smatch_flow.c

   1 /*
   2  * sparse/smatch_flow.c
   3  *
   4  * Copyright (C) 2006,2008 Dan Carpenter.
   5  *
   6  *  Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 #define _GNU_SOURCE 1
  11 #include <unistd.h>
  12 #include <stdio.h>
  13 #include "token.h"
  14 #include "smatch.h"
  15 #include "smatch_expression_stacks.h"
  16 #include "smatch_extra.h"
  17 #include "smatch_slist.h"
  18
  19 int final_pass;
  20
  21 static int __smatch_lineno = 0;
  22
  23 static const char *filename;
  24 static char *pathname;
  25 static char *full_filename;
  26 static char *cur_func;
  27 static int line_func_start;
  28 static int loop_count;
  29 int __expr_stmt_count;
  30 static struct expression_list *switch_expr_stack = NULL;
  31
  32 struct expression_list *big_expression_stack;
  33 struct statement_list *big_statement_stack;
  34 int __in_pre_condition = 0;
  35 int __bail_on_rest_of_function = 0;
  36 char *get_function(void) { return cur_func; }
  37 int get_lineno(void) { return __smatch_lineno; }
  38 int get_func_pos(void) { return __smatch_lineno - line_func_start; }
  39 int inside_loop(void) { return !!loop_count; }
  40 int in_expression_statement(void) { return !!__expr_stmt_count; }
  41
  42 static void split_symlist(struct symbol_list *sym_list);
  43 static void split_declaration(struct symbol_list *sym_list);
  44 static void split_expr_list(struct expression_list *expr_list);
  45
  46 int option_assume_loops = 0;
  47 int option_known_conditions = 0;
  48 int option_two_passes = 0;
  49 struct symbol *cur_func_sym = NULL;
  50
  51 const char *get_filename(void)
  52 {
  53         if (option_full_path)
  54                 return full_filename;
  55         return filename;
  56 }
  57
  58 static void set_position(struct expression *expr)
  59 {
  60         int len;
  61         static int prev_stream = -1;
  62
  63         __smatch_lineno = expr->pos.line;
  64
  65         if (expr->pos.stream == prev_stream)
  66                 return;
  67
  68         filename = stream_name(expr->pos.stream);
  69
  70         free(full_filename);
  71         pathname = getcwd(NULL, 0);
  72         if (pathname) {
  73                 len = strlen(pathname) + 1 + strlen(filename) + 1;
  74                 full_filename = malloc(len);
  75                 snprintf(full_filename, len, "%s/%s", pathname, filename);
  76         } else {
  77                 full_filename = alloc_string(filename);
  78         }
  79         free(pathname);
  80 }
  81
  82 void __split_expr(struct expression *expr)
  83 {
  84         if (!expr)
  85                 return;
  86
  87         // sm_msg(" Debug expr_type %d %s", expr->type, show_special(expr->op));
  88
  89         push_expression(&big_expression_stack, expr);
  90         set_position(expr);
  91         __pass_to_client(expr, EXPR_HOOK);
  92
  93         switch (expr->type) {
  94         case EXPR_PREOP:
  95                 if (expr->op == '*')
  96                         __pass_to_client(expr, DEREF_HOOK);
  97         case EXPR_POSTOP:
  98                 __pass_to_client(expr, OP_HOOK);
  99                 __split_expr(expr->unop);
 100                 break;
 101         case EXPR_STATEMENT:
 102                 __expr_stmt_count++;
 103                 __split_stmt(expr->statement);
 104                 __expr_stmt_count--;
 105                 break;
 106         case EXPR_LOGICAL:
 107         case EXPR_COMPARE:
 108                 __pass_to_client(expr, LOGIC_HOOK);
 109                 __handle_logic(expr);
 110                 break;
 111         case EXPR_BINOP:
 112                 __pass_to_client(expr, BINOP_HOOK);
 113         case EXPR_COMMA:
 114                 __split_expr(expr->left);
 115                 __split_expr(expr->right);
