smatch_parse_call_math.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 #include "smatch.h"
  19 #include "smatch_slist.h"
  20 #include "smatch_extra.h"
  21
  22 static int my_id;
  23
  24 struct {
  25         const char *func;
  26         int param;
  27 } alloc_functions[] = {
  28         {"kmalloc", 0},
  29         {"kzalloc", 0},
  30         {"__kmalloc", 0},
  31         {"vmalloc", 0},
  32         {"__vmalloc", 0},
  33         {"__vmalloc_node", 0},
  34 };
  35
  36 static struct range_list_stack *rl_stack;
  37 static struct string_list *op_list;
  38
  39 static void push_op(char c)
  40 {
  41         char *p;
  42
  43         p = malloc(1);
  44         p[0] = c;
  45         add_ptr_list(&op_list, p);
  46 }
  47
  48 static char pop_op(void)
  49 {
  50         char *p;
  51         char c;
  52
  53         if (!op_list) {
  54                 sm_perror("%s: no op_list", __func__);
  55                 return '\0';
  56         }
  57
  58         p = last_ptr_list((struct ptr_list *)op_list);
  59
  60         delete_ptr_list_last((struct ptr_list **)&op_list);
  61         c = p[0];
  62         free(p);
  63
  64         return c;
  65 }
  66
  67 static int op_precedence(char c)
  68 {
  69         switch (c) {
  70         case '+':
  71         case '-':
  72                 return 1;
  73         case '*':
  74         case '/':
  75                 return 2;
  76         default:
  77                 return 0;
  78         }
  79 }
  80
  81 static int top_op_precedence(void)
  82 {
  83         char *p;
  84
  85         if (!op_list)
  86                 return 0;
  87
  88         p = last_ptr_list((struct ptr_list *)op_list);
  89         return op_precedence(p[0]);
  90 }
  91
  92 static void rl_pop_until(char c)
  93 {
  94         char op;
  95         struct range_list *left, *right;
  96         struct range_list *res;
  97
  98         while (top_op_precedence() && op_precedence(c) <= top_op_precedence()) {
  99                 op = pop_op();
 100                 right = pop_rl(&rl_stack);
 101                 left = pop_rl(&rl_stack);
 102                 res = rl_binop(left, op, right);
 103                 if (!res)
 104                         res = alloc_whole_rl(&llong_ctype);
 105                 push_rl(&rl_stack, res);
 106         }
 107 }
 108
 109 static void rl_discard_stacks(void)
 110 {
 111         while (op_list)
 112                 pop_op();
 113         while (rl_stack)
 114                 pop_rl(&rl_stack);
 115 }
 116
 117 static int read_rl_from_var(struct expression *call, const char *p, const char **end, struct range_list **rl)
 118 {
 119         struct expression *arg;
 120         struct smatch_state *state;
 121         long param;
 122         char *name;
 123         struct symbol *sym;
 124         char buf[256];
 125         int star;
 126
 127         if (!call || call->type != EXPR_CALL)
 128                 return 0;
 129         p++;
 130         param = strtol(p, (char **)&p, 10);
 131
 132         arg = get_argument_from_call_expr(call->args, param);
 133         if (!arg)
 134                 return 0;
 135
 136         if (*p != '-' && *p != '.') {
 137                 get_absolute_rl(arg, rl);
 138                 *end = p;
 139                 return 1;
 140         }
 141
 142         *end = strchr(p, ' ');
 143
 144         if (arg->type == EXPR_PREOP && arg->op == '&') {
 145                 arg = strip_expr(arg->unop);
 146                 star = 0;
 147                 p++;
 148         } else {
 149                 star = 1;
 150                 p += 2;
 151         }
 152
 153         name = expr_to_var_sym(arg, &sym);
 154         if (!name)
 155                 return 0;
 156         snprintf(buf, sizeof(buf), "%s%s", name, star ? "->" : ".");
 157         free_string(name);
 158
 159         if (*end - p + strlen(buf) >= sizeof(buf))
 160                 return 0;
 161         strncat(buf, p, *end - p);
