smatch_sval.c

   1 /*
   2  * Copyright (C) 2012 Oracle.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
  16  */
  17
  18 /*
  19  * Basically the point of sval is that it can hold both ULLONG_MAX and
  20  * LLONG_MIN.  If it is an unsigned type then we use sval.uvalue or if it is
  21  * signed we use sval.value.
  22  *
  23  * I considered just using one bit to store whether the value was signed vs
  24  * unsigned but I think it might help to have the type information so we know
  25  * how to do type promotion.
  26  *
  27  */
  28
  29 #include "smatch.h"
  30 #include "smatch_slist.h"
  31 #include "smatch_extra.h"
  32
  33 __ALLOCATOR(sval_t, "svals", sval);
  34
  35 sval_t *sval_alloc(sval_t sval)
  36 {
  37         sval_t *ret;
  38
  39         ret = __alloc_sval(0);
  40         *ret = sval;
  41         return ret;
  42 }
  43
  44 sval_t *sval_alloc_permanent(sval_t sval)
  45 {
  46         sval_t *ret;
  47
  48         ret = malloc(sizeof(*ret));
  49         *ret = sval;
  50         return ret;
  51 }
  52
  53 sval_t sval_blank(struct expression *expr)
  54 {
  55         sval_t ret;
  56
  57         ret.type = get_type(expr);
  58         if (!ret.type)
  59                 ret.type = &int_ctype;
  60         ret.value = 123456789;
  61
  62         return ret;
  63 }
  64
  65 sval_t sval_type_val(struct symbol *type, long long val)
  66 {
  67         sval_t ret;
  68
  69         if (!type)
  70                 type = &int_ctype;
  71
  72         ret.type = type;
  73         ret.value = val;
  74         return ret;
  75 }
  76
  77 sval_t sval_from_val(struct expression *expr, long long val)
  78 {
  79         sval_t ret;
  80
  81         ret = sval_blank(expr);
  82         ret.value = val;
  83         ret = sval_cast(get_type(expr), ret);
  84
  85         return ret;
  86 }
  87
  88 int sval_unsigned(sval_t sval)
  89 {
  90         return type_unsigned(sval.type);
  91 }
  92
  93 int sval_signed(sval_t sval)
  94 {
  95         return !type_unsigned(sval.type);
  96 }
  97
  98 int sval_bits(sval_t sval)
  99 {
 100         return type_bits(sval.type);
 101 }
 102
 103 int sval_bits_used(sval_t sval)
 104 {
 105         int i;
 106
 107         for (i = 64; i >= 1; i--) {
 108                 if (sval.uvalue & (1ULL << (i - 1)))
 109                         return i;
 110         }
 111         return 0;
 112 }
 113
 114 int sval_is_negative(sval_t sval)
 115 {
 116         if (type_unsigned(sval.type))
 117                 return 0;
 118         if (sval.value < 0)
 119                 return 1;
 120         return 0;
 121 }
 122
 123 int sval_is_positive(sval_t sval)
 124 {
 125         return !sval_is_negative(sval);
 126 }
 127
 128 int sval_is_min(sval_t sval)
 129 {
 130         sval_t min = sval_type_min(sval.type);
 131
 132         if (sval_unsigned(sval)) {
 133                 if (sval.uvalue == 0)
 134                         return 1;
 135                 return 0;
 136         }
 137         /* return true for less than min as well */
 138         return (sval.value <= min.value);
 139 }
 140
 141 int sval_is_max(sval_t sval)
 142 {
 143         sval_t max = sval_type_max(sval.type);
 144
 145         if (sval_unsigned(sval))
 146                 return (sval.uvalue >= max.value);
 147         return (sval.value >= max.value);
 148 }
 149
 150 int sval_is_a_min(sval_t sval)
 151 {
 152         if (sval_signed(sval) && sval.value == SHRT_MIN)
 153                 return 1;
 154         if (sval_signed(sval) && sval.value == INT_MIN)
 155                 return 1;
 156         if (sval_signed(sval) && sval.value == LLONG_MIN)
 157                 return 1;
 158         return 0;
 159 }
 160
 161 int sval_is_a_max(sval_t sval)
 162 {
 163         if (sval.uvalue == SHRT_MAX)
 164                 return 1;
 165         if (sval.uvalue == INT_MAX)
 166                 return 1;
 167         if (sval.uvalue == LLONG_MAX)
 168                 return 1;
 169         if (sval.uvalue == USHRT_MAX)
 170                 return 1;
 171         if (sval.uvalue == UINT_MAX)
 172                 return 1;
 173         if (sval_unsigned(sval) && sval.uvalue == ULLONG_MAX)
 174                 return 1;
 175         if (sval.value > valid_ptr_max - 1000 &&
 176             sval.value < valid_ptr_max + 1000)
 177                 return 1;
 178         return 0;
 179 }
 180
 181 int sval_is_negative_min(sval_t sval)
 182 {
 183         if (!sval_is_negative(sval))
 184                 return 0;
 185         return sval_is_min(sval);
 186 }
 187
 188 int sval_cmp_t(struct symbol *type, sval_t one, sval_t two)
 189 {
 190         sval_t one_cast, two_cast;
