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_LOGICAL:
 100                 __split_whole_condition(expr);
 101                 __push_true_states();
 102                 __use_false_states();
 103                 __merge_true_states();
 104                 break;
 105         case EXPR_BINOP:
 106                 __pass_to_client(expr, BINOP_HOOK);
 107         case EXPR_COMMA:
 108         case EXPR_COMPARE:
 109                 __split_expr(expr->left);
 110                 __split_expr(expr->right);
 111                 break;
 112         case EXPR_ASSIGNMENT: {
 113                 struct expression *tmp;
 114
 115                 /* foo = !bar() */
 116                 if (__handle_condition_assigns(expr))
 117                         break;
 118
 119                 __split_expr(expr->right);
 120                 __pass_to_client(expr, ASSIGNMENT_HOOK);
 121                 tmp = strip_expr(expr->right);
 122                 if (tmp->type == EXPR_CALL)
 123                         __pass_to_client(expr, CALL_ASSIGNMENT_HOOK);
 124                 __split_expr(expr->left);
 125                 break;
 126         }
 127         case EXPR_DEREF:
 128                 __pass_to_client(expr, DEREF_HOOK);
 129                 __split_expr(expr->deref);
 130                 break;
 131         case EXPR_SLICE:
 132                 __split_expr(expr->base);
 133                 break;
 134         case EXPR_CAST:
 135         case EXPR_FORCE_CAST:
 136                 __split_expr(expr->cast_expression);
 137                 break;
 138         case EXPR_SIZEOF:
 139                 /* there isn't anything to pass a client from inside a sizeof() */
 140                 break;
 141         case EXPR_CONDITIONAL:
 142         case EXPR_SELECT:
 143                 __split_whole_condition(expr->conditional);
 144                 __split_expr(expr->cond_true);
 145                 __push_true_states();
 146                 __use_false_states();
 147                 __split_expr(expr->cond_false);
 148                 __merge_true_states();
 149                 break;
 150         case EXPR_CALL:
 151                 split_expr_list(expr->args);
 152                 __split_expr(expr->fn);
 153                 __pass_to_client(expr, FUNCTION_CALL_HOOK);
 154                 break;
 155         case EXPR_INITIALIZER:
 156                 split_expr_list(expr->expr_list);
 157                 break;
 158         case EXPR_IDENTIFIER:
 159                 __split_expr(expr->ident_expression);
 160                 break;
 161         case EXPR_INDEX:
 162                 __split_expr(expr->idx_expression);
 163                 break;
 164         case EXPR_POS:
 165                 __split_expr(expr->init_expr);
 166                 break;
 167         case EXPR_SYMBOL:
 168                 __pass_to_client(expr, SYM_HOOK);
 169                 break;
 170         default:
 171                 break;
 172         };
 173         pop_expression(&big_expression_stack);
 174 }
 175
 176 static int is_forever_loop(struct statement *stmt)
 177 {
 178
 179         struct expression *expr;
 180
 181         expr = strip_expr(stmt->iterator_pre_condition);
 182         if (!expr)
 183                 expr = stmt->iterator_post_condition;
 184         if (!expr) {
 185                 /* this is a for(;;) loop... */
 186                 return 1;
 187         }
 188
 189         if (expr->type == EXPR_VALUE && expr->value == 1) {
 190                 return 1;
 191         }
 192
 193         return 0;
 194 }
 195
 196 static int loop_num;
 197 static char *get_loop_name(int num)
 198 {
 199         char buf[256];
 200
 201         snprintf(buf, 255, "-loop%d", num);
 202         buf[255] = '\0';
 203         return alloc_sname(buf);;
 204 }
 205
 206 /*
 207  * Pre Loops are while and for loops.
