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                 if (expr->op == SPECIAL_DECREMENT ||
 141                                 expr->op == SPECIAL_INCREMENT ||
 142                                 expr->op == '&')
 143                         *complicated = 1;
 144
 145                 return;
 146         }
 147         case EXPR_POSTOP: {
 148                 const char *tmp;
 149
 150                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 151                                                  len, complicated);
 152                 tmp = show_special(expr->op);
 153                 append(buf, tmp, len);
 154
 155                 if (expr->op == SPECIAL_DECREMENT || expr->op == SPECIAL_INCREMENT)
 156                         *complicated = 1;
 157                 return;
 158         }
 159         case EXPR_COMPARE:
 160         case EXPR_LOGICAL:
 161         case EXPR_BINOP: {
 162                 char tmp[10];
 163                 struct expression *array_expr;
 164
 165                 *complicated = 1;
 166                 array_expr = get_array_expr(expr);
 167                 if (array_expr) {
 168                         __get_variable_from_expr(sym_ptr, buf, array_expr, len, complicated);
 169                         append(buf, "[", len);
 170                 } else {
 171                         __get_variable_from_expr(sym_ptr, buf, expr->left, len,
 172                                          complicated);
 173                         snprintf(tmp, sizeof(tmp), " %s ", show_special(expr->op));
 174                         append(buf, tmp, len);
 175                 }
 176                 __get_variable_from_expr(NULL, buf, expr->right,
 177                                                  len, complicated);
 178                 if (array_expr)
 179                         append(buf, "]", len);
 180                 return;
 181         }
 182         case EXPR_VALUE: {
 183                 char tmp[25];
 184
 185                 *complicated = 1;
 186                 snprintf(tmp, 25, "%lld", expr->value);
 187                 append(buf, tmp, len);
 188                 return;
 189         }
 190         case EXPR_STRING:
 191                 append(buf, "\"", len);
 192                 append(buf, expr->string->data, len);
 193                 append(buf, "\"", len);
 194                 return;
 195         case EXPR_CALL: {
 196                 struct expression *tmp;
 197                 int i;
 198
 199                 *complicated = 1;
 200                 __get_variable_from_expr(NULL, buf, expr->fn, len,
 201                                          complicated);
 202                 append(buf, "(", len);
 203                 i = 0;
 204                 FOR_EACH_PTR_REVERSE(expr->args, tmp) {
 205                         if (i++)
 206                                 append(buf, ", ", len);
 207                         __get_variable_from_expr(NULL, buf, tmp, len,
 208                                                 complicated);
 209                 } END_FOR_EACH_PTR_REVERSE(tmp);
 210                 append(buf, ")", len);
 211                 return;
 212         }
 213         case EXPR_CAST:
 214                 __get_variable_from_expr(sym_ptr, buf,
 215                                          expr->cast_expression, len,
 216                                          complicated);
 217                 return;
 218         case EXPR_SIZEOF: {
 219                 int size;
 220                 char tmp[25];
 221
 222                 if (expr->cast_type && get_base_type(expr->cast_type)) {
 223                         size = (get_base_type(expr->cast_type))->bit_size;
 224                         snprintf(tmp, 25, "%d", bits_to_bytes(size));
 225                         append(buf, tmp, len);
 226                 }
 227                 return;
 228         }
 229         default:
 230                 *complicated = 1;
 231                 //printf("unknown type = %d\n", expr->type);
 232                 return;
 233         }
 234 }
 235
 236 /*
 237  * This is returns a stylized "c looking" representation of the
 238  * variable name.
 239  *
 240  * It uses the same buffer every time so you have to save the result
 241  * yourself if you want to keep it.
 242  *
 243  */
 244
 245 char *get_variable_from_expr_complex(struct expression *expr, 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         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 257                                  &complicated);
 258         if (complicated < 2)
 259                 return alloc_string(var_name);
 260         else
 261                 return NULL;
 262 }
 263
 264 /*
 265  * get_variable_from_expr_simple() only returns simple variables.
 266  * If it's a complicated variable like a->foo instead of just 'a'
 267  * then it returns NULL.