 162
 163         state = get_state(SMATCH_EXTRA, buf, sym);
 164         if (!state)
 165                 return 0;
 166         *rl = estate_rl(state);
 167         return 1;
 168 }
 169
 170 static int read_var_num(struct expression *call, const char *p, const char **end, struct range_list **rl)
 171 {
 172         sval_t sval;
 173
 174         while (*p == ' ')
 175                 p++;
 176
 177         if (*p == '$')
 178                 return read_rl_from_var(call, p, end, rl);
 179
 180         sval.type = &llong_ctype;
 181         sval.value = strtoll(p, (char **)end, 10);
 182         if (*end == p)
 183                 return 0;
 184         *rl = alloc_rl(sval, sval);
 185         return 1;
 186 }
 187
 188 static const char *read_op(const char *p)
 189 {
 190         while (*p == ' ')
 191                 p++;
 192
 193         switch (*p) {
 194         case '+':
 195         case '-':
 196         case '*':
 197         case '/':
 198                 return p;
 199         default:
 200                 return NULL;
 201         }
 202 }
 203
 204 int parse_call_math_rl(struct expression *call, const char *math, struct range_list **rl)
 205 {
 206         struct range_list *tmp;
 207         const char *c;
 208
 209         /* try to implement shunting yard algorithm. */
 210
 211         c = math;
 212         while (1) {
 213                 if (option_debug)
 214                         sm_msg("parsing %s", c);
 215
 216                 /* read a number and push it onto the number stack */
 217                 if (!read_var_num(call, c, &c, &tmp))
 218                         goto fail;
 219                 push_rl(&rl_stack, tmp);
 220
 221                 if (option_debug)
 222                         sm_msg("val = %s remaining = %s", show_rl(tmp), c);
 223
 224                 if (!*c)
 225                         break;
 226                 if (*c == ']' && *(c + 1) == '\0')
 227                         break;
 228
 229                 c = read_op(c);
 230                 if (!c)
 231                         goto fail;
 232
 233                 if (option_debug)
 234                         sm_msg("op = %c remaining = %s", *c, c);
 235
 236                 rl_pop_until(*c);
 237                 push_op(*c);
 238                 c++;
 239         }
 240
 241         rl_pop_until(0);
 242         *rl = pop_rl(&rl_stack);
 243         return 1;
 244 fail:
 245         rl_discard_stacks();
 246         return 0;
 247 }
 248
 249 int parse_call_math(struct expression *call, char *math, sval_t *sval)
 250 {
 251         struct range_list *rl;
 252
 253         if (!parse_call_math_rl(call, math, &rl))
 254                 return 0;
 255         if (!rl_to_sval(rl, sval))
 256                 return 0;
 257         return 1;
 258 }
 259
 260 static struct smatch_state *alloc_state_sname(char *sname)
 261 {
 262         struct smatch_state *state;
 263
 264         state = __alloc_smatch_state(0);
 265         state->name = sname;
 266         state->data = INT_PTR(1);
 267         return state;
 268 }
 269
 270 static int get_arg_number(struct expression *expr)
 271 {
 272         struct symbol *sym;
 273         struct symbol *arg;
 274         int i;
 275
 276         expr = strip_expr(expr);
 277         if (expr->type != EXPR_SYMBOL)
 278                 return -1;
 279         sym = expr->symbol;
 280
 281         i = 0;
 282         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, arg) {
 283                 if (arg == sym)
 284                         return i;
 285                 i++;
 286         } END_FOR_EACH_PTR(arg);
 287
 288         return -1;
 289 }
 290
 291 static int format_name_sym_helper(char *buf, int remaining, char *name, struct symbol *sym)
 292 {
 293         int ret = 0;
 294         int arg;
 295         char *param_name;
 296         int name_len;
 297         int len;
 298
 299         if (!name || !sym || !sym->ident)
 300                 goto free;
