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_BINOP: {
 160                 char tmp[10];
 161                 struct expression *array_expr;
 162
 163                 *complicated = 1;
 164                 array_expr = get_array_expr(expr);
 165                 if (array_expr) {
 166                         __get_variable_from_expr(sym_ptr, buf, array_expr, len, complicated);
 167                         append(buf, "[", len);
 168                 } else {
 169                         __get_variable_from_expr(sym_ptr, buf, expr->left, len,
 170                                          complicated);
 171                         snprintf(tmp, sizeof(tmp), " %s ", show_special(expr->op));
 172                         append(buf, tmp, len);
 173                 }
 174                 __get_variable_from_expr(NULL, buf, expr->right,
 175                                                  len, complicated);
 176                 if (array_expr)
 177                         append(buf, "]", len);
 178                 return;
 179         }
 180         case EXPR_VALUE: {
 181                 char tmp[25];
 182
 183                 *complicated = 1;
 184                 snprintf(tmp, 25, "%lld", expr->value);
 185                 append(buf, tmp, len);
 186                 return;
 187         }
 188         case EXPR_STRING:
 189                 append(buf, "\"", len);
 190                 append(buf, expr->string->data, len);
 191                 append(buf, "\"", len);
 192                 return;
 193         case EXPR_CALL: {
 194                 struct expression *tmp;
 195                 int i;
 196
 197                 *complicated = 1;
 198                 __get_variable_from_expr(NULL, buf, expr->fn, len,
 199                                          complicated);
 200                 append(buf, "(", len);
 201                 i = 0;
 202                 FOR_EACH_PTR_REVERSE(expr->args, tmp) {
 203                         if (i++)
 204                                 append(buf, ", ", len);
 205                         __get_variable_from_expr(NULL, buf, tmp, len,
 206                                                 complicated);
 207                 } END_FOR_EACH_PTR_REVERSE(tmp);
 208                 append(buf, ")", len);
 209                 return;
 210         }
 211         case EXPR_CAST:
 212                 __get_variable_from_expr(sym_ptr, buf,
 213                                          expr->cast_expression, len,
 214                                          complicated);
 215                 return;
 216         case EXPR_SIZEOF: {
 217                 int size;
 218                 char tmp[25];
 219
 220                 if (expr->cast_type && get_base_type(expr->cast_type)) {
 221                         size = (get_base_type(expr->cast_type))->bit_size;
 222                         snprintf(tmp, 25, "%d", bits_to_bytes(size));
 223                         append(buf, tmp, len);
 224                 }
 225                 return;
 226         }
 227         default:
 228                 *complicated = 1;
 229                 //printf("unknown type = %d\n", expr->type);
 230                 return;
 231         }
 232 }
 233
 234 /*
 235  * This is returns a stylized "c looking" representation of the
 236  * variable name.
 237  *
 238  * It uses the same buffer every time so you have to save the result
 239  * yourself if you want to keep it.
 240  *
 241  */
 242
 243 char *get_variable_from_expr_complex(struct expression *expr, struct symbol **sym_ptr)
 244 {
 245         static char var_name[VAR_LEN];
 246         int complicated = 0;
 247
 248         if (sym_ptr)
 249                 *sym_ptr = NULL;
 250         var_name[0] = '\0';
 251
 252         if (!expr)
 253                 return NULL;
 254         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 255                                  &complicated);
 256         if (complicated < 2)
 257                 return alloc_string(var_name);
 258         else
 259                 return NULL;
 260 }
 261
 262 /*
 263  * get_variable_from_expr_simple() only returns simple variables.
 264  * If it's a complicated variable like a->foo instead of just 'a'
 265  * then it returns NULL.
