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 struct smatch_state *unmatched_state(struct sm_state *sm)
  37 {
  38         struct smatch_state *state;
  39
  40         state = get_state(SMATCH_EXTRA, sm->name, sm->sym);
  41         if (state && !estate_is_whole(state))
  42                 return &capped;
  43         return &uncapped;
  44 }
  45
  46 static int is_capped_macro(struct expression *expr)
  47 {
  48         char *name;
  49
  50         name = get_macro_name(expr->pos);
  51         if (!name)
  52                 return 0;
  53
  54         if (strcmp(name, "min") == 0)
  55                 return 1;
  56         if (strcmp(name, "MIN") == 0)
  57                 return 1;
  58         if (strcmp(name, "min_t") == 0)
  59                 return 1;
  60
  61         return 0;
  62 }
  63
  64 int is_capped(struct expression *expr)
  65 {
  66         sval_t dummy;
  67
  68         expr = strip_expr(expr);
  69         while (expr && expr->type == EXPR_POSTOP) {
  70                 expr = strip_expr(expr->unop);
  71         }
  72         if (!expr)
  73                 return 0;
  74
  75         if (get_hard_max(expr, &dummy))
  76                 return 1;
  77
  78         if (is_capped_macro(expr))
  79                 return 1;
  80
  81         if (expr->type == EXPR_BINOP) {
  82                 struct range_list *left_rl, *right_rl;
  83
  84                 if (expr->op == '&')
  85                         return 1;
  86                 if (expr->op == SPECIAL_RIGHTSHIFT)
  87                         return 1;
  88                 if (expr->op == '%')
  89                         return is_capped(expr->right);
  90                 if (!is_capped(expr->left))
  91                         return 0;
  92                 if (expr->op == '/')
  93                         return 1;
  94                 if (!is_capped(expr->right))
  95                         return 0;
  96                 if (expr->op == '*') {
  97                         get_absolute_rl(expr->left, &left_rl);
  98                         get_absolute_rl(expr->right, &right_rl);
  99                         if (sval_is_negative(rl_min(left_rl)) ||
 100                             sval_is_negative(rl_min(right_rl)))
 101                                 return 0;
 102                 }
 103                 return 1;
 104         }
 105         if (get_state_expr(my_id, expr) == &capped)
 106                 return 1;
 107         return 0;
 108 }
 109
 110 int is_capped_var_sym(const char *name, struct symbol *sym)
 111 {
 112         if (get_state(my_id, name, sym) == &capped)
 113                 return 1;
 114         return 0;
 115 }
 116
 117 void set_param_capped_data(const char *name, struct symbol *sym, char *key, char *value)
 118 {
 119         char fullname[256];
 120
 121         if (strncmp(key, "$", 1))
 122                 return;
 123         snprintf(fullname, 256, "%s%s", name, key + 1);
 124         set_state(my_id, fullname, sym, &capped);
 125 }
 126
 127 static void match_condition(struct expression *expr)
 128 {
 129         struct smatch_state *left_true = NULL;
 130         struct smatch_state *left_false = NULL;
 131         struct smatch_state *right_true = NULL;
 132         struct smatch_state *right_false = NULL;
 133
 134
 135         if (expr->type != EXPR_COMPARE)
 136                 return;
 137
 138         switch (expr->op) {
 139         case '<':
 140         case SPECIAL_LTE:
 141         case SPECIAL_UNSIGNED_LT:
 142         case SPECIAL_UNSIGNED_LTE:
 143                 left_true = &capped;
 144                 right_false = &capped;
 145                 break;
 146         case '>':
 147         case SPECIAL_GTE:
 148         case SPECIAL_UNSIGNED_GT:
 149         case SPECIAL_UNSIGNED_GTE:
 150                 left_false = &capped;
 151                 right_true = &capped;
 152                 break;
 153         case SPECIAL_EQUAL:
 154                 left_true = &capped;
 155                 right_true = &capped;
 156                 break;