 208  */
 209
 210 static void handle_pre_loop(struct statement *stmt)
 211 {
 212         int once_through; /* we go through the loop at least once */
 213         struct sm_state *extra_state = NULL;
 214         int unchanged = 0;
 215         char *loop_name;
 216
 217         loop_name = get_loop_name(loop_num);
 218         loop_num++;
 219
 220         __split_statements(stmt->iterator_pre_statement);
 221
 222         once_through = implied_condition_true(stmt->iterator_pre_condition);
 223
 224         __push_continues();
 225         __push_breaks();
 226
 227         __merge_gotos(loop_name);
 228
 229         __in_pre_condition++;
 230         __split_whole_condition(stmt->iterator_pre_condition);
 231         __in_pre_condition--;
 232
 233         if (once_through)
 234                 extra_state = __extra_pre_loop_hook_before(stmt->iterator_pre_statement);
 235         if (option_assume_loops)
 236                 once_through = 1;
 237         __split_statements(stmt->iterator_statement);
 238
 239         __warn_on_silly_pre_loops();
 240         if (is_forever_loop(stmt)) {
 241                 __save_gotos(loop_name);
 242                 /* forever loops don't have an iterator_post_statement */
 243                 __pop_continues();
 244                 __pop_false_states();
 245                 __use_breaks();
 246         } else if (once_through) {
 247                 __merge_continues();
 248                 if (extra_state)
 249                         unchanged = __iterator_unchanged(extra_state, stmt->iterator_post_statement);
 250                 __split_statements(stmt->iterator_post_statement);
 251                 __save_gotos(loop_name);
 252                 __split_whole_condition(stmt->iterator_pre_condition);
 253                 nullify_path();
 254                 __merge_false_states();
 255                 if (extra_state && unchanged)
 256                         __extra_pre_loop_hook_after(extra_state,
 257                                 stmt->iterator_post_statement, stmt->iterator_pre_condition);
 258                 __pop_false_states();
 259                 __merge_breaks();
 260         } else {
 261                 __merge_continues();
 262                 __split_statements(stmt->iterator_post_statement);
 263                 __save_gotos(loop_name);
 264                 __split_whole_condition(stmt->iterator_pre_condition);
 265                 nullify_path();
 266                 __merge_false_states();
 267                 __merge_false_states();
 268                 __merge_breaks();
 269         }
 270 }
 271
 272 /*
 273  * Post loops are do {} while();
 274  */
 275 static void handle_post_loop(struct statement *stmt)
 276 {
 277         char *loop_name;
 278
 279         loop_name = get_loop_name(loop_num);
 280         loop_num++;
 281
 282         __push_continues();
 283         __push_breaks();
 284         __merge_gotos(loop_name);
 285         __split_statements(stmt->iterator_statement);
 286         __merge_continues();
 287         if (!is_zero(stmt->iterator_post_condition))
 288                 __save_gotos(loop_name);
 289
 290         if (is_forever_loop(stmt)) {
 291                 __use_breaks();
 292         } else {
 293                 __split_whole_condition(stmt->iterator_post_condition);
 294                 __use_false_states();
 295                 __merge_breaks();
 296         }
 297 }
 298
 299 static struct statement *last_stmt;
 300 static int is_last_stmt(struct statement *stmt)
 301 {
 302         if (stmt == last_stmt)
 303                 return 1;
 304         return 0;
 305 }
 306
 307 static void print_unreached_initializers(struct symbol_list *sym_list)
 308 {
 309         struct symbol *sym;
 310
 311         FOR_EACH_PTR(sym_list, sym) {
 312                 if(sym->initializer)
 313                         sm_msg("info: '%s' is not actually initialized (unreached code).",
 314                                 (sym->ident ? sym->ident->name : "this variable"));
 315         } END_FOR_EACH_PTR(sym);
 316 }
 317
 318 static void print_unreached(struct statement *stmt)
 319 {
 320
 321         static int print = 1;
 322
 323         if (__path_is_null()) {
 324                 switch (stmt->type) {
 325                 case STMT_COMPOUND: /* after a switch before a case stmt */
 326                 case STMT_CASE:
 327                 case STMT_LABEL:
 328                         break;
