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                 return;
  96         case EXPR_STATEMENT:
  97                 __split_statements(expr->statement);
  98                 return;
  99         case EXPR_LOGICAL:
 100                 __split_whole_condition(expr);
 101                 __push_true_states();
 102                 __use_false_states();
 103                 __merge_true_states();
 104                 return;
 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                 return;
 112         case EXPR_ASSIGNMENT: {
 113                 struct expression *tmp;
 114
 115                 __split_expr(expr->right);
 116                 __pass_to_client(expr, ASSIGNMENT_HOOK);
 117                 tmp = strip_expr(expr->right);
 118                 if (tmp->type == EXPR_CALL)
 119                         __pass_to_client(expr, CALL_ASSIGNMENT_HOOK);
 120                 __split_expr(expr->left);
 121                 return;
 122         }
 123         case EXPR_DEREF:
 124                 __pass_to_client(expr, DEREF_HOOK);
 125                 __split_expr(expr->deref);
 126                 return;
 127         case EXPR_SLICE:
 128                 __split_expr(expr->base);
 129                 return;
 130         case EXPR_CAST:
 131         case EXPR_FORCE_CAST:
 132                 __split_expr(expr->cast_expression);
 133                 return;
 134         case EXPR_SIZEOF:
 135                 /* there isn't anything to pass a client from inside a sizeof() */
 136                 return;
 137         case EXPR_CONDITIONAL:
 138         case EXPR_SELECT:
 139                 __split_whole_condition(expr->conditional);
 140                 __split_expr(expr->cond_true);
 141                 __push_true_states();
 142                 __use_false_states();
 143                 __split_expr(expr->cond_false);
 144                 __merge_true_states();
 145                 return;
 146         case EXPR_CALL:
 147                 split_expr_list(expr->args);
 148                 __split_expr(expr->fn);
 149                 __pass_to_client(expr, FUNCTION_CALL_HOOK);
 150                 return;
 151         case EXPR_INITIALIZER:
 152                 split_expr_list(expr->expr_list);
 153                 return;
 154         case EXPR_IDENTIFIER:
 155                 __split_expr(expr->ident_expression);
 156                 return;
 157         case EXPR_INDEX:
 158                 __split_expr(expr->idx_expression);
 159                 return;
 160         case EXPR_POS:
 161                 __split_expr(expr->init_expr);
 162                 return;
 163         case EXPR_SYMBOL:
 164                 __pass_to_client(expr, SYM_HOOK);
 165                 return;
 166         default:
 167                 return;
 168         };
 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 struct statement *last_stmt;
 295 static int is_last_stmt(struct statement *stmt)
 296 {
 297         if (stmt == last_stmt)
 298                 return 1;
 299         return 0;
 300 }
 301
 302 static void print_unreached_initializers(struct symbol_list *sym_list)
 303 {
 304         struct symbol *sym;
 305
 306         FOR_EACH_PTR(sym_list, sym) {
 307                 if(sym->initializer)
 308                         sm_msg("info: '%s' is not actually initialized (unreached code).",
 309                                 (sym->ident ? sym->ident->name : "this variable"));
 310         } END_FOR_EACH_PTR(sym);
 311 }
 312
 313 static void print_unreached(struct statement *stmt)
 314 {
 315
 316         static int print = 1;
 317
 318         if (__path_is_null()) {
 319                 switch (stmt->type) {
 320                 case STMT_COMPOUND: /* after a switch before a case stmt */
 321                 case STMT_CASE:
 322                 case STMT_LABEL:
 323                         break;
 324                 case STMT_DECLARATION: /* switch (x) { int a; case foo: ... */
 325                         print_unreached_initializers(stmt->declaration);
 326                         break;
 327                 case STMT_RETURN: /* gcc complains if you don't have a return statement */
 328                         if (is_last_stmt(stmt))
 329                                 break;
 330                 default:
 331                         if (print)
 332                                 sm_msg("info: ignoring unreachable code.");
 333                         print = 0;
 334                 }
 335         } else {
 336                 print = 1;
 337         }
 338
 339 }
 340
 341 static int empty_statement(struct statement *stmt)
 342 {
 343         if (!stmt)
 344                 return 0;
 345         if (stmt->type == STMT_EXPRESSION && !stmt->expression)
 346                 return 1;
 347         return 0;
 348 }
 349
 350 void __split_statements(struct statement *stmt)
 351 {
 352         if (!stmt)
 353                 return;
 354
 355         if (out_of_memory() || __bail_on_rest_of_function) {
 356                 static char *printed = NULL;
 357
 358                 if (printed != cur_func)
 359                         sm_msg("Function too hairy.  Giving up.");
 360                 printed = cur_func;
 361                 return;
 362         }
 363
 364         add_ptr_list(&big_statement_stack, stmt);
 365         free_expression_stack(&big_expression_stack);
 366         __smatch_lineno = stmt->pos.line;
 367         print_unreached(stmt);
 368         __pass_to_client(stmt, STMT_HOOK);
 369
 370         switch (stmt->type) {
 371         case STMT_DECLARATION:
 372                 split_declaration(stmt->declaration);
