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 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
  31 char *get_function(void) { return cur_func; }
  32 int get_lineno(void) { return __smatch_lineno; }
  33 int get_func_pos(void) { return __smatch_lineno - line_func_start; }
  34
  35 static void split_symlist(struct symbol_list *sym_list);
  36 static void split_declaration(struct symbol_list *sym_list);
  37 static void split_expr_list(struct expression_list *expr_list);
  38
  39 int option_assume_loops = 0;
  40 int option_known_conditions = 0;
  41 int option_two_passes = 0;
  42 struct symbol *cur_func_sym = NULL;
  43
  44 char *get_filename(void)
  45 {
  46         if (option_full_path)
  47                 return full_filename;
  48         return filename;
  49 }
  50
  51 void __split_expr(struct expression *expr)
  52 {
  53         if (!expr)
  54                 return;
  55
  56         // printf("%d Debug expr_type %d %s\n", get_lineno(), expr->type, show_special(expr->op));
  57
  58         push_expression(&big_expression_stack, expr);
  59         __smatch_lineno = expr->pos.line;
  60         __pass_to_client(expr, EXPR_HOOK);
  61
  62         switch (expr->type) {
  63         case EXPR_PREOP:
  64                 if (expr->op == '*')
  65                         __pass_to_client(expr, DEREF_HOOK);
  66         case EXPR_POSTOP:
  67                 __pass_to_client(expr, OP_HOOK);
  68                 __split_expr(expr->unop);
  69                 return;
  70         case EXPR_STATEMENT:
  71                 __split_statements(expr->statement);
  72                 return;
  73         case EXPR_LOGICAL:
  74                 __split_whole_condition(expr);
  75                 __push_true_states();
  76                 __use_false_states();
  77                 __merge_true_states();
  78                 __pop_false_only_stack();
  79                 return;
  80
  81                 return;
  82         case EXPR_BINOP:
  83         case EXPR_COMMA:
  84         case EXPR_COMPARE:
  85                 __split_expr(expr->left);
  86                 __split_expr(expr->right);
  87                 return;
  88         case EXPR_ASSIGNMENT: {
  89                 struct expression *tmp;
  90
  91                 __split_expr(expr->right);
  92                 __pass_to_client(expr, ASSIGNMENT_HOOK);
  93                 tmp = strip_expr(expr->right);
  94                 if (tmp->type == EXPR_CALL)
  95                         __pass_to_client(expr, CALL_ASSIGNMENT_HOOK);
  96                 __split_expr(expr->left);
  97                 return;
  98         }
  99         case EXPR_DEREF:
 100                 __pass_to_client(expr, DEREF_HOOK);
 101                 __split_expr(expr->deref);
 102                 return;
 103         case EXPR_SLICE:
 104                 __split_expr(expr->base);
 105                 return;
 106         case EXPR_CAST:
 107         case EXPR_FORCE_CAST:
 108                 __split_expr(expr->cast_expression);
 109                 return;
 110         case EXPR_SIZEOF:
 111                 /* there isn't anything to pass a client from inside a sizeof() */
 112                 return;
 113         case EXPR_CONDITIONAL:
 114         case EXPR_SELECT:
 115                 __split_whole_condition(expr->conditional);
 116                 __split_expr(expr->cond_true);
 117                 __push_true_states();
 118                 __use_false_states();
 119                 __split_expr(expr->cond_false);
 120                 __merge_true_states();
 121                 __pop_false_only_stack();
 122                 return;
 123         case EXPR_CALL:
 124                 split_expr_list(expr->args);
 125                 __split_expr(expr->fn);
 126                 __pass_to_client(expr, FUNCTION_CALL_HOOK);
 127                 return;
 128         case EXPR_INITIALIZER:
 129                 split_expr_list(expr->expr_list);
 130                 return;
 131         case EXPR_IDENTIFIER:
 132                 __split_expr(expr->ident_expression);
 133                 return;
 134         case EXPR_INDEX:
 135                 __split_expr(expr->idx_expression);
 136                 return;
 137         case EXPR_POS:
 138                 __split_expr(expr->init_expr);
 139                 return;
 140         case EXPR_SYMBOL:
 141                 __pass_to_client(expr, SYM_HOOK);
 142                 return;
 143         default:
 144                 return;
 145         };
 146 }
 147
 148 static int is_forever_loop(struct statement *stmt)
 149 {
 150
 151         struct expression *expr;
 152
 153         expr = strip_expr(stmt->iterator_pre_condition);
 154         if (!expr)
 155                 expr = stmt->iterator_post_condition;
 156         if (!expr) {
 157                 /* this is a for(;;) loop... */
 158                 return 1;
 159         }
 160
 161         if (expr->type == EXPR_VALUE && expr->value == 1) {
 162                 return 1;
 163         }
 164
 165         return 0;
 166 }
 167
 168 static int loop_num;
 169 static char *get_loop_name(int num)
 170 {
 171         char buf[256];
 172
 173         snprintf(buf, 255, "-loop%d", num);
 174         buf[255] = '\0';
 175         return alloc_sname(buf);;
 176 }
 177
 178 /*
 179  * Pre Loops are while and for loops.
