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