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" // just for sname.
  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_state = NULL;
 209         int unchanged = 0;
 210         char *loop_name;
 211
 212         loop_name = get_loop_name(loop_num);
 213         loop_num++;
 214
 215         __split_statements(stmt->iterator_pre_statement);
 216
 217         once_through = implied_condition_true(stmt->iterator_pre_condition);
 218
 219         __push_continues();
 220         __push_breaks();
 221
 222         __merge_gotos(loop_name);
 223
 224         __in_pre_condition++;
 225         __split_whole_condition(stmt->iterator_pre_condition);
 226         __in_pre_condition--;
 227
 228         if (once_through)
 229                 extra_state = __extra_pre_loop_hook_before(stmt->iterator_pre_statement);
 230         if (option_assume_loops)
 231                 once_through = 1;
 232         __split_statements(stmt->iterator_statement);
 233
 234         __warn_on_silly_pre_loops();
 235         if (is_forever_loop(stmt)) {
 236                 __save_gotos(loop_name);
 237                 /* forever loops don't have an iterator_post_statement */
 238                 __pop_continues();
 239                 __pop_false_states();
 240                 __use_breaks();
 241         } else if (once_through) {
 242                 __merge_continues();
 243                 if (extra_state)
 244                         unchanged = __iterator_unchanged(extra_state, stmt->iterator_post_statement);
 245                 __split_statements(stmt->iterator_post_statement);
 246                 __save_gotos(loop_name);
 247                 __split_whole_condition(stmt->iterator_pre_condition);
 248                 nullify_path();
 249                 __merge_false_states();
 250                 if (extra_state && unchanged)
 251                         __extra_pre_loop_hook_after(extra_state,
 252                                 stmt->iterator_post_statement, stmt->iterator_pre_condition);
 253                 __pop_false_states();
 254                 __merge_breaks();
 255         } else {
 256                 __merge_continues();
 257                 __split_statements(stmt->iterator_post_statement);
 258                 __save_gotos(loop_name);
 259                 __split_whole_condition(stmt->iterator_pre_condition);
 260                 nullify_path();
 261                 __merge_false_states();
 262                 __merge_false_states();
 263                 __merge_breaks();
 264         }
 265 }
 266
 267 /*
 268  * Post loops are do {} while();
 269  */
 270 static void handle_post_loop(struct statement *stmt)
 271 {
 272         char *loop_name;
 273
 274         loop_name = get_loop_name(loop_num);
 275         loop_num++;
 276
 277         __push_continues();
 278         __push_breaks();
 279         __merge_gotos(loop_name);
 280         __split_statements(stmt->iterator_statement);
 281         __merge_continues();
 282         if (!is_zero(stmt->iterator_post_condition))
 283                 __save_gotos(loop_name);
 284
 285         if (is_forever_loop(stmt)) {
 286                 __use_breaks();
 287         } else {
 288                 __split_whole_condition(stmt->iterator_post_condition);
 289                 __use_false_states();
 290                 __merge_breaks();
 291         }
 292 }
 293
 294 static int empty_statement(struct statement *stmt)
 295 {
 296         if (!stmt)
 297                 return 0;
 298         if (stmt->type == STMT_EXPRESSION && !stmt->expression)
 299                 return 1;
 300         return 0;
 301 }
 302
 303 static struct statement *last_stmt;
 304 static int is_last_stmt(struct statement *stmt)
 305 {
 306         if (stmt == last_stmt)
 307                 return 1;
 308         return 0;
 309 }
 310
 311 static void print_unreached_initializers(struct symbol_list *sym_list)
 312 {
 313         struct symbol *sym;
 314
 315         FOR_EACH_PTR(sym_list, sym) {
 316                 if(sym->initializer)
 317                         sm_msg("info: '%s' is not actually initialized (unreached code).",
 318                                 (sym->ident ? sym->ident->name : "this variable"));
 319         } END_FOR_EACH_PTR(sym);
 320 }
 321
 322 static void print_unreached(struct statement *stmt)
 323 {
 324
 325         static int print = 1;
 326
 327         if (!__path_is_null()) {
 328                 print = 1;
 329                 return;
 330         }
 331         if (!print)
