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                 return;
  79         case EXPR_BINOP:
  80                 __pass_to_client(expr, BINOP_HOOK);
  81         case EXPR_COMMA:
  82         case EXPR_COMPARE:
  83                 __split_expr(expr->left);
  84                 __split_expr(expr->right);
  85                 return;
  86         case EXPR_ASSIGNMENT: {
  87                 struct expression *tmp;
  88
  89                 __split_expr(expr->right);
  90                 __pass_to_client(expr, ASSIGNMENT_HOOK);
  91                 tmp = strip_expr(expr->right);
  92                 if (tmp->type == EXPR_CALL)
  93                         __pass_to_client(expr, CALL_ASSIGNMENT_HOOK);
  94                 __split_expr(expr->left);
  95                 return;
  96         }
  97         case EXPR_DEREF:
  98                 __pass_to_client(expr, DEREF_HOOK);
  99                 __split_expr(expr->deref);
 100                 return;
 101         case EXPR_SLICE:
 102                 __split_expr(expr->base);
 103                 return;
 104         case EXPR_CAST:
 105         case EXPR_FORCE_CAST:
 106                 __split_expr(expr->cast_expression);
 107                 return;
 108         case EXPR_SIZEOF:
 109                 /* there isn't anything to pass a client from inside a sizeof() */
 110                 return;
 111         case EXPR_CONDITIONAL:
 112         case EXPR_SELECT:
 113                 __split_whole_condition(expr->conditional);
 114                 __split_expr(expr->cond_true);
 115                 __push_true_states();
 116                 __use_false_states();
 117                 __split_expr(expr->cond_false);
 118                 __merge_true_states();
 119                 return;
 120         case EXPR_CALL:
 121                 split_expr_list(expr->args);
 122                 __split_expr(expr->fn);
 123                 __pass_to_client(expr, FUNCTION_CALL_HOOK);
 124                 return;
 125         case EXPR_INITIALIZER:
 126                 split_expr_list(expr->expr_list);
 127                 return;
 128         case EXPR_IDENTIFIER:
 129                 __split_expr(expr->ident_expression);
 130                 return;
 131         case EXPR_INDEX:
 132                 __split_expr(expr->idx_expression);
 133                 return;
 134         case EXPR_POS:
 135                 __split_expr(expr->init_expr);
 136                 return;
 137         case EXPR_SYMBOL:
 138                 __pass_to_client(expr, SYM_HOOK);
 139                 return;
 140         default:
 141                 return;
 142         };
 143 }
 144
 145 static int is_forever_loop(struct statement *stmt)
 146 {
 147
 148         struct expression *expr;
 149
 150         expr = strip_expr(stmt->iterator_pre_condition);
 151         if (!expr)
 152                 expr = stmt->iterator_post_condition;
 153         if (!expr) {
 154                 /* this is a for(;;) loop... */
 155                 return 1;
 156         }
 157
 158         if (expr->type == EXPR_VALUE && expr->value == 1) {
 159                 return 1;
 160         }
 161
 162         return 0;
 163 }
 164
 165 static int loop_num;
 166 static char *get_loop_name(int num)
 167 {
 168         char buf[256];
 169
 170         snprintf(buf, 255, "-loop%d", num);
 171         buf[255] = '\0';
 172         return alloc_sname(buf);;
 173 }
 174
 175 /*
 176  * Pre Loops are while and for loops.
