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                 /* foo = (x < 5 ? foo : 5); */
 115                 if (__handle_select_assigns(expr))
 116                         break;
 117
 118                 __split_expr(expr->right);
 119                 __pass_to_client(expr, ASSIGNMENT_HOOK);
 120                 tmp = strip_expr(expr->right);
 121                 if (tmp->type == EXPR_CALL)
 122                         __pass_to_client(expr, CALL_ASSIGNMENT_HOOK);
 123                 __split_expr(expr->left);
 124                 break;
 125         }
 126         case EXPR_DEREF:
 127                 __pass_to_client(expr, DEREF_HOOK);
 128                 __split_expr(expr->deref);
 129                 break;
 130         case EXPR_SLICE:
 131                 __split_expr(expr->base);
 132                 break;
 133         case EXPR_CAST:
 134         case EXPR_FORCE_CAST:
 135                 __split_expr(expr->cast_expression);
 136                 break;
 137         case EXPR_SIZEOF:
 138                 /* there isn't anything to pass a client from inside a sizeof() */
 139                 break;
 140         case EXPR_CONDITIONAL:
 141         case EXPR_SELECT:
 142                 __split_whole_condition(expr->conditional);
 143                 __split_expr(expr->cond_true);
 144                 __push_true_states();
 145                 __use_false_states();
 146                 __split_expr(expr->cond_false);
 147                 __merge_true_states();
 148                 break;
 149         case EXPR_CALL:
 150                 split_expr_list(expr->args);
 151                 __split_expr(expr->fn);
 152                 __pass_to_client(expr, FUNCTION_CALL_HOOK);
 153                 break;
 154         case EXPR_INITIALIZER:
 155                 split_expr_list(expr->expr_list);
 156                 break;
 157         case EXPR_IDENTIFIER:
 158                 __split_expr(expr->ident_expression);
 159                 break;
 160         case EXPR_INDEX:
 161                 __split_expr(expr->idx_expression);
 162                 break;
 163         case EXPR_POS:
 164                 __split_expr(expr->init_expr);
 165                 break;
 166         case EXPR_SYMBOL:
 167                 __pass_to_client(expr, SYM_HOOK);
 168                 break;
 169         case EXPR_STRING:
 170                 __pass_to_client(expr, STRING_HOOK);
 171                 break;
 172         default:
 173                 break;
 174         };
 175         pop_expression(&big_expression_stack);
 176 }
 177
 178 static int is_forever_loop(struct statement *stmt)
 179 {
 180
 181         struct expression *expr;
 182
 183         expr = strip_expr(stmt->iterator_pre_condition);
 184         if (!expr)
 185                 expr = stmt->iterator_post_condition;
 186         if (!expr) {
 187                 /* this is a for(;;) loop... */
 188                 return 1;
 189         }
 190
 191         if (expr->type == EXPR_VALUE && expr->value == 1) {
 192                 return 1;
 193         }
 194
 195         return 0;
 196 }
 197
 198 static int loop_num;
 199 static char *get_loop_name(int num)
 200 {
 201         char buf[256];
 202
 203         snprintf(buf, 255, "-loop%d", num);
 204         buf[255] = '\0';
 205         return alloc_sname(buf);;
 206 }
 207
 208 /*
 209  * Pre Loops are while and for loops.