 332                 return;
 333
 334         switch (stmt->type) {
 335         case STMT_COMPOUND: /* after a switch before a case stmt */
 336         case STMT_RANGE:
 337         case STMT_CASE:
 338         case STMT_LABEL:
 339                 return;
 340         case STMT_DECLARATION: /* switch (x) { int a; case foo: ... */
 341                 print_unreached_initializers(stmt->declaration);
 342                 return;
 343         case STMT_RETURN: /* gcc complains if you don't have a return statement */
 344                 if (is_last_stmt(stmt))
 345                         return;
 346                 break;
 347         case STMT_GOTO:
 348                 if (!option_spammy)
 349                         return;
 350                 break;
 351         default:
 352                 break;
 353         }
 354         if (!option_spammy && empty_statement(stmt))
 355                 return;
 356         sm_msg("info: ignoring unreachable code.");
 357         print = 0;
 358 }
 359
 360 void __split_statements(struct statement *stmt)
 361 {
 362         if (!stmt)
 363                 return;
 364
 365         if (out_of_memory() || __bail_on_rest_of_function) {
 366                 static char *printed = NULL;
 367
 368                 if (printed != cur_func)
 369                         sm_msg("Function too hairy.  Giving up.");
 370                 printed = cur_func;
 371                 return;
 372         }
 373
 374         add_ptr_list(&big_statement_stack, stmt);
 375         free_expression_stack(&big_expression_stack);
 376         __smatch_lineno = stmt->pos.line;
 377         print_unreached(stmt);
 378         __pass_to_client(stmt, STMT_HOOK);
 379
 380         switch (stmt->type) {
 381         case STMT_DECLARATION:
 382                 split_declaration(stmt->declaration);
 383                 return;
 384         case STMT_RETURN:
 385                 __split_expr(stmt->ret_value);
 386                 __pass_to_client(stmt->ret_value, RETURN_HOOK);
 387                 nullify_path();
 388                 return;
 389         case STMT_EXPRESSION:
 390                 __split_expr(stmt->expression);
 391                 return;
 392         case STMT_COMPOUND: {
 393                 struct statement *s;
 394
 395                 if (!last_stmt)
 396                         last_stmt = last_ptr_list((struct ptr_list *)stmt->stmts);
 397                 __push_scope_hooks();
 398                 FOR_EACH_PTR(stmt->stmts, s) {
 399                         __split_statements(s);
 400                 } END_FOR_EACH_PTR(s);
 401                 __call_scope_hooks();
 402                 return;
 403         }
 404         case STMT_IF:
 405                 if (known_condition_true(stmt->if_conditional)) {
 406                         __split_statements(stmt->if_true);
 407                         return;
 408                 }
 409                 if (known_condition_false(stmt->if_conditional)) {
 410                         __split_statements(stmt->if_false);
 411                         return;
 412                 }
 413                 if (option_known_conditions &&
 414                     implied_condition_true(stmt->if_conditional)) {
 415                         sm_info("this condition is true.");
 416                         __split_statements(stmt->if_true);
 417                         return;
 418                 }
 419                 if (option_known_conditions &&
 420                     implied_condition_false(stmt->if_conditional)) {
 421                         sm_info("this condition is false.");
 422                         __split_statements(stmt->if_false);
 423                         return;
 424                 }
 425                 __split_whole_condition(stmt->if_conditional);
 426                 __split_statements(stmt->if_true);
 427                 if (empty_statement(stmt->if_true))
 428                         sm_msg("warn: if();");
 429                 __push_true_states();
 430                 __use_false_states();
 431                 __split_statements(stmt->if_false);
 432                 __merge_true_states();
 433                 return;
 434         case STMT_ITERATOR:
 435                 if (stmt->iterator_pre_condition)
 436                         handle_pre_loop(stmt);
 437                 else if (stmt->iterator_post_condition)
 438                         handle_post_loop(stmt);
 439                 else {
 440                         // these are for(;;) type loops.
