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 int sym_name_is(const char *name, struct expression *expr)
 267 {
 268         if (!expr)
 269                 return 0;
 270         if (expr->type != EXPR_SYMBOL)
 271                 return 0;
 272         if (!strcmp(expr->symbol_name->name, name))
 273                 return 1;
 274         return 0;
 275 }
 276
 277 static int _get_value(struct expression *expr, int *discard)
 278 {
 279         int dis = 0;
 280         int ret = UNDEFINED;
 281
 282         if (!expr)
 283                 return UNDEFINED;
 284         if (!discard)
 285                 discard = &dis;
 286         if (*discard)
 287                 return UNDEFINED;
 288
 289         expr = strip_expr(expr);
 290
 291         switch (expr->type){
 292         case EXPR_VALUE:
 293                 ret = expr->value;
 294                 break;
 295         case EXPR_PREOP:
 296                 if (!strcmp("-", show_special(expr->op)))
 297                         ret = - _get_value(expr->unop, discard);
 298                 else
 299                         *discard = 1;
 300                 break;
 301         case EXPR_BINOP: {
 302                 int left, right;
 303
 304                 if (!show_special(expr->op)) {
 305                         *discard = 1;
 306                         break;
 307                 }
 308                 left = _get_value(expr->left, discard);
 309                 right = _get_value(expr->right, discard);
 310                 if (!strcmp("*", show_special(expr->op))) {
 311                         ret =  left * right;
 312                 } else if (!strcmp("/", show_special(expr->op))) {
 313                         ret = left / right;
 314                 } else if (!strcmp("+", show_special(expr->op))) {
 315                         ret = left + right;
 316                 } else if (!strcmp("-", show_special(expr->op))) {
 317                         ret = left - right;
 318                 } else if (!strcmp("|", show_special(expr->op))) {
 319                         ret = left | right;
 320                 } else {
 321                         *discard = 1;
 322                 }
 323                 break;
 324         }
 325         case EXPR_SIZEOF:
 326                 if (expr->cast_type && get_base_type(expr->cast_type))
 327                         ret = (get_base_type(expr->cast_type))->bit_size / 8;
 328                 else
 329                         *discard = 1;
 330                 break;
 331         default:
 332                 //printf("ouchies-->%d\n", expr->type);
 333                 *discard = 1;
 334         }
 335         if (*discard)
 336                 return UNDEFINED;
 337         return ret;
 338 }
 339
 340 /* returns UNDEFINED on error */
 341 int get_value(struct expression *expr)
 342 {
 343         return _get_value(expr, NULL);
 344 }
 345
 346 int is_zero(struct expression *expr)
 347 {
 348         if (get_value(expr) == 0)
 349                 return 1;
 350         return 0;
 351 }
 352
 353 const char *show_state(struct smatch_state *state)
 354 {
 355         if (!state)
 356                 return NULL;
 357         return state->name;
 358 }
 359
 360 struct statement *get_block_thing(struct expression *expr)
 361 {
 362         /* What are those things called? if (({....; ret;})) { ...*/
 363
 364         if (expr->type != EXPR_PREOP)
 365                 return NULL;
 366         if (expr->op != '(')
 367                 return NULL;
 368         if (expr->unop->type != EXPR_STATEMENT)
 369                 return NULL;
 370         if (expr->unop->statement->type != STMT_COMPOUND)
 371                 return NULL;
 372         return expr->unop->statement;
 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_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 }