check_negative_error_code_type_promoted.c

   1 /*
   2  * Copyright 2023 Linaro Ltd.
   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 #include "smatch_extra.h"
  20
  21 static int my_id;
  22
  23 static bool flip_order(struct expression *expr, struct expression **left, int *op, struct expression **right)
  24 {
  25         /* flip everything to < */
  26
  27         expr = strip_expr(expr);
  28
  29         switch (expr->op) {
  30         case '>':
  31         case SPECIAL_GTE:
  32         case SPECIAL_UNSIGNED_GT:
  33         case SPECIAL_UNSIGNED_GTE:
  34                 *left = strip_parens(expr->right);
  35                 *op = flip_comparison(expr->op);
  36                 *right = strip_parens(expr->left);
  37                 return true;
  38         case '<':
  39         case SPECIAL_LTE:
  40         case SPECIAL_UNSIGNED_LT:
  41         case SPECIAL_UNSIGNED_LTE:
  42                 *left = strip_parens(expr->left);
  43                 *op = expr->op;
  44                 *right = strip_parens(expr->right);
  45                 return true;
  46         }
  47
  48         return false;
  49 }
  50
  51 static void match_condition(struct expression *expr)
  52 {
  53         struct expression *left, *right;
  54         char *name;
  55         int op;
  56
  57         if (expr->type != EXPR_COMPARE)
  58                 return;
  59
  60         if (!flip_order(expr, &left, &op, &right))
  61                 return;
  62
  63         if (op != SPECIAL_UNSIGNED_LT &&
  64             op != SPECIAL_UNSIGNED_LTE)
  65                 return;
  66
  67         if (!holds_kernel_error_codes(left))
  68                 return;
  69
  70         name = expr_to_str(left);
  71         sm_warning("error code type promoted to positive: '%s'", name);
  72         free_string(name);
  73 }
  74
  75 void check_negative_error_code_type_promoted(int id)
  76 {
  77         my_id = id;
  78
  79         if (option_project != PROJ_KERNEL)
  80                 return;
  81
  82         add_hook(&match_condition, CONDITION_HOOK);
  83 }