check_double_checking.c

   1 /*
   2  * smatch/check_double_checking.c
   3  *
   4  * Copyright (C) 2014 Oracle.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 #include "smatch.h"
  11 #include "smatch_slist.h"
  12
  13 static int my_id;
  14
  15 STATE(checked);
  16 STATE(modified);
  17
  18 struct state_list *to_check;
  19
  20 static void set_modified(struct sm_state *sm, struct expression *mod_expr)
  21 {
  22         set_state(my_id, sm->name, sm->sym, &modified);
  23 }
  24
  25 static void match_condition(struct expression *expr)
  26 {
  27         struct smatch_state *state;
  28         sval_t dummy;
  29         int is_true;
  30         char *name;
  31
  32         if (__in_pre_post_condition)
  33                 return;
  34
  35         if (get_value(expr, &dummy))
  36                 return;
  37
  38         if (get_macro_name(expr->pos))
  39                 return;
  40
  41         // FIXME:  needed?
  42         if (implied_condition_true(expr))
  43                 is_true = 1;
  44         else if (implied_condition_false(expr))
  45                 is_true = 0;
  46         else
  47                 return;
  48
  49         state = get_stored_condition(expr);
  50         if (!state || !state->data)
  51                 return;
  52         if (get_macro_name(((struct expression *)state->data)->pos))
  53                 return;
  54
  55         /*
  56          * we allow double checking for NULL because people do this all the time
  57          * and trying to stop them is a losers' battle.
  58          */
  59         if (is_pointer(expr) && is_true)
  60                 return;
  61
  62         if (definitely_inside_loop()) {
  63                 struct symbol *sym;
  64
  65                 if (__inline_fn)
  66                         return;
  67
  68                 name = expr_to_var_sym(expr, &sym);
  69                 if (!name)
  70                         return;
  71                 set_state_expr(my_id, expr, &checked);
  72                 set_state_slist(&to_check, my_id, name, sym, &checked);
  73                 free_string(name);
  74                 return;
  75         }
  76
  77         name = expr_to_str(expr);
  78         sm_msg("warn: we tested '%s' before and it was '%s'", name, state->name);
  79         free_string(name);
  80 }
  81
  82 int get_check_line(struct sm_state *sm)
  83 {
  84         struct sm_state *tmp;
  85
  86         FOR_EACH_PTR(sm->possible, tmp) {
  87                 if (tmp->state == &checked)
  88                         return tmp->line;
  89         } END_FOR_EACH_PTR(tmp);
  90
  91         return get_lineno();
  92 }
  93
  94 static void after_loop(struct statement *stmt)
  95 {
  96         struct sm_state *check, *sm;
  97
  98         if (!stmt || stmt->type != STMT_ITERATOR)
  99                 return;
 100         if (definitely_inside_loop())
 101                 return;
 102         if (__inline_fn)
 103                 return;
 104
 105         FOR_EACH_PTR(to_check, check) {
 106                 continue;
 107                 sm = get_sm_state(my_id, check->name, check->sym);
 108                 continue;
 109                 if (!sm)
 110                         continue;
 111                 if (slist_has_state(sm->possible, &modified))
 112                         continue;
 113
 114                 sm_printf("%s:%d %s() ", get_filename(), get_check_line(sm), get_function());
 115                 sm_printf("warn: we tested '%s' already\n", check->name);
 116         } END_FOR_EACH_PTR(check);
 117
 118         free_slist(&to_check);
 119 }
 120
 121 static void match_func_end(struct symbol *sym)
 122 {
 123         if (__inline_fn)
 124                 return;
 125         if (to_check)
 126                 sm_msg("debug: odd...  found an function without an end.");
 127         free_slist(&to_check);
 128 }
 129
 130 void check_double_checking(int id)
 131 {
 132         my_id = id;
 133
 134         if (!option_spammy)
 135                 return;
 136
 137         add_hook(&match_condition, CONDITION_HOOK);
 138         add_modification_hook(my_id, &set_modified);
 139         add_hook(after_loop, STMT_HOOK_AFTER);
 140         add_hook(&match_func_end, END_FUNC_HOOK);
 141 }