smatch_flow.c

   1 /*
   2  * sparse/smatch_flow.c
   3  *
   4  * Copyright (C) 2006,2008 Dan Carpenter.
   5  *
   6  *  Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 #define _GNU_SOURCE 1
  11 #include <unistd.h>
  12 #include <stdio.h>
  13 #include "token.h"
  14 #include "smatch.h"
  15 #include "smatch_expression_stacks.h"
  16 #include "smatch_extra.h"
  17 #include "smatch_slist.h" // just for sname.
  18
  19 int final_pass;
  20
  21 static int __smatch_lineno = 0;
  22
  23 static const char *filename;
  24 static char *pathname;
  25 static char *full_filename;
  26 static char *cur_func;
  27 static int line_func_start;
  28 static struct expression_list *switch_expr_stack = NULL;
  29 struct expression_list *big_expression_stack;
  30 struct statement_list *big_statement_stack;
  31 int __in_pre_condition = 0;
  32 int __bail_on_rest_of_function = 0;
  33 char *get_function(void) { return cur_func; }
  34 int get_lineno(void) { return __smatch_lineno; }
  35 int get_func_pos(void) { return __smatch_lineno - line_func_start; }
  36
  37 static void split_symlist(struct symbol_list *sym_list);
  38 static void split_declaration(struct symbol_list *sym_list);
  39 static void split_expr_list(struct expression_list *expr_list);
  40
  41 int option_assume_loops = 0;
  42 int option_known_conditions = 0;
  43 int option_two_passes = 0;
  44 struct symbol *cur_func_sym = NULL;
  45
  46 const char *get_filename(void)
  47 {
  48         if (option_full_path)
  49                 return full_filename;
  50         return filename;
  51 }
  52
  53 static void set_position(struct expression *expr)
  54 {
  55         int len;
  56         static int prev_stream = -1;
  57
  58         __smatch_lineno = expr->pos.line;
  59
  60         if (expr->pos.stream == prev_stream)
  61                 return;
  62
  63         filename = stream_name(expr->pos.stream);
  64
  65         free(full_filename);
  66         pathname = getcwd(NULL, 0);
  67         if (pathname) {
  68                 len = strlen(pathname) + 1 + strlen(filename) + 1;
  69                 full_filename = malloc(len);
  70                 snprintf(full_filename, len, "%s/%s", pathname, filename);
  71         } else {
  72                 full_filename = alloc_string(filename);
  73         }
  74         free(pathname);
  75 }
  76
  77 void __split_expr(struct expression *expr)
  78 {
  79         if (!expr)
  80                 return;
  81
  82         // printf("%d Debug expr_type %d %s\n", get_lineno(), expr->type, show_special(expr->op));
  83
  84         push_expression(&big_expression_stack, expr);
  85         set_position(expr);
  86         __pass_to_client(expr, EXPR_HOOK);
  87
  88         switch (expr->type) {
  89         case EXPR_PREOP:
  90                 if (expr->op == '*')
  91                         __pass_to_client(expr, DEREF_HOOK);
  92         case EXPR_POSTOP:
  93                 __pass_to_client(expr, OP_HOOK);
  94                 __split_expr(expr->unop);
  95                 break;
  96         case EXPR_STATEMENT:
  97                 __split_statements(expr->statement);
  98                 break;
  99         case EXPR_LOGICAL:
 100                 __split_whole_condition(expr);
 101                 __push_true_states();
 102                 __use_false_states();
 103                 __merge_true_states();
 104                 break;
 105         case EXPR_BINOP:
 106                 __pass_to_client(expr, BINOP_HOOK);
 107         case EXPR_COMMA:
 108         case EXPR_COMPARE:
 109                 __split_expr(expr->left);
 110                 __split_expr(expr->right);
 111                 break;
 112         case EXPR_ASSIGNMENT: {
 113                 struct expression *tmp;
 114
 115                 __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                 break;
 122         }
 123         case EXPR_DEREF:
 124                 __pass_to_client(expr, DEREF_HOOK);
 125                 __split_expr(expr->deref);
 126                 break;
 127         case EXPR_SLICE:
 128                 __split_expr(expr->base);
 129                 break;
 130         case EXPR_CAST:
 131         case EXPR_FORCE_CAST:
 132                 __split_expr(expr->cast_expression);
 133                 break;
 134         case EXPR_SIZEOF:
 135                 /* there isn't anything to pass a client from inside a sizeof() */
 136                 break;
 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                 break;
 146         case EXPR_CALL:
 147                 split_expr_list(expr->args);
 148                 __split_expr(expr->fn);
 149                 __pass_to_client(expr, FUNCTION_CALL_HOOK);
 150                 break;
 151         case EXPR_INITIALIZER:
 152                 split_expr_list(expr->expr_list);
 153                 break;
 154         case EXPR_IDENTIFIER:
 155                 __split_expr(expr->ident_expression);
 156                 break;
 157         case EXPR_INDEX:
 158                 __split_expr(expr->idx_expression);
