smatch_extra.c

   1 /*
   2  * sparse/smatch_extra.c
   3  *
   4  * Copyright (C) 2008 Dan Carpenter.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 /*
  11  * smatch_extra.c is supposed to track the value of every variable.
  12  */
  13
  14 #include <stdlib.h>
  15 #define __USE_ISOC99
  16 #include <limits.h>
  17 #include "parse.h"
  18 #include "smatch.h"
  19 #include "smatch_slist.h"
  20 #include "smatch_extra.h"
  21
  22 static int my_id;
  23
  24 static struct symbol *cur_func;
  25
  26 struct data_range whole_range = {
  27         .min = LLONG_MIN,
  28         .max = LLONG_MAX,
  29 };
  30
  31 static struct smatch_state *alloc_extra_state_empty()
  32 {
  33         struct smatch_state *state;
  34         struct data_info *dinfo;
  35
  36         dinfo = __alloc_data_info(0);
  37         dinfo->type = DATA_RANGE;
  38         dinfo->value_ranges = NULL;
  39         state = __alloc_smatch_state(0);
  40         state->data = dinfo;
  41         return state;
  42 }
  43
  44 static struct smatch_state *alloc_extra_state_no_name(int val)
  45 {
  46         struct smatch_state *state;
  47
  48         state = __alloc_smatch_state(0);
  49         state->data = (void *)alloc_dinfo_range(val, val);
  50         return state;
  51 }
  52
  53 /* We do this because ->value_ranges is a list */
  54 struct smatch_state *extra_undefined()
  55 {
  56         struct data_info *dinfo;
  57         static struct smatch_state *ret;
  58         static struct symbol *prev_func;
  59
  60         if  (prev_func == cur_func)
  61                 return ret;
  62         prev_func = cur_func;
  63
  64         dinfo = alloc_dinfo_range(whole_range.min, whole_range.max);
  65         ret = __alloc_smatch_state(0);
  66         ret->name = "unknown";
  67         ret->data = dinfo;
  68         return ret;
  69 }
  70
  71 struct smatch_state *alloc_extra_state(int val)
  72 {
  73         struct smatch_state *state;
  74
  75         state = alloc_extra_state_no_name(val);
  76         state->name = show_ranges(((struct data_info *)state->data)->value_ranges);
  77         return state;
  78 }
  79
  80 struct smatch_state *alloc_extra_state_range(long long min, long long max)
  81 {
  82         struct smatch_state *state;
  83
  84         if (min == whole_range.min && max == whole_range.max)
  85                 return extra_undefined();
  86         state = __alloc_smatch_state(0);
  87         state->data = (void *)alloc_dinfo_range(min, max);
  88         state->name = show_ranges(((struct data_info *)state->data)->value_ranges);
  89         return state;
  90 }
  91
  92 struct smatch_state *alloc_extra_state_range_list(struct range_list *rl)
  93 {
  94         struct smatch_state *state;
  95
  96         state = __alloc_smatch_state(0);
  97         state->data = (void *)alloc_dinfo_range_list(rl);
  98         state->name = show_ranges(((struct data_info *)state->data)->value_ranges);
  99         return state;
 100 }
 101
 102 struct smatch_state *filter_range(struct smatch_state *orig,
 103                                  long long filter_min, long long filter_max)
 104 {
 105         struct smatch_state *ret;
 106         struct data_info *orig_info;
 107         struct data_info *ret_info;
 108
 109         if (!orig)
 110                 orig = extra_undefined();
 111         orig_info = (struct data_info *)orig->data;
 112         ret = alloc_extra_state_empty();
 113         ret_info = (struct data_info *)ret->data;
 114         ret_info->value_ranges = remove_range(orig_info->value_ranges, filter_min, filter_max);
 115         ret->name = show_ranges(ret_info->value_ranges);
 116         return ret;
 117 }
 118
 119 struct smatch_state *add_filter(struct smatch_state *orig, long long num)
 120 {
 121         return filter_range(orig, num, num);
 122 }
 123
 124 static struct smatch_state *merge_func(const char *name, struct symbol *sym,
 125                                        struct smatch_state *s1,
 126                                        struct smatch_state *s2)
 127 {
 128         struct data_info *info1 = (struct data_info *)s1->data;
 129         struct data_info *info2 = (struct data_info *)s2->data;
 130         struct data_info *ret_info;
 131         struct smatch_state *tmp;
 132         struct range_list *value_ranges;
