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 || expr->op == SPECIAL_INCREMENT)
 141                         *complicated = 1;
 142
 143                 return;
 144         }
 145         case EXPR_POSTOP: {
 146                 const char *tmp;
 147
 148                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 149                                                  len, complicated);
 150                 tmp = show_special(expr->op);
 151                 append(buf, tmp, len);
 152
 153                 if (expr->op == SPECIAL_DECREMENT || expr->op == SPECIAL_INCREMENT)
 154                         *complicated = 1;
 155                 return;
 156         }
 157         case EXPR_BINOP: {
 158                 char tmp[10];
 159                 struct expression *array_expr;
 160
 161                 *complicated = 1;
 162                 array_expr = get_array_expr(expr);
 163                 if (array_expr) {
 164                         __get_variable_from_expr(sym_ptr, buf, array_expr, len, complicated);
 165                         append(buf, "[", len);
 166                 } else {
 167                         __get_variable_from_expr(sym_ptr, buf, expr->left, len,
 168                                          complicated);
 169                         snprintf(tmp, sizeof(tmp), " %s ", show_special(expr->op));
 170                         append(buf, tmp, len);
 171                 }
 172                 __get_variable_from_expr(NULL, buf, expr->right,
 173                                                  len, complicated);
 174                 if (array_expr)
 175                         append(buf, "]", len);
 176                 return;
 177         }
 178         case EXPR_VALUE: {
 179                 char tmp[25];
 180
 181                 *complicated = 1;
 182                 snprintf(tmp, 25, "%lld", expr->value);
 183                 append(buf, tmp, len);
 184                 return;
 185         }
 186         case EXPR_STRING:
 187                 append(buf, "\"", len);
 188                 append(buf, expr->string->data, len);
 189                 append(buf, "\"", len);
 190                 return;
 191         case EXPR_CALL: {
 192                 struct expression *tmp;
 193                 int i;
 194
 195                 *complicated = 1;
 196                 __get_variable_from_expr(NULL, buf, expr->fn, len,
 197                                          complicated);
 198                 append(buf, "(", len);
 199                 i = 0;
 200                 FOR_EACH_PTR_REVERSE(expr->args, tmp) {
 201                         if (i++)
 202                                 append(buf, ", ", len);
 203                         __get_variable_from_expr(NULL, buf, tmp, len,
 204                                                 complicated);
 205                 } END_FOR_EACH_PTR_REVERSE(tmp);
 206                 append(buf, ")", len);
 207                 return;
 208         }
 209         case EXPR_CAST:
 210                 __get_variable_from_expr(sym_ptr, buf,
 211                                          expr->cast_expression, len,
 212                                          complicated);
 213                 return;
 214         case EXPR_SIZEOF: {
 215                 int size;
 216                 char tmp[25];
 217
 218                 if (expr->cast_type && get_base_type(expr->cast_type)) {
 219                         size = (get_base_type(expr->cast_type))->bit_size;
 220                         snprintf(tmp, 25, "%d", bits_to_bytes(size));
 221                         append(buf, tmp, len);
 222                 }
 223                 return;
 224         }
 225         default:
 226                 *complicated = 1;
 227                 //printf("unknown type = %d\n", expr->type);
 228                 return;
 229         }
 230 }
 231
 232 /*
 233  * This is returns a stylized "c looking" representation of the
 234  * variable name.
 235  *
 236  * It uses the same buffer every time so you have to save the result
 237  * yourself if you want to keep it.
 238  *
 239  */
 240
 241 char *get_variable_from_expr_complex(struct expression *expr, struct symbol **sym_ptr)
 242 {
 243         static char var_name[VAR_LEN];
 244         int complicated = 0;
 245
 246         if (sym_ptr)
 247                 *sym_ptr = NULL;
 248         var_name[0] = '\0';
 249
 250         if (!expr)
 251                 return NULL;
 252         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 253                                  &complicated);
 254         if (complicated < 2)
 255                 return alloc_string(var_name);
 256         else
 257                 return NULL;
 258 }
 259
 260 /*
 261  * get_variable_from_expr_simple() only returns simple variables.
 262  * If it's a complicated variable like a->foo instead of just 'a'
 263  * then it returns NULL.