 180  */
 181
 182 static void handle_pre_loop(struct statement *stmt)
 183 {
 184         int once_through; /* we go through the loop at least once */
 185         struct sm_state *extra_state = NULL;
 186         int unchanged = 0;
 187         char *loop_name;
 188
 189         loop_name = get_loop_name(loop_num);
 190         loop_num++;
 191
 192         __split_statements(stmt->iterator_pre_statement);
 193
 194         once_through = implied_condition_true(stmt->iterator_pre_condition);
 195
 196         __push_continues();
 197         __push_breaks();
 198
 199         __merge_gotos(loop_name);
 200         __split_whole_condition(stmt->iterator_pre_condition);
 201         if (once_through)
 202                 extra_state = __extra_pre_loop_hook_before(stmt->iterator_pre_statement);
 203         if (option_assume_loops)
 204                 once_through = 1;
 205         __split_statements(stmt->iterator_statement);
 206
 207         __warn_on_silly_pre_loops();
 208         if (is_forever_loop(stmt)) {
 209                 __save_gotos(loop_name);
 210                 __pop_false_only_stack();
 211                 /* forever loops don't have an iterator_post_statement */
 212                 __pop_continues();
 213                 __pop_false_states();
 214                 __use_breaks();
 215         } else if (once_through) {
 216                 __merge_continues();
 217                 if (extra_state)
 218                         unchanged = __iterator_unchanged(extra_state, stmt->iterator_post_statement);
 219                 __split_statements(stmt->iterator_post_statement);
 220                 __save_gotos(loop_name);
 221                 __split_whole_condition(stmt->iterator_pre_condition);
 222                 nullify_path();
 223                 __merge_false_states();
 224                 if (extra_state && unchanged)
 225                         __extra_pre_loop_hook_after(extra_state,
 226                                 stmt->iterator_post_statement, stmt->iterator_pre_condition);
 227                 __pop_false_states();
 228                 __pop_false_only_stack();
 229                 __pop_false_only_stack();
 230                 __merge_breaks();
 231         } else {
 232                 __merge_continues();
 233                 __split_statements(stmt->iterator_post_statement);
 234                 __save_gotos(loop_name);
 235                 __merge_false_states();
 236                 __use_false_only_stack();
 237                 __merge_breaks();
 238         }
 239 }
 240
 241 /*
 242  * Post loops are do {} while();
 243  */
 244 static void handle_post_loop(struct statement *stmt)
 245 {
 246         char *loop_name;
 247
 248         loop_name = get_loop_name(loop_num);
 249         loop_num++;
 250
 251         __push_continues();
 252         __push_breaks();
 253         __merge_gotos(loop_name);
 254         __split_statements(stmt->iterator_statement);
 255         __merge_continues();
 256         if (!is_zero(stmt->iterator_post_condition))
 257                 __save_gotos(loop_name);
 258
 259         if (is_forever_loop(stmt)) {
 260                 __use_breaks();
 261         } else {
 262                 __split_whole_condition(stmt->iterator_post_condition);
 263                 __use_false_states();
 264                 __merge_breaks();
 265         }
 266         __pop_false_only_stack();
 267 }
 268
 269 static void print_unreached(struct statement *stmt)
 270 {
 271
 272         /*
 273          * GCC insists on a return statement even where it is never
 274          * reached.  Also BUG() sometimes is a forever loop and
 275          * sometimes not so people put code after a BUG().  There
 276          * are way to many false positives.