 268  */
 269
 270 char *get_variable_from_expr(struct expression *expr,
 271                                     struct symbol **sym_ptr)
 272 {
 273         static char var_name[VAR_LEN];
 274         int complicated = 0;
 275
 276         if (sym_ptr)
 277                 *sym_ptr = NULL;
 278         var_name[0] = '\0';
 279
 280         if (!expr)
 281                 return NULL;
 282         expr = strip_expr(expr);
 283         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 284                                  &complicated);
 285
 286         if (complicated) {
 287                 if (sym_ptr)
 288                         *sym_ptr = NULL;
 289                 return NULL;
 290         }
 291         return alloc_string(var_name);
 292 }
 293
 294 int sym_name_is(const char *name, struct expression *expr)
 295 {
 296         if (!expr)
 297                 return 0;
 298         if (expr->type != EXPR_SYMBOL)
 299                 return 0;
 300         if (!strcmp(expr->symbol_name->name, name))
 301                 return 1;
 302         return 0;
 303 }
 304
 305 int is_zero(struct expression *expr)
 306 {
 307         sval_t sval;
 308
 309         if (get_value_sval(expr, &sval) && sval.value == 0)
 310                 return 1;
 311         return 0;
 312 }
 313
 314 int is_array(struct expression *expr)
 315 {
 316         expr = strip_expr(expr);
 317         if (expr->type != EXPR_PREOP || expr->op != '*')
 318                 return 0;
 319         expr = expr->unop;
 320         if (expr->op != '+')
 321                 return 0;
 322         return 1;
 323 }
 324
 325 struct expression *get_array_name(struct expression *expr)
 326 {
 327         if (!is_array(expr))
 328                 return NULL;
 329         return strip_expr(expr->unop->left);
 330 }
 331
 332 struct expression *get_array_offset(struct expression *expr)
 333 {
 334         if (!is_array(expr))
 335                 return NULL;
 336         return expr->unop->right;
 337 }
 338
 339 const char *show_state(struct smatch_state *state)
 340 {
 341         if (!state)
 342                 return NULL;
 343         return state->name;
 344 }
 345
 346 struct statement *get_expression_statement(struct expression *expr)
 347 {
 348         /* What are those things called? if (({....; ret;})) { ...*/
 349
 350         if (expr->type != EXPR_PREOP)
 351                 return NULL;
 352         if (expr->op != '(')
 353                 return NULL;
 354         if (expr->unop->type != EXPR_STATEMENT)
 355                 return NULL;
 356         if (expr->unop->statement->type != STMT_COMPOUND)
 357                 return NULL;
 358         return expr->unop->statement;
 359 }
 360
 361 struct expression *strip_parens(struct expression *expr)
 362 {
 363         if (!expr)
 364                 return NULL;
 365
 366         if (expr->type == EXPR_PREOP) {
 367                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 368                         expr->unop->statement->type == STMT_COMPOUND)
 369                         return expr;
 370                 if (expr->op == '(')
 371                         return strip_parens(expr->unop);
 372         }
 373         return expr;
 374 }
 375
 376 struct expression *strip_expr(struct expression *expr)
 377 {
 378         if (!expr)
 379                 return NULL;
 380
 381         switch (expr->type) {
 382         case EXPR_FORCE_CAST:
 383         case EXPR_CAST:
 384                 return strip_expr(expr->cast_expression);
 385         case EXPR_PREOP:
 386                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 387                         expr->unop->statement->type == STMT_COMPOUND)
 388                         return expr;
 389                 if (expr->op == '(')
 390                         return strip_expr(expr->unop);
 391         }
 392         return expr;
 393 }
 394
 395 static void delete_state_tracker(struct tracker *t)
 396 {
 397         delete_state(t->owner, t->name, t->sym);
 398         __free_tracker(t);
 399 }
 400
 401 void scoped_state(int my_id, const char *name, struct symbol *sym)
 402 {
 403         struct tracker *t;
 404
 405         t = alloc_tracker(my_id, name, sym);
 406         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 407 }
 408
 409 int is_error_return(struct expression *expr)
 410 {
 411         struct symbol *cur_func = cur_func_sym;
 412         sval_t sval;
 413
 414         if (!expr)
 415                 return 0;
 416         if (cur_func->type != SYM_NODE)
 417                 return 0;
 418         cur_func = get_base_type(cur_func);
 419         if (cur_func->type != SYM_FN)
 420                 return 0;
 421         cur_func = get_base_type(cur_func);
 422         if (cur_func == &void_ctype)
 423                 return 0;
 424         if (!get_value_sval(expr, &sval))
 425                 return 0;
 426         if (sval_cmp_val(sval, 0) < 0)
 427                 return 1;
 428         if (cur_func->type == SYM_PTR && sval.value == 0)
 429                 return 1;
 430         return 0;
 431 }
 432
 433 int getting_address(void)
 434 {
 435         struct expression *tmp;
 436         int i = 0;
 437         int dot_ops = 0;
 438
 439         FOR_EACH_PTR_REVERSE(big_expression_stack, tmp) {
 440                 if (!i++)
 441                         continue;
 442                 if (tmp->type == EXPR_PREOP && tmp->op == '(')
 443                         continue;
 444                 if (tmp->op == '.' && !dot_ops++)
 445                         continue;
 446                 if (tmp->op == '&')
 447                         return 1;
 448                 return 0;
 449         } END_FOR_EACH_PTR_REVERSE(tmp);
 450         return 0;
 451 }
 452
 453 char *get_member_name(struct expression *expr)
 454 {
 455         char buf[256];
 456         struct symbol *sym;
 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
 467 char *get_fnptr_name(struct expression *expr)
 468 {
 469         if (expr->type == EXPR_SYMBOL)
 470                 return get_variable_from_expr(expr, NULL);
 471         return get_member_name(expr);
 472 }
 473
 474 int positions_eq(struct position pos1, struct position pos2)
 475 {
 476         if (pos1.line != pos2.line)
 477                 return 0;
 478         if (pos1.pos != pos2.pos)
 479                 return 0;
 480         if (pos1.stream != pos2.stream)
 481                 return 0;
 482         return 1;
 483 }
 484
 485 struct statement *get_current_statement(void)
 486 {
 487         struct statement *prev, *tmp;
 488
 489         prev = last_ptr_list((struct ptr_list *)big_statement_stack);
 490
 491         if (!prev || !get_macro_name(prev->pos))
 492                 return prev;
 493
 494         FOR_EACH_PTR_REVERSE(big_statement_stack, tmp) {
 495                 if (positions_eq(tmp->pos, prev->pos))
 496                         continue;
 497                 if (prev->pos.line > tmp->pos.line)
 498                         return prev;
 499                 return tmp;
 500         } END_FOR_EACH_PTR_REVERSE(tmp);
 501         return prev;
 502 }