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 int call_implies_callbacks(int comparison, struct expression *expr, sval_t sval, int left)
 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         struct sm_state *sm;
 297
 298         if (expr->fn->type != EXPR_SYMBOL || !expr->fn->symbol)
 299                 return 0;
 300         fn = expr->fn->symbol->ident->name;
 301         call_backs = search_callback(func_hash, (char *)expr->fn->symbol->ident->name);
 302         if (!call_backs)
 303                 return 0;
 304         value_range = alloc_range(sval, sval);
 305
 306         /* set true states */
 307         __push_fake_cur_stree();
 308         FOR_EACH_PTR(call_backs, tmp) {
 309                 if (tmp->type != RANGED_CALL)
 310                         continue;
 311                 if (!true_comparison_range_LR(comparison, tmp->range, value_range, left))
 312                         continue;
 313                 (tmp->u.ranged)(fn, expr, NULL, tmp->info);
 314         } END_FOR_EACH_PTR(tmp);
 315         tmp_stree = __pop_fake_cur_stree();
 316         merge_fake_stree(&true_states, tmp_stree);
 317         free_stree(&tmp_stree);
 318
 319         /* set false states */
 320         __push_fake_cur_stree();
 321         FOR_EACH_PTR(call_backs, tmp) {
 322                 if (tmp->type != RANGED_CALL)
 323                         continue;
 324                 if (!false_comparison_range_LR(comparison, tmp->range, value_range, left))
 325                         continue;
 326                 (tmp->u.ranged)(fn, expr, NULL, tmp->info);
 327         } END_FOR_EACH_PTR(tmp);
 328         tmp_stree = __pop_fake_cur_stree();
 329         merge_fake_stree(&false_states, tmp_stree);
 330         free_stree(&tmp_stree);
 331
 332         FOR_EACH_SM(true_states, sm) {
 333                 __set_true_false_sm(sm, NULL);
 334         } END_FOR_EACH_SM(sm);
 335         FOR_EACH_SM(false_states, sm) {
 336                 __set_true_false_sm(NULL, sm);
 337         } END_FOR_EACH_SM(sm);
 338
 339         free_stree(&true_states);
 340         free_stree(&false_states);
 341         return 1;
 342 }
 343
 344 struct db_callback_info {
 345         int true_side;
 346         int comparison;
 347         struct expression *expr;
 348         struct range_list *rl;
 349         int left;
 350         struct stree *stree;
 351         struct db_implies_list *callbacks;
 352 };
 353 static struct db_callback_info db_info;
 354 static int db_compare_callback(void *unused, int argc, char **argv, char **azColName)
 355 {
 356         struct range_list *ret_range;
 357         int type, param;
 358         char *key, *value;
 359         struct return_implies_callback *tmp;
 360
 361         if (argc != 5)
 362                 return 0;
 363
 364         call_results_to_rl(db_info.expr, get_type(strip_expr(db_info.expr)), argv[0], &ret_range);
 365         ret_range = cast_rl(get_type(db_info.expr), ret_range);
 366         type = atoi(argv[1]);
 367         param = atoi(argv[2]);
 368         key = argv[3];
 369         value = argv[4];
 370
 371         if (db_info.true_side) {
 372                 if (!possibly_true_rl_LR(db_info.comparison,
 373                                                   ret_range, db_info.rl,
 374                                                   db_info.left))
 375                         return 0;
 376         } else {
 377                 if (!possibly_false_rl_LR(db_info.comparison,
 378                                                   ret_range, db_info.rl,
 379                                                   db_info.left))
 380                         return 0;
 381         }
 382
 383         FOR_EACH_PTR(db_info.callbacks, tmp) {
 384                 if (tmp->type == type)
 385                         tmp->callback(db_info.expr, param, key, value);
 386         } END_FOR_EACH_PTR(tmp);
 387         return 0;
 388 }
 389
