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 (get_hard_max(expr, &dummy))
  81                 return 1;
  82
  83         if (is_capped_macro(expr))
  84                 return 1;
  85
  86         if (expr->type == EXPR_BINOP) {
  87                 struct range_list *left_rl, *right_rl;
  88
  89                 if (expr->op == '&')
  90                         return 1;
  91                 if (expr->op == SPECIAL_RIGHTSHIFT)
  92                         return 1;
  93                 if (expr->op == '%')
  94                         return is_capped(expr->right);
  95                 if (!is_capped(expr->left))
  96                         return 0;
  97                 if (expr->op == '/')
  98                         return 1;
  99                 if (!is_capped(expr->right))
 100                         return 0;
 101                 if (expr->op == '*') {
 102                         get_absolute_rl(expr->left, &left_rl);
 103                         get_absolute_rl(expr->right, &right_rl);
 104                         if (sval_is_negative(rl_min(left_rl)) ||
 105                             sval_is_negative(rl_min(right_rl)))
 106                                 return 0;
 107                 }
 108                 return 1;
 109         }
 110         if (get_state_expr(my_id, expr) == &capped)
 111                 return 1;
 112         return 0;
 113 }
 114
 115 int is_capped_var_sym(const char *name, struct symbol *sym)
 116 {
 117         if (get_state(my_id, name, sym) == &capped)
 118                 return 1;
 119         return 0;
 120 }
 121
 122 void set_param_capped_data(const char *name, struct symbol *sym, char *key, char *value)
 123 {
 124         char fullname[256];
 125
 126         if (strncmp(key, "$", 1))
 127                 return;
 128         snprintf(fullname, 256, "%s%s", name, key + 1);
 129         set_state(my_id, fullname, sym, &capped);
 130 }
 131
 132 static void match_condition(struct expression *expr)
 133 {
 134         struct smatch_state *left_true = NULL;
 135         struct smatch_state *left_false = NULL;
 136         struct smatch_state *right_true = NULL;
 137         struct smatch_state *right_false = NULL;
 138
 139
 140         if (expr->type != EXPR_COMPARE)
 141                 return;
 142
 143         switch (expr->op) {
 144         case '<':
 145         case SPECIAL_LTE:
 146         case SPECIAL_UNSIGNED_LT:
 147         case SPECIAL_UNSIGNED_LTE:
 148                 left_true = &capped;
 149                 right_false = &capped;
 150                 break;
 151         case '>':
 152         case SPECIAL_GTE:
 153         case SPECIAL_UNSIGNED_GT:
 154         case SPECIAL_UNSIGNED_GTE:
 155                 left_false = &capped;
 156                 right_true = &capped;
 157                 break;
 158         case SPECIAL_EQUAL:
 159                 left_true = &capped;
 160                 right_true = &capped;
 161                 break;
 162         case SPECIAL_NOTEQUAL:
 163                 left_false = &capped;
 164                 right_false = &capped;
 165                 break;
 166
 167         default:
 168                 return;
 169         }
 170
 171         set_true_false_states_expr(my_id, expr->left, left_true, left_false);
 172         set_true_false_states_expr(my_id, expr->right, right_true, right_false);
 173 }
 174
 175 static void match_assign(struct expression *expr)
 176 {
 177         if (is_capped(expr->right)) {
 178                 set_state_expr(my_id, expr->left, &capped);
 179         } else {
 180                 if (get_state_expr(my_id, expr->left))
 181                         set_state_expr(my_id, expr->left, &uncapped);
 182         }
 183 }
 184
 185 static void match_caller_info(struct expression *expr)
 186 {
 187         struct expression *tmp;
 188         sval_t sval;
 189         int i;
 190
 191         i = -1;
 192         FOR_EACH_PTR(expr->args, tmp) {
 193                 i++;
 194                 if (get_implied_value(tmp, &sval))
 195                         continue;
 196                 if (!is_capped(tmp))
 197                         continue;
 198                 sql_insert_caller_info(expr, CAPPED_DATA, i, "$", "1");
 199         } END_FOR_EACH_PTR(tmp);
 200 }
 201
 202 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *sm)
 203 {
 204         struct smatch_state *estate;
 205         sval_t sval;
 206
 207         if (sm->state != &capped)
 208                 return;
 209         estate = get_state(SMATCH_EXTRA, sm->name, sm->sym);
 210         if (estate_get_single_value(estate, &sval))
 211                 return;
 212         sql_insert_caller_info(call, CAPPED_DATA, param, printed_name, "1");
 213 }
 214
 215 static void print_return_implies_capped(int return_id, char *return_ranges, struct expression *expr)
 216 {
 217         struct smatch_state *orig, *estate;
 218         struct sm_state *sm;
 219         const char *param_name;
 220         int param;
 221         sval_t sval;
 222
 223         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 224                 if (sm->state != &capped)
 225                         continue;
 226
 227                 param = get_param_num_from_sym(sm->sym);
 228                 if (param < 0)
 229                         continue;
 230
 231                 estate = get_state(SMATCH_EXTRA, sm->name, sm->sym);
 232                 if (estate_get_single_value(estate, &sval))
 233                         continue;
 234
 235                 orig = get_state_stree(get_start_states(), my_id, sm->name, sm->sym);
 236                 if (orig == &capped)
 237                         continue;
 238
 239                 param_name = get_param_name(sm);
 240                 if (!param_name)
 241                         continue;
 242
 243                 sql_insert_return_states(return_id, return_ranges, CAPPED_DATA,
 244                                          param, param_name, "1");
 245         } END_FOR_EACH_SM(sm);
 246 }
 247
 248 static void db_return_states_capped(struct expression *expr, int param, char *key, char *value)
 249 {
 250         char *name;
 251         struct symbol *sym;
 252
 253         name = return_state_to_var_sym(expr, param, key, &sym);
 254         if (!name || !sym)
 255                 goto free;
 256
 257         set_state(my_id, name, sym, &capped);
 258 free:
 259         free_string(name);
 260 }
 261
 262 void register_capped(int id)
 263 {
 264         my_id = id;
 265
 266         add_unmatched_state_hook(my_id, &unmatched_state);
 267         select_caller_info_hook(set_param_capped_data, CAPPED_DATA);
 268         add_hook(&match_condition, CONDITION_HOOK);
 269         add_hook(&match_assign, ASSIGNMENT_HOOK);
 270         add_modification_hook(my_id, &set_uncapped);
 271
 272         add_hook(&match_caller_info, FUNCTION_CALL_HOOK);
 273         add_member_info_callback(my_id, struct_member_callback);
 274
 275         add_split_return_callback(print_return_implies_capped);
 276         select_return_states_hook(CAPPED_DATA, &db_return_states_capped);
 277 }