smatch_flow.c

   1 /*
   2  * sparse/check_string_ret.c
   3  *
   4  * Copyright (C) 2006 Dan Carpenter.
   5  *
   6  *  Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 #include <stdio.h>
  11 #include "token.h"
  12 #include "smatch.h"
  13
  14 #define KERNEL
  15
  16 int __smatch_lineno = 0;
  17 int __negate = 0;
  18 int __ors = 0;
  19 int __ands = 0;
  20
  21 static char *filename;
  22 static char *cur_func;
  23 static int line_func_start;
  24 static unsigned int path_id = 0;
  25 static unsigned int path_id_next = 1;
  26
  27 char *get_filename() {  return filename; }
  28 char *get_function() { return cur_func; }
  29 int get_lineno() { return __smatch_lineno; }
  30 int get_func_pos() { return __smatch_lineno - line_func_start; }
  31
  32 static void split_statements(struct statement *stmt);
  33 static void split_symlist(struct symbol_list *sym_list);
  34 static void split_expr_list(struct expression_list *expr_list);
  35 static void split_expr(struct expression *expr);
  36
  37 unsigned int get_path_id()
  38 {
  39         return path_id;
  40 }
  41
  42 static unsigned int split_path_id()
  43 {
  44         int tmp = path_id;
  45
  46         path_id = path_id_next++;
  47         return tmp;
  48 }
  49
  50 static void restore_path_id(int old_id)
  51 {
  52         path_id = old_id;
  53 }
  54
  55
  56 static int is_logical_and(struct expression *expr)
  57 {
  58         /* If you have if (!(a && b)) smatch translates that to
  59          * if (!a || !b).  Logically those are the same.
  60          */
  61
  62         if ((!__negate && expr->op == SPECIAL_LOGICAL_AND) ||
  63             (__negate && expr->op == SPECIAL_LOGICAL_OR))
  64                 return 1;
  65         return 0;
  66 }
  67
  68 static int is_logical_or(struct expression *expr)
  69 {
  70         if ((!__negate && expr->op == SPECIAL_LOGICAL_OR) ||
  71              (__negate && expr->op == SPECIAL_LOGICAL_AND))
  72                 return 1;
  73         return 0;
  74 }
  75
  76 static void inc_ands_ors(struct expression *expr)
  77 {
  78         if (is_logical_and(expr))
  79                 __ands++;
  80         else if (is_logical_or(expr))
  81                 __ors++;
  82 }
  83
  84 static void dec_ands_ors(struct expression *expr)
  85 {
  86         if (is_logical_and(expr))
  87                 __ands--;
  88         else if (is_logical_or(expr))
  89                 __ors--;
  90 }
  91
  92 static void special_kernel_macros(struct expression *expr)
  93 {
  94 #ifdef KERNEL
  95         struct expression *tmp;
  96
  97         tmp = first_ptr_list((struct ptr_list *) expr->args);
  98         if (tmp->op == '!' && tmp->unop->op == '!'
  99             && tmp->unop->unop->op == '(') {
 100                 split_conditions(tmp->unop->unop->unop);
 101         } else {
 102                 __pass_to_client(expr, CONDITION_HOOK);
 103                 split_expr(expr);
 104                 return;
 105         }
 106
 107 #endif
 108 }
 109
 110 static int is_zero(struct expression *expr)
 111 {
 112         if (expr->type == EXPR_VALUE && expr->value == 0)
 113                 return 1;
 114         if (expr->op == '(')
 115                 return is_zero(expr->unop);
 116         if (expr->type == EXPR_CAST)
 117                 return is_zero(expr->cast_expression);
 118         return 0;
 119 }
 120
 121 static int handle_zero_comparisons(struct expression *expr)
 122 {
 123         struct expression *tmp = NULL;
 124
 125         // if left is zero or right is zero
 126         if (is_zero(expr->left))
 127                 tmp = expr->right;
 128         else if (is_zero(expr->right))
 129                 tmp = expr->left;
 130         else
 131                 return 0;
 132
 133         // "if (foo != 0)" is the same as "if (foo)"
 134         if (expr->op == SPECIAL_NOTEQUAL) {
 135                 split_conditions(tmp);
 136                 return 1;
 137         }
 138
 139         // "if (foo == 0)" is the same as "if (!foo)"
 140         if (expr->op == SPECIAL_EQUAL) {
 141                 __negate = (__negate +  1)%2;
 142                 split_conditions(tmp);
 143                 __negate = (__negate +  1)%2;
 144                 return 1;
 145         }
 146
 147         return 0;
 148 }
 149
 150 void split_conditions(struct expression *expr)
 151 {
 152         /*
 153          * If you have if ((a || a = foo()), we know a is
 154          * non-null on the true state because 'a' is checked in both and
 155          * groups.  __ors_reached helps with that.  Unfortunately
 156          * smatch doesn't handle stuff like if (a && a = foo())
 157          * because it never occured to me that people would do that...
