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
  30 static int my_id;
  31
  32 STATE(capped);
  33 STATE(uncapped);
  34
  35 static int is_capped_macro(struct expression *expr)
  36 {
  37         char *name;
  38
  39         name = get_macro_name(expr->pos);
  40         if (!name)
  41                 return 0;
  42
  43         if (strcmp(name, "min") == 0)
  44                 return 1;
  45         if (strcmp(name, "MIN") == 0)
  46                 return 1;
  47         if (strcmp(name, "min_t") == 0)
  48                 return 1;
  49
  50         return 0;
  51 }
  52
  53 int is_capped(struct expression *expr)
  54 {
  55         sval_t dummy;
  56
  57         expr = strip_expr(expr);
  58         while (expr && expr->type == EXPR_POSTOP) {
  59                 expr = strip_expr(expr->unop);
  60         }
  61         if (!expr)
  62                 return 0;
  63
  64         if (get_hard_max(expr, &dummy))
  65                 return 1;
  66
  67         if (is_capped_macro(expr))
  68                 return 1;
  69
  70         if (expr->type == EXPR_BINOP) {
  71                 if (expr->op == '&')
  72                         return 1;
  73                 if (expr->op == SPECIAL_RIGHTSHIFT)
  74                         return 1;
  75                 if (expr->op == '%')
  76                         return is_capped(expr->right);
  77                 if (!is_capped(expr->left))
  78                         return 0;
  79                 if (expr->op == '/')
  80                         return 1;
  81                 if (!is_capped(expr->right))
  82                         return 0;
  83                 return 1;
  84         }
  85         if (get_state_expr(my_id, expr) == &capped)
  86                 return 1;
  87         return 0;
  88 }
  89
  90 int is_capped_var_sym(const char *name, struct symbol *sym)
  91 {
  92         if (get_state(my_id, name, sym) == &capped)
  93                 return 1;
  94         return 0;
  95 }
  96
  97 void set_param_capped_data(const char *name, struct symbol *sym, char *key, char *value)
  98 {
  99         char fullname[256];
 100
 101         if (strncmp(key, "$", 1))
 102                 return;
 103         snprintf(fullname, 256, "%s%s", name, key + 1);
 104         set_state(my_id, fullname, sym, &capped);
 105 }
 106
 107 static void match_condition(struct expression *expr)
 108 {
 109         struct smatch_state *left_true = NULL;
 110         struct smatch_state *left_false = NULL;
 111         struct smatch_state *right_true = NULL;
 112         struct smatch_state *right_false = NULL;
 113
 114
 115         if (expr->type != EXPR_COMPARE)
 116                 return;
 117
 118         switch (expr->op) {
 119         case '<':
 120         case SPECIAL_LTE:
 121         case SPECIAL_UNSIGNED_LT:
 122         case SPECIAL_UNSIGNED_LTE:
 123                 left_true = &capped;
 124                 right_false = &capped;
 125                 break;
 126         case '>':
 127         case SPECIAL_GTE:
 128         case SPECIAL_UNSIGNED_GT:
 129         case SPECIAL_UNSIGNED_GTE:
 130                 left_false = &capped;
 131                 right_true = &capped;
 132                 break;
 133         case SPECIAL_EQUAL:
 134                 left_true = &capped;
 135                 right_true = &capped;
 136                 break;
 137         case SPECIAL_NOTEQUAL:
 138                 left_false = &capped;
 139                 right_false = &capped;
 140                 break;
 141
 142         default:
 143                 return;
 144         }
 145
 146         set_true_false_states_expr(my_id, expr->right, right_true, right_false);
 147         set_true_false_states_expr(my_id, expr->left, left_true, left_false);
 148 }
 149
 150 static void match_assign(struct expression *expr)
 151 {
 152         if (is_capped(expr->right)) {
 153                 set_state_expr(my_id, expr->left, &capped);
 154         } else {
 155                 if (get_state_expr(my_id, expr->left))
 156                         set_state_expr(my_id, expr->left, &uncapped);
 157         }
 158 }
 159
 160 static void match_caller_info(struct expression *expr)
 161 {
 162         struct expression *tmp;
 163         int i;
 164
 165         i = 0;
 166         FOR_EACH_PTR(expr->args, tmp) {
 167                 if (is_capped(tmp))
 168                         sql_insert_caller_info(expr, CAPPED_DATA, i, "$", "1");
 169                 i++;
 170         } END_FOR_EACH_PTR(tmp);
 171 }
 172
 173 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *sm)
 174 {
 175         if (sm->state != &capped)
 176                 return;
 177         sql_insert_caller_info(call, CAPPED_DATA, param, printed_name, "1");
 178 }
 179
 180 static int is_unmodified(const char *name)
 181 {
 182         char orig[256];
 183
 184         snprintf(orig, sizeof(orig), "%s orig", name);
 185
 186         if (get_comparison_strings(name, orig) == SPECIAL_EQUAL)
 187                 return 1;
 188         return 0;
 189 }
 190
 191 static void print_return_implies_capped(int return_id, char *return_ranges, struct expression *expr)
 192 {
 193         struct smatch_state *orig;
 194         struct sm_state *sm;
 195         const char *param_name;
 196         int param;
 197
 198         FOR_EACH_SM(__get_cur_stree(), sm) {
 199                 if (sm->owner != my_id)
 200                         continue;
 201                 if (sm->state != &capped)
 202                         continue;
 203
 204                 param = get_param_num_from_sym(sm->sym);
 205                 if (param < 0)
 206                         continue;
 207
 208                 orig = get_state_stree(get_start_states(), my_id, sm->name, sm->sym);
 209                 if (orig == &capped)
 210                         continue;
 211
 212                 if (!is_unmodified(sm->name))
 213                         continue;
 214
 215                 param_name = get_param_name(sm);
 216                 if (!param_name)
 217                         continue;
 218
 219                 sql_insert_return_states(return_id, return_ranges, CAPPED_DATA,
 220                                          param, param_name, "1");
 221         } END_FOR_EACH_SM(sm);
 222 }
 223
 224 static void db_return_states_capped(struct expression *expr, int param, char *key, char *value)
 225 {
 226         char *name;
 227         struct symbol *sym;
 228
 229         name = return_state_to_var_sym(expr, param, key, &sym);
 230         if (!name || !sym)
 231                 goto free;
 232
 233         set_state(my_id, name, sym, &capped);
 234 free:
 235         free_string(name);
 236 }
 237
 238 void register_capped(int id)
 239 {
 240         my_id = id;
 241
 242         select_caller_info_hook(set_param_capped_data, CAPPED_DATA);
 243         add_hook(&match_condition, CONDITION_HOOK);
 244         add_hook(&match_assign, ASSIGNMENT_HOOK);
 245
 246         add_hook(&match_caller_info, FUNCTION_CALL_HOOK);
 247         add_member_info_callback(my_id, struct_member_callback);
 248
 249         add_split_return_callback(print_return_implies_capped);
 250         select_return_states_hook(CAPPED_DATA, &db_return_states_capped);
 251 }