 133
 134         value_ranges = range_list_union(info1->value_ranges, info2->value_ranges);
 135         tmp = alloc_extra_state_empty();
 136         ret_info = (struct data_info *)tmp->data;
 137         ret_info->value_ranges = value_ranges;
 138         tmp->name = show_ranges(ret_info->value_ranges);
 139         return tmp;
 140 }
 141
 142 struct sm_state *__extra_pre_loop_hook_before(struct statement *iterator_pre_statement)
 143 {
 144         struct expression *expr;
 145         char *name;
 146         struct symbol *sym;
 147         struct sm_state *ret = NULL;
 148
 149         if (!iterator_pre_statement)
 150                 return NULL;
 151         if (iterator_pre_statement->type != STMT_EXPRESSION)
 152                 return NULL;
 153         expr = iterator_pre_statement->expression;
 154         if (expr->type != EXPR_ASSIGNMENT)
 155                 return NULL;
 156         name = get_variable_from_expr(expr->left, &sym);
 157         if (!name || !sym)
 158                 goto free;
 159         ret = get_sm_state(my_id, name, sym);
 160 free:
 161         free_string(name);
 162         return ret;
 163 }
 164
 165 int __iterator_unchanged(struct sm_state *sm, struct statement *iterator)
 166 {
 167         struct expression *iter_expr;
 168         char *name;
 169         struct symbol *sym;
 170         int ret = 0;
 171
 172         if (!iterator)
 173                 return 0;
 174         if (iterator->type != STMT_EXPRESSION)
 175                 return 0;
 176         iter_expr = iterator->expression;
 177         if (iter_expr->op != SPECIAL_INCREMENT && iter_expr->op != SPECIAL_DECREMENT)
 178                 return 0;
 179         name = get_variable_from_expr(iter_expr->unop, &sym);
 180         if (!name || !sym)
 181                 goto free;
 182         if (get_sm_state(my_id, name, sym) == sm)
 183                 ret = 1;
 184 free:
 185         free_string(name);
 186         return ret;
 187 }
 188
 189 void __extra_pre_loop_hook_after(struct sm_state *sm,
 190                                 struct statement *iterator,
 191                                 struct expression *condition)
 192 {
 193         struct expression *iter_expr;
 194         char *name;
 195         struct symbol *sym;
 196         long long value;
 197         int left = 0;
 198         struct smatch_state *state;
 199         struct data_info *dinfo;
 200         long long min, max;
 201
 202         iter_expr = iterator->expression;
 203
 204         if (condition->type != EXPR_COMPARE)
 205                 return;
 206         if (!get_value(condition->left, &value)) {
 207                 if (!get_value(condition->right, &value))
 208                         return;
 209                 left = 1;
 210         }
 211         if (left)
 212                 name = get_variable_from_expr(condition->left, &sym);
 213         else
 214                 name = get_variable_from_expr(condition->right, &sym);
 215         if (!name || !sym)
 216                 goto free;
 217         if (sym != sm->sym || strcmp(name, sm->name))
 218                 goto free;
 219         state = get_state(my_id, name, sym);
 220         dinfo = (struct data_info *)state->data;
 221         min = get_dinfo_min(dinfo);
 222         max = get_dinfo_max(dinfo);
 223         if (iter_expr->op == SPECIAL_INCREMENT && min != whole_range.min && max == whole_range.max) {
 224                 set_state(my_id, name, sym, alloc_extra_state(min));
 225         } else if (min == whole_range.min && max != whole_range.max) {
 226                 set_state(my_id, name, sym, alloc_extra_state(max));
 227         }
 228 free:
 229         free_string(name);
 230         return;
 231 }
 232
 233 static struct smatch_state *unmatched_state(struct sm_state *sm)
 234 {
 235         return extra_undefined();
 236 }
 237
 238 static void match_function_call(struct expression *expr)
 239 {
 240         struct expression *tmp;
 241         struct symbol *sym;
 242         char *name;
 243         int i = 0;
 244
 245         FOR_EACH_PTR(expr->args, tmp) {
 246                 if (tmp->op == '&') {
 247                         name = get_variable_from_expr(tmp->unop, &sym);
 248                         if (name) {
 249                                 set_state(my_id, name, sym, extra_undefined());