 390 void compare_db_return_states_callbacks(int comparison, struct expression *expr, sval_t sval, int left)
 391 {
 392         struct stree *true_states;
 393         struct stree *false_states;
 394         struct sm_state *sm;
 395
 396         db_info.comparison = comparison;
 397         db_info.expr = expr;
 398         db_info.rl = alloc_rl(sval, sval);
 399         db_info.left = left;
 400         db_info.callbacks = db_return_states_list;
 401
 402         call_return_states_before_hooks();
 403
 404         db_info.true_side = 1;
 405         __push_fake_cur_stree();
 406         sql_select_return_states("return, type, parameter, key, value", expr,
 407                         db_compare_callback);
 408         true_states = __pop_fake_cur_stree();
 409
 410         db_info.true_side = 0;
 411         __push_fake_cur_stree();
 412         sql_select_return_states("return, type, parameter, key, value", expr,
 413                         db_compare_callback);
 414         false_states = __pop_fake_cur_stree();
 415
 416         FOR_EACH_SM(true_states, sm) {
 417                 __set_true_false_sm(sm, NULL);
 418         } END_FOR_EACH_SM(sm);
 419         FOR_EACH_SM(false_states, sm) {
 420                 __set_true_false_sm(NULL, sm);
 421         } END_FOR_EACH_SM(sm);
 422
 423         call_return_states_after_hooks();
 424
 425         free_stree(&true_states);
 426         free_stree(&false_states);
 427 }
 428
 429
 430
 431 void function_comparison(int comparison, struct expression *expr, sval_t sval, int left)
 432 {
 433         if (call_implies_callbacks(comparison, expr, sval, left))
 434                 return;
 435         compare_db_return_states_callbacks(comparison, expr, sval, left);
 436 }
 437
 438 static int prev_return_id;
 439 static int db_assign_return_states_callback(void *unused, int argc, char **argv, char **azColName)
 440 {
 441         struct range_list *ret_range;
 442         int type, param;
 443         char *key, *value;
 444         struct return_implies_callback *tmp;
 445         struct stree *stree;
 446         int return_id;
 447
 448         if (argc != 6)
 449                 return 0;
 450
 451         return_id = atoi(argv[0]);
 452         call_results_to_rl(db_info.expr->right, get_type(strip_expr(db_info.expr->right)), argv[1], &ret_range);
 453         __add_comparison_info(db_info.expr->left, strip_expr(db_info.expr->right), argv[1]);
 454         if (!ret_range)
 455                 ret_range = alloc_whole_rl(get_type(strip_expr(db_info.expr->right)));
 456         ret_range = cast_rl(get_type(db_info.expr->right), ret_range);
 457         type = atoi(argv[2]);
 458         param = atoi(argv[3]);
 459         key = argv[4];
 460         value = argv[5];
 461
 462         if (prev_return_id != -1 && return_id != prev_return_id) {
 463                 stree = __pop_fake_cur_stree();
 464                 merge_fake_stree(&db_info.stree, stree);
 465                 free_stree(&stree);
 466                 __push_fake_cur_stree();
 467         }
 468         prev_return_id = return_id;
 469
 470         FOR_EACH_PTR(db_return_states_list, tmp) {
 471                 if (tmp->type == type)
 472                         tmp->callback(db_info.expr, param, key, value);
 473         } END_FOR_EACH_PTR(tmp);
 474         ret_range = cast_rl(get_type(db_info.expr->left), ret_range);
 475         set_extra_expr_mod(db_info.expr->left, alloc_estate_rl(ret_range));
 476
 477         return 0;
 478 }
 479
 480 static int db_return_states_assign(struct expression *expr)
 481 {
 482         struct expression *right;
 483         struct sm_state *sm;
 484         struct stree *stree;
 485         int handled = 0;
 486
 487         right = strip_expr(expr->right);
 488
 489         prev_return_id = -1;
 490         db_info.expr = expr;
 491         db_info.stree = NULL;
 492
 493         call_return_states_before_hooks();
 494
 495         __push_fake_cur_stree();
 496         sql_select_return_states("return_id, return, type, parameter, key, value",
