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