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