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