 277          */
 278         return;
 279
 280         if (__path_is_null()) {
 281                 switch(stmt->type) {
 282                 case STMT_COMPOUND: /* after a switch before a case stmt */
 283                 case STMT_CASE:
 284                 case STMT_LABEL:
 285                 case STMT_DECLARATION: /* switch(x) { int a; case foo: ... */
 286                         break;
 287                 default:
 288                         sm_msg("unreachable code. %d", stmt->type);
 289                 }
 290         }
 291 }
 292
 293 void __split_statements(struct statement *stmt)
 294 {
 295         if (!stmt)
 296                 return;
 297
 298         if (out_of_memory()) {
 299                 static char *printed = NULL;
 300
 301                 if (printed != cur_func)
 302                         sm_msg("Function too big.  Giving up.");
 303                 printed = cur_func;
 304                 return;
 305         }
 306
 307         free_expression_stack(&big_expression_stack);
 308         __smatch_lineno = stmt->pos.line;
 309         print_unreached(stmt);
 310         __pass_to_client(stmt, STMT_HOOK);
 311
 312         switch (stmt->type) {
 313         case STMT_DECLARATION:
 314                 split_declaration(stmt->declaration);
 315                 return;
 316         case STMT_RETURN:
 317                 __split_expr(stmt->ret_value);
 318                 __pass_to_client(stmt->ret_value, RETURN_HOOK);
 319                 nullify_path();
 320                 return;
 321         case STMT_EXPRESSION:
 322                 __split_expr(stmt->expression);
 323                 return;
 324         case STMT_COMPOUND: {
 325                 struct statement *s;
 326                 __push_scope_hooks();
 327                 FOR_EACH_PTR(stmt->stmts, s) {
 328                         __split_statements(s);
 329                 } END_FOR_EACH_PTR(s);
 330                 __call_scope_hooks();
 331                 return;
 332         }
 333         case STMT_IF:
 334                 if (known_condition_true(stmt->if_conditional)) {
 335                         __split_statements(stmt->if_true);
 336                         return;
 337                 }
 338                 if (known_condition_false(stmt->if_conditional)) {
 339                         __split_statements(stmt->if_false);
 340                         return;
 341                 }
 342                 if (option_known_conditions &&
 343                     implied_condition_true(stmt->if_conditional)) {
 344                         sm_msg("info: this condition is true.");
 345                         __split_statements(stmt->if_true);
 346                         return;
 347                 }
 348                 if (option_known_conditions &&
 349                     implied_condition_false(stmt->if_conditional)) {
 350                         sm_msg("info: this condition is false.");
 351                         __split_statements(stmt->if_false);
 352                         return;
 353                 }
 354                 __split_whole_condition(stmt->if_conditional);
 355                 __split_statements(stmt->if_true);
 356                 __push_true_states();
 357                 __use_false_states();
 358                 __split_statements(stmt->if_false);
 359                 __merge_true_states();
 360                 __pop_false_only_stack();
 361                 return;
 362         case STMT_ITERATOR:
 363                 if (stmt->iterator_pre_condition)
 364                         handle_pre_loop(stmt);
 365                 else if (stmt->iterator_post_condition)
 366                         handle_post_loop(stmt);
 367                 else {
 368                         // these are for(;;) type loops.
