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_msg("internal smatch error %s", __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, char *p, 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         p++;
 128         param = strtol(p, &p, 10);
 129
 130         arg = get_argument_from_call_expr(call->args, param);
 131         if (!arg)
 132                 return 0;
 133
 134         if (*p != '-' && *p != '.') {
 135                 get_absolute_rl(arg, rl);
 136                 *end = p;
 137                 return 1;
 138         }
 139
 140         *end = strchr(p, ' ');
 141
 142         if (arg->type == EXPR_PREOP && arg->op == '&') {
 143                 arg = strip_expr(arg->unop);
 144                 star = 0;
 145                 p++;
 146         } else {
 147                 star = 1;
 148                 p += 2;
 149         }
 150
 151         name = expr_to_var_sym(arg, &sym);
 152         if (!name)
 153                 return 0;
 154         snprintf(buf, sizeof(buf), "%s%s", name, star ? "->" : ".");
 155         free_string(name);
 156
 157         if (*end - p + strlen(buf) >= sizeof(buf))
 158                 return 0;
 159         strncat(buf, p, *end - p);
 160
 161         state = get_state(SMATCH_EXTRA, buf, sym);
 162         if (!state)
 163                 return 0;
 164         *rl = estate_rl(state);
 165         return 1;
 166 }
 167
 168 static int read_var_num(struct expression *call, char *p, char **end, struct range_list **rl)
 169 {
 170         sval_t sval;
 171
 172         while (*p == ' ')
 173                 p++;
 174
 175         if (*p == '$')
 176                 return read_rl_from_var(call, p, end, rl);
 177
 178         sval.type = &llong_ctype;
 179         sval.value = strtoll(p, end, 10);
 180         if (*end == p)
 181                 return 0;
 182         *rl = alloc_rl(sval, sval);
 183         return 1;
 184 }
 185
 186 static char *read_op(char *p)
 187 {
 188         while (*p == ' ')
 189                 p++;
 190
 191         switch (*p) {
 192         case '+':
 193         case '-':
 194         case '*':
 195         case '/':
 196                 return p;
 197         default:
 198                 return NULL;
 199         }
 200 }
 201
 202 int parse_call_math_rl(struct expression *call, char *math, struct range_list **rl)
 203 {
 204         struct range_list *tmp;
 205         char *c;
 206
 207         /* try to implement shunting yard algorithm. */
 208
 209         c = (char *)math;
 210         while (1) {
 211                 if (option_debug)
 212                         sm_msg("parsing %s", c);
 213
 214                 /* read a number and push it onto the number stack */
 215                 if (!read_var_num(call, c, &c, &tmp))
 216                         goto fail;
 217                 push_rl(&rl_stack, tmp);
 218
 219                 if (option_debug)
 220                         sm_msg("val = %s remaining = %s", show_rl(tmp), c);
 221
 222                 if (!*c)
 223                         break;
 224                 if (*c == ']' && *(c + 1) == '\0')
 225                         break;
 226
 227                 c = read_op(c);
 228                 if (!c)
 229                         goto fail;
 230
 231                 if (option_debug)
 232                         sm_msg("op = %c remaining = %s", *c, c);
 233
 234                 rl_pop_until(*c);
 235                 push_op(*c);
 236                 c++;
 237         }
 238
 239         rl_pop_until(0);
 240         *rl = pop_rl(&rl_stack);
 241         return 1;
 242 fail:
 243         rl_discard_stacks();
 244         return 0;
 245 }
 246
 247 int parse_call_math(struct expression *call, char *math, sval_t *sval)
 248 {
 249         struct range_list *rl;
 250
 251         if (!parse_call_math_rl(call, math, &rl))
 252                 return 0;
 253         if (!rl_to_sval(rl, sval))
 254                 return 0;
 255         return 1;
 256 }
 257
 258 static struct smatch_state *alloc_state_sname(char *sname)
 259 {
 260         struct smatch_state *state;
 261
 262         state = __alloc_smatch_state(0);
 263         state->name = sname;
 264         state->data = INT_PTR(1);
