| // Copyright 2016 Google Inc. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| #include "cryptoc/util.h" |
| |
| static void always_memset_impl(volatile char *s, int c, size_t n) { |
| while (n--) |
| *s++ = c; |
| } |
| |
| void *always_memset(void *s, int c, size_t n) { |
| always_memset_impl((char*) s, c, n); |
| return s; |
| } |
| |
| int ct_memeq(const void* s1, const void* s2, uint32_t n) { |
| uint8_t diff = 0; |
| const uint8_t* ps1 = s1; |
| const uint8_t* ps2 = s2; |
| |
| while (n--) { |
| diff |= *ps1 ^ *ps2; |
| ps1++; |
| ps2++; |
| } |
| |
| // Counter-intuitive, but we can't just return diff because we don't want to |
| // leak the xor of non-equal bytes |
| return 0 != diff; |
| } |