 369                         handle_pre_loop(stmt);
 370                 }
 371                 return;
 372         case STMT_SWITCH:
 373                 __split_expr(stmt->switch_expression);
 374                 push_expression(&switch_expr_stack, stmt->switch_expression);
 375                 __save_switch_states(top_expression(switch_expr_stack));
 376                 nullify_path();
 377                 __push_default();
 378                 __push_breaks();
 379                 __split_statements(stmt->switch_statement);
 380                 if (!__pop_default())
 381                         __merge_switches(top_expression(switch_expr_stack),
 382                                       NULL);
 383                 __pop_switches();
 384                 __merge_breaks();
 385                 pop_expression(&switch_expr_stack);
 386                 return;
 387         case STMT_CASE:
 388                 __merge_switches(top_expression(switch_expr_stack),
 389                                       stmt->case_expression);
 390                 __pass_case_to_client(top_expression(switch_expr_stack),
 391                                       stmt->case_expression);
 392                 if (!stmt->case_expression)
 393                         __set_default();
 394                 __split_expr(stmt->case_expression);
 395                 __split_expr(stmt->case_to);
 396                 __split_statements(stmt->case_statement);
 397                 return;
 398         case STMT_LABEL:
 399                 if (stmt->label &&
 400                     stmt->label->type == SYM_LABEL &&
 401                     stmt->label->ident) {
 402                         __merge_gotos(stmt->label->ident->name);
 403                 }
 404                 __split_statements(stmt->label_statement);
 405                 return;
 406         case STMT_GOTO:
 407                 __split_expr(stmt->goto_expression);
 408                 if (stmt->goto_label && stmt->goto_label->type == SYM_NODE) {
 409                         if (!strcmp(stmt->goto_label->ident->name, "break")) {
 410                                 __process_breaks();
 411                         } else if (!strcmp(stmt->goto_label->ident->name,
 412                                            "continue")) {
 413                                 __process_continues();
 414                         }
 415                 } else if (stmt->goto_label &&
 416                            stmt->goto_label->type == SYM_LABEL &&
 417                            stmt->goto_label->ident) {
 418                         __save_gotos(stmt->goto_label->ident->name);
 419                 }
 420                 nullify_path();
 421                 return;
 422         case STMT_NONE:
 423                 return;
 424         case STMT_ASM:
 425                 __split_expr(stmt->asm_string);
 426                 //__split_expr(stmt->asm_outputs);
 427                 //__split_expr(stmt->asm_inputs);
 428                 //__split_expr(stmt->asm_clobbers);
 429                 return;
 430         case STMT_CONTEXT:
 431                 return;
 432         case STMT_RANGE:
 433                 __split_expr(stmt->range_expression);
 434                 __split_expr(stmt->range_low);
 435                 __split_expr(stmt->range_high);
 436                 return;
 437         }
 438 }
 439
 440 static void split_expr_list(struct expression_list *expr_list)
 441 {
 442         struct expression *expr;
 443         FOR_EACH_PTR(expr_list, expr) {
 444                 __split_expr(expr);
 445         } END_FOR_EACH_PTR(expr);
 446 }
 447
 448
 449 static void split_sym(struct symbol *sym)
 450 {
 451         if (!sym)
 452                 return;
 453         if (!(sym->namespace & NS_SYMBOL))
 454                 return;
 455
 456         __split_statements(sym->stmt);
 457         __split_expr(sym->array_size);
 458         split_symlist(sym->arguments);
 459         split_symlist(sym->symbol_list);
 460         __split_statements(sym->inline_stmt);
 461         split_symlist(sym->inline_symbol_list);
 462         __split_expr(sym->initializer);
 463 }
 464
 465 static void split_symlist(struct symbol_list *sym_list)
 466 {
 467         struct symbol *sym;
 468
 469         FOR_EACH_PTR(sym_list, sym) {
 470                 split_sym(sym);
 471         } END_FOR_EACH_PTR(sym);
 472 }
 473
 474 static struct expression *fake_assign_expr(struct symbol *sym)
 475 {
