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