 441                         handle_pre_loop(stmt);
 442                 }
 443                 return;
 444         case STMT_SWITCH:
 445                 __split_expr(stmt->switch_expression);
 446                 push_expression(&switch_expr_stack, stmt->switch_expression);
 447                 __save_switch_states(top_expression(switch_expr_stack));
 448                 nullify_path();
 449                 __push_default();
 450                 __push_breaks();
 451                 __split_statements(stmt->switch_statement);
 452                 if (!__pop_default())
 453                         __merge_switches(top_expression(switch_expr_stack),
 454                                       NULL);
 455                 __pop_switches();
 456                 __merge_breaks();
 457                 pop_expression(&switch_expr_stack);
 458                 return;
 459         case STMT_CASE:
 460                 __merge_switches(top_expression(switch_expr_stack),
 461                                       stmt->case_expression);
 462                 __pass_case_to_client(top_expression(switch_expr_stack),
 463                                       stmt->case_expression);
 464                 if (!stmt->case_expression)
 465                         __set_default();
 466                 __split_expr(stmt->case_expression);
 467                 __split_expr(stmt->case_to);
 468                 __split_statements(stmt->case_statement);
 469                 return;
 470         case STMT_LABEL:
 471                 if (stmt->label &&
 472                     stmt->label->type == SYM_LABEL &&
 473                     stmt->label->ident) {
 474                         __merge_gotos(stmt->label->ident->name);
 475                 }
 476                 __split_statements(stmt->label_statement);
 477                 return;
 478         case STMT_GOTO:
 479                 __split_expr(stmt->goto_expression);
 480                 if (stmt->goto_label && stmt->goto_label->type == SYM_NODE) {
 481                         if (!strcmp(stmt->goto_label->ident->name, "break")) {
 482                                 __process_breaks();
 483                         } else if (!strcmp(stmt->goto_label->ident->name,
 484                                            "continue")) {
 485                                 __process_continues();
 486                         }
 487                 } else if (stmt->goto_label &&
 488                            stmt->goto_label->type == SYM_LABEL &&
 489                            stmt->goto_label->ident) {
 490                         __save_gotos(stmt->goto_label->ident->name);
 491                 }
 492                 nullify_path();
 493                 return;
 494         case STMT_NONE:
 495                 return;
 496         case STMT_ASM:
 497                 __split_expr(stmt->asm_string);
 498                 //__split_expr(stmt->asm_outputs);
 499                 //__split_expr(stmt->asm_inputs);
 500                 //__split_expr(stmt->asm_clobbers);
 501                 return;
 502         case STMT_CONTEXT:
 503                 return;
 504         case STMT_RANGE:
 505                 __split_expr(stmt->range_expression);
 506                 __split_expr(stmt->range_low);
 507                 __split_expr(stmt->range_high);
 508                 return;
 509         }
 510 }
 511
 512 static void split_expr_list(struct expression_list *expr_list)
 513 {
 514         struct expression *expr;
 515         FOR_EACH_PTR(expr_list, expr) {
 516                 __split_expr(expr);
 517         } END_FOR_EACH_PTR(expr);
 518 }
 519
 520
 521 static void split_sym(struct symbol *sym)
 522 {
 523         if (!sym)
 524                 return;
 525         if (!(sym->namespace & NS_SYMBOL))
 526                 return;
 527
 528         __split_statements(sym->stmt);
 529         __split_expr(sym->array_size);
 530         split_symlist(sym->arguments);
 531         split_symlist(sym->symbol_list);
 532         __split_statements(sym->inline_stmt);
 533         split_symlist(sym->inline_symbol_list);
 534 }
 535
 536 static void split_symlist(struct symbol_list *sym_list)
