smatch_flow.c

   1 /*
   2  * sparse/check_string_ret.c
   3  *
   4  * Copyright (C) 2006 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
  14 #define KERNEL
  15
  16 int __smatch_lineno = 0;
  17 int __negate = 0;
  18 int __ors = 0;
  19 int __ands = 0;
  20
  21 static char *filename;
  22 static char *cur_func;
  23 static int line_func_start;
  24 static unsigned int path_id = 0;
  25 static unsigned int path_id_next = 1;
  26
  27 char *get_filename() {  return filename; }
  28 char *get_function() { return cur_func; }
  29 int get_lineno() { return __smatch_lineno; }
  30 int get_func_pos() { return __smatch_lineno - line_func_start; }
  31
  32 static void split_statements(struct statement *stmt);
  33 static void split_symlist(struct symbol_list *sym_list);
  34 static void split_expr_list(struct expression_list *expr_list);
  35 static void split_expr(struct expression *expr);
  36
  37 unsigned int get_path_id()
  38 {
  39         return path_id;
  40 }
  41
  42 static unsigned int split_path_id()
  43 {
  44         int tmp = path_id;
  45
  46         path_id = path_id_next++;
  47         return tmp;
  48 }
  49
  50 static void restore_path_id(int old_id)
  51 {
  52         path_id = old_id;
  53 }
  54
  55
  56 static int is_logical_and(struct expression *expr)
  57 {
  58         /* If you have if (!(a && b)) smatch translates that to
  59          * if (!a || !b).  Logically those are the same.
  60          */
  61
  62         if ((!__negate && expr->op == SPECIAL_LOGICAL_AND) ||
  63             (__negate && expr->op == SPECIAL_LOGICAL_OR))
  64                 return 1;
  65         return 0;
  66 }
  67
  68 static int is_logical_or(struct expression *expr)
  69 {
  70         if ((!__negate && expr->op == SPECIAL_LOGICAL_OR) ||
  71              (__negate && expr->op == SPECIAL_LOGICAL_AND))
  72                 return 1;
  73         return 0;
  74 }
  75
  76 static void inc_ands_ors(struct expression *expr)
  77 {
  78         if (is_logical_and(expr))
  79                 __ands++;
  80         else if (is_logical_or(expr))
  81                 __ors++;
  82 }
  83
  84 static void dec_ands_ors(struct expression *expr)
  85 {
  86         if (is_logical_and(expr))
  87                 __ands--;
  88         else if (is_logical_or(expr))
  89                 __ors--;
  90 }
  91
  92 void split_conditions(struct expression *expr)
  93 {
  94         /*
  95          * If you have if ((a || a = foo()), we know a is
  96          * non-null on the true state because 'a' is checked in both and
  97          * groups.  __ors_reached helps with that.  Unfortunately
  98          * smatch doesn't handle stuff like if (a && a = foo())
  99          * because it never occured to me that people would do that...
 100          */
 101
 102         static int __ors_reached;
 103
 104         if (expr->type == EXPR_LOGICAL) {
 105                 unsigned int path_orig;
 106
 107                 inc_ands_ors(expr);
 108                 path_orig = split_path_id();
 109                 __split_false_states_mini();
 110
 111                 split_conditions(expr->left);
 112
 113                 if (is_logical_and(expr)) {
 114                         split_path_id();
 115                         __pop_false_states_mini();
 116                         split_conditions(expr->right);
 117                 } else if (is_logical_or(expr)) {
 118                         if (!__ors_reached) {
 119                                 __ors_reached++;
 120                                 __first_and_clump();
 121                         } else
 122                                 __merge_and_clump();
 123
 124                         split_path_id();
 125                         __use_false_states_mini();
 126                         split_conditions(expr->right);
 127                 }
 128                 dec_ands_ors(expr);
 129
 130                 if (__ands + __ors == 0) {
 131                         __merge_and_clump();
 132                         __use_and_clumps();
 133                         __ors_reached = 0;
 134                 }
 135
 136                 restore_path_id(path_orig);
 137                 return;
 138         } else if (expr->type == EXPR_PREOP && expr->op == '!') {
 139                 __negate = (__negate +  1)%2;
 140                 split_conditions(expr->unop);
 141                 __negate = (__negate +  1)%2;
 142                 return;
 143         } else if (expr->type == EXPR_PREOP && expr->op == '(') {
 144                 split_conditions(expr->unop);
 145 #ifdef KERNEL
 146         } else if (expr->type == EXPR_CALL) {
 147                 struct expression *arg;
 148
 149                 if (expr->fn->type != EXPR_SYMBOL ||
 150                     strcmp("__builtin_expect", expr->fn->symbol_name->name)) {
 151                         __pass_to_client(expr, CONDITION_HOOK);
 152                         split_expr(expr);
 153                         return;
 154                 }
 155                 arg = first_ptr_list((struct ptr_list *) expr->args);
 156                 if (arg->op == '!' && arg->unop->op == '!'
