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 (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 (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                 tmp = show_special(expr->op);
 106                 append(buf, tmp, len);
 107                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 108                                                  len, complicated);
 109
 110                 if (expr->op == '(') {
 111                         append(buf, ")", len);
 112                 }
 113
 114                 if (expr->op == SPECIAL_DECREMENT || expr->op == SPECIAL_INCREMENT)
 115                         *complicated = 1;
 116
 117                 return;
 118         }
 119         case EXPR_POSTOP: {
 120                 const char *tmp;
 121
 122                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 123                                                  len, complicated);
 124                 tmp = show_special(expr->op);
 125                 append(buf, tmp, len);
 126
 127                 if (expr->op == SPECIAL_DECREMENT || expr->op == SPECIAL_INCREMENT)
 128                         *complicated = 1;
 129                 return;
 130         }
 131         case EXPR_BINOP: {
 132                 const char *tmp;
 133
 134                 *complicated = 1;
 135                 append(buf, "(", len);
 136                 __get_variable_from_expr(NULL, buf, expr->left, len,
 137                                          complicated);
 138                 tmp = show_special(expr->op);
 139                 append(buf, tmp, len);
 140                 __get_variable_from_expr(sym_ptr, buf, expr->right,
 141                                                  len, complicated);
 142                 append(buf, ")", len);
 143                 return;
 144         }
 145         case EXPR_VALUE: {
 146                 char tmp[25];
 147
 148                 snprintf(tmp, 25, "%lld", expr->value);
 149                 append(buf, tmp, len);
 150                 return;
 151         }
 152         case EXPR_STRING:
 153                 append(buf, expr->string->data, len);
 154                 return;
 155         case EXPR_CALL: {
 156                 struct expression *tmp;
 157                 int i;
 158
 159                 *complicated = 1;
 160                 __get_variable_from_expr(NULL, buf, expr->fn, len,
 161                                          complicated);
 162                 append(buf, "(", len);
 163                 i = 0;
 164                 FOR_EACH_PTR_REVERSE(expr->args, tmp) {
 165                         if (i++)
 166                                 append(buf, ", ", len);
 167                         __get_variable_from_expr(NULL, buf, tmp, len,
 168                                                 complicated);
 169                 } END_FOR_EACH_PTR_REVERSE(tmp);
 170                 append(buf, ")", len);
 171                 return;
 172         }
 173         case EXPR_CAST:
 174                 __get_variable_from_expr(sym_ptr, buf,
 175                                          expr->cast_expression, len,
 176                                          complicated);
 177                 return;
 178         case EXPR_SIZEOF: {
 179                 int size;
 180                 char tmp[25];
 181
 182                 if (expr->cast_type && get_base_type(expr->cast_type)) {
 183                         size = (get_base_type(expr->cast_type))->bit_size;
 184                         snprintf(tmp, 25, "%d", size);
 185                         append(buf, tmp, len);
 186                 }
 187                 return;
 188         }
 189         default:
 190                 *complicated = 1;
 191                 //printf("unknown type = %d\n", expr->type);
 192                 return;
 193         }
 194 }
 195
 196
 197 /*
 198  * This is returns a stylized "c looking" representation of the
 199  * variable name.
 200  *
 201  * It uses the same buffer every time so you have to save the result
 202  * yourself if you want to keep it.
 203  *
 204  */
 205
 206 char *get_variable_from_expr_complex(struct expression *expr, struct symbol **sym_ptr)
 207 {
 208         static char var_name[VAR_LEN];
 209         int complicated = 0;
 210
 211         if (sym_ptr)
 212                 *sym_ptr = NULL;
 213         var_name[0] = '\0';
 214
 215         if (!expr)
 216                 return NULL;
 217         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 218                                  &complicated);
 219         if (complicated < 2)
 220                 return alloc_string(var_name);
 221         else
 222                 return NULL;
 223 }
 224
 225 /*
 226  * get_variable_from_expr_simple() only returns simple variables.
 227  * If it's a complicated variable like a->foo instead of just 'a'
 228  * then it returns NULL.
