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