 159                 break;
 160         case EXPR_POS:
 161                 __split_expr(expr->init_expr);
 162                 break;
 163         case EXPR_SYMBOL:
 164                 __pass_to_client(expr, SYM_HOOK);
 165                 break;
 166         default:
 167                 break;
 168         };
 169         pop_expression(&big_expression_stack);
 170 }
 171
 172 static int is_forever_loop(struct statement *stmt)
 173 {
 174
 175         struct expression *expr;
 176
 177         expr = strip_expr(stmt->iterator_pre_condition);
 178         if (!expr)
 179                 expr = stmt->iterator_post_condition;
 180         if (!expr) {
 181                 /* this is a for(;;) loop... */
 182                 return 1;
 183         }
 184
 185         if (expr->type == EXPR_VALUE && expr->value == 1) {
 186                 return 1;
 187         }
 188
 189         return 0;
 190 }
 191
 192 static int loop_num;
 193 static char *get_loop_name(int num)
 194 {
 195         char buf[256];
 196
 197         snprintf(buf, 255, "-loop%d", num);
 198         buf[255] = '\0';
 199         return alloc_sname(buf);;
 200 }
 201
 202 /*
 203  * Pre Loops are while and for loops.
 204  */
 205
 206 static void handle_pre_loop(struct statement *stmt)
 207 {
 208         int once_through; /* we go through the loop at least once */
 209         struct sm_state *extra_state = NULL;
 210         int unchanged = 0;
 211         char *loop_name;
 212
 213         loop_name = get_loop_name(loop_num);
 214         loop_num++;
 215
 216         __split_statements(stmt->iterator_pre_statement);
 217
 218         once_through = implied_condition_true(stmt->iterator_pre_condition);
 219
 220         __push_continues();
 221         __push_breaks();
 222
 223         __merge_gotos(loop_name);
 224
 225         __in_pre_condition++;
 226         __split_whole_condition(stmt->iterator_pre_condition);
 227         __in_pre_condition--;
 228
 229         if (once_through)
 230                 extra_state = __extra_pre_loop_hook_before(stmt->iterator_pre_statement);
 231         if (option_assume_loops)
 232                 once_through = 1;
 233         __split_statements(stmt->iterator_statement);
 234
 235         __warn_on_silly_pre_loops();
 236         if (is_forever_loop(stmt)) {
 237                 __save_gotos(loop_name);
 238                 /* forever loops don't have an iterator_post_statement */
 239                 __pop_continues();
 240                 __pop_false_states();
 241                 __use_breaks();
 242         } else if (once_through) {
 243                 __merge_continues();
 244                 if (extra_state)
 245                         unchanged = __iterator_unchanged(extra_state, stmt->iterator_post_statement);
 246                 __split_statements(stmt->iterator_post_statement);
 247                 __save_gotos(loop_name);
 248                 __split_whole_condition(stmt->iterator_pre_condition);
 249                 nullify_path();
 250                 __merge_false_states();
 251                 if (extra_state && unchanged)
 252                         __extra_pre_loop_hook_after(extra_state,
 253                                 stmt->iterator_post_statement, stmt->iterator_pre_condition);
 254                 __pop_false_states();
 255                 __merge_breaks();
 256         } else {
 257                 __merge_continues();
 258                 __split_statements(stmt->iterator_post_statement);
 259                 __save_gotos(loop_name);
 260                 __split_whole_condition(stmt->iterator_pre_condition);
 261                 nullify_path();
 262                 __merge_false_states();
 263                 __merge_false_states();
 264                 __merge_breaks();
 265         }
 266 }
 267
 268 /*
 269  * Post loops are do {} while();
 270  */
 271 static void handle_post_loop(struct statement *stmt)
 272 {
 273         char *loop_name;
 274
 275         loop_name = get_loop_name(loop_num);
 276         loop_num++;
 277
 278         __push_continues();
 279         __push_breaks();
 280         __merge_gotos(loop_name);
 281         __split_statements(stmt->iterator_statement);
 282         __merge_continues();
 283         if (!is_zero(stmt->iterator_post_condition))
 284                 __save_gotos(loop_name);
 285
 286         if (is_forever_loop(stmt)) {
 287                 __use_breaks();
 288         } else {
 289                 __split_whole_condition(stmt->iterator_post_condition);
 290                 __use_false_states();
 291                 __merge_breaks();
 292         }
 293 }
 294
 295 static struct statement *last_stmt;
 296 static int is_last_stmt(struct statement *stmt)
 297 {
 298         if (stmt == last_stmt)
 299                 return 1;
 300         return 0;
 301 }
 302
 303 static void print_unreached_initializers(struct symbol_list *sym_list)
 304 {
 305         struct symbol *sym;
 306
 307         FOR_EACH_PTR(sym_list, sym) {
 308                 if(sym->initializer)
