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         sval_t sval;
 139
 140
 141         if (expr->type != EXPR_COMPARE)
 142                 return;
 143
 144         /* If we're dealing with known expressions, that's for smatch_extra.c */
 145         if (get_implied_value(expr->left, &sval) ||
 146             get_implied_value(expr->right, &sval))
 147                 return;
 148
 149         switch (expr->op) {
 150         case '<':
 151         case SPECIAL_LTE:
 152         case SPECIAL_UNSIGNED_LT:
 153         case SPECIAL_UNSIGNED_LTE:
 154                 left_true = &capped;
 155                 right_false = &capped;
 156                 break;
 157         case '>':
 158         case SPECIAL_GTE:
 159         case SPECIAL_UNSIGNED_GT:
 160         case SPECIAL_UNSIGNED_GTE:
 161                 left_false = &capped;
 162                 right_true = &capped;
 163                 break;
 164         case SPECIAL_EQUAL:
 165                 left_true = &capped;
 166                 right_true = &capped;
 167                 break;
 168         case SPECIAL_NOTEQUAL:
 169                 left_false = &capped;
 170                 right_false = &capped;
 171                 break;
 172
 173         default:
 174                 return;
 175         }
 176
 177         set_true_false_states_expr(my_id, expr->left, left_true, left_false);
 178         set_true_false_states_expr(my_id, expr->right, right_true, right_false);
 179 }
 180
 181 static void match_assign(struct expression *expr)
 182 {
 183         if (is_capped(expr->right)) {
 184                 set_state_expr(my_id, expr->left, &capped);
 185         } else {
 186                 if (get_state_expr(my_id, expr->left))
 187                         set_state_expr(my_id, expr->left, &uncapped);
 188         }
 189 }
 190
 191 static void match_caller_info(struct expression *expr)
 192 {
 193         struct expression *tmp;
 194         sval_t sval;
 195         int i;
 196
 197         i = -1;
 198         FOR_EACH_PTR(expr->args, tmp) {
 199                 i++;
 200                 if (get_implied_value(tmp, &sval))
 201                         continue;
 202                 if (!is_capped(tmp))
 203                         continue;
 204                 sql_insert_caller_info(expr, CAPPED_DATA, i, "$", "1");
 205         } END_FOR_EACH_PTR(tmp);
 206 }
 207
 208 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *sm)
 209 {
 210         struct smatch_state *estate;
 211         sval_t sval;
 212
 213         if (sm->state != &capped)
 214                 return;
 215         estate = get_state(SMATCH_EXTRA, sm->name, sm->sym);
 216         if (estate_get_single_value(estate, &sval))
 217                 return;
 218         sql_insert_caller_info(call, CAPPED_DATA, param, printed_name, "1");
 219 }
 220
 221 static void print_return_implies_capped(int return_id, char *return_ranges, struct expression *expr)
 222 {
 223         struct smatch_state *orig, *estate;
 224         struct sm_state *sm;
 225         struct symbol *ret_sym;
 226         const char *param_name;
 227         char *return_str;
 228         int param;
 229         sval_t sval;
 230         bool return_found = false;
 231
 232         expr = strip_expr(expr);
 233         return_str = expr_to_str(expr);
 234         ret_sym = expr_to_sym(expr);
 235
 236         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 237                 if (sm->state != &capped)
 238                         continue;
 239
 240                 param = get_param_num_from_sym(sm->sym);
 241                 if (param < 0)
 242                         continue;
 243
 244                 estate = get_state(SMATCH_EXTRA, sm->name, sm->sym);
 245                 if (estate_get_single_value(estate, &sval))
 246                         continue;
 247
 248                 orig = get_state_stree(get_start_states(), my_id, sm->name, sm->sym);
 249                 if (orig == &capped)
 250                         continue;
 251
 252                 param_name = get_param_name(sm);
 253                 if (!param_name)
 254                         continue;
 255
 256                 sql_insert_return_states(return_id, return_ranges, CAPPED_DATA,
 257                                          param, param_name, "1");
 258         } END_FOR_EACH_SM(sm);
 259
 260         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 261                 if (!ret_sym)
 262                         break;
 263                 if (ret_sym != sm->sym)
 264                         continue;
 265
 266                 param_name = state_name_to_param_name(sm->name, return_str);
 267                 if (!param_name)
 268                         continue;
 269                 if (strcmp(param_name, "$") == 0)
 270                         return_found = true;
 271                 sql_insert_return_states(return_id, return_ranges, CAPPED_DATA,
 272                                          -1, param_name, "1");
 273         } END_FOR_EACH_SM(sm);
 274
 275         if (return_found)
 276                 goto free_string;
 277
 278         if (option_project == PROJ_KERNEL && get_function() &&
 279             strstr(get_function(), "nla_get_"))
 280                 sql_insert_return_states(return_id, return_ranges, CAPPED_DATA,
 281                                          -1, "$", "1");
 282
 283 free_string:
 284         free_string(return_str);
 285 }
 286
 287 static void db_return_states_capped(struct expression *expr, int param, char *key, char *value)
 288 {
 289         char *name;
 290         struct symbol *sym;
 291
 292         name = return_state_to_var_sym(expr, param, key, &sym);
 293         if (!name || !sym)
 294                 goto free;
 295
 296         set_state(my_id, name, sym, &capped);
 297 free:
 298         free_string(name);
 299 }
 300
 301 void register_capped(int id)
 302 {
 303         my_id = id;
 304
 305         add_unmatched_state_hook(my_id, &unmatched_state);
 306         select_caller_info_hook(set_param_capped_data, CAPPED_DATA);
 307         add_hook(&match_condition, CONDITION_HOOK);
 308         add_hook(&match_assign, ASSIGNMENT_HOOK);
 309         add_modification_hook(my_id, &set_uncapped);
 310
 311         add_hook(&match_caller_info, FUNCTION_CALL_HOOK);
 312         add_member_info_callback(my_id, struct_member_callback);
 313
 314         add_split_return_callback(print_return_implies_capped);
 315         select_return_states_hook(CAPPED_DATA, &db_return_states_capped);
 316 }