 158          */
 159
 160         static int __ors_reached;
 161
 162         SM_DEBUG("%d in split_conditions type=%d\n", get_lineno(), expr->type);
 163
 164         if (expr->type == EXPR_COMPARE)
 165                 if (handle_zero_comparisons(expr))
 166                         return;
 167
 168         if (expr->type == EXPR_LOGICAL) {
 169                 unsigned int path_orig;
 170
 171                 inc_ands_ors(expr);
 172                 path_orig = split_path_id();
 173                 __split_false_states_mini();
 174
 175                 split_conditions(expr->left);
 176
 177                 if (is_logical_and(expr)) {
 178                         split_path_id();
 179                         __pop_false_states_mini();
 180                         split_conditions(expr->right);
 181                 } else if (is_logical_or(expr)) {
 182                         if (!__ors_reached) {
 183                                 __ors_reached = 1;
 184                                 __first_and_clump();
 185                         } else {
 186                                 __merge_and_clump();
 187                         }
 188                         split_path_id();
 189                         __use_false_states_mini();
 190                         split_conditions(expr->right);
 191                 }
 192                 dec_ands_ors(expr);
 193
 194                 if (__ands + __ors == 0) {
 195                         __merge_and_clump();
 196                         __use_and_clumps();
 197                         __ors_reached = 0;
 198                 }
 199
 200                 restore_path_id(path_orig);
 201                 return;
 202         } else if (expr->type == EXPR_PREOP && expr->op == '!') {
 203                 __negate = (__negate +  1)%2;
 204                 split_conditions(expr->unop);
 205                 __negate = (__negate +  1)%2;
 206                 return;
 207         } else if (expr->type == EXPR_PREOP && expr->op == '(') {
 208                 split_conditions(expr->unop);
 209         } else if (expr->type == EXPR_CALL) {
 210
 211                 if (expr->fn->type != EXPR_SYMBOL ||
 212                     strcmp("__builtin_expect", expr->fn->symbol_name->name)) {
 213                         __pass_to_client(expr, CONDITION_HOOK);
 214                         split_expr(expr);
 215                         return;
 216                 }
 217                 special_kernel_macros(expr);
 218         } else {
 219                 __pass_to_client(expr, CONDITION_HOOK);
 220                 split_expr(expr);
 221         }
 222 }
 223
 224 static void split_whole_condition(struct expression *expr)
 225 {
 226
 227         split_conditions(expr);
 228         SM_DEBUG("%d __ands = %d __ors = %d __negate = %d\n", get_lineno(),
 229                  __ands, __ors, __negate);
 230 }
 231
 232 static void split_expr(struct expression *expr)
 233 {
 234         if (!expr)
 235                 return;
 236
 237         __smatch_lineno = expr->pos.line;
 238         __pass_to_client(expr, EXPR_HOOK);
 239
 240         // printf("%d Debug expr_type %d\n", get_lineno(), expr->type);
 241
 242         switch (expr->type) {
 243         case EXPR_PREOP:
 244         case EXPR_POSTOP:
 245                 if (expr->op == '*')
