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 #include <stdio.h>
  11 #include "token.h"
  12 #include "smatch.h"
  13 #include "smatch_expression_stacks.h"
  14 #include "smatch_extra.h"
  15 #include "smatch_slist.h" // just for sname.
  16
  17 int final_pass;
  18
  19 static int __smatch_lineno = 0;
  20
  21 static char *filename;
  22 static char *cur_func;
  23 static int line_func_start;
  24 static struct expression_stack *switch_expr_stack = NULL;
  25
  26 char *get_filename(void) {      return filename; }
  27 char *get_function(void) { return cur_func; }
  28 int get_lineno(void) { return __smatch_lineno; }
  29 int get_func_pos(void) { return __smatch_lineno - line_func_start; }
  30
  31 static void split_symlist(struct symbol_list *sym_list);
  32 static void split_declaration(struct symbol_list *sym_list);
  33 static void split_expr_list(struct expression_list *expr_list);
  34
  35 int option_assume_loops = 0;
  36 int option_known_conditions = 0;
  37 int option_two_passes = 0;
  38 struct symbol *cur_func_sym = NULL;
  39
  40 void __split_expr(struct expression *expr)
  41 {
  42         if (!expr)
  43                 return;
  44
  45         // printf("%d Debug expr_type %d %s\n", get_lineno(), expr->type, show_special(expr->op));
  46
  47         __smatch_lineno = expr->pos.line;
  48         __pass_to_client(expr, EXPR_HOOK);
  49
  50         switch (expr->type) {
  51         case EXPR_PREOP:
  52                 if (expr->op == '*')
  53                         __pass_to_client(expr, DEREF_HOOK);
  54         case EXPR_POSTOP:
  55                 __pass_to_client(expr, OP_HOOK);
  56                 __split_expr(expr->unop);
  57                 return;
  58         case EXPR_STATEMENT:
  59                 __split_statements(expr->statement);
  60                 return;
  61         case EXPR_LOGICAL:
  62                 __split_whole_condition(expr);
  63                 __push_true_states();
  64                 __use_false_states();
  65                 __merge_true_states();
  66                 __pop_false_only_stack();
  67                 return;
  68
  69                 return;
  70         case EXPR_BINOP:
  71         case EXPR_COMMA:
  72         case EXPR_COMPARE:
  73                 __split_expr(expr->left);
  74                 __split_expr(expr->right);
  75                 return;
  76         case EXPR_ASSIGNMENT: {
  77                 struct expression *tmp;
  78
  79                 __split_expr(expr->right);
  80                 __pass_to_client(expr, ASSIGNMENT_HOOK);
  81                 tmp = strip_expr(expr->right);
  82                 if (tmp->type == EXPR_CALL)
  83                         __pass_to_client(expr, CALL_ASSIGNMENT_HOOK);
  84                 __split_expr(expr->left);
  85                 return;
  86         }
  87         case EXPR_DEREF:
  88                 __pass_to_client(expr, DEREF_HOOK);
  89                 __split_expr(expr->deref);
  90                 return;
  91         case EXPR_SLICE:
  92                 __split_expr(expr->base);
  93                 return;
  94         case EXPR_CAST:
  95                 __split_expr(expr->cast_expression);
  96                 return;
  97         case EXPR_SIZEOF:
  98                 /* there isn't anything to pass a client from inside a sizeof() */
  99                 return;
 100         case EXPR_CONDITIONAL:
 101         case EXPR_SELECT:
 102                 __split_whole_condition(expr->conditional);
 103                 __split_expr(expr->cond_true);
 104                 __push_true_states();
 105                 __use_false_states();
 106                 __split_expr(expr->cond_false);
 107                 __merge_true_states();
 108                 __pop_false_only_stack();
 109                 return;
 110         case EXPR_CALL:
 111                 split_expr_list(expr->args);
 112                 __split_expr(expr->fn);
 113                 __pass_to_client(expr, FUNCTION_CALL_HOOK);
 114                 return;
 115         case EXPR_INITIALIZER:
 116                 split_expr_list(expr->expr_list);
 117                 return;
 118         case EXPR_IDENTIFIER:
 119                 __split_expr(expr->ident_expression);
 120                 return;
 121         case EXPR_INDEX:
 122                 __split_expr(expr->idx_expression);
 123                 return;
 124         case EXPR_POS:
 125                 __split_expr(expr->init_expr);
 126                 return;
 127         default:
 128                 return;
 129         };
 130 }
 131