 309                         sm_msg("info: '%s' is not actually initialized (unreached code).",
 310                                 (sym->ident ? sym->ident->name : "this variable"));
 311         } END_FOR_EACH_PTR(sym);
 312 }
 313
 314 static void print_unreached(struct statement *stmt)
 315 {
 316
 317         static int print = 1;
 318
 319         if (__path_is_null()) {
 320                 switch (stmt->type) {
 321                 case STMT_COMPOUND: /* after a switch before a case stmt */
 322                 case STMT_CASE:
 323                 case STMT_LABEL:
 324                         break;
 325                 case STMT_DECLARATION: /* switch (x) { int a; case foo: ... */
 326                         print_unreached_initializers(stmt->declaration);
 327                         break;
 328                 case STMT_RETURN: /* gcc complains if you don't have a return statement */
 329                         if (is_last_stmt(stmt))
 330                                 break;
 331                 default:
 332                         if (print)
 333                                 sm_msg("info: ignoring unreachable code.");
 334                         print = 0;
 335                 }
 336         } else {
 337                 print = 1;
 338         }
 339
 340 }
 341
 342 static int empty_statement(struct statement *stmt)
 343 {
 344         if (!stmt)
 345                 return 0;
 346         if (stmt->type == STMT_EXPRESSION && !stmt->expression)
 347                 return 1;
 348         return 0;
 349 }
 350
 351 void __split_statements(struct statement *stmt)
 352 {
 353         if (!stmt)
 354                 return;
 355
 356         if (out_of_memory() || __bail_on_rest_of_function) {
 357                 static char *printed = NULL;
 358
 359                 if (printed != cur_func)
 360                         sm_msg("Function too hairy.  Giving up.");
 361                 printed = cur_func;
 362                 return;
 363         }
 364
 365         add_ptr_list(&big_statement_stack, stmt);
 366         free_expression_stack(&big_expression_stack);
 367         __smatch_lineno = stmt->pos.line;
 368         print_unreached(stmt);
 369         __pass_to_client(stmt, STMT_HOOK);
 370
 371         switch (stmt->type) {
 372         case STMT_DECLARATION:
 373                 split_declaration(stmt->declaration);
 374                 return;
 375         case STMT_RETURN:
 376                 __split_expr(stmt->ret_value);
 377                 __pass_to_client(stmt->ret_value, RETURN_HOOK);
 378                 nullify_path();
 379                 return;
 380         case STMT_EXPRESSION:
 381                 __split_expr(stmt->expression);
 382                 return;
 383         case STMT_COMPOUND: {
 384                 struct statement *s;
 385
 386                 if (!last_stmt)
 387                         last_stmt = last_ptr_list((struct ptr_list *)stmt->stmts);
 388                 __push_scope_hooks();
 389                 FOR_EACH_PTR(stmt->stmts, s) {
 390                         __split_statements(s);
 391                 } END_FOR_EACH_PTR(s);
 392                 __call_scope_hooks();
 393                 return;
 394         }
 395         case STMT_IF:
 396                 if (known_condition_true(stmt->if_conditional)) {
 397                         __split_statements(stmt->if_true);
 398                         return;
 399                 }
 400                 if (known_condition_false(stmt->if_conditional)) {
 401                         __split_statements(stmt->if_false);
 402                         return;
 403                 }
 404                 if (option_known_conditions &&
 405                     implied_condition_true(stmt->if_conditional)) {
 406                         sm_info("this condition is true.");
 407                         __split_statements(stmt->if_true);
 408                         return;
 409                 }
 410                 if (option_known_conditions &&
 411                     implied_condition_false(stmt->if_conditional)) {
 412                         sm_info("this condition is false.");
 413                         __split_statements(stmt->if_false);
 414                         return;
 415                 }
 416                 __split_whole_condition(stmt->if_conditional);
 417                 __split_statements(stmt->if_true);
 418                 if (empty_statement(stmt->if_true))
 419                         sm_msg("warn: if();");
 420                 __push_true_states();
 421                 __use_false_states();
 422                 __split_statements(stmt->if_false);
 423                 __merge_true_states();
 424                 return;
 425         case STMT_ITERATOR:
 426                 if (stmt->iterator_pre_condition)
 427                         handle_pre_loop(stmt);
 428                 else if (stmt->iterator_post_condition)
 429                         handle_post_loop(stmt);
 430                 else {
 431                         // these are for(;;) type loops.