 157                     && arg->unop->unop->op == '(')
 158                         split_conditions(arg->unop->unop->unop);
 159                 else {
 160                         __pass_to_client(expr, CONDITION_HOOK);
 161                         split_expr(expr);
 162                         return;
 163                 }
 164 #endif
 165         } else {
 166                 __pass_to_client(expr, CONDITION_HOOK);
 167                 split_expr(expr);
 168         }
 169 }
 170
 171 static void split_expr(struct expression *expr)
 172 {
 173         if (!expr)
 174                 return;
 175
 176         __smatch_lineno = expr->pos.line;
 177         __pass_to_client(expr, EXPR_HOOK);
 178
 179         //printf("Debug expr_type %d\n", expr->type);
 180
 181         switch (expr->type) {
 182         case EXPR_PREOP:
 183         case EXPR_POSTOP:
 184                 if (expr->op == '*')
 185                         __pass_to_client(expr, DEREF_HOOK);
 186                 split_expr(expr->unop);
 187                 return;
 188         case EXPR_STATEMENT:
 189                 split_statements(expr->statement);
 190                 return;
 191         case EXPR_BINOP:
 192         case EXPR_COMMA:
 193         case EXPR_COMPARE:
 194         case EXPR_LOGICAL:
 195         case EXPR_ASSIGNMENT:
 196                 if (expr->type == EXPR_ASSIGNMENT)
 197                         __pass_to_client(expr, ASSIGNMENT_HOOK);
 198                 split_expr(expr->left);
 199                 split_expr(expr->right);
 200                 if (expr->type == EXPR_ASSIGNMENT)
 201                         __pass_to_client(expr, ASSIGNMENT_AFTER_HOOK);
 202                 return;
 203         case EXPR_DEREF:
 204                 __pass_to_client(expr, DEREF_HOOK);
 205                 split_expr(expr->deref);
 206                 return;
 207         case EXPR_SLICE:
 208                 split_expr(expr->base);
 209                 return;
 210         case EXPR_CAST:
 211         case EXPR_SIZEOF:
 212                 split_expr(expr->cast_expression);
 213                 return;
 214         case EXPR_CONDITIONAL:
 215         case EXPR_SELECT:
 216                 __split_true_false_paths();
 217                 __pass_to_client(expr->conditional, WHOLE_CONDITION_HOOK);
 218                 split_conditions(expr->conditional);
 219                 __use_true_states();
 220                 split_expr(expr->cond_true);
 221                 __use_false_states();
 222                 split_expr(expr->cond_false);
 223                 __merge_true_states();
 224                 return;
 225         case EXPR_CALL:
 226                 __pass_to_client(expr, FUNCTION_CALL_HOOK);
 227                 split_expr(expr->fn);
 228                 split_expr_list(expr->args);
 229                 __pass_to_client(expr, FUNCTION_CALL_AFTER_HOOK);
 230 #ifdef KERNEL
 231                 if (expr->fn->type == EXPR_SYMBOL &&
 232                     !strcmp(expr->fn->symbol_name->name, "panic"))
 233                         nullify_path();
 234 #endif
 235                 return;
 236         case EXPR_INITIALIZER:
 237                 split_expr_list(expr->expr_list);
 238                 return;
 239         case EXPR_IDENTIFIER:
 240                 split_expr(expr->ident_expression);
 241                 return;
 242         case EXPR_INDEX:
 243                 split_expr(expr->idx_expression);
 244                 return;
 245         case EXPR_POS:
 246                 split_expr(expr->init_expr);
 247                 return;
 248         default:
 249                 return;
 250         };
 251 }
 252
 253 static int is_forever_loop(struct expression *expr)
 254 {
 255
 256         if (expr->type == EXPR_VALUE && expr->value == 1) {
 257                 return 1;
 258         }
 259         return 0;
 260 }
 261
 262 /*
 263  * Pre Loops are while and for loops.