 373                 return;
 374         case STMT_RETURN:
 375                 __split_expr(stmt->ret_value);
 376                 __pass_to_client(stmt->ret_value, RETURN_HOOK);
 377                 nullify_path();
 378                 return;
 379         case STMT_EXPRESSION:
 380                 __split_expr(stmt->expression);
 381                 return;
 382         case STMT_COMPOUND: {
 383                 struct statement *s;
 384
 385                 if (!last_stmt)
 386                         last_stmt = last_ptr_list((struct ptr_list *)stmt->stmts);
 387                 __push_scope_hooks();
 388                 FOR_EACH_PTR(stmt->stmts, s) {
 389                         __split_statements(s);
 390                 } END_FOR_EACH_PTR(s);
 391                 __call_scope_hooks();
 392                 return;
 393         }
 394         case STMT_IF:
 395                 if (known_condition_true(stmt->if_conditional)) {
 396                         __split_statements(stmt->if_true);
 397                         return;
 398                 }
 399                 if (known_condition_false(stmt->if_conditional)) {
 400                         __split_statements(stmt->if_false);
 401                         return;
 402                 }
 403                 if (option_known_conditions &&
 404                     implied_condition_true(stmt->if_conditional)) {
 405                         sm_info("this condition is true.");
 406                         __split_statements(stmt->if_true);
 407                         return;
 408                 }
 409                 if (option_known_conditions &&
 410                     implied_condition_false(stmt->if_conditional)) {
 411                         sm_info("this condition is false.");
 412                         __split_statements(stmt->if_false);
 413                         return;
 414                 }
 415                 __split_whole_condition(stmt->if_conditional);
 416                 __split_statements(stmt->if_true);
 417                 if (empty_statement(stmt->if_true))
 418                         sm_msg("warn: if();");
 419                 __push_true_states();
 420                 __use_false_states();
 421                 __split_statements(stmt->if_false);
 422                 __merge_true_states();
 423                 return;
 424         case STMT_ITERATOR:
 425                 if (stmt->iterator_pre_condition)
 426                         handle_pre_loop(stmt);
 427                 else if (stmt->iterator_post_condition)
 428                         handle_post_loop(stmt);
 429                 else {
 430                         // these are for(;;) type loops.
 431                         handle_pre_loop(stmt);
 432                 }
 433                 return;
 434         case STMT_SWITCH:
 435                 __split_expr(stmt->switch_expression);
 436                 push_expression(&switch_expr_stack, stmt->switch_expression);
 437                 __save_switch_states(top_expression(switch_expr_stack));
 438                 nullify_path();
 439                 __push_default();
 440                 __push_breaks();
 441                 __split_statements(stmt->switch_statement);
 442                 if (!__pop_default())
 443                         __merge_switches(top_expression(switch_expr_stack),
 444                                       NULL);
 445                 __pop_switches();
 446                 __merge_breaks();
 447                 pop_expression(&switch_expr_stack);
 448                 return;
 449         case STMT_CASE:
 450                 __merge_switches(top_expression(switch_expr_stack),
 451                                       stmt->case_expression);
 452                 __pass_case_to_client(top_expression(switch_expr_stack),
 453                                       stmt->case_expression);
 454                 if (!stmt->case_expression)
 455                         __set_default();
 456                 __split_expr(stmt->case_expression);
 457                 __split_expr(stmt->case_to);
 458                 __split_statements(stmt->case_statement);
 459                 return;
 460         case STMT_LABEL:
 461                 if (stmt->label &&
 462                     stmt->label->type == SYM_LABEL &&
 463                     stmt->label->ident) {
 464                         __merge_gotos(stmt->label->ident->name);
 465                 }
 466                 __split_statements(stmt->label_statement);
 467                 return;
 468         case STMT_GOTO:
 469                 __split_expr(stmt->goto_expression);
 470                 if (stmt->goto_label && stmt->goto_label->type == SYM_NODE) {
 471                         if (!strcmp(stmt->goto_label->ident->name, "break")) {
 472                                 __process_breaks();
 473                         } else if (!strcmp(stmt->goto_label->ident->name,
 474                                            "continue")) {
 475                                 __process_continues();
 476                         }
 477                 } else if (stmt->goto_label &&
 478                            stmt->goto_label->type == SYM_LABEL &&
 479                            stmt->goto_label->ident) {
 480                         __save_gotos(stmt->goto_label->ident->name);
 481                 }
 482                 nullify_path();
 483                 return;
 484         case STMT_NONE:
 485                 return;
 486         case STMT_ASM:
 487                 __split_expr(stmt->asm_string);
 488                 //__split_expr(stmt->asm_outputs);