 250                         }
 251                         free_string(name);
 252                 }
 253                 i++;
 254         } END_FOR_EACH_PTR(tmp);
 255 }
 256
 257 static void match_assign(struct expression *expr)
 258 {
 259         struct expression *left;
 260         struct expression *right;
 261         struct symbol *sym;
 262         char *name;
 263         long long value;
 264         int known;
 265         long long min = whole_range.min;
 266         long long max = whole_range.max;
 267         long long tmp;
 268
 269         left = strip_expr(expr->left);
 270         name = get_variable_from_expr(left, &sym);
 271         if (!name)
 272                 return;
 273         right = strip_expr(expr->right);
 274         while (right->type == EXPR_ASSIGNMENT && right->op == '=')
 275                 right = strip_expr(right->left);
 276         known = get_implied_value(right, &value);
 277
 278         if (expr->op == '=') {
 279                 if (known)
 280                         set_state(my_id, name, sym, alloc_extra_state(value));
 281                 else
 282                         set_state(my_id, name, sym, extra_undefined());
 283                 goto free;
 284         }
 285         if (expr->op == SPECIAL_ADD_ASSIGN) {
 286                 if (get_implied_min(left, &tmp)) {
 287                         if (known)
 288                                 min = tmp + value;
 289                         else
 290                                 min = tmp;
 291                 }
 292
 293         }
 294         if (expr->op == SPECIAL_SUB_ASSIGN) {
 295                 if (get_implied_max(left, &tmp)) {
 296                         if (known)
 297                                 max = tmp - value;
 298                         else
 299                                 max = tmp;
 300                 }
 301
 302         }
 303         set_state(my_id, name, sym, alloc_extra_state_range(min, max));
 304 free:
 305         free_string(name);
 306 }
 307
 308 static void unop_expr(struct expression *expr)
 309 {
 310         struct symbol *sym;
 311         char *name;
 312         long long min = whole_range.min;
 313         long long max = whole_range.max;
 314         long long val;
 315
 316         if (expr->op == '*')
 317                 return;
 318         if (expr->op == '(')
 319                 return;
 320
 321         name = get_variable_from_expr(expr->unop, &sym);
 322         if (!name)
 323                 goto free;
 324         if (expr->op == SPECIAL_INCREMENT) {
 325                 if (get_implied_min(expr->unop, &val))
 326                         min = val + 1;
 327         }
 328         if (expr->op == SPECIAL_DECREMENT) {
 329                 if (get_implied_max(expr->unop, &val))
 330                         max = val - 1;
 331         }
 332         set_state(my_id, name, sym, alloc_extra_state_range(min, max));
 333 free:
 334         free_string(name);
 335 }
 336
 337 static void match_declarations(struct symbol *sym)
 338 {
 339         const char *name;
 340         long long val;
 341
 342         if (sym->ident) {
 343                 name = sym->ident->name;
 344                 if (sym->initializer) {
 345                         if (get_value(sym->initializer, &val))
 346                                 set_state(my_id, name, sym, alloc_extra_state(val));
 347                         else
 348                                 set_state(my_id, name, sym, extra_undefined());
 349                         scoped_state(my_id, name, sym);
 350                 } else {
 351                         set_state(my_id, name, sym, extra_undefined());
 352                         scoped_state(my_id, name, sym);
 353                 }
 354         }
 355 }
 356
 357 static void match_function_def(struct symbol *sym)
 358 {
 359         struct symbol *arg;
 360
 361         cur_func = sym;
 362         FOR_EACH_PTR(sym->ctype.base_type->arguments, arg) {
 363                 if (!arg->ident) {
 364                         continue;
 365                 }
 366                 set_state(my_id, arg->ident->name, arg, extra_undefined());
 367         } END_FOR_EACH_PTR(arg);
 368 }
 369
 370 #define VAL_SINGLE 0
 371 #define VAL_MAX    1
 372 #define VAL_MIN    2
 373
