osfmk/corecrypto/cc/src/cc_cmp_safe.c

   1 /*
   2  *  cc_cmp_safe.c
   3  *  corecrypto
   4  *
   5  *  Created on 04/22/2014
   6  *
   7  *  Copyright (c) 2014,2015 Apple Inc. All rights reserved.
   8  *
   9  */
  10
  11 #include <corecrypto/cc_priv.h>
  12
  13 int cc_cmp_safe (size_t num, const void * ptr1, const void * ptr2)
  14 {
  15     size_t i;
  16     const uint8_t *s=(const uint8_t *)ptr1;
  17     const uint8_t *t=(const uint8_t *)ptr2;
  18     uint8_t flag=((num<=0)?1:0); // If 0 return an error
  19     for (i=0;i<num;i++)
  20     {
  21         flag|=(s[i]^t[i]);
  22     }
  23     HEAVISIDE_STEP_UINT8(flag,flag); // flag=(flag==0)?0:1;
  24     return flag; // 0 iff all bytes were equal, 1 if there is any difference
  25 }