 497                         right, db_assign_return_states_callback);
 498         stree = __pop_fake_cur_stree();
 499         merge_fake_stree(&db_info.stree, stree);
 500         free_stree(&stree);
 501
 502         FOR_EACH_SM(db_info.stree, sm) {
 503                 __set_sm(sm);
 504                 handled = 1;
 505         } END_FOR_EACH_SM(sm);
 506
 507         free_stree(&db_info.stree);
 508         call_return_states_after_hooks();
 509
 510         return handled;
 511 }
 512
 513 static int handle_implied_return(struct expression *expr)
 514 {
 515         struct range_list *rl;
 516
 517         if (!get_implied_return(expr->right, &rl))
 518                 return 0;
 519         rl = cast_rl(get_type(expr->left), rl);
 520         set_extra_expr_mod(expr->left, alloc_estate_rl(rl));
 521         return 1;
 522 }
 523
 524 static void match_assign_call(struct expression *expr)
 525 {
 526         struct call_back_list *call_backs;
 527         const char *fn;
 528         struct expression *right;
 529         int handled = 0;
 530         struct range_list *rl;
 531
 532         if (expr->op != '=')
 533                 return;
 534
 535         right = strip_expr(expr->right);
 536         if (right->fn->type != EXPR_SYMBOL || !right->fn->symbol) {
 537                 handled |= db_return_states_assign(expr);
 538                 if (!handled)
 539                         goto assigned_unknown;
 540                 return;
 541         }
 542         if (is_fake_call(right)) {
 543                 if (!get_state_expr(SMATCH_EXTRA, expr->left))
 544                         return;
 545                 set_extra_expr_mod(expr->left, alloc_estate_whole(get_type(expr->left)));
 546                 return;
 547         }
 548
 549         fn = right->fn->symbol->ident->name;
 550
 551         /*
 552          * some of these conflict (they try to set smatch extra twice), so we
 553          * call them in order from least important to most important.
 554          */
 555
 556         call_backs = search_callback(func_hash, (char *)fn);
 557         call_call_backs(call_backs, ASSIGN_CALL, fn, expr);
 558
 559         handled |= db_return_states_assign(expr);
 560         handled |= assign_ranged_funcs(fn, expr, call_backs);
 561         handled |= handle_implied_return(expr);
 562
 563         if (handled)
 564                 return;
 565
 566 assigned_unknown:
 567         get_absolute_rl(expr->right, &rl);
 568         rl = cast_rl(get_type(expr->left), rl);
 569         set_extra_expr_mod(expr->left, alloc_estate_rl(rl));
 570 }
 571
 572 static int db_return_states_callback(void *unused, int argc, char **argv, char **azColName)
 573 {
 574         struct range_list *ret_range;
 575         int type, param;
 576         char *key, *value;
 577         struct return_implies_callback *tmp;
 578         struct stree *stree;
 579         int return_id;
 580
 581         if (argc != 6)
 582                 return 0;
 583
 584         return_id = atoi(argv[0]);
 585         call_results_to_rl(db_info.expr, get_type(strip_expr(db_info.expr)), argv[1], &ret_range);
 586         ret_range = cast_rl(get_type(db_info.expr), ret_range);
 587         type = atoi(argv[2]);
 588         param = atoi(argv[3]);
 589         key = argv[4];
 590         value = argv[5];
 591
 592         if (prev_return_id != -1 && return_id != prev_return_id) {
 593                 stree = __pop_fake_cur_stree();
 594                 merge_fake_stree(&db_info.stree, stree);
 595                 free_stree(&stree);
 596                 __push_fake_cur_stree();
 597                 __unnullify_path();
 598         }
 599         prev_return_id = return_id;
 600
 601         FOR_EACH_PTR(db_return_states_list, tmp) {
 602                 if (tmp->type == type)
 603                         tmp->callback(db_info.expr, param, key, value);
 604         } END_FOR_EACH_PTR(tmp);
 605
 606         return 0;
