smatch_helper.c

   1 /*
   2  * sparse/smatch_helper.c
   3  *
   4  * Copyright (C) 2006 Dan Carpenter.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 /*
  11  * Miscellaneous helper functions.
  12  */
  13
  14 #include <stdlib.h>
  15 #include <stdio.h>
  16 #include "allocate.h"
  17 #include "smatch.h"
  18
  19 #define VAR_LEN 512
  20 #define BOGUS 12345
  21
  22 char *alloc_string(const char *str)
  23 {
  24         char *tmp;
  25
  26         if (!str)
  27                 return NULL;
  28         tmp = malloc(strlen(str) + 1);
  29         strcpy(tmp, str);
  30         return tmp;
  31 }
  32
  33 void free_string(char *str)
  34 {
  35         free(str);
  36 }
  37
  38 struct smatch_state *alloc_state_num(int num)
  39 {
  40         struct smatch_state *state;
  41         static char buff[256];
  42
  43         state = __alloc_smatch_state(0);
  44         snprintf(buff, 255, "%d", num);
  45         buff[255] = '\0';
  46         state->name = alloc_string(buff);
  47         state->data = (void *)num;
  48         return state;
  49 }
  50
  51 static void append(char *dest, const char *data, int buff_len)
  52 {
  53         strncat(dest, data, buff_len - strlen(dest) - 1);
  54 }
  55
  56 /*
  57  * If you have "foo(a, b, 1);" then use
  58  * get_argument_from_call_expr(expr, 0) to return the expression for
  59  * a.  Yes, it does start counting from 0.
  60  */
  61 struct expression *get_argument_from_call_expr(struct expression_list *args,
  62                                                int num)
  63 {
  64         struct expression *expr;
  65         int i = 0;
  66
  67         if (!args)
  68                 return NULL;
  69
  70         FOR_EACH_PTR(args, expr) {
  71                 if (i == num)
  72                         return expr;
  73                 i++;
  74         } END_FOR_EACH_PTR(expr);
  75         return NULL;
  76 }
  77
  78 static void __get_variable_from_expr(struct symbol **sym_ptr, char *buf,
  79                                      struct expression *expr, int len,
  80                                      int *complicated)
  81 {
  82         struct expression *tmp;
  83
  84         switch (expr->type) {
  85         case EXPR_DEREF:
  86                 tmp = expr->deref;
  87                 if (tmp->op == '*')  {
  88                         tmp = tmp->unop;
  89                 }
  90                 __get_variable_from_expr(sym_ptr, buf, tmp, len, complicated);
  91
  92                 tmp = expr->deref;
  93                 if (tmp->op == '*')  {
  94                         append(buf, "->", len);
  95                 } else {
  96                         append(buf, ".", len);
  97                 }
  98                 append(buf, expr->member->name, len);
  99
 100                 return;
 101         case EXPR_SYMBOL:
 102                 if (expr->symbol_name)
 103                         append(buf, expr->symbol_name->name, len);
 104                 if (sym_ptr) {
 105                         if (*sym_ptr)
 106                                 *complicated = 1;
 107                         *sym_ptr = expr->symbol;
 108                 }
 109                 return;
 110         case EXPR_PREOP: {
 111                 const char *tmp;
 112
 113                 if (get_block_thing(expr)) {
 114                         *complicated = 2;
 115                         return;
 116                 }
 117
 118                 tmp = show_special(expr->op);
 119                 append(buf, tmp, len);
 120                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 121                                                  len, complicated);
 122
 123                 if (expr->op == '(') {
 124                         append(buf, ")", len);
 125                 }
 126
 127                 if (expr->op == SPECIAL_DECREMENT || expr->op == SPECIAL_INCREMENT)
 128                         *complicated = 1;
 129
 130                 return;
 131         }
 132         case EXPR_POSTOP: {
 133                 const char *tmp;
 134
 135                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 136                                                  len, complicated);
 137                 tmp = show_special(expr->op);
 138                 append(buf, tmp, len);
 139
 140                 if (expr->op == SPECIAL_DECREMENT || expr->op == SPECIAL_INCREMENT)
 141                         *complicated = 1;
 142                 return;
 143         }
 144         case EXPR_BINOP: {
 145                 const char *tmp;
 146
 147                 *complicated = 1;
 148                 append(buf, "(", len);
 149                 __get_variable_from_expr(NULL, buf, expr->left, len,
 150                                          complicated);
