check_return_negative_var.c

   1 /*
   2  * smatch/check_return.c
   3  *
   4  * Copyright (C) 2011 Dan Carpenter.
   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 extern int check_assigned_expr_id;
  15
  16 static struct expression *get_assigned_expr(struct expression *expr)
  17 {
  18         struct smatch_state *state;
  19
  20         state = get_state_expr(check_assigned_expr_id, expr);
  21         if (!state)
  22                 return NULL;
  23         /* fixme:  handle merged states as well */
  24         return (struct expression *)state->data;
  25 }
  26
  27 static void match_return(struct expression *ret_value)
  28 {
  29         struct expression *expr;
  30         char *macro;
  31
  32         if (!ret_value)
  33                 return;
  34         expr = ret_value;
  35         if (ret_value->type != EXPR_PREOP || ret_value->op != '-')
  36                 return;
  37
  38         macro = get_macro_name(expr->unop->pos);
  39         if (macro && !strcmp(macro, "PTR_ERR")) {
  40                 sm_msg("warn: returning -%s()", macro);
  41                 return;
  42         }
  43
  44         if (!option_spammy)
  45                 return;
  46
  47         expr = get_assigned_expr(ret_value->unop);
  48         if (!expr)
  49                 return;
  50         if (expr->type != EXPR_CALL)
  51                 return;
  52
  53         sm_msg("warn: should this return really be negated?");
  54 }
  55
  56 void check_return_negative_var(int id)
  57 {
  58         if (option_project != PROJ_KERNEL)
  59                 return;
  60
  61         my_id = id;
  62         add_hook(&match_return, RETURN_HOOK);
  63 }