 537 {
 538         struct symbol *sym;
 539
 540         FOR_EACH_PTR(sym_list, sym) {
 541                 split_sym(sym);
 542         } END_FOR_EACH_PTR(sym);
 543 }
 544
 545 static struct expression *fake_assign_expr(struct symbol *sym)
 546 {
 547         struct expression *e_assign, *e_symbol;
 548
 549         e_assign = alloc_expression(sym->initializer->pos, EXPR_ASSIGNMENT);
 550         e_symbol = alloc_expression(sym->initializer->pos, EXPR_SYMBOL);
 551         e_assign->op = (int)'=';
 552         e_symbol->symbol = sym;
 553         e_symbol->symbol_name = sym->ident;
 554         e_assign->left = e_symbol;
 555         e_assign->right = sym->initializer;
 556         return e_assign;
 557 }
 558
 559 static void do_initializer_stuff(struct symbol *sym)
 560 {
 561         struct expression *assign;
 562
 563         if(!sym->initializer)
 564                 return;
 565         assign = fake_assign_expr(sym);
 566         __split_expr(assign);
 567 }
 568
 569 static void split_declaration(struct symbol_list *sym_list)
 570 {
 571         struct symbol *sym;
 572
 573         FOR_EACH_PTR(sym_list, sym) {
 574                 __pass_to_client(sym, DECLARATION_HOOK);
 575                 do_initializer_stuff(sym);
 576                 split_sym(sym);
 577         } END_FOR_EACH_PTR(sym);
 578 }
 579
 580 static void split_functions(struct symbol_list *sym_list)
 581 {
 582         struct symbol *sym;
 583
 584         FOR_EACH_PTR(sym_list, sym) {
 585                 struct symbol *base_type;
 586                 base_type = get_base_type(sym);
 587                 if (sym->type == SYM_NODE && base_type->type == SYM_FN) {
 588                         cur_func_sym = sym;
 589                         if (base_type->stmt)
 590                                 line_func_start = base_type->stmt->pos.line;
 591                         if (sym->ident)
 592                                 cur_func = sym->ident->name;
 593                         __smatch_lineno = sym->pos.line;
 594                         last_stmt = NULL;
 595                         sm_debug("new function:  %s\n", cur_func);
 596                         if (option_two_passes) {
 597                                 __unnullify_path();
 598                                 loop_num = 0;
 599                                 final_pass = 0;
 600                                 __pass_to_client(sym, FUNC_DEF_HOOK);
 601                                 __split_statements(base_type->stmt);
 602                                 nullify_path();
 603                         }
 604                         __unnullify_path();
 605                         loop_num = 0;
 606                         final_pass = 1;
 607                         __pass_to_client(sym, FUNC_DEF_HOOK);
 608                         __split_statements(base_type->stmt);
 609                         __pass_to_client(sym, END_FUNC_HOOK);
 610                         cur_func = NULL;
 611                         line_func_start = 0;
 612                         clear_all_states();
 613                         free_data_info_allocs();
 614                         free_expression_stack(&switch_expr_stack);
 615                         __free_ptr_list((struct ptr_list **)&big_statement_stack);
 616                         __bail_on_rest_of_function = 0;
 617                 } else {
 618                         __pass_to_client(sym, BASE_HOOK);
 619                 }
 620         } END_FOR_EACH_PTR(sym);
 621         __pass_to_client_no_data(END_FILE_HOOK);
 622 }
 623
 624 void smatch (int argc, char **argv)
 625 {
 626
 627         struct string_list *filelist = NULL;
 628         struct symbol_list *sym_list;
 629         char *file;
 630
 631         if (argc < 2) {
 632                 printf("Usage:  smatch [--debug] <filename.c>\n");
 633                 exit(1);
 634         }
 635         sparse_initialize(argc, argv, &filelist);
 636         FOR_EACH_PTR_NOTAG(filelist, file) {
 637                 sym_list = __sparse(file);
 638                 split_functions(sym_list);
 639         } END_FOR_EACH_PTR_NOTAG(file);
 640 }