 210  */
 211
 212 static void handle_pre_loop(struct statement *stmt)
 213 {
 214         int once_through; /* we go through the loop at least once */
 215         struct sm_state *extra_sm = NULL;
 216         int unchanged = 0;
 217         char *loop_name;
 218         struct state_list *slist = NULL;
 219         struct sm_state *sm = NULL;
 220
 221         loop_name = get_loop_name(loop_num);
 222         loop_num++;
 223
 224         __split_statements(stmt->iterator_pre_statement);
 225
 226         once_through = implied_condition_true(stmt->iterator_pre_condition);
 227
 228         __push_continues();
 229         __push_breaks();
 230
 231         __merge_gotos(loop_name);
 232
 233         extra_sm = __extra_handle_canonical_loops(stmt, &slist);
 234         __in_pre_condition++;
 235         __split_whole_condition(stmt->iterator_pre_condition);
 236         __in_pre_condition--;
 237         FOR_EACH_PTR(slist, sm) {
 238                 set_state(sm->owner, sm->name, sm->sym, sm->state);
 239         } END_FOR_EACH_PTR(sm);
 240         free_slist(&slist);
 241         if (extra_sm)
 242                 extra_sm = get_sm_state(extra_sm->owner, extra_sm->name, extra_sm->sym);
 243
 244         if (option_assume_loops)
 245                 once_through = 1;
 246
 247         __split_statements(stmt->iterator_statement);
 248         __warn_on_silly_pre_loops();
 249         if (is_forever_loop(stmt)) {
 250                 __save_gotos(loop_name);
 251                 /* forever loops don't have an iterator_post_statement */
 252                 __discard_continues();
 253                 __discard_false_states();
 254                 __use_breaks();
 255         } else {
 256                 __merge_continues();
 257                 unchanged = __iterator_unchanged(extra_sm);
 258                 __split_statements(stmt->iterator_post_statement);
 259                 __save_gotos(loop_name);
 260                 __split_whole_condition(stmt->iterator_pre_condition);
 261                 nullify_path();
 262                 __merge_false_states();
 263                 if (once_through) {
 264                         __discard_false_states();
 265                 } else {
 266                         __merge_false_states();
 267
 268                 }
 269                 if (extra_sm && unchanged)
 270                         __extra_pre_loop_hook_after(extra_sm,
 271                                                 stmt->iterator_post_statement,
 272                                                 stmt->iterator_pre_condition);
 273                 __merge_breaks();
 274         }
 275 }
 276
 277 /*
 278  * Post loops are do {} while();
 279  */
 280 static void handle_post_loop(struct statement *stmt)
 281 {
 282         char *loop_name;
 283
 284         loop_name = get_loop_name(loop_num);
 285         loop_num++;
 286
 287         __push_continues();
 288         __push_breaks();
 289         __merge_gotos(loop_name);
 290         __split_statements(stmt->iterator_statement);
 291         __merge_continues();
 292         if (!is_zero(stmt->iterator_post_condition))
 293                 __save_gotos(loop_name);
 294
 295         if (is_forever_loop(stmt)) {
 296                 __use_breaks();
 297         } else {
 298                 __split_whole_condition(stmt->iterator_post_condition);
 299                 __use_false_states();
 300                 __merge_breaks();
 301         }
 302 }
 303
 304 static int empty_statement(struct statement *stmt)
 305 {
 306         if (!stmt)
 307                 return 0;
 308         if (stmt->type == STMT_EXPRESSION && !stmt->expression)
 309                 return 1;
 310         return 0;
 311 }
 312
 313 static struct statement *last_stmt;
 314 static int is_last_stmt(struct statement *stmt)
 315 {
 316         if (stmt == last_stmt)
 317                 return 1;
 318         return 0;
 319 }
 320
 321 static void print_unreached_initializers(struct symbol_list *sym_list)
 322 {
 323         struct symbol *sym;
 324
 325         FOR_EACH_PTR(sym_list, sym) {
 326                 if(sym->initializer)
 327                         sm_msg("info: '%s' is not actually initialized (unreached code).",
 328                                 (sym->ident ? sym->ident->name : "this variable"));
 329         } END_FOR_EACH_PTR(sym);
 330 }
 331
 332 static void print_unreached(struct statement *stmt)
 333 {
 334
 335         static int print = 1;
 336
 337         if (!__path_is_null()) {
 338                 print = 1;
 339                 return;
