_PTR_LIST(void_fn_list, void_fn *);
  70 static struct void_fn_list *return_states_before;
  71 static struct void_fn_list *return_states_after;
  72
  73 static struct fcall_back *alloc_fcall_back(int type, void *call_back,
  74                                            void *info)
  75 {
  76         struct fcall_back *cb;
  77
  78         cb = __alloc_fcall_back(0);
  79         cb->type = type;
  80         cb->u.call_back = call_back;
  81         cb->info = info;
  82         return cb;
  83 }
  84
  85 void add_function_hook(const char *look_for, func_hook *call_back, void *info)
  86 {
  87         struct fcall_back *cb;
  88
  89         cb = alloc_fcall_back(REGULAR_CALL, call_back, info);
  90         add_callback(func_hash, look_for, cb);
  91 }
  92
  93 void add_function_assign_hook(const char *look_for, func_hook *call_back,
  94                               void *info)
  95 {
  96         struct fcall_back *cb;
  97
  98         cb = alloc_fcall_back(ASSIGN_CALL, call_back, info);
  99         add_callback(func_hash, look_for, cb);
 100 }
 101
 102 void add_implied_return_hook(const char *look_for,
 103                              implied_return_hook *call_back,
 104                              void *info)
 105 {
 106         struct fcall_back *cb;
 107
 108         cb = alloc_fcall_back(IMPLIED_RETURN, call_back, info);
 109         add_callback(func_hash, look_for, cb);
 110 }
 111
 112 void add_macro_assign_hook(const char *look_for, func_hook *call_back,
 113                         void *info)
 114 {
 115         struct fcall_back *cb;
 116
 117         cb = alloc_fcall_back(MACRO_ASSIGN, call_back, info);
 118         add_callback(func_hash, look_for, cb);
 119 }
 120
 121 void add_macro_assign_hook_extra(const char *look_for, func_hook *call_back,
 122                         void *info)
 123 {
 124         struct fcall_back *cb;
 125
 126         cb = alloc_fcall_back(MACRO_ASSIGN_EXTRA, call_back, info);
 127         add_callback(func_hash, look_for, cb);
 128 }
 129
 130 void return_implies_state(const char *look_for, long long start, long long end,
 131                          implication_hook *call_back, void *info)
 132 {
 133         struct fcall_back *cb;
 134
 135         cb = alloc_fcall_back(RANGED_CALL, call_back, info);
 136         cb->range = alloc_range_perm(ll_to_sval(start), ll_to_sval(end));
 137         add_callback(func_hash, look_for, cb);
 138 }
 139
 140 void select_return_states_hook(int type, return_implies_hook *callback)
 141 {
 142         struct return_implies_callback *cb = __alloc_return_implies_callback(0);
 143
 144         cb->type = type;
 145         cb->callback = callback;
 146         add_ptr_list(&db_return_states_list, cb);
 147 }
 148
 149 void select_return_states_before(void_fn *fn)
 150 {
 151         void_fn **p = malloc(sizeof(void_fn *));
 152         *p = fn;
 153         add_ptr_list(&return_states_before, p);
 154 }
 155
 156 void select_return_states_after(void_fn *fn)
 157 {
 158         void_fn **p = malloc(sizeof(void_fn *));
 159         *p = fn;
 160         add_ptr_list(&return_states_after, p);
 161 }
 162
 163 static void call_return_states_before_hooks(void)
 164 {
 165         void_fn **fn;
 166
 167         FOR_EACH_PTR(return_states_before, fn) {
 168                 (*fn)();
 169         } END_FOR_EACH_PTR(fn);
 170 }
 171
 172 static void call_return_states_after_hooks(void)
 173 {
 174         void_fn **fn;
 175
 176         FOR_EACH_PTR(return_states_after, fn) {
 177                 (*fn)();
 178         } END_FOR_EACH_PTR(fn);
 179 }
 180
 181 static int call_call_backs(struct call_back_list *list, int type,
 182                             const char *fn, struct expression *expr)
 183 {
 184         struct fcall_back *tmp;
 185         int handled = 0;
 186
 187         FOR_EACH_PTR(list, tmp) {
 188                 if (tmp->type == type) {
 189                         (tmp->u.call_back)(fn, expr, tmp->info);
 190                         handled = 1;
 191                 }
 192         } END_FOR_EACH_PTR(tmp);
 193
 194         return handled;
 195 }
 196
 197 static void call_ranged_call_backs(struct call_back_list *list,
 198                                 const char *fn, struct expression *call_expr,