 116                 break;
 117         case EXPR_ASSIGNMENT: {
 118                 struct expression *tmp;
 119
 120                 /* foo = !bar() */
 121                 if (__handle_condition_assigns(expr))
 122                         break;
 123
 124                 /* foo = (x < 5 ? foo : 5); */
 125                 if (__handle_select_assigns(expr))
 126                         break;
 127
 128                 /* foo = ({frob(); frob(); frob(); 1;}) */
 129                 if (__handle_expr_statement_assigns(expr))
 130                         break;
 131
 132                 __split_expr(expr->right);
 133                 __pass_to_client(expr, ASSIGNMENT_HOOK);
 134                 tmp = strip_expr(expr->right);
 135                 if (tmp->type == EXPR_CALL)
 136                         __pass_to_client(expr, CALL_ASSIGNMENT_HOOK);
 137                 __split_expr(expr->left);
 138                 break;
 139         }
 140         case EXPR_DEREF:
 141                 __pass_to_client(expr, DEREF_HOOK);
 142                 __split_expr(expr->deref);
 143                 break;
 144         case EXPR_SLICE:
 145                 __split_expr(expr->base);
 146                 break;
 147         case EXPR_CAST:
 148         case EXPR_FORCE_CAST:
 149                 __split_expr(expr->cast_expression);
 150                 break;
 151         case EXPR_SIZEOF:
 152                 /* there isn't anything to pass a client from inside a sizeof() */
 153                 break;
 154         case EXPR_CONDITIONAL:
 155         case EXPR_SELECT:
 156                 __split_whole_condition(expr->conditional);
 157                 __split_expr(expr->cond_true);
 158                 __push_true_states();
 159                 __use_false_states();
 160                 __split_expr(expr->cond_false);
 161                 __merge_true_states();
 162                 break;
 163         case EXPR_CALL:
 164                 split_expr_list(expr->args);
 165                 __split_expr(expr->fn);
 166                 __pass_to_client(expr, FUNCTION_CALL_HOOK);
 167                 break;
 168         case EXPR_INITIALIZER:
 169                 split_expr_list(expr->expr_list);
 170                 break;
 171         case EXPR_IDENTIFIER:
 172                 __split_expr(expr->ident_expression);
 173                 break;
 174         case EXPR_INDEX:
 175                 __split_expr(expr->idx_expression);
 176                 break;
 177         case EXPR_POS:
 178                 __split_expr(expr->init_expr);
 179                 break;
 180         case EXPR_SYMBOL:
 181                 __pass_to_client(expr, SYM_HOOK);
 182                 break;
 183         case EXPR_STRING:
 184                 __pass_to_client(expr, STRING_HOOK);
 185                 break;
 186         default:
 187                 break;
 188         };
 189         pop_expression(&big_expression_stack);
 190 }
 191
 192 static int is_forever_loop(struct statement *stmt)
 193 {
 194
 195         struct expression *expr;
 196
 197         expr = strip_expr(stmt->iterator_pre_condition);
 198         if (!expr)
 199                 expr = stmt->iterator_post_condition;
 200         if (!expr) {
 201                 /* this is a for(;;) loop... */
 202                 return 1;
 203         }
 204
 205         if (expr->type == EXPR_VALUE && expr->value == 1) {
 206                 return 1;
 207         }
 208
 209         return 0;
 210 }
 211
 212 static int loop_num;
 213 static char *get_loop_name(int num)
 214 {
 215         char buf[256];
 216
 217         snprintf(buf, 255, "-loop%d", num);
 218         buf[255] = '\0';
 219         return alloc_sname(buf);;
 220 }
 221
 222 /*
 223  * Pre Loops are while and for loops.