 132 static int is_forever_loop(struct statement *stmt)
 133 {
 134
 135         struct expression *expr;
 136
 137         expr = strip_expr(stmt->iterator_pre_condition);
 138         if (!expr)
 139                 expr = stmt->iterator_post_condition;
 140         if (!expr) {
 141                 /* this is a for(;;) loop... */
 142                 return 1;
 143         }
 144
 145         if (expr->type == EXPR_VALUE && expr->value == 1) {
 146                 return 1;
 147         }
 148
 149         return 0;
 150 }
 151
 152 static int loop_num;
 153 static char *get_loop_name(int num)
 154 {
 155         char buf[256];
 156
 157         snprintf(buf, 255, "-loop%d", num);
 158         buf[255] = '\0';
 159         return alloc_sname(buf);;
 160 }
 161
 162 /*
 163  * Pre Loops are while and for loops.
 164  */
 165
 166 static void handle_pre_loop(struct statement *stmt)
 167 {
 168         int once_through; /* we go through the loop at least once */
 169         struct sm_state *extra_state = NULL;
 170         int unchanged = 0;
 171         char *loop_name;
 172
 173         loop_name = get_loop_name(loop_num);
 174         loop_num++;
 175
 176         __split_statements(stmt->iterator_pre_statement);
 177
 178         once_through = implied_condition_true(stmt->iterator_pre_condition);
 179
 180         __push_continues();
 181         __push_breaks();
 182
 183         __merge_gotos(loop_name);
 184         __split_whole_condition(stmt->iterator_pre_condition);
 185         if (once_through)
 186                 extra_state = __extra_pre_loop_hook_before(stmt->iterator_pre_statement);
 187         if (option_assume_loops)
 188                 once_through = 1;
 189         __split_statements(stmt->iterator_statement);
 190
 191         __warn_on_silly_pre_loops();
 192         if (is_forever_loop(stmt)) {
 193                 __save_gotos(loop_name);
 194                 __pop_false_only_stack();
 195                 /* forever loops don't have an iterator_post_statement */
 196                 __pop_continues();
 197                 __pop_false_states();
 198                 __use_breaks();
 199         } else if (once_through) {
 200                 __merge_continues();
 201                 if (extra_state)
 202                         unchanged = __iterator_unchanged(extra_state, stmt->iterator_post_statement);
 203                 __split_statements(stmt->iterator_post_statement);
 204                 __save_gotos(loop_name);
 205                 __split_whole_condition(stmt->iterator_pre_condition);
 206                 nullify_path();
 207                 __merge_false_states();
 208                 if (extra_state && unchanged)
 209                         __extra_pre_loop_hook_after(extra_state,
 210                                 stmt->iterator_post_statement, stmt->iterator_pre_condition);
 211                 __pop_false_states();
 212                 __pop_false_only_stack();
 213                 __pop_false_only_stack();
 214                 __merge_breaks();
 215         } else {
 216                 __merge_continues();
 217                 __split_statements(stmt->iterator_post_statement);
 218                 __save_gotos(loop_name);
 219                 __merge_false_states();
 220                 __use_false_only_stack();
 221                 __merge_breaks();
 222         }
 223 }
 224
 225 /*
 226  * Post loops are do {} while();
 227  */
 228 static void handle_post_loop(struct statement *stmt)
 229 {
 230         char *loop_name;
 231
 232         loop_name = get_loop_name(loop_num);
 233         loop_num++;
 234
 235         __push_continues();
 236         __push_breaks();
 237         __merge_gotos(loop_name);
 238         __split_statements(stmt->iterator_statement);
 239         __merge_continues();
 240         if (!is_zero(stmt->iterator_post_condition))
 241                 __save_gotos(loop_name);
 242
 243         if (is_forever_loop(stmt)) {
 244                 __use_breaks();
 245         } else {
 246                 __split_whole_condition(stmt->iterator_post_condition);
 247                 __use_false_states();
 248                 __merge_breaks();
 249         }
 250         __pop_false_only_stack();
 251 }
 252
 253 static void print_unreached(struct statement *stmt)
 254 {
 255
 256         /*
 257          * GCC insists on a return statement even where it is never
 258          * reached.  Also BUG() sometimes is a forever loop and
 259          * sometimes not so people put code after a BUG().  There
 260          * are way to many false positives.