 301         arg = get_param_num_from_sym(sym);
 302         if (arg < 0)
 303                 goto free;
 304         if (param_was_set_var_sym(name, sym))
 305                 goto free;
 306
 307         param_name = sym->ident->name;
 308         len = strlen(name);
 309         name_len = strlen(param_name);
 310
 311         if (name_len == len)
 312                 ret = snprintf(buf, remaining, "$%d", arg);
 313         else if (name_len < len && name[name_len] == '-')
 314                 ret = snprintf(buf, remaining, "$%d%s", arg, name + name_len);
 315         else
 316                 goto free;
 317
 318         remaining -= ret;
 319         if (remaining <= 0)
 320                 ret = 0;
 321
 322 free:
 323         free_string(name);
 324
 325         return ret;
 326
 327 }
 328
 329 static int format_variable_helper(char *buf, int remaining, struct expression *expr)
 330 {
 331         char *name;
 332         struct symbol *sym;
 333
 334         name = expr_to_var_sym(expr, &sym);
 335         if (param_was_set_var_sym(name, sym))
 336                 return 0;
 337         return format_name_sym_helper(buf, remaining, name, sym);
 338 }
 339
 340 static int format_call_to_param_mapping(char *buf, int remaining, struct expression *expr)
 341 {
 342         char *name;
 343         struct symbol *sym;
 344
 345         name = map_call_to_param_name_sym(expr, &sym);
 346         if (param_was_set_var_sym(name, sym))
 347                 return 0;
 348         return format_name_sym_helper(buf, remaining, name, sym);
 349 }
 350
 351 static int is_mtag_sval(sval_t sval)
 352 {
 353         if (!is_ptr_type(sval.type))
 354                 return 0;
 355         if (sval_cmp(sval, valid_ptr_min_sval) >= 0 &&
 356             sval_cmp(sval, valid_ptr_max_sval) <= 0)
 357                 return 1;
 358         return 0;
 359 }
 360
 361 static int format_expr_helper(char *buf, int remaining, struct expression *expr)
 362 {
 363         sval_t sval;
 364         int ret;
 365         char *cur;
 366
 367         if (!expr)
 368                 return 0;
 369
 370         cur = buf;
 371
 372         if (expr->type == EXPR_BINOP) {
 373                 ret = format_expr_helper(cur, remaining, expr->left);
 374                 if (ret == 0)
 375                         return 0;
 376                 remaining -= ret;
 377                 if (remaining <= 0)
 378                         return 0;
 379                 cur += ret;
 380
 381                 ret = snprintf(cur, remaining, " %s ", show_special(expr->op));
 382                 remaining -= ret;
 383                 if (remaining <= 0)
 384                         return 0;
 385                 cur += ret;
 386
 387                 ret = format_expr_helper(cur, remaining, expr->right);
 388                 if (ret == 0)
 389                         return 0;
 390                 remaining -= ret;
 391                 if (remaining <= 0)
 392                         return 0;
 393                 cur += ret;
 394                 return cur - buf;
 395         }
 396
 397         if (!param_was_set(expr) && get_implied_value(expr, &sval) && !is_mtag_sval(sval)) {
 398                 ret = snprintf(cur, remaining, "%s", sval_to_str(sval));
 399                 remaining -= ret;
 400                 if (remaining <= 0)
 401                         return 0;
 402                 return ret;
 403         }
 404
 405         if (expr->type == EXPR_CALL)
 406                 return format_call_to_param_mapping(cur, remaining, expr);
 407
 408         return format_variable_helper(cur, remaining, expr);
 409 }
 410
 411 static char *format_expr(struct expression *expr)
 412 {
 413         char buf[256] = "";
 414         int ret;
 415
 416         ret = format_expr_helper(buf, sizeof(buf), expr);
 417         if (ret == 0)
 418                 return NULL;
 419
 420         return alloc_sname(buf);
 421 }
 422
