smatch_capped.c

   1 /*
   2  * Copyright (C) 2011 Oracle.  All rights reserved.
   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  * This is trying to make a list of the variables which
  20  * have capped values.  Sometimes we don't know what the
  21  * cap is, for example if we are comparing variables but
  22  * we don't know the values of the variables.  In that
  23  * case we only know that our variable is capped and we
  24  * sort that information here.
  25  */
  26
  27 #include "smatch.h"
  28 #include "smatch_slist.h"
  29 #include "smatch_extra.h"
  30
  31 static int my_id;
  32
  33 STATE(capped);
  34 STATE(uncapped);
  35
  36 static void set_uncapped(struct sm_state *sm, struct expression *mod_expr)
  37 {
  38         set_state(my_id, sm->name, sm->sym, &uncapped);
  39 }
  40
  41 static struct smatch_state *unmatched_state(struct sm_state *sm)
  42 {
  43         struct smatch_state *state;
  44
  45         state = get_state(SMATCH_EXTRA, sm->name, sm->sym);
  46         if (state && !estate_is_whole(state))
  47                 return &capped;
  48         return &uncapped;
  49 }
  50
  51 static int is_capped_macro(struct expression *expr)
  52 {
  53         char *name;
  54
  55         name = get_macro_name(expr->pos);
  56         if (!name)
  57                 return 0;
  58
  59         if (strcmp(name, "min") == 0)
  60                 return 1;
  61         if (strcmp(name, "MIN") == 0)
  62                 return 1;
  63         if (strcmp(name, "min_t") == 0)
  64                 return 1;
  65
  66         return 0;
  67 }
  68
  69 int is_capped(struct expression *expr)
  70 {
  71         sval_t dummy;
  72
  73         expr = strip_expr(expr);
  74         while (expr && expr->type == EXPR_POSTOP) {
  75                 expr = strip_expr(expr->unop);
  76         }
  77         if (!expr)
  78                 return 0;
  79
  80         if (is_ptr_type(get_type(expr)))
  81                 return 0;
  82
  83         if (get_hard_max(expr, &dummy))
  84                 return 1;
  85
  86         if (is_capped_macro(expr))
  87                 return 1;
  88
  89         if (expr->type == EXPR_BINOP) {
  90                 struct range_list *left_rl, *right_rl;
  91
  92                 if (expr->op == '&')
  93                         return 1;
  94                 if (expr->op == SPECIAL_RIGHTSHIFT)
  95                         return 1;
  96                 if (expr->op == '%')
  97                         return is_capped(expr->right);
  98                 if (!is_capped(expr->left))
  99                         return 0;
 100                 if (expr->op == '/')
 101                         return 1;
 102                 if (!is_capped(expr->right))
 103                         return 0;
 104                 if (expr->op == '*') {
 105                         get_absolute_rl(expr->left, &left_rl);
 106                         get_absolute_rl(expr->right, &right_rl);
 107                         if (sval_is_negative(rl_min(left_rl)) ||
 108                             sval_is_negative(rl_min(right_rl)))
 109                                 return 0;
 110                 }
 111                 return 1;
 112         }
 113         if (get_state_expr(my_id, expr) == &capped)
 114                 return 1;
 115         return 0;
 116 }
 117
 118 int is_capped_var_sym(const char *name, struct symbol *sym)
 119 {
 120         if (get_state(my_id, name, sym) == &capped)
 121                 return 1;
 122         return 0;
 123 }
 124
 125 void set_param_capped_data(const char *name, struct symbol *sym, char *key, char *value)
 126 {
 127         char fullname[256];
 128
 129         if (strncmp(key, "$", 1))
 130                 return;
 131         snprintf(fullname, 256, "%s%s", name, key + 1);
 132         set_state(my_id, fullname, sym, &capped);
 133 }
 134
 135 static void match_condition(struct expression *expr)
 136 {
 137         struct expression *left, *right;
 138         struct smatch_state *left_true = NULL;
 139         struct smatch_state *left_false = NULL;
 140         struct smatch_state *right_true = NULL;
 141         struct smatch_state *right_false = NULL;
 142         sval_t sval;
 143
 144
 145         if (expr->type != EXPR_COMPARE)
 146                 return;
 147
 148         left = strip_expr(expr->left);
 149         right = strip_expr(expr->right);
 150
 151         while (left->type == EXPR_ASSIGNMENT)
 152                 left = strip_expr(left->left);
 153
 154         /* If we're dealing with known expressions, that's for smatch_extra.c */
 155         if (get_implied_value(left, &sval) ||
 156             get_implied_value(right, &sval))
 157                 return;
 158
 159         switch (expr->op) {
 160         case '<':
 161         case SPECIAL_LTE:
 162         case SPECIAL_UNSIGNED_LT:
 163         case SPECIAL_UNSIGNED_LTE:
 164                 left_true = &capped;
 165                 right_false = &capped;
 166                 break;
 167         case '>':
 168         case SPECIAL_GTE:
 169         case SPECIAL_UNSIGNED_GT:
 170         case SPECIAL_UNSIGNED_GTE:
 171                 left_false = &capped;
 172                 right_true = &capped;
 173                 break;
 174         case SPECIAL_EQUAL:
 175                 left_true = &capped;
 176                 right_true = &capped;
 177                 break;
 178         case SPECIAL_NOTEQUAL:
 179                 left_false = &capped;
