smatch_capped.c

   1 /*
   2  * smatch/smatch_capped.c
   3  *
   4  * Copyright (C) 2011 Oracle.  All rights reserved.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 /*
  11  * This is trying to make a list of the variables which
  12  * have capped values.  Sometimes we don't know what the
  13  * cap is, for example if we are comparing variables but
  14  * we don't know the values of the variables.  In that
  15  * case we only know that our variable is capped and we
  16  * sort that information here.
  17  */
  18
  19 #include "smatch.h"
  20 #include "smatch_slist.h"
  21
  22 static int my_id;
  23
  24 STATE(capped);
  25 STATE(uncapped);
  26
  27 static int is_capped_macro(struct expression *expr)
  28 {
  29         char *name;
  30
  31         name = get_macro_name(expr->pos);
  32         if (!name)
  33                 return 0;
  34
  35         if (strcmp(name, "min") == 0)
  36                 return 1;
  37         if (strcmp(name, "MIN") == 0)
  38                 return 1;
  39         if (strcmp(name, "min_t") == 0)
  40                 return 1;
  41
  42         return 0;
  43 }
  44
  45 int is_capped(struct expression *expr)
  46 {
  47         sval_t dummy;
  48
  49         expr = strip_expr(expr);
  50         while (expr && expr->type == EXPR_POSTOP) {
  51                 expr = strip_expr(expr->unop);
  52         }
  53         if (!expr)
  54                 return 0;
  55
  56         if (get_hard_max(expr, &dummy))
  57                 return 1;
  58
  59         if (is_capped_macro(expr))
  60                 return 1;
  61
  62         if (expr->type == EXPR_BINOP) {
  63                 if (expr->op == '&')
  64                         return 1;
  65                 if (expr->op == SPECIAL_RIGHTSHIFT)
  66                         return 1;
  67                 if (expr->op == '%')
  68                         return is_capped(expr->right);
  69                 if (!is_capped(expr->left))
  70                         return 0;
  71                 if (expr->op == '/')
  72                         return 1;
  73                 if (!is_capped(expr->right))
  74                         return 0;
  75                 return 1;
  76         }
  77         if (get_state_expr(my_id, expr) == &capped)
  78                 return 1;
  79         return 0;
  80 }
  81
  82 void set_param_capped_data(const char *name, struct symbol *sym, char *key, char *value)
  83 {
  84         char fullname[256];
  85
  86         if (strncmp(key, "$$", 2))
  87                 return;
  88         snprintf(fullname, 256, "%s%s", name, key + 2);
  89         set_state(my_id, fullname, sym, &capped);
  90 }
  91
  92 static void match_condition(struct expression *expr)
  93 {
  94         struct smatch_state *left_true = NULL;
  95         struct smatch_state *left_false = NULL;
  96         struct smatch_state *right_true = NULL;
  97         struct smatch_state *right_false = NULL;
  98
  99
 100         if (expr->type != EXPR_COMPARE)
 101                 return;
 102
 103         switch (expr->op) {
 104         case '<':
 105         case SPECIAL_LTE:
 106         case SPECIAL_UNSIGNED_LT:
 107         case SPECIAL_UNSIGNED_LTE:
 108                 left_true = &capped;
 109                 right_false = &capped;
 110                 break;
 111         case '>':
 112         case SPECIAL_GTE:
 113         case SPECIAL_UNSIGNED_GT:
 114         case SPECIAL_UNSIGNED_GTE:
 115                 left_false = &capped;
 116                 right_true = &capped;
 117                 break;
 118         case SPECIAL_EQUAL:
 119                 left_true = &capped;
 120                 right_true = &capped;
 121                 break;
 122         case SPECIAL_NOTEQUAL:
 123                 left_false = &capped;
 124                 right_false = &capped;
 125                 break;
 126
 127         default:
 128                 return;
 129         }
 130
 131         set_true_false_states_expr(my_id, expr->right, right_true, right_false);
 132         set_true_false_states_expr(my_id, expr->left, left_true, left_false);
 133 }
 134
 135 static void match_assign(struct expression *expr)
 136 {
 137         if (is_capped(expr->right)) {
 138                 set_state_expr(my_id, expr->left, &capped);
 139         } else {
 140                 if (get_state_expr(my_id, expr->left))
 141                         set_state_expr(my_id, expr->left, &uncapped);
 142         }
 143 }
 144
 145 static void match_caller_info(struct expression *expr)
 146 {
 147         struct expression *tmp;
 148         int i;
 149
 150         i = 0;
 151         FOR_EACH_PTR(expr->args, tmp) {
 152                 if (is_capped(tmp))
 153                         sql_insert_caller_info(expr, CAPPED_DATA, i, "$$", "1");
 154                 i++;
 155         } END_FOR_EACH_PTR(tmp);
 156 }
 157
 158 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct smatch_state *state)
 159 {
 160         if (state != &capped)
 161                 return;
 162         sql_insert_caller_info(call, CAPPED_DATA, param, printed_name, "1");
 163 }
 164
 165 void register_capped(int id)
 166 {
 167         my_id = id;
 168
 169         add_definition_db_callback(set_param_capped_data, CAPPED_DATA);
 170         add_hook(&match_condition, CONDITION_HOOK);
 171         add_hook(&match_assign, ASSIGNMENT_HOOK);
 172
 173         add_hook(&match_caller_info, FUNCTION_CALL_HOOK);
 174         add_member_info_callback(my_id, struct_member_callback);
 175 }