 157         case SPECIAL_NOTEQUAL:
 158                 left_false = &capped;
 159                 right_false = &capped;
 160                 break;
 161
 162         default:
 163                 return;
 164         }
 165
 166         set_true_false_states_expr(my_id, expr->left, left_true, left_false);
 167         set_true_false_states_expr(my_id, expr->right, right_true, right_false);
 168 }
 169
 170 static void match_assign(struct expression *expr)
 171 {
 172         if (is_capped(expr->right)) {
 173                 set_state_expr(my_id, expr->left, &capped);
 174         } else {
 175                 if (get_state_expr(my_id, expr->left))
 176                         set_state_expr(my_id, expr->left, &uncapped);
 177         }
 178 }
 179
 180 static void match_caller_info(struct expression *expr)
 181 {
 182         struct expression *tmp;
 183         sval_t sval;
 184         int i;
 185
 186         i = -1;
 187         FOR_EACH_PTR(expr->args, tmp) {
 188                 i++;
 189                 if (get_implied_value(tmp, &sval))
 190                         continue;
 191                 if (!is_capped(tmp))
 192                         continue;
 193                 sql_insert_caller_info(expr, CAPPED_DATA, i, "$", "1");
 194         } END_FOR_EACH_PTR(tmp);
 195 }
 196
 197 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *sm)
 198 {
 199         struct smatch_state *estate;
 200         sval_t sval;
 201
 202         if (sm->state != &capped)
 203                 return;
 204         estate = get_state(SMATCH_EXTRA, sm->name, sm->sym);
 205         if (estate_get_single_value(estate, &sval))
 206                 return;
 207         sql_insert_caller_info(call, CAPPED_DATA, param, printed_name, "1");
 208 }
 209
 210 static void print_return_implies_capped(int return_id, char *return_ranges, struct expression *expr)
 211 {
 212         struct smatch_state *orig, *estate;
 213         struct sm_state *sm;
 214         const char *param_name;
 215         int param;
 216         sval_t sval;
 217
 218         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 219                 if (sm->state != &capped)
 220                         continue;
 221
 222                 param = get_param_num_from_sym(sm->sym);
 223                 if (param < 0)
 224                         continue;
 225
 226                 estate = get_state(SMATCH_EXTRA, sm->name, sm->sym);
 227                 if (estate_get_single_value(estate, &sval))
 228                         continue;
 229
 230                 orig = get_state_stree(get_start_states(), my_id, sm->name, sm->sym);
 231                 if (orig == &capped)
 232                         continue;
 233
 234                 param_name = get_param_name(sm);
 235                 if (!param_name)
 236                         continue;
 237
 238                 sql_insert_return_states(return_id, return_ranges, CAPPED_DATA,
 239                                          param, param_name, "1");
 240         } END_FOR_EACH_SM(sm);
 241 }
 242
 243 static void db_return_states_capped(struct expression *expr, int param, char *key, char *value)
 244 {
 245         char *name;
 246         struct symbol *sym;
 247
 248         name = return_state_to_var_sym(expr, param, key, &sym);
 249         if (!name || !sym)
 250                 goto free;
 251
 252         set_state(my_id, name, sym, &capped);
 253 free:
 254         free_string(name);
 255 }
 256
 257 void register_capped(int id)
 258 {
 259         my_id = id;
 260
 261         add_unmatched_state_hook(my_id, &unmatched_state);
 262         select_caller_info_hook(set_param_capped_data, CAPPED_DATA);
 263         add_hook(&match_condition, CONDITION_HOOK);
 264         add_hook(&match_assign, ASSIGNMENT_HOOK);
 265
 266         add_hook(&match_caller_info, FUNCTION_CALL_HOOK);
 267         add_member_info_callback(my_id, struct_member_callback);
 268
 269         add_split_return_callback(print_return_implies_capped);
 270         select_return_states_hook(CAPPED_DATA, &db_return_states_capped);
 271 }