 265         return state;
 266 }
 267
 268 static int get_arg_number(struct expression *expr)
 269 {
 270         struct symbol *sym;
 271         struct symbol *arg;
 272         int i;
 273
 274         expr = strip_expr(expr);
 275         if (expr->type != EXPR_SYMBOL)
 276                 return -1;
 277         sym = expr->symbol;
 278
 279         i = 0;
 280         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, arg) {
 281                 if (arg == sym)
 282                         return i;
 283                 i++;
 284         } END_FOR_EACH_PTR(arg);
 285
 286         return -1;
 287 }
 288
 289 static int format_name_sym_helper(char *buf, int remaining, char *name, struct symbol *sym)
 290 {
 291         int ret = 0;
 292         int arg;
 293         char *param_name;
 294         int name_len;
 295
 296         if (!name || !sym || !sym->ident)
 297                 goto free;
 298         arg = get_param_num_from_sym(sym);
 299         if (arg < 0)
 300                 goto free;
 301         if (param_was_set_var_sym(name, sym))
 302                 goto free;
 303
 304         param_name = sym->ident->name;
 305         name_len = strlen(param_name);
 306
 307         if (name[name_len] == '\0')
 308                 ret = snprintf(buf, remaining, "$%d", arg);
 309         else if (name[name_len] == '-')
 310                 ret = snprintf(buf, remaining, "$%d%s", arg, name + name_len);
 311         else
 312                 goto free;
 313
 314         remaining -= ret;
 315         if (remaining <= 0)
 316                 ret = 0;
 317
 318 free:
 319         free_string(name);
 320
 321         return ret;
 322
 323 }
 324
 325 static int format_variable_helper(char *buf, int remaining, struct expression *expr)
 326 {
 327         char *name;
 328         struct symbol *sym;
 329
 330         name = expr_to_var_sym(expr, &sym);
 331         return format_name_sym_helper(buf, remaining, name, sym);
 332 }
 333
 334 static int format_call_to_param_mapping(char *buf, int remaining, struct expression *expr)
 335 {
 336         char *name;
 337         struct symbol *sym;
 338
 339         name = map_call_to_param_name_sym(expr, &sym);
 340         return format_name_sym_helper(buf, remaining, name, sym);
 341 }
 342
 343 static int format_expr_helper(char *buf, int remaining, struct expression *expr)
 344 {
 345         sval_t sval;
 346         int ret;
 347         char *cur;
 348
 349         if (!expr)
 350                 return 0;
 351
 352         cur = buf;
 353
 354         if (expr->type == EXPR_BINOP) {
 355                 ret = format_expr_helper(cur, remaining, expr->left);
 356                 if (ret == 0)
 357                         return 0;
 358                 remaining -= ret;
 359                 if (remaining <= 0)
 360                         return 0;
 361                 cur += ret;
 362
 363                 ret = snprintf(cur, remaining, " %s ", show_special(expr->op));
 364                 remaining -= ret;
 365                 if (remaining <= 0)
 366                         return 0;
 367                 cur += ret;
 368
 369                 ret = format_expr_helper(cur, remaining, expr->right);
 370                 if (ret == 0)
 371                         return 0;
 372                 remaining -= ret;
 373                 if (remaining <= 0)
 374                         return 0;
 375                 cur += ret;
 376                 return cur - buf;
 377         }
 378
 379         if (get_implied_value(expr, &sval)) {
 380                 ret = snprintf(cur, remaining, "%s", sval_to_str(sval));
 381                 remaining -= ret;
 382                 if (remaining <= 0)
 383                         return 0;
 384                 return ret;
 385         }
 386
 387         if (expr->type == EXPR_CALL)
 388                 return format_call_to_param_mapping(cur, remaining, expr);
 389
 390         return format_variable_helper(cur, remaining, expr);
 391 }
 392
 393 static char *format_expr(struct expression *expr)
 394 {
 395         char buf[256];
 396         int ret;
 397
 398         ret = format_expr_helper(buf, sizeof(buf), expr);
 399         if (ret == 0)
