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(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 (expr->op == '*')
 100                         star_count++;
 101
 102                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 103                                                  len, complicated);
 104                 tmp = show_special(expr->op);
 105                 if (tmp[0] == '*') {
 106                         if (star_count-- >= 0) {
 107                                 prepend(buf, tmp, len);
 108                         }
 109                 } else {
 110                         prepend(buf, tmp, len);
 111                 }
 112
 113                 if (tmp[0] == '(') {
 114                         strncat(buf, ")", len);
 115                         buf[len - 1] = '\0';
 116                 }
 117
 118                 if ((!strcmp(tmp, "--")) || (!strcmp(tmp, "++")))
 119                         *complicated = 1;
 120
 121                 return;
 122         }
 123         case EXPR_POSTOP: {
 124                 const char *tmp;
 125
 126                 tmp = show_special(expr->op);
 127                 prepend(buf, tmp, len);
 128                 __get_variable_from_expr(sym_ptr, buf, expr->unop,
 129                                                  len, complicated);
 130
 131                 if ((!strcmp(tmp, "--")) || (!strcmp(tmp, "++")))
 132                         *complicated = 1;
 133
 134                 return;
 135         }
 136         case EXPR_BINOP: {
 137                 const char *tmp;
 138
 139                 *complicated = 1;
 140                 prepend(buf, ")", len);
 141                 __get_variable_from_expr(NULL, buf, expr->right, len,
 142                                          complicated);
 143                 tmp = show_special(expr->op);
 144                 prepend(buf, tmp, len);
 145                 __get_variable_from_expr(sym_ptr, buf, expr->left,
 146                                                  len, complicated);
 147                 prepend(buf, "(", len);
 148                 return;
 149         }
 150         case EXPR_VALUE: {
 151                 char tmp[25];
 152
 153                 snprintf(tmp, 25, "%lld", expr->value);
 154                 prepend(buf, tmp, len);
 155                 return;
 156         }
 157         case EXPR_STRING:
 158                 prepend(buf, expr->string->data, len);
 159                 return;
 160         case EXPR_CALL: {
 161                 struct expression *tmp;
 162                 int i = 0;
 163
 164                 *complicated = 1;
 165                 prepend(buf, ")", len);
 166                 FOR_EACH_PTR_REVERSE(expr->args, tmp) {
 167                         if (i++)
 168                                 prepend(buf, ", ", len);
 169                         __get_variable_from_expr(NULL, buf, tmp, len,
 170                                                  complicated);
 171                 } END_FOR_EACH_PTR_REVERSE(tmp);
 172                 prepend(buf, "(", len);
 173                 __get_variable_from_expr(NULL, buf, expr->fn, len,
 174                                          complicated);
 175                 return;
 176         }
 177         case EXPR_CAST:
 178                 __get_variable_from_expr(sym_ptr, buf,
 179                                          expr->cast_expression, len,
 180                                          complicated);
 181                 return;
 182         case EXPR_SIZEOF: {
 183                 int size;
 184                 char tmp[25];
 185
 186                 if (expr->cast_type && get_base_type(expr->cast_type)) {
 187                         size = (get_base_type(expr->cast_type))->bit_size;
 188                         snprintf(tmp, 25, "%d", size);
 189                         prepend(buf, tmp, len);
 190                 }
 191                 return;
 192         }
 193         default:
 194                 *complicated = 1;
 195                 //printf("unknown type = %d\n", expr->type);
 196                 return;
 197         }
 198 }
 199
 200
 201 /*
 202  * This is returns a stylized "c looking" representation of the
 203  * variable name.
 204  *
 205  * It uses the same buffer every time so you have to save the result
 206  * yourself if you want to keep it.