 224  */
 225
 226 static void handle_pre_loop(struct statement *stmt)
 227 {
 228         int once_through; /* we go through the loop at least once */
 229         struct sm_state *extra_sm = NULL;
 230         int unchanged = 0;
 231         char *loop_name;
 232         struct state_list *slist = NULL;
 233         struct sm_state *sm = NULL;
 234
 235         loop_name = get_loop_name(loop_num);
 236         loop_num++;
 237
 238         __split_stmt(stmt->iterator_pre_statement);
 239
 240         once_through = implied_condition_true(stmt->iterator_pre_condition);
 241
 242         loop_count++;
 243         __push_continues();
 244         __push_breaks();
 245
 246         __merge_gotos(loop_name);
 247
 248         extra_sm = __extra_handle_canonical_loops(stmt, &slist);
 249         __in_pre_condition++;
 250         __split_whole_condition(stmt->iterator_pre_condition);
 251         __in_pre_condition--;
 252         FOR_EACH_PTR(slist, sm) {
 253                 set_state(sm->owner, sm->name, sm->sym, sm->state);
 254         } END_FOR_EACH_PTR(sm);
 255         free_slist(&slist);
 256         if (extra_sm)
 257                 extra_sm = get_sm_state(extra_sm->owner, extra_sm->name, extra_sm->sym);
 258
 259         if (option_assume_loops)
 260                 once_through = 1;
 261
 262         __split_stmt(stmt->iterator_statement);
 263         __warn_on_silly_pre_loops();
 264         if (is_forever_loop(stmt)) {
 265                 __save_gotos(loop_name);
 266                 /* forever loops don't have an iterator_post_statement */
 267                 __discard_continues();
 268                 __discard_false_states();
 269                 __use_breaks();
 270         } else {
 271                 __merge_continues();
 272                 unchanged = __iterator_unchanged(extra_sm);
 273                 __split_stmt(stmt->iterator_post_statement);
 274                 __save_gotos(loop_name);
 275                 __split_whole_condition(stmt->iterator_pre_condition);
 276                 nullify_path();
 277                 __merge_false_states();
 278                 if (once_through) {
 279                         __discard_false_states();
 280                 } else {
 281                         __merge_false_states();
 282
 283                 }
 284                 if (extra_sm && unchanged)
 285                         __extra_pre_loop_hook_after(extra_sm,
 286                                                 stmt->iterator_post_statement,
 287                                                 stmt->iterator_pre_condition);
 288                 __merge_breaks();
 289         }
 290         loop_count--;
 291 }
 292
 293 /*
 294  * Post loops are do {} while();
 295  */
 296 static void handle_post_loop(struct statement *stmt)
 297 {
 298         char *loop_name;
 299
 300         loop_name = get_loop_name(loop_num);
 301         loop_num++;
 302         loop_count++;
 303
 304         __push_continues();
 305         __push_breaks();
 306         __merge_gotos(loop_name);
 307         __split_stmt(stmt->iterator_statement);
 308         __merge_continues();
 309         if (!is_zero(stmt->iterator_post_condition))
 310                 __save_gotos(loop_name);
 311
 312         if (is_forever_loop(stmt)) {
 313                 __use_breaks();
 314         } else {
 315                 __split_whole_condition(stmt->iterator_post_condition);
 316                 __use_false_states();
 317                 __merge_breaks();
 318         }
 319         loop_count--;
 320 }
 321
 322 static int empty_statement(struct statement *stmt)
 323 {
 324         if (!stmt)
 325                 return 0;
 326         if (stmt->type == STMT_EXPRESSION && !stmt->expression)
 327                 return 1;
 328         return 0;
 329 }
 330
 331 static int last_stmt_on_same_line()
 332 {
 333         struct statement *stmt;
 334         int i = 0;
 335
 336         FOR_EACH_PTR_REVERSE(big_statement_stack, stmt) {
 337                 if (!i++)
 338                         continue;
 339                 if  (stmt->pos.line == get_lineno())
 340                         return 1;
 341                 return 0;
 342         } END_FOR_EACH_PTR_REVERSE(stmt);
 343         return 0;
 344 }
 345
 346 static struct statement *last_stmt;
 347 static int is_last_stmt(struct statement *stmt)
 348 {
 349         if (stmt == last_stmt)
 350                 return 1;
 351         return 0;
 352 }
 353
 354 static void print_unreached_initializers(struct symbol_list *sym_list)
 355 {
 356         struct symbol *sym;
 357
 358         FOR_EACH_PTR(sym_list, sym) {
 359                 if(sym->initializer)
 360                         sm_msg("info: '%s' is not actually initialized (unreached code).",
 361                                 (sym->ident ? sym->ident->name : "this variable"));
 362         } END_FOR_EACH_PTR(sym);