 191
 192         one_cast = sval_cast(type, one);
 193         two_cast = sval_cast(type, two);
 194         return sval_cmp(one_cast, two_cast);
 195 }
 196
 197 int sval_cmp_val(sval_t one, long long val)
 198 {
 199         sval_t sval;
 200
 201         sval = sval_type_val(&llong_ctype, val);
 202         return sval_cmp(one, sval);
 203 }
 204
 205 sval_t sval_min(sval_t one, sval_t two)
 206 {
 207         if (sval_cmp(one, two) > 0)
 208                 return two;
 209         return one;
 210 }
 211
 212 sval_t sval_max(sval_t one, sval_t two)
 213 {
 214         if (sval_cmp(one, two) < 0)
 215                 return two;
 216         return one;
 217 }
 218
 219 int sval_too_low(struct symbol *type, sval_t sval)
 220 {
 221         if (sval_is_negative(sval) && type_unsigned(type))
 222                 return 1;
 223         if (type_signed(type) &&  sval_unsigned(sval))
 224                 return 0;
 225         if (sval_cmp(sval, sval_type_min(type)) < 0)
 226                 return 1;
 227         return 0;
 228 }
 229
 230 int sval_too_high(struct symbol *type, sval_t sval)
 231 {
 232         if (sval_is_negative(sval))
 233                 return 0;
 234         if (sval.uvalue > sval_type_max(type).uvalue)
 235                 return 1;
 236         return 0;
 237 }
 238
 239 int sval_fits(struct symbol *type, sval_t sval)
 240 {
 241         if (sval_too_low(type, sval))
 242                 return 0;
 243         if (sval_too_high(type, sval))
 244                 return 0;
 245         return 1;
 246 }
 247
 248 sval_t sval_cast(struct symbol *type, sval_t sval)
 249 {
 250         sval_t ret;
 251
 252         if (!type)
 253                 type = &int_ctype;
 254
 255         ret.type = type;
 256         switch (sval_bits(ret)) {
 257         case 8:
 258                 if (sval_unsigned(ret))
 259                         ret.value = (long long)(unsigned char)sval.value;
 260                 else
 261                         ret.value = (long long)(char)sval.value;
 262                 break;
 263         case 16:
 264                 if (sval_unsigned(ret))
 265                         ret.value = (long long)(unsigned short)sval.value;
 266                 else
 267                         ret.value = (long long)(short)sval.value;
 268                 break;
 269         case 32:
 270                 if (sval_unsigned(ret))
 271                         ret.value = (long long)(unsigned int)sval.value;
 272                 else
 273                         ret.value = (long long)(int)sval.value;
 274                 break;
 275         default:
 276                 ret.value = sval.value;
 277         }
 278         return ret;
 279
 280 }
 281
 282 sval_t sval_preop(sval_t sval, int op)
 283 {
 284         switch (op) {
 285         case '!':
 286                 sval.value = !sval.value;
 287                 break;
 288         case '~':
 289                 sval.value = ~sval.value;
 290                 sval = sval_cast(sval.type, sval);
 291                 break;
 292         case '-':
 293                 sval.value = -sval.value;
 294                 sval = sval_cast(sval.type, sval);
 295                 break;
 296         }
 297         return sval;
 298 }
 299
 300 static sval_t sval_binop_unsigned(struct symbol *type, sval_t left, int op, sval_t right)
 301 {
 302         sval_t ret;
 303
 304         ret.type = type;
 305         switch (op) {
 306         case '*':
 307                 ret.uvalue =  left.uvalue * right.uvalue;
 308                 break;
 309         case '/':
 310                 if (right.uvalue == 0) {
 311                         sm_msg("debug: %s: divide by zero", __func__);
 312                         ret.uvalue = 123456789;
 313                 } else {
 314                         ret.uvalue = left.uvalue / right.uvalue;
 315                 }
 316                 break;
 317         case '+':
 318                 ret.uvalue = left.uvalue + right.uvalue;
 319                 break;
 320         case '-':
 321                 ret.uvalue = left.uvalue - right.uvalue;
 322                 break;
 323         case '%':
 324                 if (right.uvalue == 0) {
 325                         sm_msg("internal error: %s: MOD by zero", __func__);
 326                         ret.uvalue = 123456789;
 327                 } else {
 328                         ret.uvalue = left.uvalue % right.uvalue;
 329                 }
 330                 break;
 331         case '|':
 332                 ret.uvalue = left.uvalue | right.uvalue;
 333                 break;
 334         case '&':
 335                 ret.uvalue = left.uvalue & right.uvalue;