 207  *
 208  */
 209
 210 char *get_variable_from_expr_complex(struct expression *expr, struct symbol **sym_ptr)
 211 {
 212         static char var_name[VAR_LEN];
 213         int junk;
 214
 215         if (sym_ptr)
 216                 *sym_ptr = NULL;
 217         star_count = 0;
 218         var_name[0] = '\0';
 219
 220         if (!expr)
 221                 return NULL;
 222         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 223                                  &junk);
 224
 225         return var_name;
 226 }
 227
 228 /*
 229  * get_variable_from_expr_simple() only returns simple variables.
 230  * If it's a complicated variable like a->foo instead of just 'a'
 231  * then it returns NULL.
 232  */
 233
 234 char *get_variable_from_expr(struct expression *expr,
 235                                     struct symbol **sym_ptr)
 236 {
 237         static char var_name[VAR_LEN];
 238         int complicated = 0;
 239
 240         if (sym_ptr)
 241                 *sym_ptr = NULL;
 242         star_count = 0;
 243         var_name[0] = '\0';
 244
 245         if (!expr)
 246                 return NULL;
 247         expr = strip_expr(expr);
 248         __get_variable_from_expr(sym_ptr, var_name, expr, sizeof(var_name),
 249                                  &complicated);
 250
 251         if (complicated) {
 252                 if (sym_ptr)
 253                         *sym_ptr = NULL;
 254                 return NULL;
 255         }
 256         return alloc_string(var_name);
 257 }
 258
 259 int sym_name_is(const char *name, struct expression *expr)
 260 {
 261         if (!expr)
 262                 return 0;
 263         if (expr->type != EXPR_SYMBOL)
 264                 return 0;
 265         if (!strcmp(expr->symbol_name->name, name))
 266                 return 1;
 267         return 0;
 268 }
 269
 270 static int _get_value(struct expression *expr, int *discard)
 271 {
 272         int dis = 0;
 273         int ret = UNDEFINED;
 274
 275         if (!expr)
 276                 return UNDEFINED;
 277         if (!discard)
 278                 discard = &dis;
 279         if (*discard)
 280                 return UNDEFINED;
 281
 282         switch (expr->type){
 283         case EXPR_VALUE:
 284                 ret = expr->value;
 285                 break;
 286         case EXPR_PREOP:
 287                 if (!strcmp("-", show_special(expr->op)))
 288                         ret = - _get_value(expr->unop, discard);
 289                 break;
 290         case EXPR_BINOP:
 291                 if (show_special(expr->op) &&
 292                     !strcmp("*", show_special(expr->op)))
 293                         ret = _get_value(expr->left, discard)
 294                                 * _get_value(expr->right, discard);
 295                 break;
 296         case EXPR_SIZEOF:
 297                 if (expr->cast_type && get_base_type(expr->cast_type))
 298                         ret = (get_base_type(expr->cast_type))->bit_size / 8;
 299                 if (expr->cast_expression)
 300                         ;//printf("debugs %d\n", expr->cast_expression->type);
 301                 break;
 302         default:
 303                 //printf("ouchies-->%d\n", expr->type);
 304                 *discard = 1;
 305         }
 306         if (*discard)
 307                 return UNDEFINED;
 308         return ret;
 309 }
 310
 311 int get_value(struct expression *expr)
 312 {
 313         return _get_value(expr, NULL);
 314 }
 315
 316 int is_zero(struct expression *expr)
 317 {
 318         if (expr->type == EXPR_VALUE && expr->value == 0)
 319                 return 1;
 320         if (expr->op == '(')
 321                 return is_zero(expr->unop);
 322         if (expr->type == EXPR_CAST)
 323                 return is_zero(expr->cast_expression);
 324         return 0;
 325 }
 326
 327 const char *show_state(struct smatch_state *state)
 328 {
 329         if (!state)
 330                 return NULL;
 331         return state->name;
 332 }
 333
 334 struct expression *strip_expr(struct expression *expr)
 335 {
 336
 337         switch(expr->type) {
 338         case EXPR_CAST:
 339                 return strip_expr(expr->cast_expression);
 340         case EXPR_PREOP:
 341                 if (expr->op == '(')
 342                         return strip_expr(expr->unop);
 343         }
 344         return expr;
 345 }