 607 }
 608
 609 static void db_return_states(struct expression *expr)
 610 {
 611         struct sm_state *sm;
 612         struct stree *stree;
 613
 614         if (!__get_cur_stree())  /* no return functions */
 615                 return;
 616
 617         prev_return_id = -1;
 618         db_info.expr = expr;
 619         db_info.stree = NULL;
 620
 621         call_return_states_before_hooks();
 622
 623         __push_fake_cur_stree();
 624         __unnullify_path();
 625         sql_select_return_states("return_id, return, type, parameter, key, value",
 626                         expr, db_return_states_callback);
 627         stree = __pop_fake_cur_stree();
 628         merge_fake_stree(&db_info.stree, stree);
 629         free_stree(&stree);
 630
 631         FOR_EACH_SM(db_info.stree, sm) {
 632                 __set_sm(sm);
 633         } END_FOR_EACH_SM(sm);
 634
 635         free_stree(&db_info.stree);
 636         call_return_states_after_hooks();
 637 }
 638
 639 static int is_assigned_call(struct expression *expr)
 640 {
 641         struct expression *tmp;
 642
 643         FOR_EACH_PTR_REVERSE(big_expression_stack, tmp) {
 644                 if (tmp->type == EXPR_ASSIGNMENT && strip_expr(tmp->right) == expr)
 645                         return 1;
 646                 if (tmp->pos.line < expr->pos.line)
 647                         return 0;
 648         } END_FOR_EACH_PTR_REVERSE(tmp);
 649         return 0;
 650 }
 651
 652 static void db_return_states_call(struct expression *expr)
 653 {
 654         if (is_assigned_call(expr))
 655                 return;
 656         db_return_states(expr);
 657 }
 658
 659 static void match_function_call(struct expression *expr)
 660 {
 661         struct call_back_list *call_backs;
 662
 663         if (expr->fn->type == EXPR_SYMBOL && expr->fn->symbol) {
 664                 call_backs = search_callback(func_hash, (char *)expr->fn->symbol->ident->name);
 665                 if (call_backs)
 666                         call_call_backs(call_backs, REGULAR_CALL,
 667                                         expr->fn->symbol->ident->name, expr);
 668         }
 669         db_return_states_call(expr);
 670 }
 671
 672 static void match_macro_assign(struct expression *expr)
 673 {
 674         struct call_back_list *call_backs;
 675         const char *macro;
 676         struct expression *right;
 677
 678         right = strip_expr(expr->right);
 679         macro = get_macro_name(right->pos);
 680         call_backs = search_callback(func_hash, (char *)macro);
 681         if (!call_backs)
 682                 return;
 683         call_call_backs(call_backs, MACRO_ASSIGN, macro, expr);
 684         call_call_backs(call_backs, MACRO_ASSIGN_EXTRA, macro, expr);
 685 }
 686
 687 int get_implied_return(struct expression *expr, struct range_list **rl)
 688 {
 689         struct call_back_list *call_backs;
 690         struct fcall_back *tmp;
 691         int handled = 0;
 692         char *fn;
 693
 694         *rl = NULL;
 695
 696         expr = strip_expr(expr);
 697         fn = expr_to_var(expr->fn);
 698         if (!fn)
 699                 goto out;
 700
 701         call_backs = search_callback(func_hash, fn);
 702
 703         FOR_EACH_PTR(call_backs, tmp) {
 704                 if (tmp->type == IMPLIED_RETURN) {
 705                         (tmp->u.implied_return)(expr, tmp->info, rl);
 706                         handled = 1;
 707                 }
 708         } END_FOR_EACH_PTR(tmp);
 709
 710 out:
 711         free_string(fn);
 712         return handled;
 713 }
 714
 715 void create_function_hook_hash(void)
 716 {
 717         func_hash = create_function_hashtable(5000);
 718 }
 719
 720 void register_function_hooks(int id)
 721 {
 722         add_hook(&match_function_call, CALL_HOOK_AFTER_INLINE);
 723         add_hook(&match_assign_call, CALL_ASSIGNMENT_HOOK);
 724         add_hook(&match_macro_assign, MACRO_ASSIGNMENT_HOOK);
 725 }