 199                                 struct expression *assign_expr)
 200 {
 201         struct fcall_back *tmp;
 202
 203         FOR_EACH_PTR(list, tmp) {
 204                 (tmp->u.ranged)(fn, call_expr, assign_expr, tmp->info);
 205         } END_FOR_EACH_PTR(tmp);
 206 }
 207
 208 static struct call_back_list *get_same_ranged_call_backs(struct call_back_list *list,
 209                                                 struct data_range *drange)
 210 {
 211         struct call_back_list *ret = NULL;
 212         struct fcall_back *tmp;
 213
 214         FOR_EACH_PTR(list, tmp) {
 215                 if (tmp->type != RANGED_CALL)
 216                         continue;
 217                 if (ranges_equiv(tmp->range, drange))
 218                         add_ptr_list(&ret, tmp);
 219         } END_FOR_EACH_PTR(tmp);
 220         return ret;
 221 }
 222
 223 static int in_list_exact_sval(struct range_list *list, struct data_range *drange)
 224 {
 225         struct data_range *tmp;
 226
 227         FOR_EACH_PTR(list, tmp) {
 228                 if (ranges_equiv(tmp, drange))
 229                         return 1;
 230         } END_FOR_EACH_PTR(tmp);
 231         return 0;
 232 }
 233
 234 static int assign_ranged_funcs(const char *fn, struct expression *expr,
 235                                  struct call_back_list *call_backs)
 236 {
 237         struct fcall_back *tmp;
 238         struct sm_state *sm;
 239         char *var_name;
 240         struct symbol *sym;
 241         struct smatch_state *estate;
 242         struct stree *tmp_stree;
 243         struct stree *final_states = NULL;
 244         struct range_list *handled_ranges = NULL;
 245         struct call_back_list *same_range_call_backs = NULL;
 246         int handled = 0;
 247
 248         if (!call_backs)
 249                 return 0;
 250
 251         var_name = expr_to_var_sym(expr->left, &sym);
 252         if (!var_name || !sym)
 253                 goto free;
 254
 255         FOR_EACH_PTR(call_backs, tmp) {
 256                 if (tmp->type != RANGED_CALL)
 257                         continue;
 258
 259                 if (in_list_exact_sval(handled_ranges, tmp->range))
 260                         continue;
 261                 __push_fake_cur_stree();
 262                 tack_on(&handled_ranges, tmp->range);
 263
 264                 same_range_call_backs = get_same_ranged_call_backs(call_backs, tmp->range);
 265                 call_ranged_call_backs(same_range_call_backs, fn, expr->right, expr);
 266                 __free_ptr_list((struct ptr_list **)&same_range_call_backs);
 267
 268                 estate = alloc_estate_range(tmp->range->min, tmp->range->max);
 269                 set_extra_mod(var_name, sym, estate);
 270
 271                 tmp_stree = __pop_fake_cur_stree();
 272                 merge_fake_stree(&final_states, tmp_stree);
 273                 free_stree(&tmp_stree);
 274                 handled = 1;
 275         } END_FOR_EACH_PTR(tmp);
 276
 277         FOR_EACH_SM(final_states, sm) {
 278                 __set_sm(sm);
 279         } END_FOR_EACH_SM(sm);
 280
 281         free_stree(&final_states);
 282 free:
 283         free_string(var_name);
 284         return handled;
 285 }
 286
 287 static void call_implies_callbacks(int comparison, struct expression *expr, sval_t sval, int left, struct stree **implied_true, struct stree **implied_false)
 288 {
 289         struct call_back_list *call_backs;
 290         struct fcall_back *tmp;
 291         const char *fn;
 292         struct data_range *value_range;
 293         struct stree *true_states = NULL;
 294         struct stree *false_states = NULL;
 295         struct stree *tmp_stree;
 296
 297         *implied_true = NULL;
 298         *implied_false = NULL;
 299         if (expr->fn->type != EXPR_SYMBOL || !expr->fn->symbol)
 300                 return;
 301         fn = expr->fn->symbol->ident->name;
 302         call_backs = search_callback(func_hash, (char *)expr->fn->symbol->ident->name);
 303         if (!call_backs)
 304                 return;
 305         value_range = alloc_range(sval, sval);
 306
 307         /* set true states */
 308         __push_fake_cur_stree();
