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 #include <stdlib.h>
  11 #include <stdio.h>
  12 #include "allocate.h"
  13 #include "smatch.h"
  14
  15 static int star_count;
  16 #define VAR_LEN 512
  17
  18
  19 char *alloc_string(const char *str)
  20 {
  21         char *tmp;
  22
  23         if (!str)
  24                 return NULL;
  25         tmp = malloc(strlen(str) + 1);
  26         strcpy(tmp, str);
  27         return tmp;
  28 }
  29
  30 void free_string(char *str)
  31 {
  32         free(str);
  33 }
  34
  35 static void prepend(char *dest, const char *data, int buff_len)
  36 {
  37         int space_needed;
  38         int i;
  39
  40         space_needed = strlen(data);
  41         for (i = buff_len - space_needed - 1; i >= 0 ; i--)
  42                 dest[i + space_needed] = dest[i];
  43         for (i = 0; i < space_needed % buff_len ; i++)
  44                 dest[i] = data[i];
  45         dest[buff_len - 1] = '\0';
  46 }
  47
  48 /*
  49  * If you have "foo(a, b, 1);" then use
  50  * get_argument_from_call_expr(expr, 0) to return the expression for
  51  * a.  Yes, it does start counting from 0.
  52  */
  53 struct expression *get_argument_from_call_expr(struct expression_list *args,
  54                                                int num)
  55 {
  56         struct expression *expr;
  57         int i = 0;
  58
  59         if (!args)
  60                 return NULL;
  61
  62         FOR_EACH_PTR(args, expr) {
  63                 if (i == num)
  64                         return expr;
  65                 i++;
  66         } END_FOR_EACH_PTR(expr);
  67         return NULL;
  68 }
  69
  70 static void __get_variable_from_expr(struct symbol **sym_ptr, char *buf,
  71                                      struct expression *expr, int len,
  72                                      int *complicated)
  73 {
  74         switch(expr->type) {
  75         case EXPR_DEREF:
  76                 prepend(buf, expr->member->name, len);
  77                 if (!strcmp(show_special(expr->deref->op), "*"))
  78                         prepend(buf, "->", len);
  79                 else
  80                         prepend(buf, ".", len);
  81
  82                 //printf("debug:  %d\n", expr->deref
  83
  84                 __get_variable_from_expr(sym_ptr, buf, expr->deref,
  85                                                  len, complicated);
  86                 return;
  87         case EXPR_SYMBOL:
  88                 if (expr->symbol_name)
  89                         prepend(buf, expr->symbol_name->name, len);
  90                 if (sym_ptr) {
  91                         if (*sym_ptr)
  92                                 *complicated = 1;
  93                         *sym_ptr = expr->symbol;
  94                 }
  95                 return;
  96         case EXPR_PREOP: {
  97                 const char *tmp;
  98
  99                 if (get_block_thing(expr)) {
 100                         *complicated = 2;
 101                         return;
 102                 }
 103
 104                 if (expr->op == '*')
 105                         star_count++;
 106
 107                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 108                                                  len, complicated);
 109                 tmp = show_special(expr->op);
 110                 if (tmp[0] == '*') {
 111                         if (star_count-- >= 0) {
 112                                 prepend(buf, tmp, len);
 113                         }
 114                 } else {
 115                         prepend(buf, tmp, len);
 116                 }
 117
 118                 if (tmp[0] == '(') {
 119                         strncat(buf, ")", len);
 120                         buf[len - 1] = '\0';
 121                 }
 122
 123                 if ((!strcmp(tmp, "--")) || (!strcmp(tmp, "++")))
 124                         *complicated = 1;
 125
 126                 return;
 127         }
 128         case EXPR_POSTOP: {
 129                 const char *tmp;
 130
 131                 tmp = show_special(expr->op);
 132                 prepend(buf, tmp, len);
 133                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 134                                                  len, complicated);
 135
 136                 if ((!strcmp(tmp, "--")) || (!strcmp(tmp, "++")))
 137                         *complicated = 1;
 138
 139                 return;
 140         }
 141         case EXPR_BINOP: {
 142                 const char *tmp;
 143
 144                 *complicated = 1;
 145                 prepend(buf, ")", len);
 146                 __get_variable_from_expr(NULL, buf, expr->right, len,
 147                                          complicated);
 148                 tmp = show_special(expr->op);
 149                 prepend(buf, tmp, len);
 150                 __get_variable_from_expr(sym_ptr, buf, expr->left,
 151                                                  len, complicated);
 152                 prepend(buf, "(", len);
 153                 return;
 154         }
 155         case EXPR_VALUE: {
 156                 char tmp[25];
 157
 158                 snprintf(tmp, 25, "%lld", expr->value);
 159                 prepend(buf, tmp, len);
 160                 return;
 161         }