 329                 case STMT_DECLARATION: /* switch (x) { int a; case foo: ... */
 330                         print_unreached_initializers(stmt->declaration);
 331                         break;
 332                 case STMT_RETURN: /* gcc complains if you don't have a return statement */
 333                         if (is_last_stmt(stmt))
 334                                 break;
 335                 default:
 336                         if (print)
 337                                 sm_msg("info: ignoring unreachable code.");
 338                         print = 0;
 339                 }
 340         } else {
 341                 print = 1;
 342         }
 343
 344 }
 345
 346 static int empty_statement(struct statement *stmt)
 347 {
 348         if (!stmt)
 349                 return 0;
 350         if (stmt->type == STMT_EXPRESSION && !stmt->expression)
 351                 return 1;
 352         return 0;
 353 }
 354
 355 void __split_statements(struct statement *stmt)
 356 {
 357         if (!stmt)
 358                 return;
 359
 360         if (out_of_memory() || __bail_on_rest_of_function) {
 361                 static char *printed = NULL;
 362
 363                 if (printed != cur_func)
 364                         sm_msg("Function too hairy.  Giving up.");
 365                 printed = cur_func;
 366                 return;
 367         }
 368
 369         add_ptr_list(&big_statement_stack, stmt);
 370         free_expression_stack(&big_expression_stack);
 371         __smatch_lineno = stmt->pos.line;
 372         print_unreached(stmt);
 373         __pass_to_client(stmt, STMT_HOOK);
 374
 375         switch (stmt->type) {
 376         case STMT_DECLARATION:
 377                 split_declaration(stmt->declaration);
 378                 return;
 379         case STMT_RETURN:
 380                 __split_expr(stmt->ret_value);
 381                 __pass_to_client(stmt->ret_value, RETURN_HOOK);
 382                 nullify_path();
 383                 return;
 384         case STMT_EXPRESSION:
 385                 __split_expr(stmt->expression);
 386                 return;
 387         case STMT_COMPOUND: {
 388                 struct statement *s;
 389
 390                 if (!last_stmt)
 391                         last_stmt = last_ptr_list((struct ptr_list *)stmt->stmts);
 392                 __push_scope_hooks();
 393                 FOR_EACH_PTR(stmt->stmts, s) {
 394                         __split_statements(s);
 395                 } END_FOR_EACH_PTR(s);
 396                 __call_scope_hooks();
 397                 return;
 398         }
 399         case STMT_IF:
 400                 if (known_condition_true(stmt->if_conditional)) {
 401                         __split_statements(stmt->if_true);
 402                         return;
 403                 }
 404                 if (known_condition_false(stmt->if_conditional)) {
 405                         __split_statements(stmt->if_false);
 406                         return;
 407                 }
 408                 if (option_known_conditions &&
 409                     implied_condition_true(stmt->if_conditional)) {
 410                         sm_info("this condition is true.");
 411                         __split_statements(stmt->if_true);
 412                         return;
 413                 }
 414                 if (option_known_conditions &&
 415                     implied_condition_false(stmt->if_conditional)) {
 416                         sm_info("this condition is false.");
 417                         __split_statements(stmt->if_false);
 418                         return;
 419                 }
 420                 __split_whole_condition(stmt->if_conditional);
 421                 __split_statements(stmt->if_true);
 422                 if (empty_statement(stmt->if_true))
 423                         sm_msg("warn: if();");
 424                 __push_true_states();
 425                 __use_false_states();
 426                 __split_statements(stmt->if_false);
 427                 __merge_true_states();
 428                 return;
 429         case STMT_ITERATOR:
 430                 if (stmt->iterator_pre_condition)
 431                         handle_pre_loop(stmt);
 432                 else if (stmt->iterator_post_condition)
 433                         handle_post_loop(stmt);
 434                 else {
 435                         // these are for(;;) type loops.