 309         FOR_EACH_PTR(call_backs, tmp) {
 310                 if (tmp->type != RANGED_CALL)
 311                         continue;
 312                 if (!true_comparison_range_LR(comparison, tmp->range, value_range, left))
 313                         continue;
 314                 (tmp->u.ranged)(fn, expr, NULL, tmp->info);
 315         } END_FOR_EACH_PTR(tmp);
 316         tmp_stree = __pop_fake_cur_stree();
 317         merge_fake_stree(&true_states, tmp_stree);
 318         free_stree(&tmp_stree);
 319
 320         /* set false states */
 321         __push_fake_cur_stree();
 322         FOR_EACH_PTR(call_backs, tmp) {
 323                 if (tmp->type != RANGED_CALL)
 324                         continue;
 325                 if (!false_comparison_range_LR(comparison, tmp->range, value_range, left))
 326                         continue;
 327                 (tmp->u.ranged)(fn, expr, NULL, tmp->info);
 328         } END_FOR_EACH_PTR(tmp);
 329         tmp_stree = __pop_fake_cur_stree();
 330         merge_fake_stree(&false_states, tmp_stree);
 331         free_stree(&tmp_stree);
 332
 333         *implied_true = true_states;
 334         *implied_false = false_states;
 335 }
 336
 337 struct db_callback_info {
 338         int true_side;
 339         int comparison;
 340         struct expression *expr;
 341         struct range_list *rl;
 342         int left;
 343         struct stree *stree;
 344         struct db_implies_list *callbacks;
 345         int prev_return_id;
 346         int cull;
 347         struct smatch_state *ret_state;
 348 };
 349
 350 static void store_return_state(struct db_callback_info *db_info, struct smatch_state *state)
 351 {
 352         db_info->ret_state = state;
 353 }
 354
 355 static void set_return_state(struct db_callback_info *db_info)
 356 {
 357         if (db_info->expr->type != EXPR_ASSIGNMENT) {
 358                 sm_msg("Smatch Internal Error: expected an assignment");
 359                 return;
 360         }
 361         if (!db_info->ret_state)
 362                 return;
 363
 364         set_extra_expr_mod(db_info->expr->left, db_info->ret_state);
 365         db_info->ret_state = NULL;
 366 }
 367
 368 static void handle_ret_equals_param(char *ret_string, struct range_list *rl, struct expression *call)
 369 {
 370         char *str;
 371         long long param;
 372         struct expression *arg;
 373         struct range_list *orig;
 374
 375         str = strstr(ret_string, "==$");
 376         if (!str)
 377                 return;
 378         str += 3;
 379         param = strtoll(str, NULL, 10);
 380         arg = get_argument_from_call_expr(call->args, param);
 381         if (!arg)
 382                 return;
 383         get_absolute_rl(arg, &orig);
 384         rl = rl_intersection(orig, rl);
 385         if (!rl)
 386                 return;
 387         set_extra_expr_nomod(arg, alloc_estate_rl(rl));
 388 }
 389
 390 static int impossible_limit(struct expression *expr, int param, char *key, char *value)
 391 {
 392         struct expression *arg;
 393         struct range_list *passed;
 394         struct range_list *limit;
 395         struct symbol *compare_type;
 396
 397         if (strcmp(key, "$") != 0)
 398                 return 0;
 399
 400         while (expr->type == EXPR_ASSIGNMENT)
 401                 expr = strip_expr(expr->right);
 402         if (expr->type != EXPR_CALL)
 403                 return 0;
 404
 405         arg = get_argument_from_call_expr(expr->args, param);
 406         if (!arg)
 407                 return 0;
 408         if (!get_implied_rl(arg, &passed))
 409                 return 0;
 410         if (!passed || is_whole_rl(passed))
 411                 return 0;
 412
 413         compare_type = get_arg_type(expr->fn, param);
 414         call_results_to_rl(expr, compare_type, value, &limit);
 415         if (!limit || is_whole_rl(limit))
 416                 return 0;
 417         if (possibly_true_rl(passed, SPECIAL_EQUAL, limit))
 418                 return 0;
 419         return 1;
 420 }
 421
 422 static int db_compare_callback(void *_info, int argc, char **argv, char **azColName)
 423 {
 424         struct db_callback_info *db_info = _info;
