check_propagate.c

   1 /*
   2  * Copyright (C) 2010 Dan Carpenter.
   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 /*
  19  * People should just return the error codes they received
  20  * instead of making up there own dumb error codes all the time.
  21  */
  22
  23 #include "smatch.h"
  24
  25 static int my_id;
  26
  27 static struct expression *last_return;
  28 static struct expression *last_func;
  29
  30 static char *get_fn_name(struct expression *expr)
  31 {
  32         if (expr->type != EXPR_CALL)
  33                 return NULL;
  34         if (expr->fn->type != EXPR_SYMBOL)
  35                 return NULL;
  36         return expr_to_var(expr->fn);
  37 }
  38
  39 static void match_call_assignment(struct expression *expr)
  40 {
  41         if (get_macro_name(expr->left->pos))
  42                 return;
  43         last_return = expr->left;
  44         last_func = expr->right;
  45 }
  46
  47 static void match_unset(struct expression *expr)
  48 {
  49         last_return = NULL;
  50 }
  51
  52 static void match_return(struct expression *ret_value)
  53 {
  54         sval_t rval;
  55         sval_t lret;
  56         char *name;
  57
  58         if (!get_value(ret_value, &rval) || rval.value >= 0)
  59                 return;
  60         if (get_implied_value(last_return, &lret))
  61                 return;
  62         if (!get_implied_max(last_return, &lret) || lret.value >= 0)
  63                 return;
  64         if (get_implied_min(last_return, &lret) && !sval_is_min(lret))
  65                 return;
  66         name = expr_to_var(last_return);
  67         sm_msg("info: why not propagate '%s' from %s() instead of %s?",
  68                 name, get_fn_name(last_func), sval_to_str(rval));
  69         free_string(name);
  70 }
  71
  72 void check_propagate(int id)
  73 {
  74         if (option_project != PROJ_KERNEL)
  75                 return;
  76
  77         my_id = id;
  78         add_hook(&match_unset, ASSIGNMENT_HOOK);
  79         add_hook(&match_call_assignment, CALL_ASSIGNMENT_HOOK);
  80         add_hook(&match_return, RETURN_HOOK);
  81 }