 400                 return NULL;
 401
 402         return alloc_sname(buf);
 403 }
 404
 405 char *get_value_in_terms_of_parameter_math(struct expression *expr)
 406 {
 407         struct expression *tmp;
 408         char buf[256];
 409         sval_t dummy;
 410         int ret;
 411
 412         tmp = get_assigned_expr(expr);
 413         if (tmp)
 414                 expr = tmp;
 415
 416         if (get_implied_value(expr, &dummy))
 417                 return NULL;
 418
 419         ret = format_expr_helper(buf, sizeof(buf), expr);
 420         if (ret == 0)
 421                 return NULL;
 422
 423         return alloc_sname(buf);
 424 }
 425
 426 char *get_value_in_terms_of_parameter_math_var_sym(const char *name, struct symbol *sym)
 427 {
 428         struct expression *tmp, *expr;
 429         char buf[256];
 430         int ret;
 431         int cnt = 0;
 432
 433         expr = get_assigned_expr_name_sym(name, sym);
 434         if (!expr)
 435                 return NULL;
 436         while ((tmp = get_assigned_expr(expr))) {
 437                 expr = strip_expr(tmp);
 438                 if (++cnt > 3)
 439                         break;
 440         }
 441
 442         ret = format_expr_helper(buf, sizeof(buf), expr);
 443         if (ret == 0)
 444                 return NULL;
 445
 446         return alloc_sname(buf);
 447
 448 }
 449
 450 static void match_alloc(const char *fn, struct expression *expr, void *_size_arg)
 451 {
 452         int size_arg = PTR_INT(_size_arg);
 453         struct expression *right;
 454         struct expression *size_expr;
 455         char *sname;
 456
 457         right = strip_expr(expr->right);
 458         size_expr = get_argument_from_call_expr(right->args, size_arg);
 459
 460         sname = format_expr(size_expr);
 461         if (!sname)
 462                 return;
 463         set_state_expr(my_id, expr->left, alloc_state_sname(sname));
 464 }
 465
 466 static char *swap_format(struct expression *call, char *format)
 467 {
 468         char buf[256];
 469         sval_t sval;
 470         long param;
 471         struct expression *arg;
 472         char *p;
 473         char *out;
 474         int ret;
 475
 476         if (format[0] == '$' && format[2] == '\0') {
 477                 param = strtol(format + 1, NULL, 10);
 478                 arg = get_argument_from_call_expr(call->args, param);
 479                 if (!arg)
 480                         return NULL;
 481                 return format_expr(arg);
 482         }
 483
 484         buf[0] = '\0';
 485         p = format;
 486         out = buf;
 487         while (*p) {
 488                 if (*p == '$') {
 489                         p++;
 490                         param = strtol(p, &p, 10);
 491                         arg = get_argument_from_call_expr(call->args, param);
 492                         if (!arg)
 493                                 return NULL;
 494                         param = get_arg_number(arg);
 495                         if (param >= 0) {
 496                                 ret = snprintf(out, buf + sizeof(buf) - out, "$%ld", param);
 497                                 out += ret;
 498                                 if (out >= buf + sizeof(buf))
 499                                         return NULL;
 500                         } else if (get_implied_value(arg, &sval)) {
 501                                 ret = snprintf(out, buf + sizeof(buf) - out, "%s", sval_to_str(sval));
 502                                 out += ret;
 503                                 if (out >= buf + sizeof(buf))
 504                                         return NULL;
 505                         } else {
 506                                 return NULL;
 507                         }
 508                 }
 509                 *out = *p;
 510                 p++;
 511                 out++;
 512         }
 513         if (buf[0] == '\0')
 514                 return NULL;
 515         *out = '\0';
 516         return alloc_sname(buf);
 517 }
 518
 519 static char *buf_size_recipe;
 520 static int db_buf_size_callback(void *unused, int argc, char **argv, char **azColName)
 521 {
 522         if (argc != 1)