 436                         handle_pre_loop(stmt);
 437                 }
 438                 return;
 439         case STMT_SWITCH:
 440                 __split_expr(stmt->switch_expression);
 441                 push_expression(&switch_expr_stack, stmt->switch_expression);
 442                 __save_switch_states(top_expression(switch_expr_stack));
 443                 nullify_path();
 444                 __push_default();
 445                 __push_breaks();
 446                 __split_statements(stmt->switch_statement);
 447                 if (!__pop_default())
 448                         __merge_switches(top_expression(switch_expr_stack),
 449                                       NULL);
 450                 __pop_switches();
 451                 __merge_breaks();
 452                 pop_expression(&switch_expr_stack);
 453                 return;
 454         case STMT_CASE:
 455                 __merge_switches(top_expression(switch_expr_stack),
 456                                       stmt->case_expression);
 457                 __pass_case_to_client(top_expression(switch_expr_stack),
 458                                       stmt->case_expression);
 459                 if (!stmt->case_expression)
 460                         __set_default();
 461                 __split_expr(stmt->case_expression);
 462                 __split_expr(stmt->case_to);
 463                 __split_statements(stmt->case_statement);
 464                 return;
 465         case STMT_LABEL:
 466                 if (stmt->label &&
 467                     stmt->label->type == SYM_LABEL &&
 468                     stmt->label->ident) {
 469                         __merge_gotos(stmt->label->ident->name);
 470                 }
 471                 __split_statements(stmt->label_statement);
 472                 return;
 473         case STMT_GOTO:
 474                 __split_expr(stmt->goto_expression);
 475                 if (stmt->goto_label && stmt->goto_label->type == SYM_NODE) {
 476                         if (!strcmp(stmt->goto_label->ident->name, "break")) {
 477                                 __process_breaks();
 478                         } else if (!strcmp(stmt->goto_label->ident->name,
 479                                            "continue")) {
 480                                 __process_continues();
 481                         }
 482                 } else if (stmt->goto_label &&
 483                            stmt->goto_label->type == SYM_LABEL &&
 484                            stmt->goto_label->ident) {
 485                         __save_gotos(stmt->goto_label->ident->name);
 486                 }
 487                 nullify_path();
 488                 return;
 489         case STMT_NONE:
 490                 return;
 491         case STMT_ASM:
 492                 __split_expr(stmt->asm_string);
 493                 //__split_expr(stmt->asm_outputs);
 494                 //__split_expr(stmt->asm_inputs);
 495                 //__split_expr(stmt->asm_clobbers);
 496                 return;
 497         case STMT_CONTEXT:
 498                 return;
 499         case STMT_RANGE:
 500                 __split_expr(stmt->range_expression);
 501                 __split_expr(stmt->range_low);
 502                 __split_expr(stmt->range_high);
 503                 return;
 504         }
 505 }
 506
 507 static void split_expr_list(struct expression_list *expr_list)
 508 {
 509         struct expression *expr;
 510         FOR_EACH_PTR(expr_list, expr) {
 511                 __split_expr(expr);
 512         } END_FOR_EACH_PTR(expr);
 513 }
 514
 515
 516 static void split_sym(struct symbol *sym)
 517 {
 518         if (!sym)
 519                 return;
 520         if (!(sym->namespace & NS_SYMBOL))
 521                 return;
 522
 523         __split_statements(sym->stmt);
 524         __split_expr(sym->array_size);
 525         split_symlist(sym->arguments);
 526         split_symlist(sym->symbol_list);
 527         __split_statements(sym->inline_stmt);
 528         split_symlist(sym->inline_symbol_list);
 529         __split_expr(sym->initializer);
 530 }
 531
 532 static void split_symlist(struct symbol_list *sym_list)
 533 {
 534         struct symbol *sym;
 535
 536         FOR_EACH_PTR(sym_list, sym) {
 537                 split_sym(sym);
 538         } END_FOR_EACH_PTR(sym);
 539 }
 540
 541 static struct expression *fake_assign_expr(struct symbol *sym)
 542 {
 543         struct expression *e_assign, *e_symbol;
 544
 545         e_assign = alloc_expression(sym->initializer->pos, EXPR_ASSIGNMENT);
 546         e_symbol = alloc_expression(sym->initializer->pos, EXPR_SYMBOL);
 547         e_assign->op = (int)'=';
 548         e_symbol->symbol = sym;
 549         e_symbol->symbol_name = sym->ident;
 550         e_assign->left = e_symbol;
 551         e_assign->right = sym->initializer;
 552         return e_assign;
 553 }
 554
 555 static void do_initializer_stuff(struct symbol *sym)
 556 {
 557         struct expression *assign;
 558         struct expression *tmp;
 559
 560         if(!sym->initializer)
 561                 return;
 562         __split_expr(sym->initializer);
 563         assign = fake_assign_expr(sym);
 564         if (__handle_condition_assigns(assign))
 565                 return;
 566         __pass_to_client(assign, ASSIGNMENT_HOOK);
 567         tmp = strip_expr(assign->right);
 568         if (tmp->type == EXPR_CALL)
 569                 __pass_to_client(assign, CALL_ASSIGNMENT_HOOK);
 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 }