 374 static int get_implied_value_helper(struct expression *expr, long long *val, int what)
 375 {
 376         struct smatch_state *state;
 377         struct symbol *sym;
 378         char *name;
 379
 380         if (get_value(expr, val))
 381                 return 1;
 382
 383         name = get_variable_from_expr(expr, &sym);
 384         if (!name)
 385                 return 0;
 386         state = get_state(my_id, name, sym);
 387         free_string(name);
 388         if (!state || !state->data)
 389                 return 0;
 390         if (what == VAL_SINGLE)
 391                 return get_single_value_from_range((struct data_info *)state->data, val);
 392         if (what == VAL_MAX) {
 393                 *val = get_dinfo_max((struct data_info *)state->data);
 394                 if (*val == whole_range.max) /* this means just guessing */
 395                         return 0;
 396                 return 1;
 397         }
 398         *val = get_dinfo_min((struct data_info *)state->data);
 399         if (*val == whole_range.min)
 400                 return 0;
 401         return 1;
 402 }
 403
 404 int get_implied_single_val(struct expression *expr, long long *val)
 405 {
 406         return get_implied_value_helper(expr, val, VAL_SINGLE);
 407 }
 408
 409 int get_implied_max(struct expression *expr, long long *val)
 410 {
 411         return get_implied_value_helper(expr, val, VAL_MAX);
 412 }
 413
 414 int get_implied_min(struct expression *expr, long long *val)
 415 {
 416         return get_implied_value_helper(expr, val, VAL_MIN);
 417 }
 418
 419 static int last_stmt_val(struct statement *stmt, long long *val)
 420 {
 421         struct expression *expr;
 422
 423         if (!stmt)
 424                 return 0;
 425
 426         stmt = last_ptr_list((struct ptr_list *)stmt->stmts);
 427         if (stmt->type != STMT_EXPRESSION)
 428                 return 0;
 429         expr = stmt->expression;
 430         return get_value(expr, val);
 431 }
 432
 433 static void match_comparison(struct expression *expr)
 434 {
 435         long long fixed;
 436         char *name = NULL;
 437         struct symbol *sym;
 438         struct smatch_state *one_state;
 439         struct smatch_state *two_state;
 440         struct smatch_state *orig;
 441         int left = 0;
 442         int comparison = expr->op;
 443         struct expression *varies = expr->right;
 444
 445         if (!get_value(expr->left, &fixed)) {
 446                 if (!get_value(expr->right, &fixed))
 447                         return;
 448                 varies = expr->left;
 449                 left = 1;
 450         }
 451         if (varies->op == SPECIAL_INCREMENT || varies->op == SPECIAL_DECREMENT)
 452                 varies = varies->unop;
 453         if (varies->type == EXPR_CALL) {
 454                 function_comparison(comparison, varies, fixed, left);
 455                 return;
 456         }
 457
 458         name = get_variable_from_expr(varies, &sym);
 459         if (!name || !sym)
 460                 goto free;
 461
 462         orig = get_state(my_id, name, sym);
 463         if (!orig)
 464                 orig = extra_undefined();
 465
 466         switch(comparison){
 467         case '<':
 468         case SPECIAL_UNSIGNED_LT:
 469                 one_state = filter_range(orig, whole_range.min, fixed - 1);
 470                 two_state = filter_range(orig, fixed, whole_range.max);
 471                 if (left)
 472                         set_true_false_states(my_id, name, sym, two_state, one_state);
 473                 else
 474                         set_true_false_states(my_id, name, sym, one_state, two_state);
 475                 return;
 476         case SPECIAL_UNSIGNED_LTE:
 477         case SPECIAL_LTE:
 478                 one_state = filter_range(orig, whole_range.min, fixed);
 479                 two_state = filter_range(orig, fixed + 1, whole_range.max);
 480                 if (left)
 481                         set_true_false_states(my_id, name, sym, two_state, one_state);
 482                 else
 483                         set_true_false_states(my_id, name, sym, one_state, two_state);
 484                 return;
 485         case SPECIAL_EQUAL:
 486                 // todo.  print a warning here for impossible conditions.
