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 static int empty_statement(struct statement *stmt)
 293 {
 294         if (!stmt)
 295                 return 0;
 296         if (stmt->type == STMT_EXPRESSION && !stmt->expression)
 297                 return 1;
 298         return 0;
 299 }
 300
 301 void __split_statements(struct statement *stmt)
 302 {
 303         if (!stmt)
 304                 return;
 305
 306         if (out_of_memory()) {
 307                 static char *printed = NULL;
 308
 309                 if (printed != cur_func)
 310                         sm_msg("Function too big.  Giving up.");
 311                 printed = cur_func;
 312                 return;
 313         }
 314
 315         free_expression_stack(&big_expression_stack);
 316         __smatch_lineno = stmt->pos.line;
 317         print_unreached(stmt);
 318         __pass_to_client(stmt, STMT_HOOK);
 319
 320         switch (stmt->type) {
 321         case STMT_DECLARATION:
 322                 split_declaration(stmt->declaration);
 323                 return;
 324         case STMT_RETURN:
 325                 __split_expr(stmt->ret_value);
 326                 __pass_to_client(stmt->ret_value, RETURN_HOOK);
 327                 nullify_path();
 328                 return;
 329         case STMT_EXPRESSION:
 330                 __split_expr(stmt->expression);
 331                 return;
 332         case STMT_COMPOUND: {
 333                 struct statement *s;
 334                 __push_scope_hooks();
 335                 FOR_EACH_PTR(stmt->stmts, s) {
 336                         __split_statements(s);
 337                 } END_FOR_EACH_PTR(s);
 338                 __call_scope_hooks();
 339                 return;
 340         }
 341         case STMT_IF:
 342                 if (known_condition_true(stmt->if_conditional)) {
 343                         __split_statements(stmt->if_true);
 344                         return;
 345                 }
 346                 if (known_condition_false(stmt->if_conditional)) {
 347                         __split_statements(stmt->if_false);
 348                         return;
 349                 }
 350                 if (option_known_conditions &&
 351                     implied_condition_true(stmt->if_conditional)) {
 352                         sm_info("this condition is true.");
 353                         __split_statements(stmt->if_true);
 354                         return;
 355                 }
 356                 if (option_known_conditions &&
 357                     implied_condition_false(stmt->if_conditional)) {
 358                         sm_info("this condition is false.");
 359                         __split_statements(stmt->if_false);
 360                         return;
 361                 }
 362                 __split_whole_condition(stmt->if_conditional);
 363                 __split_statements(stmt->if_true);
 364                 if (empty_statement(stmt->if_true))
 365                         sm_msg("warning: if();");
 366                 __push_true_states();
 367                 __use_false_states();
 368                 __split_statements(stmt->if_false);
 369                 __merge_true_states();
 370                 __pop_false_only_stack();
 371                 return;
 372         case STMT_ITERATOR:
 373                 if (stmt->iterator_pre_condition)
 374                         handle_pre_loop(stmt);
 375                 else if (stmt->iterator_post_condition)
 376                         handle_post_loop(stmt);
 377                 else {
 378                         // these are for(;;) type loops.
 379                         handle_pre_loop(stmt);
 380                 }
 381                 return;
 382         case STMT_SWITCH:
 383                 __split_expr(stmt->switch_expression);
 384                 push_expression(&switch_expr_stack, stmt->switch_expression);
 385                 __save_switch_states(top_expression(switch_expr_stack));
 386                 nullify_path();
 387                 __push_default();
 388                 __push_breaks();
 389                 __split_statements(stmt->switch_statement);
 390                 if (!__pop_default())
 391                         __merge_switches(top_expression(switch_expr_stack),
 392                                       NULL);
 393                 __pop_switches();
 394                 __merge_breaks();
 395                 pop_expression(&switch_expr_stack);
 396                 return;
 397         case STMT_CASE:
 398                 __merge_switches(top_expression(switch_expr_stack),
 399                                       stmt->case_expression);
 400                 __pass_case_to_client(top_expression(switch_expr_stack),
 401                                       stmt->case_expression);
 402                 if (!stmt->case_expression)
 403                         __set_default();
 404                 __split_expr(stmt->case_expression);
 405                 __split_expr(stmt->case_to);
 406                 __split_statements(stmt->case_statement);
 407                 return;
 408         case STMT_LABEL:
 409                 if (stmt->label &&
 410                     stmt->label->type == SYM_LABEL &&
 411                     stmt->label->ident) {
 412                         __merge_gotos(stmt->label->ident->name);
 413                 }
 414                 __split_statements(stmt->label_statement);
 415                 return;
 416         case STMT_GOTO:
 417                 __split_expr(stmt->goto_expression);
 418                 if (stmt->goto_label && stmt->goto_label->type == SYM_NODE) {
 419                         if (!strcmp(stmt->goto_label->ident->name, "break")) {
 420                                 __process_breaks();
 421                         } else if (!strcmp(stmt->goto_label->ident->name,
 422                                            "continue")) {
 423                                 __process_continues();
 424                         }
 425                 } else if (stmt->goto_label &&
 426                            stmt->goto_label->type == SYM_LABEL &&
 427                            stmt->goto_label->ident) {
 428                         __save_gotos(stmt->goto_label->ident->name);
 429                 }