 246                         __pass_to_client(expr, DEREF_HOOK);
 247                 split_expr(expr->unop);
 248                 return;
 249         case EXPR_STATEMENT:
 250                 split_statements(expr->statement);
 251                 return;
 252         case EXPR_BINOP:
 253         case EXPR_COMMA:
 254         case EXPR_COMPARE:
 255         case EXPR_LOGICAL:
 256         case EXPR_ASSIGNMENT:
 257                 if (expr->type == EXPR_ASSIGNMENT)
 258                         __pass_to_client(expr, ASSIGNMENT_HOOK);
 259                 split_expr(expr->left);
 260                 split_expr(expr->right);
 261                 if (expr->type == EXPR_ASSIGNMENT)
 262                         __pass_to_client(expr, ASSIGNMENT_AFTER_HOOK);
 263                 return;
 264         case EXPR_DEREF:
 265                 __pass_to_client(expr, DEREF_HOOK);
 266                 split_expr(expr->deref);
 267                 return;
 268         case EXPR_SLICE:
 269                 split_expr(expr->base);
 270                 return;
 271         case EXPR_CAST:
 272         case EXPR_SIZEOF:
 273                 split_expr(expr->cast_expression);
 274                 return;
 275         case EXPR_CONDITIONAL:
 276         case EXPR_SELECT:
 277                 __split_true_false_paths();
 278                 __pass_to_client(expr->conditional, WHOLE_CONDITION_HOOK);
 279                 split_whole_condition(expr->conditional);
 280                 __use_true_states();
 281                 split_expr(expr->cond_true);
 282                 __use_false_states();
 283                 split_expr(expr->cond_false);
 284                 __merge_true_states();
 285                 return;
 286         case EXPR_CALL:
 287                 __pass_to_client(expr, FUNCTION_CALL_HOOK);
 288                 split_expr(expr->fn);
 289                 split_expr_list(expr->args);
 290                 __pass_to_client(expr, FUNCTION_CALL_AFTER_HOOK);
 291 #ifdef KERNEL
 292                 if (expr->fn->type == EXPR_SYMBOL &&
 293                     !strcmp(expr->fn->symbol_name->name, "panic"))
 294                         nullify_path();
 295 #endif
 296                 return;
 297         case EXPR_INITIALIZER:
 298                 split_expr_list(expr->expr_list);
 299                 return;
 300         case EXPR_IDENTIFIER:
 301                 split_expr(expr->ident_expression);
 302                 return;
 303         case EXPR_INDEX:
 304                 split_expr(expr->idx_expression);
 305                 return;
 306         case EXPR_POS:
 307                 split_expr(expr->init_expr);
 308                 return;
 309         default:
 310                 return;
 311         };
 312 }
 313
 314 static int is_forever_loop(struct statement *stmt)
 315 {
 316
 317         struct expression *expr;
 318
 319         expr = stmt->iterator_pre_condition;
 320         if (!expr)
 321                 expr = stmt->iterator_post_condition;
 322         if (!expr) {
 323                 // this is a for(;;) loop...
 324                 return 1;
 325         }
 326
 327         if (expr->type == EXPR_VALUE && expr->value == 1) {
 328                 return 1;
 329         }
 330
 331         return 0;
 332 }
 333
 334 /*
 335  * Pre Loops are while and for loops.
