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
  21 char *alloc_string(const char *str)
  22 {
  23         char *tmp;
  24
  25         if (!str)
  26                 return NULL;
  27         tmp = malloc(strlen(str) + 1);
  28         strcpy(tmp, str);
  29         return tmp;
  30 }
  31
  32 void free_string(char *str)
  33 {
  34         free(str);
  35 }
  36
  37 struct smatch_state *alloc_state_num(int num)
  38 {
  39         struct smatch_state *state;
  40         static char buff[256];
  41
  42         state = __alloc_smatch_state(0);
  43         snprintf(buff, 255, "%d", num);
  44         buff[255] = '\0';
  45         state->name = alloc_string(buff);
  46         state->data = INT_PTR(num);
  47         return state;
  48 }
  49
  50 static void append(char *dest, const char *data, int buff_len)
  51 {
  52         strncat(dest, data, buff_len - strlen(dest) - 1);
  53 }
  54
  55 /*
  56  * If you have "foo(a, b, 1);" then use
  57  * get_argument_from_call_expr(expr, 0) to return the expression for
  58  * a.  Yes, it does start counting from 0.
  59  */
  60 struct expression *get_argument_from_call_expr(struct expression_list *args,
  61                                                int num)
  62 {
  63         struct expression *expr;
  64         int i = 0;
  65
  66         if (!args)
  67                 return NULL;
  68
  69         FOR_EACH_PTR(args, expr) {
  70                 if (i == num)
  71                         return expr;
  72                 i++;
  73         } END_FOR_EACH_PTR(expr);
  74         return NULL;
  75 }
  76
  77 static struct expression *get_array_expr(struct expression *expr)
  78 {
  79         struct symbol *type;
  80
  81         if (expr->type != EXPR_BINOP || expr->op != '+')
  82                 return NULL;
  83
  84         type = get_type(expr->left);
  85         if (!type || type->type != SYM_ARRAY)
  86                 return NULL;
  87         return expr->left;
  88 }
  89
  90 static void __get_variable_from_expr(struct symbol **sym_ptr, char *buf,
  91                                      struct expression *expr, int len,
  92                                      int *complicated)
  93 {
  94         struct expression *tmp;
  95
  96         switch (expr->type) {
  97         case EXPR_DEREF:
  98                 tmp = expr->deref;
  99                 if (tmp->op == '*')  {
 100                         tmp = tmp->unop;
 101                 }
 102                 __get_variable_from_expr(sym_ptr, buf, tmp, len, complicated);
 103
 104                 tmp = expr->deref;
 105                 if (tmp->op == '*')  {
 106                         append(buf, "->", len);
 107                 } else {
 108                         append(buf, ".", len);
 109                 }
 110                 append(buf, expr->member->name, len);
 111
 112                 return;
 113         case EXPR_SYMBOL:
 114                 if (expr->symbol_name)
 115                         append(buf, expr->symbol_name->name, len);
 116                 if (sym_ptr) {
 117                         if (*sym_ptr)
 118                                 *complicated = 1;
 119                         *sym_ptr = expr->symbol;
 120                 }
 121                 return;
 122         case EXPR_PREOP: {
 123                 const char *tmp;
 124
 125                 if (get_expression_statement(expr)) {
 126                         *complicated = 2;
 127                         return;
 128                 }
 129
 130                 if (expr->op != '*' || !get_array_expr(expr->unop)) {
 131                         tmp = show_special(expr->op);
 132                         append(buf, tmp, len);
 133                 }
 134                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 135                                                  len, complicated);
 136
 137                 if (expr->op == '(') {
 138                         append(buf, ")", len);
 139                 }
 140
 141                 if (expr->op == SPECIAL_DECREMENT || expr->op == SPECIAL_INCREMENT)
 142                         *complicated = 1;
 143
 144                 return;
 145         }
 146         case EXPR_POSTOP: {
 147                 const char *tmp;
 148
 149                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 150                                                  len, complicated);
 151                 tmp = show_special(expr->op);