 430                 nullify_path();
 431                 return;
 432         case STMT_NONE:
 433                 return;
 434         case STMT_ASM:
 435                 __split_expr(stmt->asm_string);
 436                 //__split_expr(stmt->asm_outputs);
 437                 //__split_expr(stmt->asm_inputs);
 438                 //__split_expr(stmt->asm_clobbers);
 439                 return;
 440         case STMT_CONTEXT:
 441                 return;
 442         case STMT_RANGE:
 443                 __split_expr(stmt->range_expression);
 444                 __split_expr(stmt->range_low);
 445                 __split_expr(stmt->range_high);
 446                 return;
 447         }
 448 }
 449
 450 static void split_expr_list(struct expression_list *expr_list)
 451 {
 452         struct expression *expr;
 453         FOR_EACH_PTR(expr_list, expr) {
 454                 __split_expr(expr);
 455         } END_FOR_EACH_PTR(expr);
 456 }
 457
 458
 459 static void split_sym(struct symbol *sym)
 460 {
 461         if (!sym)
 462                 return;
 463         if (!(sym->namespace & NS_SYMBOL))
 464                 return;
 465
 466         __split_statements(sym->stmt);
 467         __split_expr(sym->array_size);
 468         split_symlist(sym->arguments);
 469         split_symlist(sym->symbol_list);
 470         __split_statements(sym->inline_stmt);
 471         split_symlist(sym->inline_symbol_list);
 472         __split_expr(sym->initializer);
 473 }
 474
 475 static void split_symlist(struct symbol_list *sym_list)
 476 {
 477         struct symbol *sym;
 478
 479         FOR_EACH_PTR(sym_list, sym) {
 480                 split_sym(sym);
 481         } END_FOR_EACH_PTR(sym);
 482 }
 483
 484 static struct expression *fake_assign_expr(struct symbol *sym)
 485 {
 486         struct expression *e_assign, *e_symbol;
 487
 488         e_assign = alloc_expression(sym->initializer->pos, EXPR_ASSIGNMENT);
 489         e_symbol = alloc_expression(sym->initializer->pos, EXPR_SYMBOL);
 490         e_assign->op = (int)'=';
 491         e_symbol->symbol = sym;
 492         e_symbol->symbol_name = sym->ident;
 493         e_assign->left = e_symbol;
 494         e_assign->right = sym->initializer;
 495         return e_assign;
 496 }
 497
 498 static void split_declaration(struct symbol_list *sym_list)
 499 {
 500         struct symbol *sym;
 501         struct expression *assign, *tmp;
 502
 503         FOR_EACH_PTR(sym_list, sym) {
 504                 __pass_to_client(sym, DECLARATION_HOOK);
 505                 __split_expr(sym->initializer);
 506                 if(sym->initializer) {
 507                         assign = fake_assign_expr(sym);
 508                         __pass_to_client(assign, ASSIGNMENT_HOOK);
 509                         tmp = strip_expr(assign->right);
 510                         if (tmp->type == EXPR_CALL)
 511                                 __pass_to_client(assign, CALL_ASSIGNMENT_HOOK);
 512                 }
 513                 split_sym(sym);
 514         } END_FOR_EACH_PTR(sym);
 515 }
 516
 517 static void split_functions(struct symbol_list *sym_list)
 518 {
 519         struct symbol *sym;
 520
 521         FOR_EACH_PTR(sym_list, sym) {
 522                 struct symbol *base_type;
 523                 base_type = get_base_type(sym);
 524                 if (sym->type == SYM_NODE && base_type->type == SYM_FN) {
 525                         cur_func_sym = sym;
 526                         if (base_type->stmt)
 527                                 line_func_start = base_type->stmt->pos.line;
 528                         if (sym->ident)
 529                                 cur_func = sym->ident->name;
 530                         __smatch_lineno = sym->pos.line;
 531                         sm_debug("new function:  %s\n", cur_func);
 532                         if (option_two_passes) {
 533                                 __unnullify_path();
 534                                 loop_num = 0;
 535                                 final_pass = 0;
 536                                 __pass_to_client(sym, FUNC_DEF_HOOK);
 537                                 __split_statements(base_type->stmt);
 538                                 nullify_path();
 539                         }
 540                         __unnullify_path();
 541                         loop_num = 0;
 542                         final_pass = 1;
 543                         __pass_to_client(sym, FUNC_DEF_HOOK);
 544                         __split_statements(base_type->stmt);
 545                         __pass_to_client(sym, END_FUNC_HOOK);
 546                         cur_func = NULL;
 547                         line_func_start = 0;
 548                         clear_all_states();
 549                         free_data_info_allocs();
 550                         free_expression_stack(&switch_expr_stack);
 551                 } else {
 552                         __pass_to_client(sym, BASE_HOOK);
 553                 }
 554         } END_FOR_EACH_PTR(sym);
 555         __pass_to_client_no_data(END_FILE_HOOK);
 556 }
 557
 558 void smatch (int argc, char **argv)
 559 {
 560
 561         struct string_list *filelist = NULL;
 562         struct symbol_list *sym_list;
 563
 564         if (argc < 2) {
 565                 printf("Usage:  smatch [--debug] <filename.c>\n");
 566                 exit(1);
 567         }
 568         sparse_initialize(argc, argv, &filelist);
 569         FOR_EACH_PTR_NOTAG(filelist, filename) {
 570                 int len;
 571
 572                 pathname = get_current_dir_name();
 573                 if (pathname) {
 574                         len = strlen(pathname) + 1 + strlen(filename) + 1;
 575                         full_filename = malloc(len);
 576                         snprintf(full_filename, len, "%s/%s", pathname, filename);
 577                 } else {
 578                         full_filename = filename;
 579                 }
 580
 581                 sym_list = __sparse(filename);
 582                 split_functions(sym_list);
 583
 584                 if (pathname) {
 585                         free(full_filename);
 586                         free(pathname);
 587                 }
 588         } END_FOR_EACH_PTR_NOTAG(filename);
 589 }