 432                         handle_pre_loop(stmt);
 433                 }
 434                 return;
 435         case STMT_SWITCH:
 436                 __split_expr(stmt->switch_expression);
 437                 push_expression(&switch_expr_stack, stmt->switch_expression);
 438                 __save_switch_states(top_expression(switch_expr_stack));
 439                 nullify_path();
 440                 __push_default();
 441                 __push_breaks();
 442                 __split_statements(stmt->switch_statement);
 443                 if (!__pop_default())
 444                         __merge_switches(top_expression(switch_expr_stack),
 445                                       NULL);
 446                 __pop_switches();
 447                 __merge_breaks();
 448                 pop_expression(&switch_expr_stack);
 449                 return;
 450         case STMT_CASE:
 451                 __merge_switches(top_expression(switch_expr_stack),
 452                                       stmt->case_expression);
 453                 __pass_case_to_client(top_expression(switch_expr_stack),
 454                                       stmt->case_expression);
 455                 if (!stmt->case_expression)
 456                         __set_default();
 457                 __split_expr(stmt->case_expression);
 458                 __split_expr(stmt->case_to);
 459                 __split_statements(stmt->case_statement);
 460                 return;
 461         case STMT_LABEL:
 462                 if (stmt->label &&
 463                     stmt->label->type == SYM_LABEL &&
 464                     stmt->label->ident) {
 465                         __merge_gotos(stmt->label->ident->name);
 466                 }
 467                 __split_statements(stmt->label_statement);
 468                 return;
 469         case STMT_GOTO:
 470                 __split_expr(stmt->goto_expression);
 471                 if (stmt->goto_label && stmt->goto_label->type == SYM_NODE) {
 472                         if (!strcmp(stmt->goto_label->ident->name, "break")) {
 473                                 __process_breaks();
 474                         } else if (!strcmp(stmt->goto_label->ident->name,
 475                                            "continue")) {
 476                                 __process_continues();
 477                         }
 478                 } else if (stmt->goto_label &&
 479                            stmt->goto_label->type == SYM_LABEL &&
 480                            stmt->goto_label->ident) {
 481                         __save_gotos(stmt->goto_label->ident->name);
 482                 }
 483                 nullify_path();
 484                 return;
 485         case STMT_NONE:
 486                 return;
 487         case STMT_ASM:
 488                 __split_expr(stmt->asm_string);
 489                 //__split_expr(stmt->asm_outputs);
 490                 //__split_expr(stmt->asm_inputs);
 491                 //__split_expr(stmt->asm_clobbers);
 492                 return;
 493         case STMT_CONTEXT:
 494                 return;
 495         case STMT_RANGE:
 496                 __split_expr(stmt->range_expression);
 497                 __split_expr(stmt->range_low);
 498                 __split_expr(stmt->range_high);
 499                 return;
 500         }
 501 }
 502
 503 static void split_expr_list(struct expression_list *expr_list)
 504 {
 505         struct expression *expr;
 506         FOR_EACH_PTR(expr_list, expr) {
 507                 __split_expr(expr);
 508         } END_FOR_EACH_PTR(expr);
 509 }
 510
 511
 512 static void split_sym(struct symbol *sym)
 513 {
 514         if (!sym)
 515                 return;
 516         if (!(sym->namespace & NS_SYMBOL))
 517                 return;
 518
 519         __split_statements(sym->stmt);
 520         __split_expr(sym->array_size);
 521         split_symlist(sym->arguments);
 522         split_symlist(sym->symbol_list);
 523         __split_statements(sym->inline_stmt);
 524         split_symlist(sym->inline_symbol_list);
 525         __split_expr(sym->initializer);
 526 }
 527
 528 static void split_symlist(struct symbol_list *sym_list)
 529 {
 530         struct symbol *sym;
 531