 177  */
 178
 179 static void handle_pre_loop(struct statement *stmt)
 180 {
 181         int once_through; /* we go through the loop at least once */
 182         struct sm_state *extra_state = NULL;
 183         int unchanged = 0;
 184         char *loop_name;
 185
 186         loop_name = get_loop_name(loop_num);
 187         loop_num++;
 188
 189         __split_statements(stmt->iterator_pre_statement);
 190
 191         once_through = implied_condition_true(stmt->iterator_pre_condition);
 192
 193         __push_continues();
 194         __push_breaks();
 195
 196         __merge_gotos(loop_name);
 197         __split_whole_condition(stmt->iterator_pre_condition);
 198         if (once_through)
 199                 extra_state = __extra_pre_loop_hook_before(stmt->iterator_pre_statement);
 200         if (option_assume_loops)
 201                 once_through = 1;
 202         __split_statements(stmt->iterator_statement);
 203
 204         __warn_on_silly_pre_loops();
 205         if (is_forever_loop(stmt)) {
 206                 __save_gotos(loop_name);
 207                 /* forever loops don't have an iterator_post_statement */
 208                 __pop_continues();
 209                 __pop_false_states();
 210                 __use_breaks();
 211         } else if (once_through) {
 212                 __merge_continues();
 213                 if (extra_state)
 214                         unchanged = __iterator_unchanged(extra_state, stmt->iterator_post_statement);
 215                 __split_statements(stmt->iterator_post_statement);
 216                 __save_gotos(loop_name);
 217                 __split_whole_condition(stmt->iterator_pre_condition);
 218                 nullify_path();
 219                 __merge_false_states();
 220                 if (extra_state && unchanged)
 221                         __extra_pre_loop_hook_after(extra_state,
 222                                 stmt->iterator_post_statement, stmt->iterator_pre_condition);
 223                 __pop_false_states();
 224                 __merge_breaks();
 225         } else {
 226                 __merge_continues();
 227                 __split_statements(stmt->iterator_post_statement);
 228                 __save_gotos(loop_name);
 229                 __split_whole_condition(stmt->iterator_pre_condition);
 230                 nullify_path();
 231                 __merge_false_states();
 232                 __merge_false_states();
 233                 __merge_breaks();
 234         }
 235 }
 236
 237 /*
 238  * Post loops are do {} while();
 239  */
 240 static void handle_post_loop(struct statement *stmt)
 241 {
 242         char *loop_name;
 243
 244         loop_name = get_loop_name(loop_num);
 245         loop_num++;
 246
 247         __push_continues();
 248         __push_breaks();
 249         __merge_gotos(loop_name);
 250         __split_statements(stmt->iterator_statement);
 251         __merge_continues();
 252         if (!is_zero(stmt->iterator_post_condition))
 253                 __save_gotos(loop_name);
 254
 255         if (is_forever_loop(stmt)) {
 256                 __use_breaks();
 257         } else {
 258                 __split_whole_condition(stmt->iterator_post_condition);
 259                 __use_false_states();
 260                 __merge_breaks();
 261         }
 262 }
 263
 264 static void print_unreached(struct statement *stmt)
 265 {
 266
 267         /*
 268          * GCC insists on a return statement even where it is never
 269          * reached.  Also BUG() sometimes is a forever loop and
 270          * sometimes not so people put code after a BUG().  There
 271          * are way to many false positives.
 272          */
 273         return;
 274
 275         if (__path_is_null()) {
 276                 switch(stmt->type) {
 277                 case STMT_COMPOUND: /* after a switch before a case stmt */
 278                 case STMT_CASE:
 279                 case STMT_LABEL:
 280                 case STMT_DECLARATION: /* switch(x) { int a; case foo: ... */
 281                         break;
 282                 default:
 283                         sm_msg("unreachable code. %d", stmt->type);
 284                 }
 285         }
 286 }
 287
 288 static int empty_statement(struct statement *stmt)
 289 {
 290         if (!stmt)
 291                 return 0;
 292         if (stmt->type == STMT_EXPRESSION && !stmt->expression)
 293                 return 1;
 294         return 0;
 295 }
 296
 297 void __split_statements(struct statement *stmt)
 298 {
 299         if (!stmt)
 300                 return;
 301
 302         if (out_of_memory()) {
 303                 static char *printed = NULL;
 304
 305                 if (printed != cur_func)
 306                         sm_msg("Function too big.  Giving up.");
 307                 printed = cur_func;
 308                 return;
 309         }
 310
 311         free_expression_stack(&big_expression_stack);
 312         __smatch_lineno = stmt->pos.line;
 313         print_unreached(stmt);
 314         __pass_to_client(stmt, STMT_HOOK);
 315
 316         switch (stmt->type) {
 317         case STMT_DECLARATION:
 318                 split_declaration(stmt->declaration);
 319                 return;
 320         case STMT_RETURN:
 321                 __split_expr(stmt->ret_value);
 322                 __pass_to_client(stmt->ret_value, RETURN_HOOK);
 323                 nullify_path();
 324                 return;
 325         case STMT_EXPRESSION:
 326                 __split_expr(stmt->expression);
 327                 return;
 328         case STMT_COMPOUND: {
 329                 struct statement *s;
 330                 __push_scope_hooks();
 331                 FOR_EACH_PTR(stmt->stmts, s) {
 332                         __split_statements(s);
 333                 } END_FOR_EACH_PTR(s);
 334                 __call_scope_hooks();
 335                 return;
 336         }
 337         case STMT_IF:
 338                 if (known_condition_true(stmt->if_conditional)) {
 339                         __split_statements(stmt->if_true);
 340                         return;
 341                 }
 342                 if (known_condition_false(stmt->if_conditional)) {
 343                         __split_statements(stmt->if_false);
 344                         return;
 345                 }
 346                 if (option_known_conditions &&
 347                     implied_condition_true(stmt->if_conditional)) {
 348                         sm_info("this condition is true.");
 349                         __split_statements(stmt->if_true);
 350                         return;
 351                 }
 352                 if (option_known_conditions &&
 353                     implied_condition_false(stmt->if_conditional)) {
 354                         sm_info("this condition is false.");
 355                         __split_statements(stmt->if_false);
 356                         return;
 357                 }
 358                 __split_whole_condition(stmt->if_conditional);
 359                 __split_statements(stmt->if_true);
 360                 if (empty_statement(stmt->if_true))
 361                         sm_msg("warn: if();");
 362                 __push_true_states();
 363                 __use_false_states();
 364                 __split_statements(stmt->if_false);
 365                 __merge_true_states();
 366                 return;
 367         case STMT_ITERATOR:
 368                 if (stmt->iterator_pre_condition)
 369                         handle_pre_loop(stmt);
 370                 else if (stmt->iterator_post_condition)
 371                         handle_post_loop(stmt);
 372                 else {
 373                         // these are for(;;) type loops.
