| /* |
| * Copyright (C) 2018 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. |
| */ |
| |
| #include<errno.h> |
| #include<fcntl.h> |
| #include<limits.h> |
| #include<sys/random.h> |
| #include<unistd.h> |
| |
| #include"private/ScopedFd.h" |
| |
| staticint getentropy_urandom(void* buffer,size_t buffer_size,int saved_errno){ |
| ScopedFd fd(TEMP_FAILURE_RETRY(open("/dev/urandom", O_RDONLY| O_NOFOLLOW| O_CLOEXEC,0))); |
| if(fd.get()==-1)return-1; |
| |
| size_t collected=0; |
| while(collected< buffer_size){ |
| ssize_t count= TEMP_FAILURE_RETRY(read(fd.get(),static_cast<char*>(buffer)+ collected, |
| buffer_size- collected)); |
| if(count==-1)return-1; |
| collected+= count; |
| } |
| |
| errno= saved_errno; |
| return0; |
| } |
| |
| int getentropy(void* buffer,size_t buffer_size){ |
| if(buffer_size> GETENTROPY_MAX){ |
| errno= EIO; |
| return-1; |
| } |
| |
| int saved_errno= errno; |
| |
| size_t collected=0; |
| while(collected< buffer_size){ |
| long count= TEMP_FAILURE_RETRY(getrandom(static_cast<char*>(buffer)+ collected, |
| buffer_size- collected, GRND_NONBLOCK)); |
| if(count==-1){ |
| // EAGAIN: there isn't enough entropy right now. |
| // ENOSYS/EINVAL: getrandom(2) or GRND_NONBLOCK isn't supported. |
| // EFAULT: `buffer` is invalid. |
| // Try /dev/urandom regardless because it can't hurt, |
| // and we don't need to optimize the EFAULT case. |
| // See http://b/33059407 and http://b/67015565. |
| return getentropy_urandom(buffer, buffer_size, saved_errno); |
| } |
| collected+= count; |
| } |
| |
| errno= saved_errno; |
| return0; |
| } |