 425         struct range_list *ret_range;
 426         int type, param;
 427         char *key, *value;
 428         struct return_implies_callback *tmp;
 429         struct stree *stree;
 430         int return_id;
 431         int comparison;
 432
 433         if (argc != 6)
 434                 return 0;
 435
 436         return_id = atoi(argv[0]);
 437         type = atoi(argv[2]);
 438         param = atoi(argv[3]);
 439         key = argv[4];
 440         value = argv[5];
 441
 442         if (db_info->prev_return_id != -1 && return_id != db_info->prev_return_id) {
 443                 stree = __pop_fake_cur_stree();
 444                 if (!db_info->cull)
 445                         merge_fake_stree(&db_info->stree, stree);
 446                 free_stree(&stree);
 447                 __push_fake_cur_stree();
 448                 db_info->cull = 0;
 449         }
 450         db_info->prev_return_id = return_id;
 451
 452         if (type == LIMITED_VALUE && impossible_limit(db_info->expr, param, key, value))
 453                 db_info->cull = 1;
 454         if (db_info->cull)
 455                 return 0;
 456
 457         call_results_to_rl(db_info->expr, get_type(strip_expr(db_info->expr)), argv[1], &ret_range);
 458         ret_range = cast_rl(get_type(db_info->expr), ret_range);
 459         if (!ret_range)
 460                 ret_range = alloc_whole_rl(get_type(db_info->expr));
 461
 462         comparison = db_info->comparison;
 463         if (!db_info->left)
 464                 comparison = flip_comparison(comparison);
 465
 466         if (db_info->true_side) {
 467                 if (!possibly_true_rl(ret_range, comparison, db_info->rl))
 468                         return 0;
 469                 filter_by_comparison(&ret_range, comparison, db_info->rl);
 470         } else {
 471                 if (!possibly_false_rl(ret_range, comparison, db_info->rl))
 472                         return 0;
 473                 filter_by_comparison(&ret_range, negate_comparison(comparison), db_info->rl);
 474         }
 475
 476         handle_ret_equals_param(argv[1], ret_range, db_info->expr);
 477
 478         FOR_EACH_PTR(db_info->callbacks, tmp) {
 479                 if (tmp->type == type)
 480                         tmp->callback(db_info->expr, param, key, value);
 481         } END_FOR_EACH_PTR(tmp);
 482         return 0;
 483 }
 484
 485 static void compare_db_return_states_callbacks(int comparison, struct expression *expr, sval_t sval, int left, struct stree *implied_true, struct stree *implied_false)
 486 {
 487         struct stree *stree;
 488         struct stree *true_states;
 489         struct stree *false_states;
 490         struct sm_state *sm;
 491         struct db_callback_info db_info = {};
 492
 493         db_info.comparison = comparison;
 494         db_info.expr = expr;
 495         db_info.rl = alloc_rl(sval, sval);
 496         db_info.left = left;
 497         db_info.callbacks = db_return_states_list;
 498
 499         call_return_states_before_hooks();
 500
 501         db_info.true_side = 1;
 502         db_info.stree = NULL;
 503         db_info.prev_return_id = -1;
 504         __push_fake_cur_stree();
 505         sql_select_return_states("return_id, return, type, parameter, key, value", expr,
 506                         db_compare_callback, &db_info);
 507         stree = __pop_fake_cur_stree();
 508         if (!db_info.cull)
 509                 merge_fake_stree(&db_info.stree, stree);
 510         free_stree(&stree);
 511         true_states = db_info.stree;
 512
 513         db_info.true_side = 0;
 514         db_info.stree = NULL;
 515         db_info.prev_return_id = -1;
 516         db_info.cull = 0;
 517         __push_fake_cur_stree();
 518         sql_select_return_states("return_id, return, type, parameter, key, value", expr,
 519                         db_compare_callback, &db_info);
 520         stree = __pop_fake_cur_stree();
 521         if (!db_info.cull)
 522                 merge_fake_stree(&db_info.stree, stree);
 523         free_stree(&stree);
 524         false_states = db_info.stree;
 525
 526         FOR_EACH_SM(true_states, sm) {
 527                 __set_true_false_sm(sm, NULL);