 180                 right_false = &capped;
 181                 break;
 182
 183         default:
 184                 return;
 185         }
 186
 187         set_true_false_states_expr(my_id, left, left_true, left_false);
 188         set_true_false_states_expr(my_id, right, right_true, right_false);
 189 }
 190
 191 static void match_assign(struct expression *expr)
 192 {
 193         if (is_capped(expr->right)) {
 194                 set_state_expr(my_id, expr->left, &capped);
 195         } else {
 196                 if (get_state_expr(my_id, expr->left))
 197                         set_state_expr(my_id, expr->left, &uncapped);
 198         }
 199 }
 200
 201 static void match_caller_info(struct expression *expr)
 202 {
 203         struct expression *tmp;
 204         sval_t sval;
 205         int i;
 206
 207         i = -1;
 208         FOR_EACH_PTR(expr->args, tmp) {
 209                 i++;
 210                 if (get_implied_value(tmp, &sval))
 211                         continue;
 212                 if (!is_capped(tmp))
 213                         continue;
 214                 sql_insert_caller_info(expr, CAPPED_DATA, i, "$", "1");
 215         } END_FOR_EACH_PTR(tmp);
 216 }
 217
 218 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *sm)
 219 {
 220         struct smatch_state *estate;
 221         sval_t sval;
 222
 223         if (sm->state != &capped)
 224                 return;
 225         estate = get_state(SMATCH_EXTRA, sm->name, sm->sym);
 226         if (estate_get_single_value(estate, &sval))
 227                 return;
 228         sql_insert_caller_info(call, CAPPED_DATA, param, printed_name, "1");
 229 }
 230
 231 static void print_return_implies_capped(int return_id, char *return_ranges, struct expression *expr)
 232 {
 233         struct smatch_state *orig, *estate;
 234         struct sm_state *sm;
 235         struct symbol *ret_sym;
 236         const char *param_name;
 237         char *return_str;
 238         int param;
 239         sval_t sval;
 240         bool return_found = false;
 241
 242         expr = strip_expr(expr);
 243         return_str = expr_to_str(expr);
 244         ret_sym = expr_to_sym(expr);
 245
 246         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 247                 if (sm->state != &capped)
 248                         continue;
 249
 250                 param = get_param_num_from_sym(sm->sym);
 251                 if (param < 0)
 252                         continue;
 253
 254                 estate = get_state(SMATCH_EXTRA, sm->name, sm->sym);
 255                 if (estate_get_single_value(estate, &sval))
 256                         continue;
 257
 258                 orig = get_state_stree(get_start_states(), my_id, sm->name, sm->sym);
 259                 if (orig == &capped)
 260                         continue;
 261
 262                 param_name = get_param_name(sm);
 263                 if (!param_name)
 264                         continue;
 265
 266                 sql_insert_return_states(return_id, return_ranges, CAPPED_DATA,
 267                                          param, param_name, "1");
 268         } END_FOR_EACH_SM(sm);
 269
 270         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 271                 if (!ret_sym)
 272                         break;
 273                 if (sm->state != &capped)
 274                         continue;
 275                 if (ret_sym != sm->sym)
 276                         continue;
 277
 278                 param_name = state_name_to_param_name(sm->name, return_str);
 279                 if (!param_name)
 280                         continue;
 281                 if (strcmp(param_name, "$") == 0)
 282                         return_found = true;
 283                 sql_insert_return_states(return_id, return_ranges, CAPPED_DATA,
 284                                          -1, param_name, "1");
 285         } END_FOR_EACH_SM(sm);
 286
 287         if (return_found)
 288                 goto free_string;
 289
 290         if (option_project == PROJ_KERNEL && get_function() &&
 291             strstr(get_function(), "nla_get_"))
 292                 sql_insert_return_states(return_id, return_ranges, CAPPED_DATA,
 293                                          -1, "$", "1");
 294
 295 free_string:
 296         free_string(return_str);
 297 }
 298
 299 static void db_return_states_capped(struct expression *expr, int param, char *key, char *value)
 300 {
 301         char *name;
 302         struct symbol *sym;
 303
 304         name = return_state_to_var_sym(expr, param, key, &sym);
 305         if (!name || !sym)
 306                 goto free;
 307
 308         set_state(my_id, name, sym, &capped);
 309 free:
 310         free_string(name);
 311 }
 312
 313 void register_capped(int id)
 314 {
 315         my_id = id;
 316
 317         add_unmatched_state_hook(my_id, &unmatched_state);
 318         select_caller_info_hook(set_param_capped_data, CAPPED_DATA);
 319         add_hook(&match_condition, CONDITION_HOOK);
 320         add_hook(&match_assign, ASSIGNMENT_HOOK);
 321         add_modification_hook(my_id, &set_uncapped);
 322
 323         add_hook(&match_caller_info, FUNCTION_CALL_HOOK);
 324         add_member_info_callback(my_id, struct_member_callback);
 325
 326         add_split_return_callback(print_return_implies_capped);
 327         select_return_states_hook(CAPPED_DATA, &db_return_states_capped);
 328 }