 340         }
 341         if (!print)
 342                 return;
 343
 344         switch (stmt->type) {
 345         case STMT_COMPOUND: /* after a switch before a case stmt */
 346         case STMT_RANGE:
 347         case STMT_CASE:
 348         case STMT_LABEL:
 349                 return;
 350         case STMT_DECLARATION: /* switch (x) { int a; case foo: ... */
 351                 print_unreached_initializers(stmt->declaration);
 352                 return;
 353         case STMT_RETURN: /* gcc complains if you don't have a return statement */
 354                 if (is_last_stmt(stmt))
 355                         return;
 356                 break;
 357         case STMT_GOTO:
 358                 if (!option_spammy)
 359                         return;
 360                 break;
 361         default:
 362                 break;
 363         }
 364         if (!option_spammy && empty_statement(stmt))
 365                 return;
 366         sm_msg("info: ignoring unreachable code.");
 367         print = 0;
 368 }
 369
 370 void __split_statements(struct statement *stmt)
 371 {
 372         if (!stmt)
 373                 return;
 374
 375         if (out_of_memory() || __bail_on_rest_of_function) {
 376                 static char *printed = NULL;
 377
 378                 if (printed != cur_func)
 379                         sm_msg("Function too hairy.  Giving up.");
 380                 printed = cur_func;
 381                 return;
 382         }
 383
 384         add_ptr_list(&big_statement_stack, stmt);
 385         free_expression_stack(&big_expression_stack);
 386         __smatch_lineno = stmt->pos.line;
 387         print_unreached(stmt);
 388         __pass_to_client(stmt, STMT_HOOK);
 389
 390         switch (stmt->type) {
 391         case STMT_DECLARATION:
 392                 split_declaration(stmt->declaration);
 393                 return;
 394         case STMT_RETURN:
 395                 __split_expr(stmt->ret_value);
 396                 __pass_to_client(stmt->ret_value, RETURN_HOOK);
 397                 nullify_path();
 398                 return;
 399         case STMT_EXPRESSION:
 400                 __split_expr(stmt->expression);
 401                 return;
 402         case STMT_COMPOUND: {
 403                 struct statement *s;
 404
 405                 if (!last_stmt)
 406                         last_stmt = last_ptr_list((struct ptr_list *)stmt->stmts);
 407                 __push_scope_hooks();
 408                 FOR_EACH_PTR(stmt->stmts, s) {
 409                         __split_statements(s);
 410                 } END_FOR_EACH_PTR(s);
 411                 __call_scope_hooks();
 412                 return;
 413         }
 414         case STMT_IF:
 415                 if (known_condition_true(stmt->if_conditional)) {
 416                         __split_statements(stmt->if_true);
 417                         return;
 418                 }
 419                 if (known_condition_false(stmt->if_conditional)) {
 420                         __split_statements(stmt->if_false);
 421                         return;
 422                 }
 423                 if (option_known_conditions &&
 424                     implied_condition_true(stmt->if_conditional)) {
 425                         sm_info("this condition is true.");
 426                         __split_statements(stmt->if_true);
 427                         return;
 428                 }
 429                 if (option_known_conditions &&
 430                     implied_condition_false(stmt->if_conditional)) {
 431                         sm_info("this condition is false.");
 432                         __split_statements(stmt->if_false);
 433                         return;
 434                 }
 435                 __split_whole_condition(stmt->if_conditional);
 436                 __split_statements(stmt->if_true);
 437                 if (empty_statement(stmt->if_true))
 438                         sm_msg("warn: if();");
 439                 __push_true_states();
 440                 __use_false_states();
 441                 __split_statements(stmt->if_false);
 442                 __merge_true_states();
 443                 return;
 444         case STMT_ITERATOR:
 445                 if (stmt->iterator_pre_condition)
 446                         handle_pre_loop(stmt);
 447                 else if (stmt->iterator_post_condition)
 448                         handle_post_loop(stmt);
 449                 else {
 450                         // these are for(;;) type loops.
