check_sizeof_pointer.c

   1 /*
   2  * smatch/check_sizeof_pointer.c
   3  *
   4  * Copyright (C) 2012 Oracle.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 #include "smatch.h"
  11
  12 static int my_id;
  13
  14 static void check_sizeof(struct expression *expr, char *ptr_name)
  15 {
  16         char *name;
  17         sval_t sval;
  18
  19         if (!expr || expr->type != EXPR_SIZEOF)
  20                 return;
  21
  22         get_value_sval(expr, &sval);
  23
  24         expr = strip_expr(expr->cast_expression);
  25         name = get_variable_from_expr_complex(expr, NULL);
  26         if (!name)
  27                 return;
  28
  29         if (strcmp(ptr_name, name) == 0)
  30                 sm_msg("warn: was 'sizeof(*%s)' intended?", ptr_name);
  31         free_string(name);
  32 }
  33
  34 static void match_call_assignment(struct expression *expr)
  35 {
  36         struct expression *call = strip_expr(expr->right);
  37         struct expression *arg;
  38         char *ptr_name;
  39
  40         if (!is_pointer(expr->left))
  41                 return;
  42
  43         ptr_name = get_variable_from_expr_complex(expr->left, NULL);
  44         if (!ptr_name)
  45                 return;
  46
  47         FOR_EACH_PTR(call->args, arg) {
  48                 check_sizeof(arg, ptr_name);
  49         } END_FOR_EACH_PTR(arg);
  50 }
  51
  52 static void check_passes_pointer(char *name, struct expression *call)
  53 {
  54         struct expression *arg;
  55         char *ptr_name;
  56
  57         FOR_EACH_PTR(call->args, arg) {
  58                 ptr_name = get_variable_from_expr(arg, NULL);
  59                 if (!ptr_name)
  60                         continue;
  61                 if (strcmp(name, ptr_name) == 0)
  62                         sm_msg("warn: was 'sizeof(*%s)' intended?", name);
  63                 free_string(ptr_name);
  64         } END_FOR_EACH_PTR(arg);
  65 }
  66
  67 static void match_check_params(struct expression *call)
  68 {
  69         struct expression *arg;
  70         struct expression *obj;
  71         char *name;
  72
  73         FOR_EACH_PTR(call->args, arg) {
  74                 if (arg->type != EXPR_SIZEOF)
  75                         continue;
  76                 obj = strip_expr(arg->cast_expression);
  77                 if (!is_pointer(obj))
  78                         continue;
  79                 name = get_variable_from_expr(obj, NULL);
  80                 if (!name)
  81                         continue;
  82                 check_passes_pointer(name, call);
  83                 free_string(name);
  84         } END_FOR_EACH_PTR(arg);
  85 }
  86
  87 void check_sizeof_pointer(int id)
  88 {
  89         my_id = id;
  90
  91         add_hook(&match_call_assignment, CALL_ASSIGNMENT_HOOK);
  92         add_hook(&match_check_params, FUNCTION_CALL_HOOK);
  93 }