 363 }
 364
 365 static void print_unreached(struct statement *stmt)
 366 {
 367
 368         static int print = 1;
 369
 370         if (!__path_is_null()) {
 371                 print = 1;
 372                 return;
 373         }
 374         if (!print)
 375                 return;
 376
 377         switch (stmt->type) {
 378         case STMT_COMPOUND: /* after a switch before a case stmt */
 379         case STMT_RANGE:
 380         case STMT_CASE:
 381         case STMT_LABEL:
 382                 return;
 383         case STMT_DECLARATION: /* switch (x) { int a; case foo: ... */
 384                 print_unreached_initializers(stmt->declaration);
 385                 return;
 386         case STMT_RETURN: /* gcc complains if you don't have a return statement */
 387                 if (is_last_stmt(stmt))
 388                         return;
 389                 break;
 390         case STMT_GOTO:
 391                 if (!option_spammy)
 392                         return;
 393                 break;
 394         default:
 395                 break;
 396         }
 397         if (!option_spammy && empty_statement(stmt))
 398                 return;
 399         sm_msg("info: ignoring unreachable code.");
 400         print = 0;
 401 }
 402
 403 void __split_stmt(struct statement *stmt)
 404 {
 405         if (!stmt)
 406                 return;
 407
 408         if (out_of_memory() || __bail_on_rest_of_function) {
 409                 static char *printed = NULL;
 410
 411                 if (printed != cur_func)
 412                         sm_msg("Function too hairy.  Giving up.");
 413                 printed = cur_func;
 414                 return;
 415         }
 416
 417         add_ptr_list(&big_statement_stack, stmt);
 418         free_expression_stack(&big_expression_stack);
 419         __smatch_lineno = stmt->pos.line;
 420         print_unreached(stmt);
 421         __pass_to_client(stmt, STMT_HOOK);
 422
 423         switch (stmt->type) {
 424         case STMT_DECLARATION:
 425                 split_declaration(stmt->declaration);
 426                 return;
 427         case STMT_RETURN:
 428                 __split_expr(stmt->ret_value);
 429                 __pass_to_client(stmt->ret_value, RETURN_HOOK);
 430                 nullify_path();
 431                 return;
 432         case STMT_EXPRESSION:
 433                 __split_expr(stmt->expression);
 434                 return;
 435         case STMT_COMPOUND: {
 436                 struct statement *tmp;
 437
 438                 if (!last_stmt)
 439                         last_stmt = last_ptr_list((struct ptr_list *)stmt->stmts);
 440                 __push_scope_hooks();
 441                 FOR_EACH_PTR(stmt->stmts, tmp) {
 442                         __split_stmt(tmp);
 443                 } END_FOR_EACH_PTR(tmp);
 444                 __call_scope_hooks();
 445                 return;
 446         }
 447         case STMT_IF:
 448                 if (known_condition_true(stmt->if_conditional)) {
 449                         __split_stmt(stmt->if_true);
 450                         return;
 451                 }
 452                 if (known_condition_false(stmt->if_conditional)) {
 453                         __split_stmt(stmt->if_false);
 454                         return;
 455                 }
 456                 if (option_known_conditions &&
 457                     implied_condition_true(stmt->if_conditional)) {
 458                         sm_info("this condition is true.");
 459                         __split_stmt(stmt->if_true);
 460                         return;
 461                 }
 462                 if (option_known_conditions &&
 463                     implied_condition_false(stmt->if_conditional)) {
 464                         sm_info("this condition is false.");
 465                         __split_stmt(stmt->if_false);
 466                         return;
 467                 }
 468                 __split_whole_condition(stmt->if_conditional);
 469                 __split_stmt(stmt->if_true);
 470                 if (empty_statement(stmt->if_true) &&
 471                         last_stmt_on_same_line() &&
 472                         !get_macro_name(&stmt->if_true->pos))
 473                         sm_msg("warn: if();");
 474                 __push_true_states();
 475                 __use_false_states();
 476                 __split_stmt(stmt->if_false);
 477                 __merge_true_states();
 478                 return;
 479         case STMT_ITERATOR:
 480                 if (stmt->iterator_pre_condition)
 481                         handle_pre_loop(stmt);
 482                 else if (stmt->iterator_post_condition)
 483                         handle_post_loop(stmt);
 484                 else {
 485                         // these are for(;;) type loops.