 162         case EXPR_STRING:
 163                 prepend(buf, expr->string->data, len);
 164                 return;
 165         case EXPR_CALL: {
 166                 struct expression *tmp;
 167                 int i = 0;
 168
 169                 *complicated = 1;
 170                 prepend(buf, ")", len);
 171                 FOR_EACH_PTR_REVERSE(expr->args, tmp) {
 172                         if (i++)
 173                                 prepend(buf, ", ", len);
 174                         __get_variable_from_expr(NULL, buf, tmp, len,
 175                                                  complicated);
 176                 } END_FOR_EACH_PTR_REVERSE(tmp);
 177                 prepend(buf, "(", len);
 178                 __get_variable_from_expr(NULL, buf, expr->fn, len,
 179                                          complicated);
 180                 return;
 181         }
 182         case EXPR_CAST:
 183                 __get_variable_from_expr(sym_ptr, buf,
 184                                          expr->cast_expression, len,
 185                                          complicated);
 186                 return;
 187         case EXPR_SIZEOF: {
 188                 int size;
 189                 char tmp[25];
 190
 191                 if (expr->cast_type && get_base_type(expr->cast_type)) {
 192                         size = (get_base_type(expr->cast_type))->bit_size;
 193                         snprintf(tmp, 25, "%d", size);
 194                         prepend(buf, tmp, len);
 195                 }
 196                 return;
 197         }
 198         default:
 199                 *complicated = 1;
 200                 //printf("unknown type = %d\n", expr->type);
 201                 return;
 202         }
 203 }
 204
 205
 206 /*
 207  * This is returns a stylized "c looking" representation of the
 208  * variable name.
 209  *
 210  * It uses the same buffer every time so you have to save the result
 211  * yourself if you want to keep it.
 212  *
 213  */
 214
 215 char *get_variable_from_expr_complex(struct expression *expr, struct symbol **sym_ptr)
 216 {
 217         static char var_name[VAR_LEN];
 218         int complicated = 0;
 219
 220         if (sym_ptr)
 221                 *sym_ptr = NULL;
 222         star_count = 0;
 223         var_name[0] = '\0';
 224
 225         if (!expr)
 226                 return NULL;
 227         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 228                                  &complicated);
 229         if (complicated < 2)
 230                 return alloc_string(var_name);
 231         else
 232                 return NULL;
 233 }
 234
 235 /*
 236  * get_variable_from_expr_simple() only returns simple variables.
 237  * If it's a complicated variable like a->foo instead of just 'a'
 238  * then it returns NULL.
 239  */
 240
 241 char *get_variable_from_expr(struct expression *expr,
 242                                     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         star_count = 0;
 250         var_name[0] = '\0';
 251
 252         if (!expr)
 253                 return NULL;
 254         expr = strip_expr(expr);
 255         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 256                                  &complicated);
 257
 258         if (complicated) {
 259                 if (sym_ptr)
 260                         *sym_ptr = NULL;
 261                 return NULL;
 262         }
 263         return alloc_string(var_name);
 264 }
 265
 266 struct symbol *get_ptr_type_ptr(struct symbol *sym)
 267 {
 268         if (!sym) {
 269                 return NULL;
 270         }
 271
 272         if (sym->type != SYM_NODE)
 273                 return NULL;
 274         sym = get_base_type(sym);
 275         if (sym->type != SYM_PTR)
 276                 return NULL;
 277         sym = get_base_type(sym);
 278         return sym;
 279 }
 280
 281 static struct symbol *get_struct_sym(struct expression *expr)
 282 {
 283         struct symbol *base_type;
 284         struct symbol *parent_struct;
 285         struct symbol *tmp;
 286
 287         if (expr->type != EXPR_PREOP)
 288                 return NULL;
 289
 290         expr = expr->unop;
 291         if (expr->type == EXPR_DEREF) {
 292                 parent_struct = get_struct_sym(expr->deref);
 293                 if (!parent_struct)
 294                         return NULL;
 295                 tmp = NULL;
 296                 FOR_EACH_PTR(parent_struct->symbol_list, tmp) {
 297                         if (tmp->ident == expr->member)
 298                                 break;
 299                 } END_FOR_EACH_PTR(tmp);
 300                 if (!tmp || tmp->ident != expr->member)
 301                         return NULL;
 302                 base_type = get_base_type(tmp);
 303         } else if (expr->type == EXPR_SYMBOL) {
 304                 base_type = get_base_type(expr->symbol);
 305         } else {
 306                 return NULL;
 307         }
 308         if (base_type->type != SYM_PTR)
 309                 return NULL;
 310         base_type = get_base_type(base_type);
 311         if (base_type->type != SYM_STRUCT && base_type->type != SYM_UNION)
 312                 return NULL;
 313         return base_type;
 314 }
 315
 316 struct symbol *get_deref_type(struct expression *expr)
 317 {
