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