 152                 append(buf, tmp, len);
 153
 154                 if (expr->op == SPECIAL_DECREMENT || expr->op == SPECIAL_INCREMENT)
 155                         *complicated = 1;
 156                 return;
 157         }
 158         case EXPR_BINOP: {
 159                 char tmp[10];
 160                 struct expression *array_expr;
 161
 162                 *complicated = 1;
 163                 array_expr = get_array_expr(expr);
 164                 if (array_expr) {
 165                         __get_variable_from_expr(sym_ptr, buf, array_expr, len, complicated);
 166                         append(buf, "[", len);
 167                 } else {
 168                         __get_variable_from_expr(sym_ptr, buf, expr->left, len,
 169                                          complicated);
 170                         snprintf(tmp, sizeof(tmp), " %s ", show_special(expr->op));
 171                         append(buf, tmp, len);
 172                 }
 173                 __get_variable_from_expr(NULL, buf, expr->right,
 174                                                  len, complicated);
 175                 if (array_expr)
 176                         append(buf, "]", len);
 177                 return;
 178         }
 179         case EXPR_VALUE: {
 180                 char tmp[25];
 181
 182                 *complicated = 1;
 183                 snprintf(tmp, 25, "%lld", expr->value);
 184                 append(buf, tmp, len);
 185                 return;
 186         }
 187         case EXPR_STRING:
 188                 append(buf, "\"", len);
 189                 append(buf, expr->string->data, len);
 190                 append(buf, "\"", len);
 191                 return;
 192         case EXPR_CALL: {
 193                 struct expression *tmp;
 194                 int i;
 195
 196                 *complicated = 1;
 197                 __get_variable_from_expr(NULL, buf, expr->fn, len,
 198                                          complicated);
 199                 append(buf, "(", len);
 200                 i = 0;
 201                 FOR_EACH_PTR_REVERSE(expr->args, tmp) {
 202                         if (i++)
 203                                 append(buf, ", ", len);
 204                         __get_variable_from_expr(NULL, buf, tmp, len,
 205                                                 complicated);
 206                 } END_FOR_EACH_PTR_REVERSE(tmp);
 207                 append(buf, ")", len);
 208                 return;
 209         }
 210         case EXPR_CAST:
 211                 __get_variable_from_expr(sym_ptr, buf,
 212                                          expr->cast_expression, len,
 213                                          complicated);
 214                 return;
 215         case EXPR_SIZEOF: {
 216                 int size;
 217                 char tmp[25];
 218
 219                 if (expr->cast_type && get_base_type(expr->cast_type)) {
 220                         size = (get_base_type(expr->cast_type))->bit_size;
 221                         snprintf(tmp, 25, "%d", bits_to_bytes(size));
 222                         append(buf, tmp, len);
 223                 }
 224                 return;
 225         }
 226         default:
 227                 *complicated = 1;
 228                 //printf("unknown type = %d\n", expr->type);
 229                 return;
 230         }
 231 }
 232
 233 /*
 234  * This is returns a stylized "c looking" representation of the
 235  * variable name.
 236  *
 237  * It uses the same buffer every time so you have to save the result
 238  * yourself if you want to keep it.
 239  *
 240  */
 241
 242 char *get_variable_from_expr_complex(struct expression *expr, struct symbol **sym_ptr)
 243 {
 244         static char var_name[VAR_LEN];
 245         int complicated = 0;
 246
 247         if (sym_ptr)
 248                 *sym_ptr = NULL;
 249         var_name[0] = '\0';
 250
 251         if (!expr)
 252                 return NULL;
 253         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 254                                  &complicated);
 255         if (complicated < 2)
 256                 return alloc_string(var_name);
 257         else
 258                 return NULL;
 259 }
 260
 261 /*
 262  * get_variable_from_expr_simple() only returns simple variables.
 263  * If it's a complicated variable like a->foo instead of just 'a'
 264  * then it returns NULL.