 451                         handle_pre_loop(stmt);
 452                 }
 453                 return;
 454         case STMT_SWITCH:
 455                 __split_expr(stmt->switch_expression);
 456                 push_expression(&switch_expr_stack, stmt->switch_expression);
 457                 __save_switch_states(top_expression(switch_expr_stack));
 458                 nullify_path();
 459                 __push_default();
 460                 __push_breaks();
 461                 __split_statements(stmt->switch_statement);
 462                 if (!__pop_default())
 463                         __merge_switches(top_expression(switch_expr_stack),
 464                                       NULL);
 465                 __discard_switches();
 466                 __merge_breaks();
 467                 pop_expression(&switch_expr_stack);
 468                 return;
 469         case STMT_CASE:
 470                 __merge_switches(top_expression(switch_expr_stack),
 471                                       stmt->case_expression);
 472                 __pass_case_to_client(top_expression(switch_expr_stack),
 473                                       stmt->case_expression);
 474                 if (!stmt->case_expression)
 475                         __set_default();
 476                 __split_expr(stmt->case_expression);
 477                 __split_expr(stmt->case_to);
 478                 __split_statements(stmt->case_statement);
 479                 return;
 480         case STMT_LABEL:
 481                 if (stmt->label &&
 482                     stmt->label->type == SYM_LABEL &&
 483                     stmt->label->ident) {
 484                         __merge_gotos(stmt->label->ident->name);
 485                 }
 486                 __split_statements(stmt->label_statement);
 487                 return;
 488         case STMT_GOTO:
 489                 __split_expr(stmt->goto_expression);
 490                 if (stmt->goto_label && stmt->goto_label->type == SYM_NODE) {
 491                         if (!strcmp(stmt->goto_label->ident->name, "break")) {
 492                                 __process_breaks();
 493                         } else if (!strcmp(stmt->goto_label->ident->name,
 494                                            "continue")) {
 495                                 __process_continues();
 496                         }
 497                 } else if (stmt->goto_label &&
 498                            stmt->goto_label->type == SYM_LABEL &&
 499                            stmt->goto_label->ident) {
 500                         __save_gotos(stmt->goto_label->ident->name);
 501                 }
 502                 nullify_path();
 503                 return;
 504         case STMT_NONE:
 505                 return;
 506         case STMT_ASM:
 507                 __split_expr(stmt->asm_string);
 508                 split_expr_list(stmt->asm_outputs);
 509                 split_expr_list(stmt->asm_inputs);
 510                 split_expr_list(stmt->asm_clobbers);
 511                 return;
 512         case STMT_CONTEXT:
 513                 return;
 514         case STMT_RANGE:
 515                 __split_expr(stmt->range_expression);
 516                 __split_expr(stmt->range_low);
 517                 __split_expr(stmt->range_high);
 518                 return;
 519         }
 520 }
 521
 522 static void split_expr_list(struct expression_list *expr_list)
 523 {
 524         struct expression *expr;
 525         FOR_EACH_PTR(expr_list, expr) {
 526                 __split_expr(expr);
 527         } END_FOR_EACH_PTR(expr);
 528 }
 529
 530
 531 static void split_sym(struct symbol *sym)
 532 {
 533         if (!sym)
 534                 return;
 535         if (!(sym->namespace & NS_SYMBOL))
 536                 return;
 537
 538         __split_statements(sym->stmt);
 539         __split_expr(sym->array_size);
 540         split_symlist(sym->arguments);
 541         split_symlist(sym->symbol_list);
 542         __split_statements(sym->inline_stmt);
 543         split_symlist(sym->inline_symbol_list);
 544 }
 545
 546 static void split_symlist(struct symbol_list *sym_list)