 374                         handle_pre_loop(stmt);
 375                 }
 376                 return;
 377         case STMT_SWITCH:
 378                 __split_expr(stmt->switch_expression);
 379                 push_expression(&switch_expr_stack, stmt->switch_expression);
 380                 __save_switch_states(top_expression(switch_expr_stack));
 381                 nullify_path();
 382                 __push_default();
 383                 __push_breaks();
 384                 __split_statements(stmt->switch_statement);
 385                 if (!__pop_default())
 386                         __merge_switches(top_expression(switch_expr_stack),
 387                                       NULL);
 388                 __pop_switches();
 389                 __merge_breaks();
 390                 pop_expression(&switch_expr_stack);
 391                 return;
 392         case STMT_CASE:
 393                 __merge_switches(top_expression(switch_expr_stack),
 394                                       stmt->case_expression);
 395                 __pass_case_to_client(top_expression(switch_expr_stack),
 396                                       stmt->case_expression);
 397                 if (!stmt->case_expression)
 398                         __set_default();
 399                 __split_expr(stmt->case_expression);
 400                 __split_expr(stmt->case_to);
 401                 __split_statements(stmt->case_statement);
 402                 return;
 403         case STMT_LABEL:
 404                 if (stmt->label &&
 405                     stmt->label->type == SYM_LABEL &&
 406                     stmt->label->ident) {
 407                         __merge_gotos(stmt->label->ident->name);
 408                 }
 409                 __split_statements(stmt->label_statement);
 410                 return;
 411         case STMT_GOTO:
 412                 __split_expr(stmt->goto_expression);
 413                 if (stmt->goto_label && stmt->goto_label->type == SYM_NODE) {
 414                         if (!strcmp(stmt->goto_label->ident->name, "break")) {
 415                                 __process_breaks();
 416                         } else if (!strcmp(stmt->goto_label->ident->name,
 417                                            "continue")) {
 418                                 __process_continues();
 419                         }
 420                 } else if (stmt->goto_label &&
 421                            stmt->goto_label->type == SYM_LABEL &&
 422                            stmt->goto_label->ident) {
 423                         __save_gotos(stmt->goto_label->ident->name);
 424                 }
 425                 nullify_path();
 426                 return;
 427         case STMT_NONE:
 428                 return;
 429         case STMT_ASM:
 430                 __split_expr(stmt->asm_string);
 431                 //__split_expr(stmt->asm_outputs);
 432                 //__split_expr(stmt->asm_inputs);
 433                 //__split_expr(stmt->asm_clobbers);
 434                 return;
 435         case STMT_CONTEXT:
 436                 return;
 437         case STMT_RANGE:
 438                 __split_expr(stmt->range_expression);
 439                 __split_expr(stmt->range_low);
 440                 __split_expr(stmt->range_high);
 441                 return;
 442         }
 443 }
 444
 445 static void split_expr_list(struct expression_list *expr_list)
 446 {
 447         struct expression *expr;
 448         FOR_EACH_PTR(expr_list, expr) {
 449                 __split_expr(expr);
 450         } END_FOR_EACH_PTR(expr);
 451 }
 452
 453
 454 static void split_sym(struct symbol *sym)
 455 {
 456         if (!sym)
 457                 return;
 458         if (!(sym->namespace & NS_SYMBOL))
 459                 return;
 460
 461         __split_statements(sym->stmt);
 462         __split_expr(sym->array_size);
 463         split_symlist(sym->arguments);
 464         split_symlist(sym->symbol_list);
 465         __split_statements(sym->inline_stmt);
 466         split_symlist(sym->inline_symbol_list);
 467         __split_expr(sym->initializer);
 468 }
 469
 470 static void split_symlist(struct symbol_list *sym_list)
 471 {
 472         struct symbol *sym;
 473
 474         FOR_EACH_PTR(sym_list, sym) {
 475                 split_sym(sym);
 476         } END_FOR_EACH_PTR(sym);
 477 }
 478
 479 static struct expression *fake_assign_expr(struct symbol *sym)
 480 {