 486                         handle_pre_loop(stmt);
 487                 }
 488                 return;
 489         case STMT_SWITCH:
 490                 __split_expr(stmt->switch_expression);
 491                 push_expression(&switch_expr_stack, stmt->switch_expression);
 492                 __save_switch_states(top_expression(switch_expr_stack));
 493                 nullify_path();
 494                 __push_default();
 495                 __push_breaks();
 496                 __split_stmt(stmt->switch_statement);
 497                 if (!__pop_default())
 498                         __merge_switches(top_expression(switch_expr_stack),
 499                                       NULL);
 500                 __discard_switches();
 501                 __merge_breaks();
 502                 pop_expression(&switch_expr_stack);
 503                 return;
 504         case STMT_CASE:
 505                 __merge_switches(top_expression(switch_expr_stack),
 506                                       stmt->case_expression);
 507                 __pass_case_to_client(top_expression(switch_expr_stack),
 508                                       stmt->case_expression);
 509                 if (!stmt->case_expression)
 510                         __set_default();
 511                 __split_expr(stmt->case_expression);
 512                 __split_expr(stmt->case_to);
 513                 __split_stmt(stmt->case_statement);
 514                 return;
 515         case STMT_LABEL:
 516                 if (stmt->label &&
 517                     stmt->label->type == SYM_LABEL &&
 518                     stmt->label->ident) {
 519                         loop_count = 1000000;
 520                         __merge_gotos(stmt->label->ident->name);
 521                 }
 522                 __split_stmt(stmt->label_statement);
 523                 return;
 524         case STMT_GOTO:
 525                 __split_expr(stmt->goto_expression);
 526                 if (stmt->goto_label && stmt->goto_label->type == SYM_NODE) {
 527                         if (!strcmp(stmt->goto_label->ident->name, "break")) {
 528                                 __process_breaks();
 529                         } else if (!strcmp(stmt->goto_label->ident->name,
 530                                            "continue")) {
 531                                 __process_continues();
 532                         }
 533                 } else if (stmt->goto_label &&
 534                            stmt->goto_label->type == SYM_LABEL &&
 535                            stmt->goto_label->ident) {
 536                         __save_gotos(stmt->goto_label->ident->name);
 537                 }
 538                 nullify_path();
 539                 return;
 540         case STMT_NONE:
 541                 return;
 542         case STMT_ASM:
 543                 __split_expr(stmt->asm_string);
 544                 split_expr_list(stmt->asm_outputs);
 545                 split_expr_list(stmt->asm_inputs);
 546                 split_expr_list(stmt->asm_clobbers);
 547                 return;
 548         case STMT_CONTEXT:
 549                 return;
 550         case STMT_RANGE:
 551                 __split_expr(stmt->range_expression);
 552                 __split_expr(stmt->range_low);
 553                 __split_expr(stmt->range_high);
 554                 return;
 555         }
 556 }
 557
 558 static void split_expr_list(struct expression_list *expr_list)
 559 {
 560         struct expression *expr;
 561         FOR_EACH_PTR(expr_list, expr) {
 562                 __split_expr(expr);
 563         } END_FOR_EACH_PTR(expr);
 564 }
 565
 566
 567 static void split_sym(struct symbol *sym)
 568 {
 569         if (!sym)
 570                 return;
 571         if (!(sym->namespace & NS_SYMBOL))
 572                 return;
 573
 574         __split_stmt(sym->stmt);
 575         __split_expr(sym->array_size);
 576         split_symlist(sym->arguments);