 151                 tmp = show_special(expr->op);
 152                 append(buf, tmp, len);
 153                 __get_variable_from_expr(sym_ptr, buf, expr->right,
 154                                                  len, complicated);
 155                 append(buf, ")", len);
 156                 return;
 157         }
 158         case EXPR_VALUE: {
 159                 char tmp[25];
 160
 161                 snprintf(tmp, 25, "%lld", expr->value);
 162                 append(buf, tmp, len);
 163                 return;
 164         }
 165         case EXPR_STRING:
 166                 append(buf, expr->string->data, len);
 167                 return;
 168         case EXPR_CALL: {
 169                 struct expression *tmp;
 170                 int i;
 171
 172                 *complicated = 1;
 173                 __get_variable_from_expr(NULL, buf, expr->fn, len,
 174                                          complicated);
 175                 append(buf, "(", len);
 176                 i = 0;
 177                 FOR_EACH_PTR_REVERSE(expr->args, tmp) {
 178                         if (i++)
 179                                 append(buf, ", ", len);
 180                         __get_variable_from_expr(NULL, buf, tmp, len,
 181                                                 complicated);
 182                 } END_FOR_EACH_PTR_REVERSE(tmp);
 183                 append(buf, ")", len);
 184                 return;
 185         }
 186         case EXPR_CAST:
 187                 __get_variable_from_expr(sym_ptr, buf,
 188                                          expr->cast_expression, len,
 189                                          complicated);
 190                 return;
 191         case EXPR_SIZEOF: {
 192                 int size;
 193                 char tmp[25];
 194
 195                 if (expr->cast_type && get_base_type(expr->cast_type)) {
 196                         size = (get_base_type(expr->cast_type))->bit_size;
 197                         snprintf(tmp, 25, "%d", size);
 198                         append(buf, tmp, len);
 199                 }
 200                 return;
 201         }
 202         default:
 203                 *complicated = 1;
 204                 //printf("unknown type = %d\n", expr->type);
 205                 return;
 206         }
 207 }
 208
 209
 210 /*
 211  * This is returns a stylized "c looking" representation of the
 212  * variable name.
 213  *
 214  * It uses the same buffer every time so you have to save the result
 215  * yourself if you want to keep it.
 216  *
 217  */
 218
 219 char *get_variable_from_expr_complex(struct expression *expr, struct symbol **sym_ptr)
 220 {
 221         static char var_name[VAR_LEN];
 222         int complicated = 0;
 223
 224         if (sym_ptr)
 225                 *sym_ptr = NULL;
 226         var_name[0] = '\0';
 227
 228         if (!expr)
 229                 return NULL;
 230         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 231                                  &complicated);
 232         if (complicated < 2)
 233                 return alloc_string(var_name);
 234         else
 235                 return NULL;
 236 }
 237
 238 /*
 239  * get_variable_from_expr_simple() only returns simple variables.
 240  * If it's a complicated variable like a->foo instead of just 'a'
 241  * then it returns NULL.
 242  */
 243
 244 char *get_variable_from_expr(struct expression *expr,
 245                                     struct symbol **sym_ptr)
 246 {
 247         static char var_name[VAR_LEN];
 248         int complicated = 0;
 249
 250         if (sym_ptr)
 251                 *sym_ptr = NULL;
 252         var_name[0] = '\0';
 253
 254         if (!expr)
 255                 return NULL;
 256         expr = strip_expr(expr);
 257         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 258                                  &complicated);
 259
 260         if (complicated) {
 261                 if (sym_ptr)
 262                         *sym_ptr = NULL;
 263                 return NULL;
 264         }
 265         return alloc_string(var_name);
 266 }
 267
 268 int sym_name_is(const char *name, struct expression *expr)
 269 {
 270         if (!expr)
 271                 return 0;
 272         if (expr->type != EXPR_SYMBOL)
 273                 return 0;
 274         if (!strcmp(expr->symbol_name->name, name))
 275                 return 1;
 276         return 0;
 277 }
 278
 279 #define NOTIMPLIED 0
 280 #define IMPLIED 1
 281 #define FUZZYMAX 2
 282
 283 static int _get_value(struct expression *expr, int *discard, int *undefined, int implied)
 284 {
 285         int dis = 0;
 286         long long ret = BOGUS;
 287
 288         if (!expr) {
 289                 *undefined = 1;
 290                 return BOGUS;
