| /* | |
| * Copyright (C) 2016 The Android Open Source Project | |
| * All rights reserved. | |
| * | |
| * Redistribution and use in source and binary forms, with or without | |
| * modification, are permitted provided that the following conditions | |
| * are met: | |
| * * Redistributions of source code must retain the above copyright | |
| * notice, this list of conditions and the following disclaimer. | |
| * * Redistributions in binary form must reproduce the above copyright | |
| * notice, this list of conditions and the following disclaimer in | |
| * the documentation and/or other materials provided with the | |
| * distribution. | |
| * | |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS | |
| * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE | |
| * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, | |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, | |
| * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS | |
| * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED | |
| * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, | |
| * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT | |
| * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
| * SUCH DAMAGE. | |
| */ | |
| #pragma once | |
| #include <sys/cdefs.h> | |
| #include <stddef.h> | |
| #include <stdlib.h> | |
| #include <unistd.h> | |
| // Before first_stage_init runs, some platforms might not have /dev/urandom and | |
| // if they do, reading that node could take seconds if they don't have access to | |
| // a hwrng. Let's skip randomness for those very specific cases. | |
| bool __libc_arc4random_ready(); | |
| // arc4random(3) aborts if it's unable to fetch entropy, which might be the case | |
| // on some low-end devices without any hwrng before first_stage_init. GCE | |
| // kernels have a workaround to ensure sufficient entropy during early boot, but | |
| // no device kernels do. This wrapper falls back to AT_RANDOM if the kernel | |
| // doesn't have enough entropy for getrandom(2) or /dev/urandom but note that | |
| // AT_RANDOM only gives us 16 bytes, and they're already taken, so it won't be | |
| // possible to add new callers. | |
| void __libc_arc4random_buf_or_die(void* buf, size_t n); | |
| // Unsafe wrapper during first_stage_init. | |
| uint32_t __libc_arc4random_uniform_or_zero(uint32_t upper_bound); |