check_assign_vs_compare.c

   1 /*
   2  * Copyright (C) 2012 Oracle.
   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 #include "smatch.h"
  19
  20 static int my_id;
  21
  22 static bool is_false_positive(struct expression *expr)
  23 {
  24         char *macro;
  25
  26         if (option_project != PROJ_KERNEL)
  27                 return false;
  28
  29         macro = get_macro_name(expr->pos);
  30         if (!macro)
  31                 return false;
  32
  33         if (strcmp(macro, "btree_err_on") == 0)
  34                 return true;
  35         if (strcmp(macro, "btree_err") == 0)
  36                 return true;
  37
  38         return false;
  39 }
  40
  41 static void check_constant(struct expression *expr)
  42 {
  43         sval_t val;
  44
  45         if (!get_value(expr->right, &val))
  46                 return;
  47         if (is_false_positive(expr))
  48                 return;
  49         sm_warning("was '== %s' instead of '='", sval_to_str(val));
  50 }
  51
  52 static void check_address(struct expression *expr)
  53 {
  54         char *str;
  55         struct expression *right = strip_expr(expr->right);
  56
  57         if (!__cur_stmt || __cur_stmt->type != STMT_IF)
  58                 return;
  59
  60         if (right->type != EXPR_PREOP ||
  61             right->op != '&')
  62                 return;
  63
  64         if (get_macro_name(expr->pos))
  65                 return;
  66
  67         str = expr_to_str(right);
  68         sm_warning("was '== %s' instead of '='", str);
  69         free_string(str);
  70 }
  71
  72 static void match_condition(struct expression *expr)
  73 {
  74         if (expr->type != EXPR_ASSIGNMENT || expr->op != '=')
  75                 return;
  76
  77         check_constant(expr);
  78         check_address(expr);
  79 }
  80
  81 void check_assign_vs_compare(int id)
  82 {
  83         my_id = id;
  84         add_hook(&match_condition, CONDITION_HOOK);
  85 }