 489                 //__split_expr(stmt->asm_inputs);
 490                 //__split_expr(stmt->asm_clobbers);
 491                 return;
 492         case STMT_CONTEXT:
 493                 return;
 494         case STMT_RANGE:
 495                 __split_expr(stmt->range_expression);
 496                 __split_expr(stmt->range_low);
 497                 __split_expr(stmt->range_high);
 498                 return;
 499         }
 500 }
 501
 502 static void split_expr_list(struct expression_list *expr_list)
 503 {
 504         struct expression *expr;
 505         FOR_EACH_PTR(expr_list, expr) {
 506                 __split_expr(expr);
 507         } END_FOR_EACH_PTR(expr);
 508 }
 509
 510
 511 static void split_sym(struct symbol *sym)
 512 {
 513         if (!sym)
 514                 return;
 515         if (!(sym->namespace & NS_SYMBOL))
 516                 return;
 517
 518         __split_statements(sym->stmt);
 519         __split_expr(sym->array_size);
 520         split_symlist(sym->arguments);
 521         split_symlist(sym->symbol_list);
 522         __split_statements(sym->inline_stmt);
 523         split_symlist(sym->inline_symbol_list);
 524         __split_expr(sym->initializer);
 525 }
 526
 527 static void split_symlist(struct symbol_list *sym_list)
 528 {
 529         struct symbol *sym;
 530
 531         FOR_EACH_PTR(sym_list, sym) {
 532                 split_sym(sym);
 533         } END_FOR_EACH_PTR(sym);
 534 }
 535
 536 static struct expression *fake_assign_expr(struct symbol *sym)
 537 {
 538         struct expression *e_assign, *e_symbol;
 539
 540         e_assign = alloc_expression(sym->initializer->pos, EXPR_ASSIGNMENT);
 541         e_symbol = alloc_expression(sym->initializer->pos, EXPR_SYMBOL);
 542         e_assign->op = (int)'=';
 543         e_symbol->symbol = sym;
 544         e_symbol->symbol_name = sym->ident;
 545         e_assign->left = e_symbol;
 546         e_assign->right = sym->initializer;
 547         return e_assign;
 548 }
 549
 550 static void split_declaration(struct symbol_list *sym_list)
 551 {
 552         struct symbol *sym;
 553         struct expression *assign, *tmp;
 554
 555         FOR_EACH_PTR(sym_list, sym) {
 556                 __pass_to_client(sym, DECLARATION_HOOK);
 557                 __split_expr(sym->initializer);
 558                 if(sym->initializer) {
 559                         assign = fake_assign_expr(sym);
 560                         __pass_to_client(assign, ASSIGNMENT_HOOK);
 561                         tmp = strip_expr(assign->right);
 562                         if (tmp->type == EXPR_CALL)
 563                                 __pass_to_client(assign, CALL_ASSIGNMENT_HOOK);
 564                 }
 565                 split_sym(sym);
 566         } END_FOR_EACH_PTR(sym);
 567 }
 568
 569 static void split_functions(struct symbol_list *sym_list)
 570 {
 571         struct symbol *sym;
 572
 573         FOR_EACH_PTR(sym_list, sym) {
 574                 struct symbol *base_type;
 575                 base_type = get_base_type(sym);
 576                 if (sym->type == SYM_NODE && base_type->type == SYM_FN) {
 577                         cur_func_sym = sym;
 578                         if (base_type->stmt)
 579                                 line_func_start = base_type->stmt->pos.line;
 580                         if (sym->ident)
 581                                 cur_func = sym->ident->name;
 582                         __smatch_lineno = sym->pos.line;
 583                         last_stmt = NULL;
 584                         sm_debug("new function:  %s\n", cur_func);
 585                         if (option_two_passes) {
 586                                 __unnullify_path();
 587                                 loop_num = 0;
 588                                 final_pass = 0;
 589                                 __pass_to_client(sym, FUNC_DEF_HOOK);
 590                                 __split_statements(base_type->stmt);
 591                                 nullify_path();
 592                         }
 593                         __unnullify_path();
 594                         loop_num = 0;
 595                         final_pass = 1;
 596                         __pass_to_client(sym, FUNC_DEF_HOOK);
 597                         __split_statements(base_type->stmt);
 598                         __pass_to_client(sym, END_FUNC_HOOK);
 599                         cur_func = NULL;
 600                         line_func_start = 0;
 601                         clear_all_states();
 602                         free_data_info_allocs();
 603                         free_expression_stack(&switch_expr_stack);
 604                         __free_ptr_list((struct ptr_list **)&big_statement_stack);
 605                         __bail_on_rest_of_function = 0;
 606                 } else {
 607                         __pass_to_client(sym, BASE_HOOK);
 608                 }
 609         } END_FOR_EACH_PTR(sym);
 610         __pass_to_client_no_data(END_FILE_HOOK);
 611 }
 612
 613 void smatch (int argc, char **argv)
 614 {
 615
 616         struct string_list *filelist = NULL;
 617         struct symbol_list *sym_list;
 618         char *file;
 619
 620         if (argc < 2) {
 621                 printf("Usage:  smatch [--debug] <filename.c>\n");
 622                 exit(1);
 623         }
 624         sparse_initialize(argc, argv, &filelist);
 625         FOR_EACH_PTR_NOTAG(filelist, file) {
 626                 sym_list = __sparse(file);
 627                 split_functions(sym_list);
 628         } END_FOR_EACH_PTR_NOTAG(file);
 629 }