 528         } END_FOR_EACH_SM(sm);
 529         FOR_EACH_SM(false_states, sm) {
 530                 __set_true_false_sm(NULL, sm);
 531         } END_FOR_EACH_SM(sm);
 532
 533         free_stree(&true_states);
 534         free_stree(&false_states);
 535
 536         call_return_states_after_hooks();
 537
 538         FOR_EACH_SM(implied_true, sm) {
 539                 __set_true_false_sm(sm, NULL);
 540         } END_FOR_EACH_SM(sm);
 541         FOR_EACH_SM(implied_false, sm) {
 542                 __set_true_false_sm(NULL, sm);
 543         } END_FOR_EACH_SM(sm);
 544
 545 }
 546
 547 void function_comparison(int comparison, struct expression *expr, sval_t sval, int left)
 548 {
 549         struct stree *implied_true, *implied_false;
 550
 551         call_implies_callbacks(comparison, expr, sval, left, &implied_true, &implied_false);
 552         compare_db_return_states_callbacks(comparison, expr, sval, left, implied_true, implied_false);
 553         free_stree(&implied_true);
 554         free_stree(&implied_false);
 555 }
 556
 557 static int db_assign_return_states_callback(void *_info, int argc, char **argv, char **azColName)
 558 {
 559         struct db_callback_info *db_info = _info;
 560         struct range_list *ret_range;
 561         int type, param;
 562         char *key, *value;
 563         struct return_implies_callback *tmp;
 564         struct stree *stree;
 565         int return_id;
 566
 567         if (argc != 6)
 568                 return 0;
 569
 570         return_id = atoi(argv[0]);
 571         type = atoi(argv[2]);
 572         param = atoi(argv[3]);
 573         key = argv[4];
 574         value = argv[5];
 575
 576         if (db_info->prev_return_id != -1 && return_id != db_info->prev_return_id) {
 577                 set_return_state(db_info);
 578                 stree = __pop_fake_cur_stree();
 579                 if (!db_info->cull)
 580                         merge_fake_stree(&db_info->stree, stree);
 581                 free_stree(&stree);
 582                 __push_fake_cur_stree();
 583                 db_info->cull = 0;
 584         }
 585         db_info->prev_return_id = return_id;
 586
 587         if (type == LIMITED_VALUE && impossible_limit(db_info->expr, param, key, value))
 588                 db_info->cull = 1;
 589         if (db_info->cull)
 590                 return 0;
 591
 592         call_results_to_rl(db_info->expr->right, get_type(strip_expr(db_info->expr->right)), argv[1], &ret_range);
 593         __add_comparison_info(db_info->expr->left, strip_expr(db_info->expr->right), argv[1]);
 594         if (!ret_range)
 595                 ret_range = alloc_whole_rl(get_type(strip_expr(db_info->expr->right)));
 596         ret_range = cast_rl(get_type(db_info->expr->right), ret_range);
 597
 598         FOR_EACH_PTR(db_return_states_list, tmp) {
 599                 if (tmp->type == type)
 600                         tmp->callback(db_info->expr, param, key, value);
 601         } END_FOR_EACH_PTR(tmp);
 602         ret_range = cast_rl(get_type(db_info->expr->left), ret_range);
 603         store_return_state(db_info, alloc_estate_rl(ret_range));
 604
 605         return 0;
 606 }
 607
 608 static int db_return_states_assign(struct expression *expr)
 609 {
 610         struct expression *right;
 611         struct sm_state *sm;
 612         struct stree *stree;
 613         int handled = 0;
 614         struct db_callback_info db_info = {};
 615
 616         right = strip_expr(expr->right);
 617
 618         db_info.prev_return_id = -1;
 619         db_info.expr = expr;
 620         db_info.stree = NULL;
 621
 622         call_return_states_before_hooks();
 623
 624         __push_fake_cur_stree();
 625         sql_select_return_states("return_id, return, type, parameter, key, value",
 626                         right, db_assign_return_states_callback, &db_info);
 627         set_return_state(&db_info);
 628         stree = __pop_fake_cur_stree();
 629         if (!db_info.cull)
 630                 merge_fake_stree(&db_info.stree, stree);
 631         free_stree(&stree);
 632
 633         FOR_EACH_SM(db_info.stree, sm) {
 634                 __set_sm(sm);
 635                 handled = 1;