 532         FOR_EACH_PTR(sym_list, sym) {
 533                 split_sym(sym);
 534         } END_FOR_EACH_PTR(sym);
 535 }
 536
 537 static struct expression *fake_assign_expr(struct symbol *sym)
 538 {
 539         struct expression *e_assign, *e_symbol;
 540
 541         e_assign = alloc_expression(sym->initializer->pos, EXPR_ASSIGNMENT);
 542         e_symbol = alloc_expression(sym->initializer->pos, EXPR_SYMBOL);
 543         e_assign->op = (int)'=';
 544         e_symbol->symbol = sym;
 545         e_symbol->symbol_name = sym->ident;
 546         e_assign->left = e_symbol;
 547         e_assign->right = sym->initializer;
 548         return e_assign;
 549 }
 550
 551 static void split_declaration(struct symbol_list *sym_list)
 552 {
 553         struct symbol *sym;
 554         struct expression *assign, *tmp;
 555
 556         FOR_EACH_PTR(sym_list, sym) {
 557                 __pass_to_client(sym, DECLARATION_HOOK);
 558                 __split_expr(sym->initializer);
 559                 if(sym->initializer) {
 560                         assign = fake_assign_expr(sym);
 561                         __pass_to_client(assign, ASSIGNMENT_HOOK);
 562                         tmp = strip_expr(assign->right);
 563                         if (tmp->type == EXPR_CALL)
 564                                 __pass_to_client(assign, CALL_ASSIGNMENT_HOOK);
 565                 }
 566                 split_sym(sym);
 567         } END_FOR_EACH_PTR(sym);
 568 }
 569
 570 static void split_functions(struct symbol_list *sym_list)
 571 {
 572         struct symbol *sym;
 573
 574         FOR_EACH_PTR(sym_list, sym) {
 575                 struct symbol *base_type;
 576                 base_type = get_base_type(sym);
 577                 if (sym->type == SYM_NODE && base_type->type == SYM_FN) {
 578                         cur_func_sym = sym;
 579                         if (base_type->stmt)
 580                                 line_func_start = base_type->stmt->pos.line;
 581                         if (sym->ident)
 582                                 cur_func = sym->ident->name;
 583                         __smatch_lineno = sym->pos.line;
 584                         last_stmt = NULL;
 585                         sm_debug("new function:  %s\n", cur_func);
 586                         if (option_two_passes) {
 587                                 __unnullify_path();
 588                                 loop_num = 0;
 589                                 final_pass = 0;
 590                                 __pass_to_client(sym, FUNC_DEF_HOOK);
 591                                 __split_statements(base_type->stmt);
 592                                 nullify_path();
 593                         }
 594                         __unnullify_path();
 595                         loop_num = 0;
 596                         final_pass = 1;
 597                         __pass_to_client(sym, FUNC_DEF_HOOK);
 598                         __split_statements(base_type->stmt);
 599                         __pass_to_client(sym, END_FUNC_HOOK);
 600                         cur_func = NULL;
 601                         line_func_start = 0;
 602                         clear_all_states();
 603                         free_data_info_allocs();
 604                         free_expression_stack(&switch_expr_stack);
 605                         __free_ptr_list((struct ptr_list **)&big_statement_stack);
 606                         __bail_on_rest_of_function = 0;
 607                 } else {
 608                         __pass_to_client(sym, BASE_HOOK);
 609                 }
 610         } END_FOR_EACH_PTR(sym);
 611         __pass_to_client_no_data(END_FILE_HOOK);
 612 }
 613
 614 void smatch (int argc, char **argv)
 615 {
 616
 617         struct string_list *filelist = NULL;
 618         struct symbol_list *sym_list;
 619         char *file;
 620
 621         if (argc < 2) {
 622                 printf("Usage:  smatch [--debug] <filename.c>\n");
 623                 exit(1);
 624         }
 625         sparse_initialize(argc, argv, &filelist);
 626         FOR_EACH_PTR_NOTAG(filelist, file) {
 627                 sym_list = __sparse(file);
 628                 split_functions(sym_list);
 629         } END_FOR_EACH_PTR_NOTAG(file);
 630 }