 266  */
 267
 268 char *get_variable_from_expr(struct expression *expr,
 269                                     struct symbol **sym_ptr)
 270 {
 271         static char var_name[VAR_LEN];
 272         int complicated = 0;
 273
 274         if (sym_ptr)
 275                 *sym_ptr = NULL;
 276         var_name[0] = '\0';
 277
 278         if (!expr)
 279                 return NULL;
 280         expr = strip_expr(expr);
 281         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 282                                  &complicated);
 283
 284         if (complicated) {
 285                 if (sym_ptr)
 286                         *sym_ptr = NULL;
 287                 return NULL;
 288         }
 289         return alloc_string(var_name);
 290 }
 291
 292 int sym_name_is(const char *name, struct expression *expr)
 293 {
 294         if (!expr)
 295                 return 0;
 296         if (expr->type != EXPR_SYMBOL)
 297                 return 0;
 298         if (!strcmp(expr->symbol_name->name, name))
 299                 return 1;
 300         return 0;
 301 }
 302
 303 int is_zero(struct expression *expr)
 304 {
 305         long long val;
 306
 307         if (get_value(expr, &val) && val == 0)
 308                 return 1;
 309         return 0;
 310 }
 311
 312 int is_array(struct expression *expr)
 313 {
 314         expr = strip_expr(expr);
 315         if (expr->type != EXPR_PREOP || expr->op != '*')
 316                 return 0;
 317         expr = expr->unop;
 318         if (expr->op != '+')
 319                 return 0;
 320         return 1;
 321 }
 322
 323 struct expression *get_array_name(struct expression *expr)
 324 {
 325         if (!is_array(expr))
 326                 return NULL;
 327         return strip_expr(expr->unop->left);
 328 }
 329
 330 struct expression *get_array_offset(struct expression *expr)
 331 {
 332         if (!is_array(expr))
 333                 return NULL;
 334         return expr->unop->right;
 335 }
 336
 337 const char *show_state(struct smatch_state *state)
 338 {
 339         if (!state)
 340                 return NULL;
 341         return state->name;
 342 }
 343
 344 struct statement *get_expression_statement(struct expression *expr)
 345 {
 346         /* What are those things called? if (({....; ret;})) { ...*/
 347
 348         if (expr->type != EXPR_PREOP)
 349                 return NULL;
 350         if (expr->op != '(')
 351                 return NULL;
 352         if (expr->unop->type != EXPR_STATEMENT)
 353                 return NULL;
 354         if (expr->unop->statement->type != STMT_COMPOUND)
 355                 return NULL;
 356         return expr->unop->statement;
 357 }
 358
 359 struct expression *strip_parens(struct expression *expr)
 360 {
 361         if (!expr)
 362                 return NULL;
 363
 364         if (expr->type == EXPR_PREOP) {
 365                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 366                         expr->unop->statement->type == STMT_COMPOUND)
 367                         return expr;
 368                 if (expr->op == '(')
 369                         return strip_parens(expr->unop);
 370         }
 371         return expr;
 372 }
 373
 374 struct expression *strip_expr(struct expression *expr)
 375 {
 376         if (!expr)
 377                 return NULL;
 378
 379         switch (expr->type) {
 380         case EXPR_FORCE_CAST:
 381         case EXPR_CAST:
 382                 return strip_expr(expr->cast_expression);
 383         case EXPR_PREOP:
 384                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 385                         expr->unop->statement->type == STMT_COMPOUND)
 386                         return expr;
 387                 if (expr->op == '(')
 388                         return strip_expr(expr->unop);
 389         }
 390         return expr;
 391 }
 392
 393 static void delete_state_tracker(struct tracker *t)
 394 {
 395         delete_state(t->owner, t->name, t->sym);
 396         __free_tracker(t);
 397 }
 398
 399 void scoped_state(int my_id, const char *name, struct symbol *sym)
 400 {
 401         struct tracker *t;
 402
 403         t = alloc_tracker(my_id, name, sym);
 404         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 405 }
 406
 407 int is_error_return(struct expression *expr)
 408 {
 409         struct symbol *cur_func = cur_func_sym;
 410         long long val;
 411
 412         if (!expr)
 413                 return 0;
 414         if (cur_func->type != SYM_NODE)
 415                 return 0;
 416         cur_func = get_base_type(cur_func);
 417         if (cur_func->type != SYM_FN)
 418                 return 0;
 419         cur_func = get_base_type(cur_func);
 420         if (cur_func == &void_ctype)
 421                 return 0;
 422         if (!get_value(expr, &val))
 423                 return 0;
 424         if (val < 0)
 425                 return 1;
 426         if (cur_func->type == SYM_PTR && val == 0)
 427                 return 1;
 428         return 0;
 429 }
 430
 431 int getting_address(void)
 432 {
 433         struct expression *tmp;
 434         int i = 0;
 435         int dot_ops = 0;
 436
 437         FOR_EACH_PTR_REVERSE(big_expression_stack, tmp) {
 438                 if (!i++)
 439                         continue;
 440                 if (tmp->type == EXPR_PREOP && tmp->op == '(')
 441                         continue;
 442                 if (tmp->op == '.' && !dot_ops++)
 443                         continue;
 444                 if (tmp->op == '&')
 445                         return 1;
 446                 return 0;
 447         } END_FOR_EACH_PTR_REVERSE(tmp);
 448         return 0;
 449 }
 450
 451 char *get_fnptr_name(struct expression *expr)
 452 {
 453         char buf[256];
 454         struct symbol *sym;
 455
 456         if (expr->type == EXPR_SYMBOL)
 457                 return get_variable_from_expr(expr, NULL);
 458
 459         if (expr->type != EXPR_DEREF)
 460                 return NULL;
 461         sym = get_type(expr->deref);
 462         if (!sym || !sym->ident)
 463                 return NULL;
 464         snprintf(buf, sizeof(buf), "(struct %s)->%s", sym->ident->name, expr->member->name);
 465         return alloc_string(buf);
 466 }
 467