 636         } END_FOR_EACH_SM(sm);
 637
 638         free_stree(&db_info.stree);
 639         call_return_states_after_hooks();
 640
 641         return handled;
 642 }
 643
 644 static int handle_implied_return(struct expression *expr)
 645 {
 646         struct range_list *rl;
 647
 648         if (!get_implied_return(expr->right, &rl))
 649                 return 0;
 650         rl = cast_rl(get_type(expr->left), rl);
 651         set_extra_expr_mod(expr->left, alloc_estate_rl(rl));
 652         return 1;
 653 }
 654
 655 static void match_assign_call(struct expression *expr)
 656 {
 657         struct call_back_list *call_backs;
 658         const char *fn;
 659         struct expression *right;
 660         int handled = 0;
 661         struct range_list *rl;
 662
 663         if (expr->op != '=')
 664                 return;
 665
 666         right = strip_expr(expr->right);
 667         if (right->fn->type != EXPR_SYMBOL || !right->fn->symbol) {
 668                 handled |= db_return_states_assign(expr);
 669                 if (!handled)
 670                         goto assigned_unknown;
 671                 return;
 672         }
 673         if (is_fake_call(right)) {
 674                 if (!get_state_expr(SMATCH_EXTRA, expr->left))
 675                         return;
 676                 set_extra_expr_mod(expr->left, alloc_estate_whole(get_type(expr->left)));
 677                 return;
 678         }
 679
 680         fn = right->fn->symbol->ident->name;
 681
 682         /*
 683          * some of these conflict (they try to set smatch extra twice), so we
 684          * call them in order from least important to most important.
 685          */
 686
 687         call_backs = search_callback(func_hash, (char *)fn);
 688         call_call_backs(call_backs, ASSIGN_CALL, fn, expr);
 689
 690         handled |= db_return_states_assign(expr);
 691         handled |= assign_ranged_funcs(fn, expr, call_backs);
 692         handled |= handle_implied_return(expr);
 693
 694         if (handled)
 695                 return;
 696
 697 assigned_unknown:
 698         get_absolute_rl(expr->right, &rl);
 699         rl = cast_rl(get_type(expr->left), rl);
 700         set_extra_expr_mod(expr->left, alloc_estate_rl(rl));
 701 }
 702
 703 static int db_return_states_callback(void *_info, int argc, char **argv, char **azColName)
 704 {
 705         struct db_callback_info *db_info = _info;
 706         struct range_list *ret_range;
 707         int type, param;
 708         char *key, *value;
 709         struct return_implies_callback *tmp;
 710         struct stree *stree;
 711         int return_id;
 712         char buf[64];
 713
 714         if (argc != 6)
 715                 return 0;
 716
 717         return_id = atoi(argv[0]);
 718         type = atoi(argv[2]);
 719         param = atoi(argv[3]);
 720         key = argv[4];
 721         value = argv[5];
 722
 723         if (db_info->prev_return_id != -1 && return_id != db_info->prev_return_id) {
 724                 stree = __pop_fake_cur_stree();
 725                 if (!db_info->cull)
 726                         merge_fake_stree(&db_info->stree, stree);
 727                 free_stree(&stree);
 728                 __push_fake_cur_stree();
 729                 __unnullify_path();
 730                 db_info->cull = 0;
 731         }
 732         db_info->prev_return_id = return_id;
 733
 734         if (type == LIMITED_VALUE && impossible_limit(db_info->expr, param, key, value))
 735                 db_info->cull = 1;
 736         if (db_info->cull)
 737                 return 0;
 738
 739         call_results_to_rl(db_info->expr, get_type(strip_expr(db_info->expr)), argv[1], &ret_range);
 740         ret_range = cast_rl(get_type(db_info->expr), ret_range);
 741
 742         FOR_EACH_PTR(db_return_states_list, tmp) {
 743                 if (tmp->type == type)
 744                         tmp->callback(db_info->expr, param, key, value);
 745         } END_FOR_EACH_PTR(tmp);
 746
 747         /*
 748          * We want to store the return values so that we can split the strees
 749          * in smatch_db.c.  This uses set_state() directly because it's not a
 750          * real smatch_extra state.