 487                 one_state = alloc_extra_state(fixed);
 488                 two_state = filter_range(orig, fixed, fixed);
 489                 set_true_false_states(my_id, name, sym, one_state, two_state);
 490                 return;
 491         case SPECIAL_UNSIGNED_GTE:
 492         case SPECIAL_GTE:
 493                 one_state = filter_range(orig, whole_range.min, fixed - 1);
 494                 two_state = filter_range(orig, fixed, whole_range.max);
 495                 if (left)
 496                         set_true_false_states(my_id, name, sym, one_state, two_state);
 497                 else
 498                         set_true_false_states(my_id, name, sym, two_state, one_state);
 499                 return;
 500         case '>':
 501         case SPECIAL_UNSIGNED_GT:
 502                 one_state = filter_range(orig, whole_range.min, fixed);
 503                 two_state = filter_range(orig, fixed + 1, whole_range.max);
 504                 if (left)
 505                         set_true_false_states(my_id, name, sym, one_state, two_state);
 506                 else
 507                         set_true_false_states(my_id, name, sym, two_state, one_state);
 508                 return;
 509         case SPECIAL_NOTEQUAL:
 510                 one_state = alloc_extra_state(fixed);
 511                 two_state = filter_range(orig, fixed, fixed);
 512                 set_true_false_states(my_id, name, sym, two_state, one_state);
 513                 return;
 514         default:
 515                 sm_msg("unhandled comparison %d\n", comparison);
 516                 return;
 517         }
 518         return;
 519 free:
 520         free_string(name);
 521 }
 522
 523 /* this is actually hooked from smatch_implied.c...  it's hacky, yes */
 524 void __extra_match_condition(struct expression *expr)
 525 {
 526         struct symbol *sym;
 527         char *name;
 528         struct smatch_state *pre_state;
 529         struct smatch_state *true_state;
 530         struct smatch_state *false_state;
 531
 532         expr = strip_expr(expr);
 533         switch(expr->type) {
 534         case EXPR_CALL:
 535                 function_comparison(SPECIAL_NOTEQUAL, expr, 0, 1);
 536                 return;
 537         case EXPR_PREOP:
 538         case EXPR_SYMBOL:
 539         case EXPR_DEREF:
 540                 name = get_variable_from_expr(expr, &sym);
 541                 if (!name)
 542                         return;
 543                 pre_state = get_state(my_id, name, sym);
 544                 true_state = add_filter(pre_state, 0);
 545                 false_state = alloc_extra_state(0);
 546                 set_true_false_states(my_id, name, sym, true_state, false_state);
 547                 free_string(name);
 548                 return;
 549         case EXPR_COMPARE:
 550                 match_comparison(expr);
 551                 return;
 552         case EXPR_ASSIGNMENT:
 553                 __extra_match_condition(expr->left);
 554                 return;
 555         }
 556 }
 557
 558 /* returns 1 if it is not possible for expr to be value, otherwise returns 0 */
 559 int implied_not_equal(struct expression *expr, long long val)
 560 {
 561         char *name;
 562         struct symbol *sym;
 563         struct smatch_state *state;
 564         int ret = 0;
 565
 566         name = get_variable_from_expr(expr, &sym);
 567         if (!name || !sym)
 568                 goto exit;
 569         state = get_state(my_id, name, sym);
 570         if (!state || !state->data)
 571                 goto exit;
 572         ret = !possibly_false(SPECIAL_NOTEQUAL, (struct data_info *)state->data, val, 1);
 573 exit:
 574         free_string(name);
 575         return ret;
 576 }
 577
 578 int known_condition_true(struct expression *expr)
 579 {
 580         long long tmp;
 581
 582         if (!expr)
 583                 return 0;
 584
 585         if (get_value(expr, &tmp) && tmp)
 586                 return 1;
 587
 588         expr = strip_expr(expr);
 589         switch(expr->type) {
 590         case EXPR_PREOP:
 591                 if (expr->op == '!') {
 592                         if (known_condition_false(expr->unop))
 593                                 return 1;
 594                         break;
 595                 }
 596                 break;
 597         default:
 598                 break;
 599         }
 600         return 0;
 601 }
 602
 603 int known_condition_false(struct expression *expr)
 604 {
 605         if (!expr)
 606                 return 0;
 607
 608         if (is_zero(expr))
 609                 return 1;
 610
 611         switch(expr->type) {
 612         case EXPR_PREOP:
 613                 if (expr->op == '!') {
 614                         if (known_condition_true(expr->unop))
 615                                 return 1;
 616                         break;
 617                 }
 618                 break;