 523                 return 0;
 524
 525         if (!buf_size_recipe)
 526                 buf_size_recipe = alloc_sname(argv[0]);
 527         else if (strcmp(buf_size_recipe, argv[0]) != 0)
 528                 buf_size_recipe = alloc_sname("invalid");
 529         return 0;
 530 }
 531
 532 static char *get_allocation_recipe_from_call(struct expression *expr)
 533 {
 534         struct symbol *sym;
 535         static char sql_filter[1024];
 536         int i;
 537
 538         if (is_fake_call(expr))
 539                 return NULL;
 540         expr = strip_expr(expr);
 541         if (expr->fn->type != EXPR_SYMBOL)
 542                 return NULL;
 543         sym = expr->fn->symbol;
 544         if (!sym)
 545                 return NULL;
 546
 547         for (i = 0; i < ARRAY_SIZE(alloc_functions); i++) {
 548                 if (strcmp(sym->ident->name, alloc_functions[i].func) == 0) {
 549                         char buf[32];
 550
 551                         snprintf(buf, sizeof(buf), "$%d", alloc_functions[i].param);
 552                         buf_size_recipe = alloc_sname(buf);
 553                         return swap_format(expr, buf_size_recipe);
 554                 }
 555         }
 556
 557         if (sym->ctype.modifiers & MOD_STATIC) {
 558                 snprintf(sql_filter, 1024, "file = '%s' and function = '%s';",
 559                          get_filename(), sym->ident->name);
 560         } else {
 561                 snprintf(sql_filter, 1024, "function = '%s' and static = 0;",
 562                                 sym->ident->name);
 563         }
 564
 565         buf_size_recipe = NULL;
 566         run_sql(db_buf_size_callback, NULL,
 567                 "select value from return_states where type=%d and %s",
 568                 BUF_SIZE, sql_filter);
 569         if (!buf_size_recipe || strcmp(buf_size_recipe, "invalid") == 0)
 570                 return NULL;
 571         return swap_format(expr, buf_size_recipe);
 572 }
 573
 574 static void match_call_assignment(struct expression *expr)
 575 {
 576         char *sname;
 577
 578         sname = get_allocation_recipe_from_call(expr->right);
 579         if (!sname)
 580                 return;
 581         set_state_expr(my_id, expr->left, alloc_state_sname(sname));
 582 }
 583
 584 static void match_returns_call(int return_id, char *return_ranges, struct expression *call)
 585 {
 586         char *sname;
 587
 588         sname = get_allocation_recipe_from_call(call);
 589         if (option_debug)
 590                 sm_msg("sname = %s", sname);
 591         if (!sname)
 592                 return;
 593
 594         sql_insert_return_states(return_id, return_ranges, BUF_SIZE, -1, "",
 595                         sname);
 596 }
 597
 598 static void print_returned_allocations(int return_id, char *return_ranges, struct expression *expr)
 599 {
 600         struct expression *tmp;
 601         struct smatch_state *state;
 602         struct symbol *sym;
 603         char *name;
 604         int cnt = 0;
 605
 606         expr = strip_expr(expr);
 607         while ((tmp = get_assigned_expr(expr))) {
 608                 if (cnt++ > 5)  /* assignments to self cause infinite loops */
 609                         break;
 610                 expr = strip_expr(tmp);
 611         }
 612         if (!expr)
 613                 return;
 614
 615         if (expr->type == EXPR_CALL) {
 616                 match_returns_call(return_id, return_ranges, expr);
 617                 return;
 618         }
 619
 620         name = expr_to_var_sym(expr, &sym);
 621         if (!name || !sym)
 622                 goto free;
 623
 624         state = get_state(my_id, name, sym);
 625         if (!state || !state->data)
 626                 goto free;
 627
 628         sql_insert_return_states(return_id, return_ranges, BUF_SIZE, -1, "",
 629                         state->name);
 630 free:
 631         free_string(name);
 632 }
 633
 634 void register_parse_call_math(int id)
 635 {
 636         int i;
 637
 638         my_id = 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         add_split_return_callback(print_returned_allocations);
 645 }
 646