 291         }
 292         if (!discard)
 293                 discard = &dis;
 294         if (*discard) {
 295                 *undefined = 1;
 296                 return BOGUS;
 297         }
 298
 299         expr = strip_parens(expr);
 300
 301         switch (expr->type){
 302         case EXPR_VALUE:
 303                 ret = expr->value;
 304                 break;
 305         case EXPR_PREOP:
 306                 if (expr->op == '-') {
 307                         ret = - _get_value(expr->unop, discard, undefined, implied);
 308                 } else {
 309                         *undefined = 1;
 310                         *discard = 1;
 311                 }
 312                 break;
 313         case EXPR_CAST:
 314         case EXPR_FORCE_CAST:
 315         case EXPR_IMPLIED_CAST:
 316         {
 317                 struct symbol *type = get_base_type(expr->cast_type);
 318
 319                 ret = _get_value(expr->cast_expression, discard, undefined, implied);
 320                 switch (type->bit_size) {
 321                 case 8:
 322                         if (type->ctype.modifiers & MOD_UNSIGNED)
 323                                 ret = (int)(unsigned char) ret;
 324                         else
 325                                 ret = (int)(char) ret;
 326                         break;
 327                 case 16:
 328                         if (type->ctype.modifiers & MOD_UNSIGNED)
 329                                 ret = (int)(unsigned short) ret;
 330                         else
 331                                 ret = (int)(short) ret;
 332                         break;
 333                 case 32:
 334                         if (type->ctype.modifiers & MOD_UNSIGNED)
 335                                 ret = (int)(unsigned int) ret;
 336                         else
 337                                 ret = (int)(int) ret;
 338                         break;
 339                 }
 340                 return ret;
 341         }
 342         case EXPR_BINOP: {
 343                 int left, right;
 344
 345                 left = _get_value(expr->left, discard, undefined, implied);
 346                 right = _get_value(expr->right, discard, undefined, implied);
 347                 if (expr->op == '*') {
 348                         ret =  left * right;
 349                 } else if (expr->op == '/') {
 350                         ret = left / right;
 351                 } else if (expr->op == '+') {
 352                         ret = left + right;
 353                 } else if (expr->op == '-') {
 354                         ret = left - right;
 355                 } else if (expr->op == '|') {
 356                         ret = left | right;
 357                 } else if (expr->op == '&') {
 358                         ret = left & right;
 359                 } else if (expr->op == SPECIAL_RIGHTSHIFT) {
 360                         ret = left >> right;
 361                 } else if (expr->op == SPECIAL_LEFTSHIFT) {
 362                         ret = left << right;
 363                 } else {
 364                         *undefined = 1;
 365                         *discard = 1;
 366                 }
 367                 break;
 368         }
 369         case EXPR_PTRSIZEOF:
 370         case EXPR_SIZEOF:
 371                 ret = get_expression_value(expr);
 372                 break;
 373         default:
 374                 if (implied == IMPLIED) {
 375                         if (!get_implied_single_val(expr, &ret)) {
 376                                 *undefined = 1;
 377                                 *discard = 1;
 378                         }
 379                 } else if (implied == FUZZYMAX) {
 380                         if (!get_implied_single_fuzzy_max(expr, &ret)) {
 381                                 *undefined = 1;
 382                                 *discard = 1;
 383                         }
 384                 } else {
 385                         *undefined = 1;
 386                         *discard = 1;
 387                 }
 388         }
 389         if (*discard) {
 390                 *undefined = 1;
 391                 return BOGUS;
 392         }
 393         return ret;
 394 }
 395
 396 /* returns 1 if it can get a value literal or else returns 0 */
 397 int get_value(struct expression *expr, long long *val)
 398 {
 399         int undefined = 0;
 400
 401         *val = _get_value(expr, NULL, &undefined, NOTIMPLIED);
 402         if (undefined)
 403                 return 0;
 404         return 1;
 405 }
 406
 407 int get_implied_value(struct expression *expr, long long *val)
 408 {
 409         int undefined = 0;
 410
 411         *val =  _get_value(expr, NULL, &undefined, IMPLIED);
 412         return !undefined;
 413 }
 414
