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