 423 char *get_value_in_terms_of_parameter_math(struct expression *expr)
 424 {
 425         struct expression *tmp;
 426         char buf[256] = "";
 427         sval_t dummy;
 428         int ret;
 429
 430         tmp = get_assigned_expr(expr);
 431         if (tmp)
 432                 expr = tmp;
 433         if (param_was_set(expr))
 434                 return NULL;
 435
 436         if (get_implied_value(expr, &dummy))
 437                 return NULL;
 438
 439         ret = format_expr_helper(buf, sizeof(buf), expr);
 440         if (ret == 0)
 441                 return NULL;
 442
 443         return alloc_sname(buf);
 444 }
 445
 446 char *get_value_in_terms_of_parameter_math_var_sym(const char *name, struct symbol *sym)
 447 {
 448         struct expression *tmp, *expr;
 449         char buf[256] = "";
 450         int ret;
 451         int cnt = 0;
 452
 453         expr = get_assigned_expr_name_sym(name, sym);
 454         if (!expr)
 455                 return NULL;
 456         while ((tmp = get_assigned_expr(expr))) {
 457                 expr = strip_expr(tmp);
 458                 if (++cnt > 3)
 459                         break;
 460         }
 461
 462         ret = format_expr_helper(buf, sizeof(buf), expr);
 463         if (ret == 0)
 464                 return NULL;
 465
 466         return alloc_sname(buf);
 467
 468 }
 469
 470 static void match_alloc(const char *fn, struct expression *expr, void *_size_arg)
 471 {
 472         int size_arg = PTR_INT(_size_arg);
 473         struct expression *right;
 474         struct expression *size_expr;
 475         char *sname;
 476
 477         right = strip_expr(expr->right);
 478         size_expr = get_argument_from_call_expr(right->args, size_arg);
 479
 480         sname = format_expr(size_expr);
 481         if (!sname)
 482                 return;
 483         set_state_expr(my_id, expr->left, alloc_state_sname(sname));
 484 }
 485
 486 static char *swap_format(struct expression *call, char *format)
 487 {
 488         char buf[256];
 489         sval_t sval;
 490         long param;
 491         struct expression *arg;
 492         char *p;
 493         char *out;
 494         int ret;
 495
 496         if (format[0] == '$' && format[2] == '\0') {
 497                 param = strtol(format + 1, NULL, 10);
 498                 arg = get_argument_from_call_expr(call->args, param);
 499                 if (!arg)
 500                         return NULL;
 501                 return format_expr(arg);
 502         }
 503
 504         buf[0] = '\0';
 505         p = format;
 506         out = buf;
 507         while (*p) {
 508                 if (*p == '$') {
 509                         p++;
 510                         param = strtol(p, (char **)&p, 10);
 511                         arg = get_argument_from_call_expr(call->args, param);
 512                         if (!arg)
 513                                 return NULL;
 514                         param = get_arg_number(arg);
 515                         if (param >= 0) {
 516                                 ret = snprintf(out, buf + sizeof(buf) - out, "$%ld", param);
 517                                 out += ret;
 518                                 if (out >= buf + sizeof(buf))
 519                                         return NULL;
 520                         } else if (get_implied_value(arg, &sval)) {
 521                                 ret = snprintf(out, buf + sizeof(buf) - out, "%s", sval_to_str(sval));
 522                                 out += ret;
 523                                 if (out >= buf + sizeof(buf))
 524                                         return NULL;
 525                         } else {
 526                                 return NULL;
 527                         }
 528                 }
 529                 *out = *p;
 530                 p++;
 531                 out++;
 532         }
 533         if (buf[0] == '\0')
 534                 return NULL;