 481         struct expression *e_assign, *e_symbol;
 482
 483         e_assign = alloc_expression(sym->initializer->pos, EXPR_ASSIGNMENT);
 484         e_symbol = alloc_expression(sym->initializer->pos, EXPR_SYMBOL);
 485         e_assign->op = (int)'=';
 486         e_symbol->symbol = sym;
 487         e_symbol->symbol_name = sym->ident;
 488         e_assign->left = e_symbol;
 489         e_assign->right = sym->initializer;
 490         return e_assign;
 491 }
 492
 493 static void split_declaration(struct symbol_list *sym_list)
 494 {
 495         struct symbol *sym;
 496         struct expression *assign, *tmp;
 497
 498         FOR_EACH_PTR(sym_list, sym) {
 499                 __pass_to_client(sym, DECLARATION_HOOK);
 500                 __split_expr(sym->initializer);
 501                 if(sym->initializer) {
 502                         assign = fake_assign_expr(sym);
 503                         __pass_to_client(assign, ASSIGNMENT_HOOK);
 504                         tmp = strip_expr(assign->right);
 505                         if (tmp->type == EXPR_CALL)
 506                                 __pass_to_client(assign, CALL_ASSIGNMENT_HOOK);
 507                 }
 508                 split_sym(sym);
 509         } END_FOR_EACH_PTR(sym);
 510 }
 511
 512 static void split_functions(struct symbol_list *sym_list)
 513 {
 514         struct symbol *sym;
 515
 516         FOR_EACH_PTR(sym_list, sym) {
 517                 struct symbol *base_type;
 518                 base_type = get_base_type(sym);
 519                 if (sym->type == SYM_NODE && base_type->type == SYM_FN) {
 520                         cur_func_sym = sym;
 521                         if (base_type->stmt)
 522                                 line_func_start = base_type->stmt->pos.line;
 523                         if (sym->ident)
 524                                 cur_func = sym->ident->name;
 525                         __smatch_lineno = sym->pos.line;
 526                         sm_debug("new function:  %s\n", cur_func);
 527                         if (option_two_passes) {
 528                                 __unnullify_path();
 529                                 loop_num = 0;
 530                                 final_pass = 0;
 531                                 __pass_to_client(sym, FUNC_DEF_HOOK);
 532                                 __split_statements(base_type->stmt);
 533                                 nullify_path();
 534                         }
 535                         __unnullify_path();
 536                         loop_num = 0;
 537                         final_pass = 1;
 538                         __pass_to_client(sym, FUNC_DEF_HOOK);
 539                         __split_statements(base_type->stmt);
 540                         __pass_to_client(sym, END_FUNC_HOOK);
 541                         cur_func = NULL;
 542                         line_func_start = 0;
 543                         clear_all_states();
 544                         free_data_info_allocs();
 545                         free_expression_stack(&switch_expr_stack);
 546                 } else {
 547                         __pass_to_client(sym, BASE_HOOK);
 548                 }
 549         } END_FOR_EACH_PTR(sym);
 550         __pass_to_client_no_data(END_FILE_HOOK);
 551 }
 552
 553 void smatch (int argc, char **argv)
 554 {
 555
 556         struct string_list *filelist = NULL;
 557         struct symbol_list *sym_list;
 558
 559         if (argc < 2) {
 560                 printf("Usage:  smatch [--debug] <filename.c>\n");
 561                 exit(1);
 562         }
 563         sparse_initialize(argc, argv, &filelist);
 564         FOR_EACH_PTR_NOTAG(filelist, filename) {
 565                 int len;
 566
 567                 pathname = get_current_dir_name();
 568                 if (pathname) {
 569                         len = strlen(pathname) + 1 + strlen(filename) + 1;
 570                         full_filename = malloc(len);
 571                         snprintf(full_filename, len, "%s/%s", pathname, filename);
 572                 } else {
 573                         full_filename = filename;
 574                 }
 575
 576                 sym_list = __sparse(filename);
 577                 split_functions(sym_list);
 578
 579                 if (pathname) {
 580                         free(full_filename);
 581                         free(pathname);
 582                 }
 583         } END_FOR_EACH_PTR_NOTAG(filename);
 584 }