 336                 break;
 337         case SPECIAL_RIGHTSHIFT:
 338                 ret.uvalue = left.uvalue >> right.uvalue;
 339                 break;
 340         case SPECIAL_LEFTSHIFT:
 341                 ret.uvalue = left.uvalue << right.uvalue;
 342                 break;
 343         case '^':
 344                 ret.uvalue = left.uvalue ^ right.uvalue;
 345                 break;
 346         default:
 347                 sm_msg("internal error: %s: unhandled binop %s", __func__,
 348                        show_special(op));
 349                 ret.uvalue = 1234567;
 350         }
 351         return ret;
 352 }
 353
 354
 355 static sval_t sval_binop_signed(struct symbol *type, sval_t left, int op, sval_t right)
 356 {
 357         sval_t ret;
 358
 359         ret.type = type;
 360         switch (op) {
 361         case '*':
 362                 ret.value =  left.value * right.value;
 363                 break;
 364         case '/':
 365                 if (right.value == 0) {
 366                         sm_msg("debug: %s: divide by zero", __func__);
 367                         ret.value = 123456789;
 368                 } else if (left.value == LLONG_MIN && right.value == -1) {
 369                         sm_msg("debug: %s: invalid divide LLONG_MIN/-1", __func__);
 370                         ret.value = 12345678;
 371                 } else {
 372                         ret.value = left.value / right.value;
 373                 }
 374                 break;
 375         case '+':
 376                 ret.value = left.value + right.value;
 377                 break;
 378         case '-':
 379                 ret.value = left.value - right.value;
 380                 break;
 381         case '%':
 382                 if (right.value == 0) {
 383                         sm_msg("internal error: %s: MOD by zero", __func__);
 384                         ret.value = 123456789;
 385                 } else {
 386                         ret.value = left.value % right.value;
 387                 }
 388                 break;
 389         case '|':
 390                 ret.value = left.value | right.value;
 391                 break;
 392         case '&':
 393                 ret.value = left.value & right.value;
 394                 break;
 395         case SPECIAL_RIGHTSHIFT:
 396                 ret.value = left.value >> right.value;
 397                 break;
 398         case SPECIAL_LEFTSHIFT:
 399                 ret.value = left.value << right.value;
 400                 break;
 401         case '^':
 402                 ret.value = left.value ^ right.value;
 403                 break;
 404         default:
 405                 sm_msg("internal error: %s: unhandled binop %s", __func__,
 406                        show_special(op));
 407                 ret.value = 1234567;
 408         }
 409         return ret;
 410 }
 411
 412 sval_t sval_binop(sval_t left, int op, sval_t right)
 413 {
 414         struct symbol *type;
 415         sval_t ret;
 416
 417         type = left.type;
 418         if (sval_positive_bits(right) > sval_positive_bits(left))
 419                 type = right.type;
 420         if (type_positive_bits(type) < 31)
 421                 type = &int_ctype;
 422
 423         if (type_unsigned(type))
 424                 ret = sval_binop_unsigned(type, left, op, right);
 425         else
 426                 ret = sval_binop_signed(type, left, op, right);
 427         return sval_cast(type, ret);
 428 }
 429
 430 int sval_unop_overflows(sval_t sval, int op)
 431 {
 432         if (op != '-')
 433                 return 0;
 434         if (sval_positive_bits(sval) == 32 && sval.value == INT_MIN)
 435                 return 1;
 436         if (sval_positive_bits(sval) == 64 && sval.value == LLONG_MIN)
 437                 return 1;
 438         if (sval_is_negative(sval))
 439                 return 0;
 440         if (sval_signed(sval))
 441                 return 0;
 442         if (sval_bits(sval) == 32 && sval.uvalue > INT_MAX)
 443                 return 1;
 444         if (sval_bits(sval) == 64 && sval.uvalue > LLONG_MAX)
 445                 return 1;
 446         return 0;
 447 }
 448
 449 int sval_binop_overflows(sval_t left, int op, sval_t right)
 450 {
 451         struct symbol *type;
 452         sval_t max, min;
 453
 454         type = left.type;
 455         if (type_positive_bits(right.type) > type_positive_bits(left.type))
 456                 type = right.type;
 457         if (type_positive_bits(type) < 31)
 458                 type = &int_ctype;
 459
 460         max = sval_type_max(type);
 461         min = sval_type_min(type);
 462
