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