 751          */
 752         snprintf(buf, sizeof(buf), "return %p", db_info->expr);
 753         set_state(SMATCH_EXTRA, buf, NULL, alloc_estate_rl(ret_range));
 754
 755         return 0;
 756 }
 757
 758 static void db_return_states(struct expression *expr)
 759 {
 760         struct sm_state *sm;
 761         struct stree *stree;
 762         struct db_callback_info db_info = {};
 763
 764         if (!__get_cur_stree())  /* no return functions */
 765                 return;
 766
 767         db_info.prev_return_id = -1;
 768         db_info.expr = expr;
 769         db_info.stree = NULL;
 770
 771         call_return_states_before_hooks();
 772
 773         __push_fake_cur_stree();
 774         __unnullify_path();
 775         sql_select_return_states("return_id, return, type, parameter, key, value",
 776                         expr, db_return_states_callback, &db_info);
 777         stree = __pop_fake_cur_stree();
 778         if (!db_info.cull)
 779                 merge_fake_stree(&db_info.stree, stree);
 780         free_stree(&stree);
 781
 782         FOR_EACH_SM(db_info.stree, sm) {
 783                 __set_sm(sm);
 784         } END_FOR_EACH_SM(sm);
 785
 786         free_stree(&db_info.stree);
 787         call_return_states_after_hooks();
 788 }
 789
 790 static void db_return_states_call(struct expression *expr)
 791 {
 792         if (is_assigned_call(expr))
 793                 return;
 794         db_return_states(expr);
 795 }
 796
 797 static void match_function_call(struct expression *expr)
 798 {
 799         struct call_back_list *call_backs;
 800
 801         if (expr->fn->type == EXPR_SYMBOL && expr->fn->symbol) {
 802                 call_backs = search_callback(func_hash, (char *)expr->fn->symbol->ident->name);
 803                 if (call_backs)
 804                         call_call_backs(call_backs, REGULAR_CALL,
 805                                         expr->fn->symbol->ident->name, expr);
 806         }
 807         db_return_states_call(expr);
 808 }
 809
 810 static void match_macro_assign(struct expression *expr)
 811 {
 812         struct call_back_list *call_backs;
 813         const char *macro;
 814         struct expression *right;
 815
 816         right = strip_expr(expr->right);
 817         macro = get_macro_name(right->pos);
 818         call_backs = search_callback(func_hash, (char *)macro);
 819         if (!call_backs)
 820                 return;
 821         call_call_backs(call_backs, MACRO_ASSIGN, macro, expr);
 822         call_call_backs(call_backs, MACRO_ASSIGN_EXTRA, macro, expr);
 823 }
 824
 825 int get_implied_return(struct expression *expr, struct range_list **rl)
 826 {
 827         struct call_back_list *call_backs;
 828         struct fcall_back *tmp;
 829         int handled = 0;
 830         char *fn;
 831
 832         *rl = NULL;
 833
 834         expr = strip_expr(expr);
 835         fn = expr_to_var(expr->fn);
 836         if (!fn)
 837                 goto out;
 838
 839         call_backs = search_callback(func_hash, fn);
 840
 841         FOR_EACH_PTR(call_backs, tmp) {
 842                 if (tmp->type == IMPLIED_RETURN) {
 843                         (tmp->u.implied_return)(expr, tmp->info, rl);
 844                         handled = 1;
 845                 }
 846         } END_FOR_EACH_PTR(tmp);
 847
 848 out:
 849         free_string(fn);
 850         return handled;
 851 }
 852
 853 void create_function_hook_hash(void)
 854 {
 855         func_hash = create_function_hashtable(5000);
 856 }
 857
 858 void register_function_hooks(int id)
 859 {
 860         add_hook(&match_function_call, CALL_HOOK_AFTER_INLINE);
 861         add_hook(&match_assign_call, CALL_ASSIGNMENT_HOOK);
 862         add_hook(&match_macro_assign, MACRO_ASSIGNMENT_HOOK);
 863 }