 261          */
 262 #ifdef KERNEL
 263         return;
 264 #endif
 265         if (__path_is_null()) {
 266                 switch(stmt->type) {
 267                 case STMT_COMPOUND: /* after a switch before a case stmt */
 268                 case STMT_CASE:
 269                 case STMT_LABEL:
 270                 case STMT_DECLARATION: /* switch(x) { int a; case foo: ... */
 271                         break;
 272                 default:
 273                         sm_msg("unreachable code. %d", stmt->type);
 274                 }
 275         }
 276 }
 277
 278 void __split_statements(struct statement *stmt)
 279 {
 280         if (!stmt)
 281                 return;
 282
 283         if (out_of_memory()) {
 284                 static char *printed = NULL;
 285
 286                 if (printed != cur_func)
 287                         sm_msg("Function too big.  Giving up.");
 288                 printed = cur_func;
 289                 return;
 290         }
 291
 292         __smatch_lineno = stmt->pos.line;
 293         print_unreached(stmt);
 294         __pass_to_client(stmt, STMT_HOOK);
 295
 296         switch (stmt->type) {
 297         case STMT_DECLARATION:
 298                 split_declaration(stmt->declaration);
 299                 return;
 300         case STMT_RETURN:
 301                 __split_expr(stmt->ret_value);
 302                 __pass_to_client(stmt->ret_value, RETURN_HOOK);
 303                 nullify_path();
 304                 return;
 305         case STMT_EXPRESSION:
 306                 __split_expr(stmt->expression);
 307                 return;
 308         case STMT_COMPOUND: {
 309                 struct statement *s;
 310                 __push_scope_hooks();
 311                 FOR_EACH_PTR(stmt->stmts, s) {
 312                         __split_statements(s);
 313                 } END_FOR_EACH_PTR(s);
 314                 __call_scope_hooks();
 315                 return;
 316         }
 317         case STMT_IF:
 318                 if (known_condition_true(stmt->if_conditional)) {
 319                         __split_statements(stmt->if_true);
 320                         return;
 321                 }
 322                 if (known_condition_false(stmt->if_conditional)) {
 323                         __split_statements(stmt->if_false);
 324                         return;
 325                 }
 326                 if (option_known_conditions &&
 327                     implied_condition_true(stmt->if_conditional)) {
 328                         sm_msg("info: this condition is true.");
 329                         __split_statements(stmt->if_true);
 330                         return;
 331                 }
 332                 if (option_known_conditions &&
 333                     implied_condition_false(stmt->if_conditional)) {
 334                         sm_msg("info: this condition is false.");
 335                         __split_statements(stmt->if_false);
 336                         return;
 337                 }
 338                 __split_whole_condition(stmt->if_conditional);
 339                 __split_statements(stmt->if_true);
 340                 __push_true_states();
 341                 __use_false_states();
 342                 __split_statements(stmt->if_false);
 343                 __merge_true_states();
 344                 __pop_false_only_stack();
 345                 return;
 346         case STMT_ITERATOR:
 347                 if (stmt->iterator_pre_condition)
 348                         handle_pre_loop(stmt);
 349                 else if (stmt->iterator_post_condition)
 350                         handle_post_loop(stmt);
 351                 else {
 352                         // these are for(;;) type loops.