 264  */
 265
 266 char *get_variable_from_expr(struct expression *expr,
 267                                     struct symbol **sym_ptr)
 268 {
 269         static char var_name[VAR_LEN];
 270         int complicated = 0;
 271
 272         if (sym_ptr)
 273                 *sym_ptr = NULL;
 274         var_name[0] = '\0';
 275
 276         if (!expr)
 277                 return NULL;
 278         expr = strip_expr(expr);
 279         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 280                                  &complicated);
 281
 282         if (complicated) {
 283                 if (sym_ptr)
 284                         *sym_ptr = NULL;
 285                 return NULL;
 286         }
 287         return alloc_string(var_name);
 288 }
 289
 290 int sym_name_is(const char *name, struct expression *expr)
 291 {
 292         if (!expr)
 293                 return 0;
 294         if (expr->type != EXPR_SYMBOL)
 295                 return 0;
 296         if (!strcmp(expr->symbol_name->name, name))
 297                 return 1;
 298         return 0;
 299 }
 300
 301 int is_zero(struct expression *expr)
 302 {
 303         long long val;
 304
 305         if (get_value(expr, &val) && val == 0)
 306                 return 1;
 307         return 0;
 308 }
 309
 310 int is_array(struct expression *expr)
 311 {
 312         expr = strip_expr(expr);
 313         if (expr->type != EXPR_PREOP || expr->op != '*')
 314                 return 0;
 315         expr = expr->unop;
 316         if (expr->op != '+')
 317                 return 0;
 318         return 1;
 319 }
 320
 321 struct expression *get_array_name(struct expression *expr)
 322 {
 323         if (!is_array(expr))
 324                 return NULL;
 325         return strip_expr(expr->unop->left);
 326 }
 327
 328 struct expression *get_array_offset(struct expression *expr)
 329 {
 330         if (!is_array(expr))
 331                 return NULL;
 332         return expr->unop->right;
 333 }
 334
 335 const char *show_state(struct smatch_state *state)
 336 {
 337         if (!state)
 338                 return NULL;
 339         return state->name;
 340 }
 341
 342 struct statement *get_expression_statement(struct expression *expr)
 343 {
 344         /* What are those things called? if (({....; ret;})) { ...*/
 345
 346         if (expr->type != EXPR_PREOP)
 347                 return NULL;
 348         if (expr->op != '(')
 349                 return NULL;
 350         if (expr->unop->type != EXPR_STATEMENT)
 351                 return NULL;
 352         if (expr->unop->statement->type != STMT_COMPOUND)
 353                 return NULL;
 354         return expr->unop->statement;
 355 }
 356
 357 struct expression *strip_parens(struct expression *expr)
 358 {
 359         if (!expr)
 360                 return NULL;
 361
 362         if (expr->type == EXPR_PREOP) {
 363                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 364                         expr->unop->statement->type == STMT_COMPOUND)
 365                         return expr;
 366                 if (expr->op == '(')
 367                         return strip_parens(expr->unop);
 368         }
 369         return expr;
 370 }
 371
 372 struct expression *strip_expr(struct expression *expr)
 373 {
 374         if (!expr)
 375                 return NULL;
 376
 377         switch (expr->type) {
 378         case EXPR_FORCE_CAST:
 379         case EXPR_CAST:
 380                 return strip_expr(expr->cast_expression);
 381         case EXPR_PREOP:
 382                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 383                         expr->unop->statement->type == STMT_COMPOUND)
 384                         return expr;
 385                 if (expr->op == '(')
 386                         return strip_expr(expr->unop);
 387         }
 388         return expr;
 389 }
 390
 391 static void delete_state_tracker(struct tracker *t)
 392 {
 393         delete_state(t->owner, t->name, t->sym);
 394         __free_tracker(t);
 395 }
 396
 397 void scoped_state(int my_id, const char *name, struct symbol *sym)
 398 {
 399         struct tracker *t;
 400
 401         t = alloc_tracker(my_id, name, sym);
 402         add_scope_hook((scope_hook *)&delete_state_tracker, t);
 403 }
 404
 405 int is_error_return(struct expression *expr)
 406 {
 407         struct symbol *cur_func = cur_func_sym;
 408         long long val;
 409
 410         if (!expr)
 411                 return 0;
 412         if (cur_func->type != SYM_NODE)
 413                 return 0;
 414         cur_func = get_base_type(cur_func);
 415         if (cur_func->type != SYM_FN)
 416                 return 0;
 417         cur_func = get_base_type(cur_func);
 418         if (cur_func == &void_ctype)
 419                 return 0;
 420         if (!get_value(expr, &val))
 421                 return 0;
 422         if (val < 0)
 423                 return 1;
 424         if (cur_func->type == SYM_PTR && val == 0)
 425                 return 1;
 426         return 0;
 427 }
 428
 429 int getting_address(void)
 430 {
 431         struct expression *tmp;
 432         int i = 0;
 433         int dot_ops = 0;
 434
 435         FOR_EACH_PTR_REVERSE(big_expression_stack, tmp) {
 436                 if (!i++)
 437                         continue;
 438                 if (tmp->type == EXPR_PREOP && tmp->op == '(')
 439                         continue;
 440                 if (tmp->op == '.' && !dot_ops++)
 441                         continue;
 442                 if (tmp->op == '&')
 443                         return 1;
 444                 return 0;
 445         } END_FOR_EACH_PTR_REVERSE(tmp);
 446         return 0;
 447 }
 448
 449 char *get_fnptr_name(struct expression *expr)
 450 {
 451         char buf[256];
 452         struct symbol *sym;
 453
 454         if (expr->type == EXPR_SYMBOL)
 455                 return get_variable_from_expr(expr, NULL);
 456
 457         if (expr->type != EXPR_DEREF)
 458                 return NULL;
 459         sym = get_type(expr->deref);
 460         if (!sym || !sym->ident)
 461                 return NULL;
 462         snprintf(buf, sizeof(buf), "(struct %s)->%s", sym->ident->name, expr->member->name);
 463         return alloc_string(buf);
 464 }
 465