 535         *out = '\0';
 536         return alloc_sname(buf);
 537 }
 538
 539 static char *buf_size_recipe;
 540 static int db_buf_size_callback(void *unused, int argc, char **argv, char **azColName)
 541 {
 542         if (argc != 1)
 543                 return 0;
 544
 545         if (!buf_size_recipe)
 546                 buf_size_recipe = alloc_sname(argv[0]);
 547         else if (strcmp(buf_size_recipe, argv[0]) != 0)
 548                 buf_size_recipe = alloc_sname("invalid");
 549         return 0;
 550 }
 551
 552 static char *get_allocation_recipe_from_call(struct expression *expr)
 553 {
 554         struct symbol *sym;
 555         static char sql_filter[1024];
 556         int i;
 557
 558         if (is_fake_call(expr))
 559                 return NULL;
 560         expr = strip_expr(expr);
 561         if (expr->fn->type != EXPR_SYMBOL)
 562                 return NULL;
 563         sym = expr->fn->symbol;
 564         if (!sym)
 565                 return NULL;
 566
 567         for (i = 0; i < ARRAY_SIZE(alloc_functions); i++) {
 568                 if (strcmp(sym->ident->name, alloc_functions[i].func) == 0) {
 569                         char buf[32];
 570
 571                         snprintf(buf, sizeof(buf), "$%d", alloc_functions[i].param);
 572                         buf_size_recipe = alloc_sname(buf);
 573                         return swap_format(expr, buf_size_recipe);
 574                 }
 575         }
 576
 577         if (sym->ctype.modifiers & MOD_STATIC) {
 578                 snprintf(sql_filter, 1024, "file = '%s' and function = '%s';",
 579                          get_filename(), sym->ident->name);
 580         } else {
 581                 snprintf(sql_filter, 1024, "function = '%s' and static = 0;",
 582                                 sym->ident->name);
 583         }
 584
 585         buf_size_recipe = NULL;
 586         run_sql(db_buf_size_callback, NULL,
 587                 "select value from return_states where type=%d and %s",
 588                 BUF_SIZE, sql_filter);
 589         if (!buf_size_recipe || strcmp(buf_size_recipe, "invalid") == 0)
 590                 return NULL;
 591         /* Known sizes should be handled in smatch_buf_size.c */
 592         if (!strchr(buf_size_recipe, '$'))
 593                 return NULL;
 594         return swap_format(expr, buf_size_recipe);
 595 }
 596
 597 static void match_call_assignment(struct expression *expr)
 598 {
 599         char *sname;
 600
 601         sname = get_allocation_recipe_from_call(expr->right);
 602         if (!sname)
 603                 return;
 604         set_state_expr(my_id, expr->left, alloc_state_sname(sname));
 605 }
 606
 607 const char *get_allocation_math(struct expression *expr)
 608 {
 609         struct expression *tmp;
 610         struct smatch_state *state;
 611         int cnt = 0;
 612
 613         expr = strip_expr(expr);
 614         while ((tmp = get_assigned_expr(expr))) {
 615                 if (cnt++ > 5)  /* assignments to self cause infinite loops */
 616                         break;
 617                 expr = strip_expr(tmp);
 618         }
 619         if (!expr)
 620                 return NULL;
 621
 622         if (expr->type == EXPR_CALL)
 623                 return get_allocation_recipe_from_call(expr);
 624
 625         state = get_state_expr(my_id, expr);
 626         if (!state || !state->data)
 627                 return NULL;
 628
 629         return state->name;
 630 }
 631
 632 void register_parse_call_math(int id)
 633 {
 634         int i;
 635
 636         my_id = id;
 637
 638         set_dynamic_states(my_id);
 639
 640         for (i = 0; i < ARRAY_SIZE(alloc_functions); i++)
 641                 add_function_assign_hook(alloc_functions[i].func, &match_alloc,
 642                                          INT_PTR(alloc_functions[i].param));
 643         add_hook(&match_call_assignment, CALL_ASSIGNMENT_HOOK);
 644 }
 645