 353                         handle_pre_loop(stmt);
 354                 }
 355                 return;
 356         case STMT_SWITCH:
 357                 __split_expr(stmt->switch_expression);
 358                 push_expression(&switch_expr_stack, stmt->switch_expression);
 359                 __save_switch_states(top_expression(switch_expr_stack));
 360                 nullify_path();
 361                 __push_default();
 362                 __push_breaks();
 363                 __split_statements(stmt->switch_statement);
 364                 if (!__pop_default())
 365                         __merge_switches(top_expression(switch_expr_stack),
 366                                       NULL);
 367                 __pop_switches();
 368                 __merge_breaks();
 369                 pop_expression(&switch_expr_stack);
 370                 return;
 371         case STMT_CASE:
 372                 __merge_switches(top_expression(switch_expr_stack),
 373                                       stmt->case_expression);
 374                 __pass_case_to_client(top_expression(switch_expr_stack),
 375                                       stmt->case_expression);
 376                 if (!stmt->case_expression)
 377                         __set_default();
 378                 __split_expr(stmt->case_expression);
 379                 __split_expr(stmt->case_to);
 380                 __split_statements(stmt->case_statement);
 381                 return;
 382         case STMT_LABEL:
 383                 if (stmt->label &&
 384                     stmt->label->type == SYM_LABEL &&
 385                     stmt->label->ident) {
 386                         __merge_gotos(stmt->label->ident->name);
 387                 }
 388                 __split_statements(stmt->label_statement);
 389                 return;
 390         case STMT_GOTO:
 391                 __split_expr(stmt->goto_expression);
 392                 if (stmt->goto_label && stmt->goto_label->type == SYM_NODE) {
 393                         if (!strcmp(stmt->goto_label->ident->name, "break")) {
 394                                 __process_breaks();
 395                         } else if (!strcmp(stmt->goto_label->ident->name,
 396                                            "continue")) {
 397                                 __process_continues();
 398                         }
 399                 } else if (stmt->goto_label &&
 400                            stmt->goto_label->type == SYM_LABEL &&
 401                            stmt->goto_label->ident) {
 402                         __save_gotos(stmt->goto_label->ident->name);
 403                 }
 404                 nullify_path();
 405                 return;
 406         case STMT_NONE:
 407                 return;
 408         case STMT_ASM:
 409                 __split_expr(stmt->asm_string);
 410                 //__split_expr(stmt->asm_outputs);
 411                 //__split_expr(stmt->asm_inputs);
 412                 //__split_expr(stmt->asm_clobbers);
 413                 return;
 414         case STMT_CONTEXT:
 415                 return;
 416         case STMT_RANGE:
 417                 __split_expr(stmt->range_expression);
 418                 __split_expr(stmt->range_low);
 419                 __split_expr(stmt->range_high);
 420                 return;
 421         }
 422 }
 423
 424 static void split_expr_list(struct expression_list *expr_list)
 425 {
 426         struct expression *expr;
 427         FOR_EACH_PTR(expr_list, expr) {
 428                 __split_expr(expr);
 429         } END_FOR_EACH_PTR(expr);
 430 }
 431
 432
 433 static void split_sym(struct symbol *sym)
 434 {
 435         if (!sym)
 436                 return;
 437         if (!(sym->namespace & NS_SYMBOL))
 438                 return;
 439
 440         __pass_to_client(sym, SYM_HOOK);
 441         __split_statements(sym->stmt);
 442         __split_expr(sym->array_size);
 443         split_symlist(sym->arguments);
 444         split_symlist(sym->symbol_list);
 445         __split_statements(sym->inline_stmt);
 446         split_symlist(sym->inline_symbol_list);
 447         __split_expr(sym->initializer);