 264  */
 265
 266 static void handle_pre_loop(struct statement *stmt)
 267 {
 268         unsigned int path_orig;
 269
 270         split_statements(stmt->iterator_pre_statement);
 271
 272         __split_true_false_paths();
 273         __push_continues();
 274         __push_breaks();
 275         __pass_to_client(stmt->iterator_pre_condition, WHOLE_CONDITION_HOOK);
 276         split_conditions(stmt->iterator_pre_condition);
 277         path_orig = split_path_id();
 278         __use_true_states();
 279
 280         split_statements(stmt->iterator_statement);
 281         split_statements(stmt->iterator_post_statement);
 282         if (is_forever_loop(stmt->iterator_pre_condition)) {
 283                 __pop_continues();
 284                 __pop_false_states();
 285                 nullify_path();
 286         } else {
 287                 nullify_path();
 288                 __merge_false_states();
 289                 __merge_continues();
 290         }
 291         __merge_breaks();
 292         restore_path_id(path_orig);
 293 }
 294
 295 /*
 296  * Post loops are do {} while();
 297  */
 298 static void handle_post_loop(struct statement *stmt)
 299 {
 300         __push_continues();
 301         __push_breaks();
 302         split_statements(stmt->iterator_statement);
 303
 304         __split_true_false_paths();
 305         __pass_to_client(stmt->iterator_post_condition, WHOLE_CONDITION_HOOK);
 306         split_conditions(stmt->iterator_post_condition);
 307         /* It would prossibly be cleaner to make this all one function */
 308         __use_true_states();
 309         __use_false_states();
 310         __pop_true_states();
 311
 312         if (is_forever_loop(stmt->iterator_post_condition)) {
 313                 __pop_continues();
 314                 nullify_path();
 315         } else {
 316                 __merge_continues();
 317         }
 318         __merge_breaks();
 319 }
 320
 321 static void split_statements(struct statement *stmt)
 322 {
 323         unsigned int path_orig;
 324
 325         if (!stmt)
 326                 return;
 327
 328         __pass_to_client(stmt, STMT_HOOK);
 329
 330         switch (stmt->type) {
 331         case STMT_DECLARATION:
 332                 __pass_declarations_to_client(stmt->declaration);
 333                 split_symlist(stmt->declaration);
 334                 return;
 335         case STMT_RETURN:
 336                 __pass_to_client(stmt, RETURN_HOOK);
 337                 split_expr(stmt->ret_value);
 338                 nullify_path();
 339                 return;
 340         case STMT_EXPRESSION:
 341                 split_expr(stmt->expression);
 342                 return;
 343         case STMT_COMPOUND: {
 344                 struct statement *s;
 345                 FOR_EACH_PTR(stmt->stmts, s) {
 346                         split_statements(s);
 347                 } END_FOR_EACH_PTR(s);
 348                 return;
 349         }
 350         case STMT_IF:
 351                 __split_true_false_paths();
 352                 __pass_to_client(stmt->if_conditional, WHOLE_CONDITION_HOOK);
 353                 split_conditions(stmt->if_conditional);
 354                 path_orig = split_path_id();
 355                 __use_true_states();
 356                 split_statements(stmt->if_true);
 357                 split_path_id();
 358                 __use_false_states();
 359                 split_statements(stmt->if_false);
 360                 __merge_true_states();
 361                 restore_path_id(path_orig);
 362                 return;
 363         case STMT_ITERATOR:
 364                 if (stmt->iterator_pre_condition)
 365                         handle_pre_loop(stmt);
 366                 else if (stmt->iterator_post_condition)
 367                         handle_post_loop(stmt);
 368                 return;
 369         case STMT_SWITCH:
 370                 split_expr(stmt->switch_expression);
 371                 __save_switch_states();
 372                 __push_default();
 373                 __push_breaks();
 374                 nullify_path();
 375                 path_orig = get_path_id();
 376                 split_statements(stmt->switch_statement);
 377                 if (!__pop_default())
 378                         __merge_switches();
 379                 __pop_switches();
 380                 __merge_breaks();
 381                 restore_path_id(path_orig);
 382                 return;
 383         case STMT_CASE:
 384                 split_path_id();
 385                 __merge_switches();
 386                 if (!stmt->case_expression)
 387                         __set_default();
 388                 split_expr(stmt->case_expression);
