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 static bool binop_capped(struct expression *expr)
  70 {
  71         bool left_capped, right_capped;
  72         sval_t sval;
  73
  74         if (expr->op == '&' && !get_value(expr->right, &sval))
  75                 return true;
  76         if (expr->op == SPECIAL_RIGHTSHIFT)
  77                 return false;
  78         if (expr->op == '%' &&
  79             !get_value(expr->right, &sval) && is_capped(expr->right))
  80                 return true;
  81
  82         left_capped = is_capped(expr->left);
  83         right_capped = is_capped(expr->right);
  84
  85         if (left_capped && right_capped)
  86                 return true;
  87         if (!left_capped && !right_capped)
  88                 return false;
  89         if (left_capped && get_hard_max(expr->right, &sval))
  90                 return true;
  91         if (right_capped && get_hard_max(expr->left, &sval))
  92                 return true;
  93
  94         return false;
  95 }
  96
  97 int is_capped(struct expression *expr)
  98 {
  99         struct symbol *type;
 100
 101         expr = strip_expr(expr);
 102         while (expr && expr->type == EXPR_POSTOP) {
 103                 expr = strip_expr(expr->unop);
 104         }
 105         if (!expr)
 106                 return 0;
 107
 108         type = get_type(expr);
 109         if (is_ptr_type(type))
 110                 return 0;
 111         if (type == &bool_ctype)
 112                 return 0;
 113         if (type_bits(type) >= 0 && type_bits(type) <= 2)
 114                 return 0;
 115
 116         if (is_capped_macro(expr))
 117                 return 1;
 118
 119         if (expr->type == EXPR_BINOP)
 120                 return binop_capped(expr);
 121
 122         if (get_state_expr(my_id, expr) == &capped)
 123                 return 1;
 124         return 0;
 125 }
 126
 127 int is_capped_var_sym(const char *name, struct symbol *sym)
 128 {
 129         if (get_state(my_id, name, sym) == &capped)
 130                 return 1;
 131         return 0;
 132 }
 133
 134 void set_param_capped_data(const char *name, struct symbol *sym, char *key, char *value)
 135 {
 136         char fullname[256];
 137
 138         if (strncmp(key, "$", 1))
 139                 return;
 140         snprintf(fullname, 256, "%s%s", name, key + 1);
 141         set_state(my_id, fullname, sym, &capped);
 142 }
 143
 144 static void match_condition(struct expression *expr)
 145 {
 146         struct expression *left, *right;
 147         struct smatch_state *left_true = NULL;
 148         struct smatch_state *left_false = NULL;
 149         struct smatch_state *right_true = NULL;
 150         struct smatch_state *right_false = NULL;
 151         sval_t sval;
 152
 153         if (expr->type != EXPR_COMPARE)
 154                 return;
 155
 156         left = strip_expr(expr->left);
 157         right = strip_expr(expr->right);
 158
 159         while (left->type == EXPR_ASSIGNMENT)
 160                 left = strip_expr(left->left);
 161
 162         /* If we're dealing with known expressions, that's for smatch_extra.c */
 163         if (__in_pre_condition) {
 164                 if (get_implied_value(right, &sval))
 165                         return;
 166         } else {
 167                 if (get_implied_value(left, &sval) ||
 168                     get_implied_value(right, &sval))
 169                         return;
 170         }
 171
 172         switch (expr->op) {
 173         case '<':
 174         case SPECIAL_LTE:
 175         case SPECIAL_UNSIGNED_LT:
 176         case SPECIAL_UNSIGNED_LTE:
 177                 left_true = &capped;
 178                 right_false = &capped;
 179                 break;
 180         case '>':
 181         case SPECIAL_GTE:
 182         case SPECIAL_UNSIGNED_GT:
 183         case SPECIAL_UNSIGNED_GTE:
 184                 left_false = &capped;
 185                 right_true = &capped;
 186                 break;
 187         case SPECIAL_EQUAL:
 188                 left_true = &capped;
 189                 right_true = &capped;
 190                 break;
 191         case SPECIAL_NOTEQUAL:
 192                 left_false = &capped;
 193                 right_false = &capped;
 194                 break;
 195