 336  */
 337
 338 static void handle_pre_loop(struct statement *stmt)
 339 {
 340         unsigned int path_orig;
 341
 342         split_statements(stmt->iterator_pre_statement);
 343
 344         __split_true_false_paths();
 345         __push_continues();
 346         __push_breaks();
 347         if (stmt->iterator_pre_condition) {
 348                 __pass_to_client(stmt->iterator_pre_condition, WHOLE_CONDITION_HOOK);
 349                 split_whole_condition(stmt->iterator_pre_condition);
 350         }
 351         path_orig = split_path_id();
 352         __use_true_states();
 353
 354         split_statements(stmt->iterator_statement);
 355         split_statements(stmt->iterator_post_statement);
 356         if (is_forever_loop(stmt)) {
 357                 __pop_continues();
 358                 __pop_false_states();
 359                 nullify_path();
 360         } else {
 361                 __merge_false_states();
 362                 __merge_continues();
 363         }
 364         __merge_breaks();
 365         restore_path_id(path_orig);
 366 }
 367
 368 /*
 369  * Post loops are do {} while();
 370  */
 371 static void handle_post_loop(struct statement *stmt)
 372 {
 373         __push_continues();
 374         __push_breaks();
 375         split_statements(stmt->iterator_statement);
 376
 377         __split_true_false_paths();
 378         __pass_to_client(stmt->iterator_post_condition, WHOLE_CONDITION_HOOK);
 379         split_whole_condition(stmt->iterator_post_condition);
 380         /* It would prossibly be cleaner to make this all one function */
 381         __use_true_states();
 382         __use_false_states();
 383         __pop_true_states();
 384
 385         if (is_forever_loop(stmt)) {
 386                 __pop_continues();
 387                 nullify_path();
 388         } else {
 389                 __merge_continues();
 390         }
 391         __merge_breaks();
 392 }
 393
 394 static void split_statements(struct statement *stmt)
 395 {
 396         unsigned int path_orig;
 397
 398         if (!stmt)
 399                 return;
 400
 401         __smatch_lineno = stmt->pos.line;
 402         __pass_to_client(stmt, STMT_HOOK);
 403
 404         switch (stmt->type) {
 405         case STMT_DECLARATION:
 406                 __pass_declarations_to_client(stmt->declaration);
 407                 split_symlist(stmt->declaration);
 408                 return;
 409         case STMT_RETURN:
 410                 __pass_to_client(stmt, RETURN_HOOK);
 411                 split_expr(stmt->ret_value);
 412                 nullify_path();
 413                 return;
 414         case STMT_EXPRESSION:
 415                 split_expr(stmt->expression);
 416                 return;
 417         case STMT_COMPOUND: {
 418                 struct statement *s;
 419                 FOR_EACH_PTR(stmt->stmts, s) {
 420                         split_statements(s);
 421                 } END_FOR_EACH_PTR(s);
 422                 return;
 423         }
 424         case STMT_IF:
 425                 __split_true_false_paths();
 426                 __pass_to_client(stmt->if_conditional, WHOLE_CONDITION_HOOK);
 427                 split_whole_condition(stmt->if_conditional);
 428                 path_orig = split_path_id();
 429                 __use_true_states();
 430                 split_statements(stmt->if_true);
 431                 split_path_id();
 432                 __use_false_states();
 433                 split_statements(stmt->if_false);
 434                 __merge_true_states();
 435                 restore_path_id(path_orig);
 436                 return;
 437         case STMT_ITERATOR:
 438                 if (stmt->iterator_pre_condition)
 439                         handle_pre_loop(stmt);
 440                 else if (stmt->iterator_post_condition)
 441                         handle_post_loop(stmt);
 442                 else {
 443                         // these are for(;;) type loops.
 444                         handle_pre_loop(stmt);
 445                 }
 446                 return;
 447         case STMT_SWITCH:
 448                 split_expr(stmt->switch_expression);
 449                 __save_switch_states();
 450                 __push_default();
 451                 __push_breaks();
 452                 nullify_path();
 453                 path_orig = get_path_id();
 454                 split_statements(stmt->switch_statement);
 455                 if (!__pop_default())
 456                         __merge_switches();
 457                 __pop_switches();
 458                 __merge_breaks();
 459                 restore_path_id(path_orig);
 460                 return;
 461         case STMT_CASE:
 462                 split_path_id();
 463                 __merge_switches();
 464                 if (!stmt->case_expression)