 577         split_symlist(sym->symbol_list);
 578         __split_stmt(sym->inline_stmt);
 579         split_symlist(sym->inline_symbol_list);
 580 }
 581
 582 static void split_symlist(struct symbol_list *sym_list)
 583 {
 584         struct symbol *sym;
 585
 586         FOR_EACH_PTR(sym_list, sym) {
 587                 split_sym(sym);
 588         } END_FOR_EACH_PTR(sym);
 589 }
 590
 591 static struct expression *fake_assign_expr(struct symbol *sym)
 592 {
 593         struct expression *e_assign, *e_symbol;
 594
 595         e_assign = alloc_expression(sym->initializer->pos, EXPR_ASSIGNMENT);
 596         e_symbol = alloc_expression(sym->initializer->pos, EXPR_SYMBOL);
 597         e_assign->op = (int)'=';
 598         e_symbol->symbol = sym;
 599         e_symbol->symbol_name = sym->ident;
 600         e_assign->left = e_symbol;
 601         e_assign->right = sym->initializer;
 602         return e_assign;
 603 }
 604
 605 static void do_initializer_stuff(struct symbol *sym)
 606 {
 607         struct expression *assign;
 608
 609         if(!sym->initializer)
 610                 return;
 611         assign = fake_assign_expr(sym);
 612         __split_expr(assign);
 613 }
 614
 615 static void split_declaration(struct symbol_list *sym_list)
 616 {
 617         struct symbol *sym;
 618
 619         FOR_EACH_PTR(sym_list, sym) {
 620                 __pass_to_client(sym, DECLARATION_HOOK);
 621                 do_initializer_stuff(sym);
 622                 split_sym(sym);
 623         } END_FOR_EACH_PTR(sym);
 624 }
 625
 626 static void split_function(struct symbol *sym)
 627 {
 628         struct symbol *base_type = get_base_type(sym);
 629
 630         cur_func_sym = sym;
 631         if (base_type->stmt)
 632                 line_func_start = base_type->stmt->pos.line;
 633         if (sym->ident)
 634                 cur_func = sym->ident->name;
 635         __smatch_lineno = sym->pos.line;
 636         last_stmt = NULL;
 637         loop_count = 0;
 638         sm_debug("new function:  %s\n", cur_func);
 639         if (option_two_passes) {
 640                 __unnullify_path();
 641                 loop_num = 0;
 642                 final_pass = 0;
 643                 __pass_to_client(sym, FUNC_DEF_HOOK);
 644                 __split_stmt(base_type->stmt);
 645                 nullify_path();
 646         }
 647         __unnullify_path();
 648         loop_num = 0;
 649         final_pass = 1;
 650         __pass_to_client(sym, FUNC_DEF_HOOK);
 651         __split_stmt(base_type->stmt);
 652         __pass_to_client(sym, END_FUNC_HOOK);
 653         cur_func = NULL;
 654         line_func_start = 0;
 655         clear_all_states();
 656         free_data_info_allocs();
 657         free_expression_stack(&switch_expr_stack);
 658         __free_ptr_list((struct ptr_list **)&big_statement_stack);
 659         __bail_on_rest_of_function = 0;
 660 }
 661
 662 static void split_functions(struct symbol_list *sym_list)
 663 {
 664         struct symbol *sym;
 665
 666         FOR_EACH_PTR(sym_list, sym) {
 667                 if (sym->type == SYM_NODE && get_base_type(sym)->type == SYM_FN) {
 668                         split_function(sym);
 669                 } else {
 670                         __pass_to_client(sym, BASE_HOOK);
 671                 }
 672         } END_FOR_EACH_PTR(sym);
 673         __pass_to_client_no_data(END_FILE_HOOK);
 674 }
 675
 676 void smatch (int argc, char **argv)
 677 {
 678
 679         struct string_list *filelist = NULL;
 680         struct symbol_list *sym_list;
 681         char *file;
 682
 683         if (argc < 2) {
 684                 printf("Usage:  smatch [--debug] <filename.c>\n");
 685                 exit(1);
 686         }
 687         sparse_initialize(argc, argv, &filelist);
 688         FOR_EACH_PTR_NOTAG(filelist, file) {
 689                 sym_list = sparse_keep_tokens(file);
 690                 split_functions(sym_list);
 691         } END_FOR_EACH_PTR_NOTAG(file);
 692 }