 229  */
 230
 231 char *get_variable_from_expr(struct expression *expr,
 232                                     struct symbol **sym_ptr)
 233 {
 234         static char var_name[VAR_LEN];
 235         int complicated = 0;
 236
 237         if (sym_ptr)
 238                 *sym_ptr = NULL;
 239         var_name[0] = '\0';
 240
 241         if (!expr)
 242                 return NULL;
 243         expr = strip_expr(expr);
 244         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 245                                  &complicated);
 246
 247         if (complicated) {
 248                 if (sym_ptr)
 249                         *sym_ptr = NULL;
 250                 return NULL;
 251         }
 252         return alloc_string(var_name);
 253 }
 254
 255 int sym_name_is(const char *name, struct expression *expr)
 256 {
 257         if (!expr)
 258                 return 0;
 259         if (expr->type != EXPR_SYMBOL)
 260                 return 0;
 261         if (!strcmp(expr->symbol_name->name, name))
 262                 return 1;
 263         return 0;
 264 }
 265
 266 #define NOTIMPLIED 0
 267 #define IMPLIED 1
 268
 269 static int _get_value(struct expression *expr, int *discard, int *undefined, int implied)
 270 {
 271         int dis = 0;
 272         long long ret = BOGUS;
 273
 274         if (!expr) {
 275                 *undefined = 1;
 276                 return BOGUS;
 277         }
 278         if (!discard)
 279                 discard = &dis;
 280         if (*discard) {
 281                 *undefined = 1;
 282                 return BOGUS;
 283         }
 284
 285         expr = strip_expr(expr);
 286
 287         switch (expr->type){
 288         case EXPR_VALUE:
 289                 ret = expr->value;
 290                 break;
 291         case EXPR_PREOP:
 292                 if (expr->op == '-') {
 293                         ret = - _get_value(expr->unop, discard, undefined, implied);
 294                 } else {
 295                         *undefined = 1;
 296                         *discard = 1;
 297                 }
 298                 break;
 299         case EXPR_BINOP: {
 300                 int left, right;
 301
 302                 left = _get_value(expr->left, discard, undefined, implied);
 303                 right = _get_value(expr->right, discard, undefined, implied);
 304                 if (expr->op == '*') {
 305                         ret =  left * right;
 306                 } else if (expr->op == '/') {
 307                         ret = left / right;
 308                 } else if (expr->op == '+') {
 309                         ret = left + right;
 310                 } else if (expr->op == '-') {
 311                         ret = left - right;
 312                 } else if (expr->op == '|') {
 313                         ret = left | right;
 314                 } else if (expr->op == '&') {
 315                         ret = left & right;
 316                 } else if (expr->op == SPECIAL_RIGHTSHIFT) {
 317                         ret = left >> right;
 318                 } else if (expr->op == SPECIAL_LEFTSHIFT) {
 319                         ret = left << right;
 320                 } else {
 321                         *undefined = 1;
 322                         *discard = 1;
 323                 }
 324                 break;
 325         }
 326         case EXPR_PTRSIZEOF:
 327         case EXPR_SIZEOF:
 328                 ret = get_expression_value(expr);
 329                 break;
 330         default:
 331                 if (implied) {
 332                         if (!get_implied_single_val(expr, &ret)) {
 333                                 *undefined = 1;
 334                                 *discard = 1;
 335                         }
 336                 } else {
 337                         *undefined = 1;
 338                         *discard = 1;
 339                 }
 340         }
 341         if (*discard) {
 342                 *undefined = 1;
 343                 return BOGUS;
 344         }
 345         return ret;
 346 }
 347
 348 /* returns 1 if it can get a value literal or else returns 0 */
 349 int get_value(struct expression *expr, long long *val)
 350 {
 351         int undefined = 0;
 352
 353         *val = _get_value(expr, NULL, &undefined, NOTIMPLIED);
 354         if (undefined)
 355                 return 0;
 356         return 1;
 357 }
 358
 359 int get_implied_value(struct expression *expr, long long *val)
 360 {
 361         int undefined = 0;
 362
 363         *val =  _get_value(expr, NULL, &undefined, IMPLIED);
 364         return !undefined;
 365 }
 366
 367 int is_zero(struct expression *expr)
 368 {
 369         long long val;
 370
 371         if (get_value(expr, &val) && val == 0)
 372                 return 1;
 373         return 0;
 374 }
 375
 376 int is_array(struct expression *expr)
 377 {
 378         expr = strip_expr(expr);
 379         if (expr->type != EXPR_PREOP || expr->op != '*')
 380                 return 0;
 381         expr = expr->unop;
 382         if (expr->op != '+')
 383                 return 0;
 384         return 1;
 385 }
 386
 387 struct expression *get_array_name(struct expression *expr)
 388 {
 389         if (!is_array(expr))
 390                 return NULL;
 391         return expr->unop->left;
 392 }
 393
 394 struct expression *get_array_offset(struct expression *expr)
 395 {
 396         if (!is_array(expr))
 397                 return NULL;
 398         return expr->unop->right;
 399 }
 400
 401 const char *show_state(struct smatch_state *state)
 402 {
 403         if (!state)
 404                 return NULL;
 405         return state->name;
 406 }
 407
 408 struct statement *get_block_thing(struct expression *expr)
 409 {
 410         /* What are those things called? if (({....; ret;})) { ...*/
 411
 412         if (expr->type != EXPR_PREOP)
 413                 return NULL;
 414         if (expr->op != '(')
 415                 return NULL;
 416         if (expr->unop->type != EXPR_STATEMENT)
 417                 return NULL;
 418         if (expr->unop->statement->type != STMT_COMPOUND)
 419                 return NULL;
 420         return expr->unop->statement;
 421 }
 422
 423 struct expression *strip_expr(struct expression *expr)
 424 {
 425         if (!expr)
 426                 return NULL;
 427
 428         switch(expr->type) {
 429         case EXPR_CAST:
 430                 return strip_expr(expr->cast_expression);
 431         case EXPR_PREOP:
 432                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 433                         expr->unop->statement->type == STMT_COMPOUND)
 434                         return expr;
 435                 if (expr->op == '(')
 436                         return strip_expr(expr->unop);
 437         }
 438         return expr;
 439 }
 440
 441 static void delete_state_tracker(struct tracker *t)
 442 {
 443         delete_state(t->owner, t->name, t->sym);
 444         __free_tracker(t);
 445 }
 446
 447 void scoped_state(int my_id, const char *name, struct symbol *sym)
 448 {
 449         struct tracker *t;
 450
 451         t = alloc_tracker(my_id, name, sym);
 452         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 453 }
 454
 455 int is_error_return(struct expression *expr)
 456 {
 457         struct symbol *cur_func = cur_func_sym;
 458         long long val;
 459
 460         if (!expr)
 461                 return 0;
 462         if (cur_func->type != SYM_NODE)
 463                 return 0;
 464         cur_func = get_base_type(cur_func);
 465         if (cur_func->type != SYM_FN)
 466                 return 0;
 467         cur_func = get_base_type(cur_func);
 468         if (cur_func == &void_ctype)
 469                 return 0;
 470         if (!get_value(expr, &val))
 471                 return 0;
 472         if (val < 0)
 473                 return 1;
 474         if (cur_func->type == SYM_PTR && val == 0)
 475                 return 1;
 476         return 0;
 477 }