 415 int get_fuzzy_max(struct expression *expr, long long *val)
 416 {
 417         int undefined = 0;
 418
 419         *val =  _get_value(expr, NULL, &undefined, FUZZYMAX);
 420         return !undefined;
 421 }
 422
 423 int is_zero(struct expression *expr)
 424 {
 425         long long val;
 426
 427         if (get_value(expr, &val) && val == 0)
 428                 return 1;
 429         return 0;
 430 }
 431
 432 int is_array(struct expression *expr)
 433 {
 434         expr = strip_expr(expr);
 435         if (expr->type != EXPR_PREOP || expr->op != '*')
 436                 return 0;
 437         expr = expr->unop;
 438         if (expr->op != '+')
 439                 return 0;
 440         return 1;
 441 }
 442
 443 struct expression *get_array_name(struct expression *expr)
 444 {
 445         if (!is_array(expr))
 446                 return NULL;
 447         return strip_expr(expr->unop->left);
 448 }
 449
 450 struct expression *get_array_offset(struct expression *expr)
 451 {
 452         if (!is_array(expr))
 453                 return NULL;
 454         return expr->unop->right;
 455 }
 456
 457 const char *show_state(struct smatch_state *state)
 458 {
 459         if (!state)
 460                 return NULL;
 461         return state->name;
 462 }
 463
 464 struct statement *get_block_thing(struct expression *expr)
 465 {
 466         /* What are those things called? if (({....; ret;})) { ...*/
 467
 468         if (expr->type != EXPR_PREOP)
 469                 return NULL;
 470         if (expr->op != '(')
 471                 return NULL;
 472         if (expr->unop->type != EXPR_STATEMENT)
 473                 return NULL;
 474         if (expr->unop->statement->type != STMT_COMPOUND)
 475                 return NULL;
 476         return expr->unop->statement;
 477 }
 478
 479 struct expression *strip_parens(struct expression *expr)
 480 {
 481         if (!expr)
 482                 return NULL;
 483
 484         if (expr->type == EXPR_PREOP) {
 485                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 486                         expr->unop->statement->type == STMT_COMPOUND)
 487                         return expr;
 488                 if (expr->op == '(')
 489                         return strip_parens(expr->unop);
 490         }
 491         return expr;
 492 }
 493
 494 struct expression *strip_expr(struct expression *expr)
 495 {
 496         if (!expr)
 497                 return NULL;
 498
 499         switch (expr->type) {
 500         case EXPR_CAST:
 501                 return strip_expr(expr->cast_expression);
 502         case EXPR_PREOP:
 503                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 504                         expr->unop->statement->type == STMT_COMPOUND)
 505                         return expr;
 506                 if (expr->op == '(')
 507                         return strip_expr(expr->unop);
 508         }
 509         return expr;
 510 }
 511
 512 static void delete_state_tracker(struct tracker *t)
 513 {
 514         delete_state(t->owner, t->name, t->sym);
 515         __free_tracker(t);
 516 }
 517
 518 void scoped_state(int my_id, const char *name, struct symbol *sym)
 519 {
 520         struct tracker *t;
 521
 522         t = alloc_tracker(my_id, name, sym);
 523         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 524 }
 525
 526 int is_error_return(struct expression *expr)
 527 {
 528         struct symbol *cur_func = cur_func_sym;
 529         long long val;
 530
 531         if (!expr)
 532                 return 0;
 533         if (cur_func->type != SYM_NODE)
 534                 return 0;
 535         cur_func = get_base_type(cur_func);
 536         if (cur_func->type != SYM_FN)
 537                 return 0;
 538         cur_func = get_base_type(cur_func);
 539         if (cur_func == &void_ctype)
 540                 return 0;
 541         if (!get_value(expr, &val))
 542                 return 0;
 543         if (val < 0)
 544                 return 1;
 545         if (cur_func->type == SYM_PTR && val == 0)
 546                 return 1;
 547         return 0;
 548 }
 549
 550 int getting_address()
 551 {
 552         struct expression *tmp;
 553         int i = 0;
 554         int dot_ops = 0;
 555
 556         FOR_EACH_PTR_REVERSE(big_expression_stack, tmp) {
 557                 if (!i++)
 558                         continue;
 559                 if (tmp->type == EXPR_PREOP && tmp->op == '(')
 560                         continue;
 561                 if (tmp->op == '.' && !dot_ops++)
 562                         continue;
 563                 if (tmp->op == '&')
 564                         return 1;
 565                 return 0;
 566         } END_FOR_EACH_PTR_REVERSE(tmp);
 567         return 0;
 568 }
 569