 389                 split_expr(stmt->case_to);
 390                 split_statements(stmt->case_statement);
 391                 return;
 392         case STMT_LABEL:
 393                 if (stmt->label &&
 394                     stmt->label->type == SYM_LABEL &&
 395                     stmt->label->ident) {
 396                         __merge_gotos(stmt->label->ident->name);
 397                 }
 398                 split_statements(stmt->label_statement);
 399                 return;
 400         case STMT_GOTO:
 401                 split_expr(stmt->goto_expression);
 402                 if (stmt->goto_label && stmt->goto_label->type == SYM_NODE) {
 403                         if (!strcmp(stmt->goto_label->ident->name, "break")) {
 404                                 __process_breaks();
 405                         } else if (!strcmp(stmt->goto_label->ident->name,
 406                                            "continue")) {
 407                                 __process_continues();
 408                         }
 409                 } else if (stmt->goto_label &&
 410                            stmt->goto_label->type == SYM_LABEL &&
 411                            stmt->goto_label->ident) {
 412                         __save_gotos(stmt->goto_label->ident->name);
 413                 }
 414                 nullify_path();
 415                 return;
 416         case STMT_NONE:
 417                 return;
 418         case STMT_ASM:
 419                 split_expr(stmt->asm_string);
 420                 //split_expr(stmt->asm_outputs);
 421                 //split_expr(stmt->asm_inputs);
 422                 //split_expr(stmt->asm_clobbers);
 423                 return;
 424         case STMT_CONTEXT:
 425                 return;
 426         case STMT_RANGE:
 427                 split_expr(stmt->range_expression);
 428                 split_expr(stmt->range_low);
 429                 split_expr(stmt->range_high);
 430                 return;
 431         }
 432 }
 433
 434 static void split_expr_list(struct expression_list *expr_list)
 435 {
 436         struct expression *expr;
 437         FOR_EACH_PTR(expr_list, expr) {
 438                 split_expr(expr);
 439         } END_FOR_EACH_PTR(expr);
 440 }
 441
 442
 443 static void split_sym(struct symbol *sym)
 444 {
 445         if (!sym)
 446                 return;
 447         if (!(sym->namespace & NS_SYMBOL))
 448                 return;
 449
 450         __pass_to_client(sym, SYM_HOOK);
 451         split_statements(sym->stmt);
 452         split_expr(sym->array_size);
 453         split_symlist(sym->arguments);
 454         split_symlist(sym->symbol_list);
 455         split_statements(sym->inline_stmt);
 456         split_symlist(sym->inline_symbol_list);
 457         split_expr(sym->initializer);
 458 }
 459
 460 static void split_symlist(struct symbol_list *sym_list)
 461 {
 462         struct symbol *sym;
 463
 464         FOR_EACH_PTR(sym_list, sym) {
 465                 split_sym(sym);
 466         } END_FOR_EACH_PTR(sym);
 467 }
 468
 469 static void split_functions(struct symbol_list *sym_list)
 470 {
 471         struct symbol *sym;
 472
 473         FOR_EACH_PTR(sym_list, sym) {
 474                 struct symbol *base_type;
 475                 base_type = get_base_type(sym);
 476                 if (sym->type == SYM_NODE && base_type->type == SYM_FN) {
 477                         if (base_type->stmt)
 478                                 line_func_start = base_type->stmt->pos.line;
 479                         if (sym->ident)
 480                                 cur_func = sym->ident->name;
 481                         __smatch_lineno = sym->pos.line;
 482                         __pass_to_client(sym, FUNC_DEF_HOOK);
 483                         split_statements(base_type->stmt);
 484                         __pass_to_client(sym, END_FUNC_HOOK);
 485                         cur_func = NULL;
 486                         line_func_start = 0;
 487                         clear_all_states();
 488
 489                 } else {
 490                         __pass_to_client(sym, BASE_HOOK);
 491                 }
 492         } END_FOR_EACH_PTR(sym);
 493 }
 494
 495 void smatch (int argc, char **argv)
 496 {
 497
 498         struct string_list *filelist = NULL;
 499         struct symbol_list *sym_list;
 500
 501         if (argc < 2) {
 502                 printf("Usage:  smatch <filename.c>\n");
 503                 exit(1);
 504         }
 505         sparse_initialize(argc, argv, &filelist);
 506         FOR_EACH_PTR_NOTAG(filelist, filename) {
 507                 sym_list = __sparse(filename);
 508                 split_functions(sym_list);
 509         } END_FOR_EACH_PTR_NOTAG(filename);
 510 }