 547 {
 548         struct symbol *sym;
 549
 550         FOR_EACH_PTR(sym_list, sym) {
 551                 split_sym(sym);
 552         } END_FOR_EACH_PTR(sym);
 553 }
 554
 555 static struct expression *fake_assign_expr(struct symbol *sym)
 556 {
 557         struct expression *e_assign, *e_symbol;
 558
 559         e_assign = alloc_expression(sym->initializer->pos, EXPR_ASSIGNMENT);
 560         e_symbol = alloc_expression(sym->initializer->pos, EXPR_SYMBOL);
 561         e_assign->op = (int)'=';
 562         e_symbol->symbol = sym;
 563         e_symbol->symbol_name = sym->ident;
 564         e_assign->left = e_symbol;
 565         e_assign->right = sym->initializer;
 566         return e_assign;
 567 }
 568
 569 static void do_initializer_stuff(struct symbol *sym)
 570 {
 571         struct expression *assign;
 572
 573         if(!sym->initializer)
 574                 return;
 575         assign = fake_assign_expr(sym);
 576         __split_expr(assign);
 577 }
 578
 579 static void split_declaration(struct symbol_list *sym_list)
 580 {
 581         struct symbol *sym;
 582
 583         FOR_EACH_PTR(sym_list, sym) {
 584                 __pass_to_client(sym, DECLARATION_HOOK);
 585                 do_initializer_stuff(sym);
 586                 split_sym(sym);
 587         } END_FOR_EACH_PTR(sym);
 588 }
 589
 590 static void split_functions(struct symbol_list *sym_list)
 591 {
 592         struct symbol *sym;
 593
 594         FOR_EACH_PTR(sym_list, sym) {
 595                 struct symbol *base_type;
 596                 base_type = get_base_type(sym);
 597                 if (sym->type == SYM_NODE && base_type->type == SYM_FN) {
 598                         cur_func_sym = sym;
 599                         if (base_type->stmt)
 600                                 line_func_start = base_type->stmt->pos.line;
 601                         if (sym->ident)
 602                                 cur_func = sym->ident->name;
 603                         __smatch_lineno = sym->pos.line;
 604                         last_stmt = NULL;
 605                         sm_debug("new function:  %s\n", cur_func);
 606                         if (option_two_passes) {
 607                                 __unnullify_path();
 608                                 loop_num = 0;
 609                                 final_pass = 0;
 610                                 __pass_to_client(sym, FUNC_DEF_HOOK);
 611                                 __split_statements(base_type->stmt);
 612                                 nullify_path();
 613                         }
 614                         __unnullify_path();
 615                         loop_num = 0;
 616                         final_pass = 1;
 617                         __pass_to_client(sym, FUNC_DEF_HOOK);
 618                         __split_statements(base_type->stmt);
 619                         __pass_to_client(sym, END_FUNC_HOOK);
 620                         cur_func = NULL;
 621                         line_func_start = 0;
 622                         clear_all_states();
 623                         free_data_info_allocs();
 624                         free_expression_stack(&switch_expr_stack);
 625                         __free_ptr_list((struct ptr_list **)&big_statement_stack);
 626                         __bail_on_rest_of_function = 0;
 627                 } else {
 628                         __pass_to_client(sym, BASE_HOOK);
 629                 }
 630         } END_FOR_EACH_PTR(sym);
 631         __pass_to_client_no_data(END_FILE_HOOK);
 632 }
 633
 634 void smatch (int argc, char **argv)
 635 {
 636
 637         struct string_list *filelist = NULL;
 638         struct symbol_list *sym_list;
 639         char *file;
 640
 641         if (argc < 2) {
 642                 printf("Usage:  smatch [--debug] <filename.c>\n");
 643                 exit(1);
 644         }
 645         sparse_initialize(argc, argv, &filelist);
 646         FOR_EACH_PTR_NOTAG(filelist, file) {
 647                 sym_list = __sparse(file);
 648                 split_functions(sym_list);
 649         } END_FOR_EACH_PTR_NOTAG(file);
 650 }