 463         switch (op) {
 464         case '+':
 465                 if (sval_is_negative(left) && sval_is_negative(right)) {
 466                         if (left.value < min.value + right.value)
 467                                 return 1;
 468                         return 0;
 469                 }
 470                 if (sval_is_negative(left) || sval_is_negative(right))
 471                         return 0;
 472                 if (left.uvalue > max.uvalue - right.uvalue)
 473                                 return 1;
 474                 return 0;
 475         case '*':
 476                 return right.uvalue != 0 && left.uvalue > max.uvalue / right.uvalue;
 477         case '-':
 478                 if (type_unsigned(type)) {
 479                         if (sval_cmp(left, right) < 0)
 480                                 return 1;
 481                         return 0;
 482                 }
 483                 if (sval_is_negative(left) && sval_is_negative(right))
 484                         return 0;
 485
 486                 if (sval_is_negative(left)) {
 487                         if (left.value < min.value + right.value)
 488                                 return 1;
 489                         return 0;
 490                 }
 491                 if (sval_is_negative(right)) {
 492                         if (right.value == min.value)
 493                                 return 1;
 494                         right = sval_preop(right, '-');
 495                         if (sval_binop_overflows(left, '+', right))
 496                                 return 1;
 497                         return 0;
 498                 }
 499                 return 0;
 500         case SPECIAL_LEFTSHIFT:
 501                 if (sval_cmp(left, sval_binop(max, invert_op(op), right)) > 0)
 502                         return 1;
 503                 return 0;
 504         }
 505         return 0;
 506 }
 507
 508 unsigned long long fls_mask(unsigned long long uvalue)
 509 {
 510         unsigned long long high_bit = 0;
 511
 512         while (uvalue) {
 513                 uvalue >>= 1;
 514                 high_bit++;
 515         }
 516
 517         if (high_bit == 0)
 518                 return 0;
 519
 520         return ((unsigned long long)-1) >> (64 - high_bit);
 521 }
 522
 523 unsigned long long sval_fls_mask(sval_t sval)
 524 {
 525         return fls_mask(sval.uvalue);
 526 }
 527
 528 const char *sval_to_str(sval_t sval)
 529 {
 530         char buf[30];
 531
 532         if (sval_unsigned(sval) && sval.value == ULLONG_MAX)
 533                 return "u64max";
 534         if (sval_unsigned(sval) && sval.value == UINT_MAX)
 535                 return "u32max";
 536         if (sval_unsigned(sval) && sval.value == USHRT_MAX)
 537                 return "u16max";
 538
 539         if (sval_signed(sval) && sval.value == LLONG_MAX)
 540                 return "s64max";
 541         if (sval_signed(sval) && sval.value == INT_MAX)
 542                 return "s32max";
 543         if (sval_signed(sval) && sval.value == SHRT_MAX)
 544                 return "s16max";
 545
 546         if (sval_signed(sval) && sval.value == SHRT_MIN)
 547                 return "s16min";
 548         if (sval_signed(sval) && sval.value == INT_MIN)
 549                 return "s32min";
 550         if (sval_signed(sval) && sval.value == LLONG_MIN)
 551                 return "s64min";
 552
 553         if (sval_unsigned(sval))
 554                 snprintf(buf, sizeof(buf), "%llu", sval.value);
 555         else if (sval.value < 0)
 556                 snprintf(buf, sizeof(buf), "(%lld)", sval.value);
 557         else
 558                 snprintf(buf, sizeof(buf), "%lld", sval.value);
 559
 560         return alloc_sname(buf);
 561 }
 562
 563 const char *sval_to_numstr(sval_t sval)
 564 {
 565         char buf[30];
 566
 567         if (sval_unsigned(sval))
 568                 snprintf(buf, sizeof(buf), "%llu", sval.value);
 569         else if (sval.value < 0)
 570                 snprintf(buf, sizeof(buf), "(%lld)", sval.value);
 571         else
 572                 snprintf(buf, sizeof(buf), "%lld", sval.value);
 573
 574         return alloc_sname(buf);
 575 }
 576
 577 sval_t ll_to_sval(long long val)
 578 {
 579         sval_t ret;
 580
 581         ret.type = &llong_ctype;
 582         ret.value = val;
 583         return ret;
 584 }
 585
 586 static void free_svals(struct symbol *sym)
 587 {
 588         if (__inline_fn)
 589                 return;
 590         clear_sval_alloc();
 591 }
 592
 593 void register_sval(int my_id)
 594 {
 595         add_hook(&free_svals, AFTER_FUNC_HOOK);
 596 }