 318         struct ident *member = expr->member;
 319         struct symbol *struct_sym;
 320         struct symbol *tmp;
 321
 322         struct_sym = get_struct_sym(expr->deref);
 323         if (!struct_sym || (struct_sym->type != SYM_STRUCT
 324                             && struct_sym->type != SYM_UNION))
 325                 return NULL;
 326         FOR_EACH_PTR(struct_sym->symbol_list, tmp) {
 327                 if (tmp->ident == member)
 328                         return get_ptr_type_ptr(tmp);
 329         } END_FOR_EACH_PTR(tmp);
 330         return NULL;
 331 }
 332
 333 struct symbol *get_ptr_type(struct expression *expr)
 334 {
 335         struct symbol *ptr_type = NULL;
 336
 337         if (!expr)
 338                 return NULL;
 339         if (expr->type == EXPR_DEREF)
 340                 ptr_type = get_deref_type(expr);
 341         if (expr->type == EXPR_SYMBOL)
 342                 ptr_type = get_ptr_type_ptr(expr->symbol);
 343         return ptr_type;
 344 }
 345
 346 int sym_name_is(const char *name, struct expression *expr)
 347 {
 348         if (!expr)
 349                 return 0;
 350         if (expr->type != EXPR_SYMBOL)
 351                 return 0;
 352         if (!strcmp(expr->symbol_name->name, name))
 353                 return 1;
 354         return 0;
 355 }
 356
 357 static int _get_value(struct expression *expr, int *discard)
 358 {
 359         int dis = 0;
 360         int ret = UNDEFINED;
 361
 362         if (!expr)
 363                 return UNDEFINED;
 364         if (!discard)
 365                 discard = &dis;
 366         if (*discard)
 367                 return UNDEFINED;
 368
 369         expr = strip_expr(expr);
 370
 371         switch (expr->type){
 372         case EXPR_VALUE:
 373                 ret = expr->value;
 374                 break;
 375         case EXPR_PREOP:
 376                 if (!strcmp("-", show_special(expr->op)))
 377                         ret = - _get_value(expr->unop, discard);
 378                 else
 379                         *discard = 1;
 380                 break;
 381         case EXPR_BINOP: {
 382                 int left, right;
 383
 384                 if (!show_special(expr->op)) {
 385                         *discard = 1;
 386                         break;
 387                 }
 388                 left = _get_value(expr->left, discard);
 389                 right = _get_value(expr->right, discard);
 390                 if (!strcmp("*", show_special(expr->op))) {
 391                         ret =  left * right;
 392                 } else if (!strcmp("/", show_special(expr->op))) {
 393                         ret = left / right;
 394                 } else if (!strcmp("+", show_special(expr->op))) {
 395                         ret = left + right;
 396                 } else if (!strcmp("-", show_special(expr->op))) {
 397                         ret = left - right;
 398                 } else if (!strcmp("|", show_special(expr->op))) {
 399                         ret = left | right;
 400                 } else {
 401                         *discard = 1;
 402                 }
 403                 break;
 404         }
 405         case EXPR_SIZEOF:
 406                 if (expr->cast_type && get_base_type(expr->cast_type))
 407                         ret = (get_base_type(expr->cast_type))->bit_size / 8;
 408                 else
 409                         *discard = 1;
 410                 break;
 411         default:
 412                 //printf("ouchies-->%d\n", expr->type);
 413                 *discard = 1;
 414         }
 415         if (*discard)
 416                 return UNDEFINED;
 417         return ret;
 418 }
 419
 420 /* returns UNDEFINED on error */
 421 int get_value(struct expression *expr)
 422 {
 423         return _get_value(expr, NULL);
 424 }
 425
 426 int is_zero(struct expression *expr)
 427 {
 428         if (get_value(expr) == 0)
 429                 return 1;
 430         return 0;
 431 }
 432
 433 const char *show_state(struct smatch_state *state)
 434 {
 435         if (!state)
 436                 return NULL;
 437         return state->name;
 438 }
 439
 440 struct statement *get_block_thing(struct expression *expr)
 441 {
 442         /* What are those things called? if (({....; ret;})) { ...*/
 443
 444         if (expr->type != EXPR_PREOP)
 445                 return NULL;
 446         if (expr->op != '(')
 447                 return NULL;
 448         if (expr->unop->type != EXPR_STATEMENT)
 449                 return NULL;
 450         if (expr->unop->statement->type != STMT_COMPOUND)
 451                 return NULL;
 452         return expr->unop->statement;
 453 }
 454
 455 struct expression *strip_expr(struct expression *expr)
 456 {
 457         if (!expr)
 458                 return NULL;
 459
 460         switch(expr->type) {
 461         case EXPR_CAST:
 462                 return strip_expr(expr->cast_expression);
 463         case EXPR_PREOP:
 464                 if (expr->op == '(' && expr->unop->type == EXPR_STATEMENT &&
 465                         expr->unop->statement->type == STMT_COMPOUND)
 466                         return expr;
 467                 if (expr->op == '(')
 468                         return strip_expr(expr->unop);
 469         }
 470         return expr;
 471 }