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 sval;
  48
  49         expr = strip_expr(expr);
  50         if (!expr)
  51                 return 0;
  52
  53         if (is_capped_macro(expr))
  54                 return 1;
  55
  56         if (expr->type == EXPR_BINOP) {
  57                 if (expr->op == '&')
  58                         return 1;
  59                 if (expr->op == SPECIAL_RIGHTSHIFT)
  60                         return 1;
  61                 if (expr->op == '%')
  62                         return is_capped(expr->right);
  63                 if (!is_capped(expr->left))
  64                         return 0;
  65                 if (expr->op == '/')
  66                         return 1;
  67                 if (!is_capped(expr->right))
  68                         return 0;
  69                 return 1;
  70         }
  71         if (get_implied_max_sval(expr, &sval))
  72                 return 1;
  73         if (get_state_expr(my_id, expr) == &capped)
  74                 return 1;
  75         return 0;
  76 }
  77
  78 void set_param_capped_data(const char *name, struct symbol *sym, char *key, char *value)
  79 {
  80         char fullname[256];
  81
  82         if (strncmp(key, "$$", 2))
  83                 return;
  84         snprintf(fullname, 256, "%s%s", name, key + 2);
  85         set_state(my_id, fullname, sym, &capped);
  86 }
  87
  88 static void match_condition(struct expression *expr)
  89 {
  90         struct smatch_state *left_true = NULL;
  91         struct smatch_state *left_false = NULL;
  92         struct smatch_state *right_true = NULL;
  93         struct smatch_state *right_false = NULL;
  94
  95
  96         if (expr->type != EXPR_COMPARE)
  97                 return;
  98
  99         switch (expr->op) {
 100         case '<':
 101         case SPECIAL_LTE:
 102         case SPECIAL_UNSIGNED_LT:
 103         case SPECIAL_UNSIGNED_LTE:
 104                 left_true = &capped;
 105                 right_false = &capped;
 106                 break;
 107         case '>':
 108         case SPECIAL_GTE:
 109         case SPECIAL_UNSIGNED_GT:
 110         case SPECIAL_UNSIGNED_GTE:
 111                 left_false = &capped;
 112                 right_true = &capped;
 113                 break;
 114         case SPECIAL_EQUAL:
 115                 left_true = &capped;
 116                 right_true = &capped;
 117                 break;
 118         case SPECIAL_NOTEQUAL:
 119                 left_false = &capped;
 120                 right_false = &capped;
 121                 break;
 122
 123         default:
 124                 return;
 125         }
 126
 127         set_true_false_states_expr(my_id, expr->right, right_true, right_false);
 128         set_true_false_states_expr(my_id, expr->left, left_true, left_false);
 129 }
 130
 131 static void match_assign(struct expression *expr)
 132 {
 133         if (is_capped(expr->right)) {
 134                 set_state_expr(my_id, expr->left, &capped);
 135         } else {
 136                 if (get_state_expr(my_id, expr->left))
 137                         set_state_expr(my_id, expr->left, &uncapped);
 138         }
 139 }
 140
 141 static void match_caller_info(struct expression *expr)
 142 {
 143         struct expression *tmp;
 144         char *func;
 145         int i;
 146
 147         func = get_fnptr_name(expr->fn);
 148         if (!func)
 149                 return;
 150
 151         i = 0;
 152         FOR_EACH_PTR(expr->args, tmp) {
 153                 if (is_capped(tmp))
 154                         sm_msg("info: passes capped_data %s %d '$$' %s", func,
 155                                i, is_static(expr->fn) ? "static" : "global");
 156                 i++;
 157         } END_FOR_EACH_PTR(tmp);
 158 }
 159
 160 static void struct_member_callback(char *fn, char *global_static, int param, char *printed_name, struct smatch_state *state)
 161 {
 162         if (state != &capped)
 163                 return;
 164         sm_msg("info: passes capped_data '%s' %d '%s' %s", fn, param, printed_name, global_static);
 165 }
 166
 167 void register_capped(int id)
 168 {
 169         my_id = id;
 170
 171         add_definition_db_callback(set_param_capped_data, CAPPED_DATA);
 172         add_hook(&match_condition, CONDITION_HOOK);
 173         add_hook(&match_assign, ASSIGNMENT_HOOK);
 174         if (option_info) {
 175                 add_hook(&match_caller_info, FUNCTION_CALL_HOOK);
 176                 add_member_info_callback(my_id, struct_member_callback);
 177         }
 178 }