 476         struct expression *e_assign, *e_symbol;
 477
 478         e_assign = alloc_expression(sym->initializer->pos, EXPR_ASSIGNMENT);
 479         e_symbol = alloc_expression(sym->initializer->pos, EXPR_SYMBOL);
 480         e_assign->op = (int)'=';
 481         e_symbol->symbol = sym;
 482         e_symbol->symbol_name = sym->ident;
 483         e_assign->left = e_symbol;
 484         e_assign->right = sym->initializer;
 485         return e_assign;
 486 }
 487
 488 static void split_declaration(struct symbol_list *sym_list)
 489 {
 490         struct symbol *sym;
 491         struct expression *assign, *tmp;
 492
 493         FOR_EACH_PTR(sym_list, sym) {
 494                 __pass_to_client(sym, DECLARATION_HOOK);
 495                 __split_expr(sym->initializer);
 496                 if(sym->initializer) {
 497                         assign = fake_assign_expr(sym);
 498                         __pass_to_client(assign, ASSIGNMENT_HOOK);
 499                         tmp = strip_expr(assign->right);
 500                         if (tmp->type == EXPR_CALL)
 501                                 __pass_to_client(assign, CALL_ASSIGNMENT_HOOK);
 502                 }
 503                 split_sym(sym);
 504         } END_FOR_EACH_PTR(sym);
 505 }
 506
 507 static void split_functions(struct symbol_list *sym_list)
 508 {
 509         struct symbol *sym;
 510
 511         FOR_EACH_PTR(sym_list, sym) {
 512                 struct symbol *base_type;
 513                 base_type = get_base_type(sym);
 514                 if (sym->type == SYM_NODE && base_type->type == SYM_FN) {
 515                         cur_func_sym = sym;
 516                         if (base_type->stmt)
 517                                 line_func_start = base_type->stmt->pos.line;
 518                         if (sym->ident)
 519                                 cur_func = sym->ident->name;
 520                         __smatch_lineno = sym->pos.line;
 521                         sm_debug("new function:  %s\n", cur_func);
 522                         if (option_two_passes) {
 523                                 __unnullify_path();
 524                                 loop_num = 0;
 525                                 final_pass = 0;
 526                                 __pass_to_client(sym, FUNC_DEF_HOOK);
 527                                 __split_statements(base_type->stmt);
 528                                 nullify_path();
 529                         }
 530                         __unnullify_path();
 531                         loop_num = 0;
 532                         final_pass = 1;
 533                         __pass_to_client(sym, FUNC_DEF_HOOK);
 534                         __split_statements(base_type->stmt);
 535                         __pass_to_client(sym, END_FUNC_HOOK);
 536                         cur_func = NULL;
 537                         line_func_start = 0;
 538                         clear_all_states();
 539                         free_data_info_allocs();
 540                         free_expression_stack(&switch_expr_stack);
 541                 } else {
 542                         __pass_to_client(sym, BASE_HOOK);
 543                 }
 544         } END_FOR_EACH_PTR(sym);
 545         __pass_to_client_no_data(END_FILE_HOOK);
 546 }
 547
 548 void smatch (int argc, char **argv)
 549 {
 550
 551         struct string_list *filelist = NULL;
 552         struct symbol_list *sym_list;
 553
 554         if (argc < 2) {
 555                 printf("Usage:  smatch [--debug] <filename.c>\n");
 556                 exit(1);
 557         }
 558         sparse_initialize(argc, argv, &filelist);
 559         FOR_EACH_PTR_NOTAG(filelist, filename) {
 560                 int len;
 561
 562                 pathname = get_current_dir_name();
 563                 if (pathname) {
 564                         len = strlen(pathname) + 1 + strlen(filename) + 1;
 565                         full_filename = malloc(len);
 566                         snprintf(full_filename, len, "%s/%s", pathname, filename);
 567                 } else {
 568                         full_filename = filename;
 569                 }
 570
 571                 sym_list = __sparse(filename);
 572                 split_functions(sym_list);
 573
 574                 if (pathname) {
 575                         free(full_filename);
 576                         free(pathname);
 577                 }
 578         } END_FOR_EACH_PTR_NOTAG(filename);
 579 }