 196         default:
 197                 return;
 198         }
 199
 200         set_true_false_states_expr(my_id, left, left_true, left_false);
 201         set_true_false_states_expr(my_id, right, right_true, right_false);
 202 }
 203
 204 static void match_assign(struct expression *expr)
 205 {
 206         struct symbol *type;
 207         struct range_list *rl;
 208
 209         if (expr->op != '=')
 210                 return;
 211
 212         type = get_type(expr);
 213         if (is_ptr_type(type))
 214                 return;
 215         if (type == &bool_ctype)
 216                 return;
 217         if (type_bits(type) >= 0 && type_bits(type) <= 2)
 218                 return;
 219
 220         if (is_capped(expr->right)) {
 221                 set_state_expr(my_id, expr->left, &capped);
 222                 return;
 223         }
 224
 225         if (!get_state_expr(my_id, expr->left))
 226                 return;
 227
 228         if (get_implied_rl(expr->right, &rl) &&
 229             !is_whole_rl(rl)) {
 230                 set_state_expr(my_id, expr->left, &capped);
 231                 return;
 232         }
 233 }
 234
 235 static void match_caller_info(struct expression *expr)
 236 {
 237         struct expression *tmp;
 238         sval_t sval;
 239         int i;
 240
 241         i = -1;
 242         FOR_EACH_PTR(expr->args, tmp) {
 243                 i++;
 244                 if (get_implied_value(tmp, &sval))
 245                         continue;
 246                 if (!is_capped(tmp))
 247                         continue;
 248                 sql_insert_caller_info(expr, CAPPED_DATA, i, "$", "1");
 249         } END_FOR_EACH_PTR(tmp);
 250 }
 251
 252 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *sm)
 253 {
 254         struct smatch_state *estate;
 255         sval_t sval;
 256
 257         if (sm->state != &capped)
 258                 return;
 259         estate = __get_state(SMATCH_EXTRA, sm->name, sm->sym);
 260         if (estate_get_single_value(estate, &sval))
 261                 return;
 262         sql_insert_caller_info(call, CAPPED_DATA, param, printed_name, "1");
 263 }
 264
 265 static void return_info_callback(int return_id, char *return_ranges,
 266                                  struct expression *returned_expr,
 267                                  int param,
 268                                  const char *printed_name,
 269                                  struct sm_state *sm)
 270 {
 271         struct smatch_state *orig, *estate;
 272         sval_t sval;
 273
 274         if (param < -1 || sm->state != &capped)
 275                 return;
 276         if (printed_name[0] == '&')
 277                 return;
 278
 279         estate = __get_state(SMATCH_EXTRA, sm->name, sm->sym);
 280         if (estate_get_single_value(estate, &sval))
 281                 return;
 282
 283         orig = get_state_stree(get_start_states(), my_id, sm->name, sm->sym);
 284         if (orig == &capped && !param_was_set_var_sym(sm->name, sm->sym))
 285                 return;
 286
 287         sql_insert_return_states(return_id, return_ranges, CAPPED_DATA,
 288                                  param, printed_name, "");
 289 }
 290
 291 static void db_return_states_capped(struct expression *expr, int param, char *key, char *value)
 292 {
 293         char *name;
 294         struct symbol *sym;
 295
 296         name = get_name_sym_from_param_key(expr, param, key, &sym);
 297         if (!name || !sym)
 298                 goto free;
 299
 300         set_state(my_id, name, sym, &capped);
 301 free:
 302         free_string(name);
 303 }
 304
 305 void register_capped(int id)
 306 {
 307         my_id = id;
 308
 309         add_unmatched_state_hook(my_id, &unmatched_state);
 310         select_caller_info_hook(set_param_capped_data, CAPPED_DATA);
 311         add_hook(&match_condition, CONDITION_HOOK);
 312         add_hook(&match_assign, ASSIGNMENT_HOOK);
 313         add_modification_hook(my_id, &set_uncapped);
 314
 315         add_hook(&match_caller_info, FUNCTION_CALL_HOOK);
 316         add_member_info_callback(my_id, struct_member_callback);
 317
 318         add_return_info_callback(my_id, return_info_callback);
 319         select_return_states_hook(CAPPED_DATA, &db_return_states_capped);
 320 }