 619         default:
 620                 break;
 621         }
 622         return 0;
 623 }
 624
 625 static int do_comparison_range(struct expression *expr)
 626 {
 627         struct symbol *sym;
 628         char *name;
 629         struct smatch_state *state;
 630         long long value;
 631         int left = 0;
 632         int poss_true, poss_false;
 633
 634         if (!get_value(expr->left, &value)) {
 635                 if (!get_value(expr->right, &value))
 636                         return 3;
 637                 left = 1;
 638         }
 639         if (left)
 640                 name = get_variable_from_expr(expr->left, &sym);
 641         else
 642                 name = get_variable_from_expr(expr->right, &sym);
 643         if (!name || !sym)
 644                 goto free;
 645         state = get_state(SMATCH_EXTRA, name, sym);
 646         if (!state)
 647                 goto free;
 648         poss_true = possibly_true(expr->op, (struct data_info *)state->data, value, left);
 649         poss_false = possibly_false(expr->op, (struct data_info *)state->data, value, left);
 650         if (!poss_true && !poss_false)
 651                 return 0;
 652         if (poss_true && !poss_false)
 653                 return 1;
 654         if (!poss_true && poss_false)
 655                 return 2;
 656         if (poss_true && poss_false)
 657                 return 3;
 658 free:
 659         free_string(name);
 660         return 3;
 661 }
 662
 663 int implied_condition_true(struct expression *expr)
 664 {
 665         struct statement *stmt;
 666         long long tmp;
 667         long long val;
 668
 669         if (!expr)
 670                 return 0;
 671
 672         if (get_value(expr, &tmp) && tmp)
 673                 return 1;
 674
 675         expr = strip_expr(expr);
 676         switch(expr->type) {
 677         case EXPR_COMPARE:
 678                 if (do_comparison_range(expr) == 1)
 679                         return 1;
 680                 break;
 681         case EXPR_PREOP:
 682                 if (expr->op == '!') {
 683                         if (implied_condition_false(expr->unop))
 684                                 return 1;
 685                         break;
 686                 }
 687                 stmt = get_block_thing(expr);
 688                 if (last_stmt_val(stmt, &val) && val == 1)
 689                         return 1;
 690                 break;
 691         default:
 692                 if (implied_not_equal(expr, 0) == 1)
 693                         return 1;
 694                 break;
 695         }
 696         return 0;
 697 }
 698
 699 int implied_condition_false(struct expression *expr)
 700 {
 701         struct statement *stmt;
 702         struct expression *tmp;
 703         long long val;
 704
 705         if (!expr)
 706                 return 0;
 707
 708         if (is_zero(expr))
 709                 return 1;
 710
 711         switch(expr->type) {
 712         case EXPR_COMPARE:
 713                 if (do_comparison_range(expr) == 2)
 714                         return 1;
 715         case EXPR_PREOP:
 716                 if (expr->op == '!') {
 717                         if (implied_condition_true(expr->unop))
 718                                 return 1;
 719                         break;
 720                 }
 721                 stmt = get_block_thing(expr);
 722                 if (last_stmt_val(stmt, &val) && val == 0)
 723                         return 1;
 724                 tmp = strip_expr(expr);
 725                 if (tmp != expr)
 726                         return implied_condition_false(tmp);
 727                 break;
 728         default:
 729                 if (get_implied_value(expr, &val) && val == 0)
 730                         return 1;
 731                 break;
 732         }
 733         return 0;
 734 }
 735
 736 void register_smatch_extra(int id)
 737 {
 738         my_id = id;
 739         add_merge_hook(my_id, &merge_func);
 740         add_unmatched_state_hook(my_id, &unmatched_state);
 741         add_hook(&unop_expr, OP_HOOK);
 742         add_hook(&match_function_def, FUNC_DEF_HOOK);
 743         add_hook(&match_function_call, FUNCTION_CALL_HOOK);
 744         add_hook(&match_assign, ASSIGNMENT_HOOK);
 745         add_hook(&match_declarations, DECLARATION_HOOK);
 746
 747         if (option_project == PROJ_KERNEL) {
 748                 /* I don't know how to test for the ATTRIB_NORET attribute. :( */
 749                 add_function_hook("panic", &__match_nullify_path_hook, NULL);
 750                 add_function_hook("do_exit", &__match_nullify_path_hook, NULL);
 751                 add_function_hook("complete_and_exit", &__match_nullify_path_hook, NULL);
 752                 add_function_hook("__module_put_and_exit", &__match_nullify_path_hook, NULL);
 753                 add_function_hook("do_group_exit", &__match_nullify_path_hook, NULL);
 754         }
 755 }