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