 448 }
 449
 450 static void split_symlist(struct symbol_list *sym_list)
 451 {
 452         struct symbol *sym;
 453
 454         FOR_EACH_PTR(sym_list, sym) {
 455                 split_sym(sym);
 456         } END_FOR_EACH_PTR(sym);
 457 }
 458
 459 static struct expression *fake_assign_expr(struct symbol *sym)
 460 {
 461         struct expression *e_assign, *e_symbol;
 462
 463         e_assign = alloc_expression(sym->initializer->pos, EXPR_ASSIGNMENT);
 464         e_symbol = alloc_expression(sym->initializer->pos, EXPR_SYMBOL);
 465         e_symbol->symbol = sym;
 466         e_symbol->symbol_name = sym->ident;
 467         e_assign->left = e_symbol;
 468         e_assign->right = sym->initializer;
 469         return e_assign;
 470 }
 471
 472 static void split_declaration(struct symbol_list *sym_list)
 473 {
 474         struct symbol *sym;
 475         struct expression *assign, *tmp;
 476
 477         FOR_EACH_PTR(sym_list, sym) {
 478                 __pass_to_client(sym, DECLARATION_HOOK);
 479                 __split_expr(sym->initializer);
 480                 if(sym->initializer) {
 481                         assign = fake_assign_expr(sym);
 482                         __pass_to_client(assign, ASSIGNMENT_HOOK);
 483                         tmp = strip_expr(assign->right);
 484                         if (tmp->type == EXPR_CALL)
 485                                 __pass_to_client(assign, CALL_ASSIGNMENT_HOOK);
 486                 }
 487                 split_sym(sym);
 488         } END_FOR_EACH_PTR(sym);
 489 }
 490
 491 static void split_functions(struct symbol_list *sym_list)
 492 {
 493         struct symbol *sym;
 494
 495         FOR_EACH_PTR(sym_list, sym) {
 496                 struct symbol *base_type;
 497                 base_type = get_base_type(sym);
 498                 if (sym->type == SYM_NODE && base_type->type == SYM_FN) {
 499                         cur_func_sym = sym;
 500                         if (base_type->stmt)
 501                                 line_func_start = base_type->stmt->pos.line;
 502                         if (sym->ident)
 503                                 cur_func = sym->ident->name;
 504                         __smatch_lineno = sym->pos.line;
 505                         sm_debug("new function:  %s\n", cur_func);
 506                         if (option_two_passes) {
 507                                 __unnullify_path();
 508                                 loop_num = 0;
 509                                 final_pass = 0;
 510                                 __pass_to_client(sym, FUNC_DEF_HOOK);
 511                                 __split_statements(base_type->stmt);
 512                                 nullify_path();
 513                         }
 514                         __unnullify_path();
 515                         loop_num = 0;
 516                         final_pass = 1;
 517                         __pass_to_client(sym, FUNC_DEF_HOOK);
 518                         __split_statements(base_type->stmt);
 519                         __pass_to_client(sym, END_FUNC_HOOK);
 520                         cur_func = NULL;
 521                         line_func_start = 0;
 522                         clear_all_states();
 523                         free_data_info_allocs();
 524                         free_expression_stack(&switch_expr_stack);
 525                 } else {
 526                         __pass_to_client(sym, BASE_HOOK);
 527                 }
 528         } END_FOR_EACH_PTR(sym);
 529         __pass_to_client_no_data(END_FILE_HOOK);
 530 }
 531
 532 void smatch (int argc, char **argv)
 533 {
 534
 535         struct string_list *filelist = NULL;
 536         struct symbol_list *sym_list;
 537
 538         if (argc < 2) {
 539                 printf("Usage:  smatch [--debug] <filename.c>\n");
 540                 exit(1);
 541         }
 542         sparse_initialize(argc, argv, &filelist);
 543         FOR_EACH_PTR_NOTAG(filelist, filename) {
 544                 sym_list = __sparse(filename);
 545                 split_functions(sym_list);
 546         } END_FOR_EACH_PTR_NOTAG(filename);
 547 }