 265  */
 266
 267 char *get_variable_from_expr(struct expression *expr,
 268                                     struct symbol **sym_ptr)
 269 {
 270         static char var_name[VAR_LEN];
 271         int complicated = 0;
 272
 273         if (sym_ptr)
 274                 *sym_ptr = NULL;
 275         var_name[0] = '\0';
 276
 277         if (!expr)
 278                 return NULL;
 279         expr = strip_expr(expr);
 280         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 281                                  &complicated);
 282
 283         if (complicated) {
 284                 if (sym_ptr)
 285                         *sym_ptr = NULL;
 286                 return NULL;
 287         }
 288         return alloc_string(var_name);
 289 }
 290
 291 int sym_name_is(const char *name, struct expression *expr)
 292 {
 293         if (!expr)
 294                 return 0;
 295         if (expr->type != EXPR_SYMBOL)
 296                 return 0;
 297         if (!strcmp(expr->symbol_name->name, name))
 298                 return 1;
 299         return 0;
 300 }
 301
 302 int is_zero(struct expression *expr)
 303 {
 304         long long val;
 305
 306         if (get_value(expr, &val) && val == 0)
 307                 return 1;
 308         return 0;
 309 }
 310
 311 int is_array(struct expression *expr)
 312 {
 313         expr = strip_expr(expr);
 314         if (expr->type != EXPR_PREOP || expr->op != '*')
 315                 return 0;
 316         expr = expr->unop;
 317         if (expr->op != '+')
 318                 return 0;
 319         return 1;
 320 }
 321
 322 struct expression *get_array_name(struct expression *expr)
 323 {
 324         if (!is_array(expr))
 325                 return NULL;
 326         return strip_expr(expr->unop->left);
 327 }
 328
 329 struct expression *get_array_offset(struct expression *expr)
 330 {
 331         if (!is_array(expr))
 332                 return NULL;
 333         return expr->unop->right;
 334 }
 335
 336 const char *show_state(struct smatch_state *state)
 337 {
 338         if (!state)
 339                 return NULL;
 340         return state->name;
 341 }
 342
 343 struct statement *get_expression_statement(struct expression *expr)
 344 {
 345         /* What are those things called? if (({....; ret;})) { ...*/
 346
 347         if (expr->type != EXPR_PREOP)
 348                 return NULL;
 349         if (expr->op != '(')
 350                 return NULL;
 351         if (expr->unop->type != EXPR_STATEMENT)
 352                 return NULL;
 353         if (expr->unop->statement->type != STMT_COMPOUND)
 354                 return NULL;
 355         return expr->unop->statement;
 356 }
 357
 358 struct expression *strip_parens(struct expression *expr)
 359 {
 360         if (!expr)
 361                 return NULL;
 362
 363         if (expr->type == EXPR_PREOP) {
 364                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 365                         expr->unop->statement->type == STMT_COMPOUND)
 366                         return expr;
 367                 if (expr->op == '(')
 368                         return strip_parens(expr->unop);
 369         }
 370         return expr;
 371 }
 372
 373 struct expression *strip_expr(struct expression *expr)
 374 {
 375         if (!expr)
 376                 return NULL;
 377
 378         switch (expr->type) {
 379         case EXPR_FORCE_CAST:
 380         case EXPR_CAST:
 381                 return strip_expr(expr->cast_expression);
 382         case EXPR_PREOP:
 383                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 384                         expr->unop->statement->type == STMT_COMPOUND)
 385                         return expr;
 386                 if (expr->op == '(')
 387                         return strip_expr(expr->unop);
 388         }
 389         return expr;
 390 }
 391
 392 static void delete_state_tracker(struct tracker *t)
 393 {
 394         delete_state(t->owner, t->name, t->sym);
 395         __free_tracker(t);
 396 }
 397
 398 void scoped_state(int my_id, const char *name, struct symbol *sym)
 399 {
 400         struct tracker *t;
 401
 402         t = alloc_tracker(my_id, name, sym);
 403         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 404 }
 405
 406 int is_error_return(struct expression *expr)
 407 {
 408         struct symbol *cur_func = cur_func_sym;
 409         long long val;
 410
 411         if (!expr)
 412                 return 0;
 413         if (cur_func->type != SYM_NODE)
 414                 return 0;
 415         cur_func = get_base_type(cur_func);
 416         if (cur_func->type != SYM_FN)
 417                 return 0;
 418         cur_func = get_base_type(cur_func);
 419         if (cur_func == &void_ctype)
 420                 return 0;
 421         if (!get_value(expr, &val))
 422                 return 0;
 423         if (val < 0)
 424                 return 1;
 425         if (cur_func->type == SYM_PTR && val == 0)
 426                 return 1;
 427         return 0;
 428 }
 429
 430 int getting_address(void)
 431 {
 432         struct expression *tmp;
 433         int i = 0;
 434         int dot_ops = 0;
 435
 436         FOR_EACH_PTR_REVERSE(big_expression_stack, tmp) {
 437                 if (!i++)
 438                         continue;
 439                 if (tmp->type == EXPR_PREOP && tmp->op == '(')
 440                         continue;
 441                 if (tmp->op == '.' && !dot_ops++)
 442                         continue;
 443                 if (tmp->op == '&')
 444                         return 1;
 445                 return 0;
 446         } END_FOR_EACH_PTR_REVERSE(tmp);
 447         return 0;
 448 }
 449
 450 char *get_fnptr_name(struct expression *expr)
 451 {
 452         char buf[256];
 453         struct symbol *sym;
 454
 455         if (expr->type == EXPR_SYMBOL)
 456                 return get_variable_from_expr(expr, NULL);
 457
 458         if (expr->type != EXPR_DEREF)
 459                 return NULL;
 460         sym = get_type(expr->deref);
 461         if (!sym || !sym->ident)
 462                 return NULL;
 463         snprintf(buf, sizeof(buf), "(struct %s)->%s", sym->ident->name, expr->member->name);
 464         return alloc_string(buf);
 465 }
 466