 465                         __set_default();
 466                 split_expr(stmt->case_expression);
 467                 split_expr(stmt->case_to);
 468                 split_statements(stmt->case_statement);
 469                 return;
 470         case STMT_LABEL:
 471                 if (stmt->label &&
 472                     stmt->label->type == SYM_LABEL &&
 473                     stmt->label->ident) {
 474                         __merge_gotos(stmt->label->ident->name);
 475                 }
 476                 split_statements(stmt->label_statement);
 477                 return;
 478         case STMT_GOTO:
 479                 split_expr(stmt->goto_expression);
 480                 if (stmt->goto_label && stmt->goto_label->type == SYM_NODE) {
 481                         if (!strcmp(stmt->goto_label->ident->name, "break")) {
 482                                 __process_breaks();
 483                         } else if (!strcmp(stmt->goto_label->ident->name,
 484                                            "continue")) {
 485                                 __process_continues();
 486                         }
 487                 } else if (stmt->goto_label &&
 488                            stmt->goto_label->type == SYM_LABEL &&
 489                            stmt->goto_label->ident) {
 490                         __save_gotos(stmt->goto_label->ident->name);
 491                 }
 492                 nullify_path();
 493                 return;
 494         case STMT_NONE:
 495                 return;
 496         case STMT_ASM:
 497                 split_expr(stmt->asm_string);
 498                 //split_expr(stmt->asm_outputs);
 499                 //split_expr(stmt->asm_inputs);
 500                 //split_expr(stmt->asm_clobbers);
 501                 return;
 502         case STMT_CONTEXT:
 503                 return;
 504         case STMT_RANGE:
 505                 split_expr(stmt->range_expression);
 506                 split_expr(stmt->range_low);
 507                 split_expr(stmt->range_high);
 508                 return;
 509         }
 510 }
 511
 512 static void split_expr_list(struct expression_list *expr_list)
 513 {
 514         struct expression *expr;
 515         FOR_EACH_PTR(expr_list, expr) {
 516                 split_expr(expr);
 517         } END_FOR_EACH_PTR(expr);
 518 }
 519
 520
 521 static void split_sym(struct symbol *sym)
 522 {
 523         if (!sym)
 524                 return;
 525         if (!(sym->namespace & NS_SYMBOL))
 526                 return;
 527
 528         __pass_to_client(sym, SYM_HOOK);
 529         split_statements(sym->stmt);
 530         split_expr(sym->array_size);
 531         split_symlist(sym->arguments);
 532         split_symlist(sym->symbol_list);
 533         split_statements(sym->inline_stmt);
 534         split_symlist(sym->inline_symbol_list);
 535         split_expr(sym->initializer);
 536 }
 537
 538 static void split_symlist(struct symbol_list *sym_list)
 539 {
 540         struct symbol *sym;
 541
 542         FOR_EACH_PTR(sym_list, sym) {
 543                 split_sym(sym);
 544         } END_FOR_EACH_PTR(sym);
 545 }
 546
 547 static void split_functions(struct symbol_list *sym_list)
 548 {
 549         struct symbol *sym;
 550
 551         FOR_EACH_PTR(sym_list, sym) {
 552                 struct symbol *base_type;
 553                 base_type = get_base_type(sym);
 554                 if (sym->type == SYM_NODE && base_type->type == SYM_FN) {
 555                         if (base_type->stmt)
 556                                 line_func_start = base_type->stmt->pos.line;
 557                         if (sym->ident)
 558                                 cur_func = sym->ident->name;
 559                         __smatch_lineno = sym->pos.line;
 560                         __pass_to_client(sym, FUNC_DEF_HOOK);
 561                         split_statements(base_type->stmt);
 562                         __pass_to_client(sym, END_FUNC_HOOK);
 563                         cur_func = NULL;
 564                         line_func_start = 0;
 565                         clear_all_states();
 566
 567                 } else {
 568                         __pass_to_client(sym, BASE_HOOK);
 569                 }
 570         } END_FOR_EACH_PTR(sym);
 571 }
 572
 573 void smatch (int argc, char **argv)
 574 {
 575
 576         struct string_list *filelist = NULL;
 577         struct symbol_list *sym_list;
 578
 579         if (argc < 2) {
 580                 printf("Usage:  smatch <filename.c>\n");
 581                 exit(1);
 582         }
 583         sparse_initialize(argc, argv, &filelist);
 584         FOR_EACH_PTR_NOTAG(filelist, filename) {
 585                 sym_list = __sparse(filename);
 586                 split_functions(sym_list);
 587         } END_FOR_EACH_PTR_NOTAG(filename);
 588 }