1 /* Fill a buffer with random bytes. 2 Copyright 2020-2021 Free Software Foundation, Inc. 3 4 This file is free software: you can redistribute it and/or modify 5 it under the terms of the GNU Lesser General Public License as 6 published by the Free Software Foundation; either version 3 of the 7 License, or (at your option) any later version. 8 9 This file is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 GNU Lesser General Public License for more details. 13 14 You should have received a copy of the GNU Lesser General Public License 15 along with this program. If not, see <https://www.gnu.org/licenses/>. */ 16 17 /* Written by Paul Eggert. */ 18 19 #include <config.h> 20 21 #include <unistd.h> 22 23 #include <errno.h> 24 #include <sys/random.h> 25 26 /* Overwrite BUFFER with random data. BUFFER contains LENGTH bytes. 27 LENGTH must be at most 256. Return 0 on success, -1 (setting 28 errno) on failure. */ 29 int 30 getentropy (void *buffer, size_t length) /* */ 31 { 32 char *buf = buffer; 33 34 if (length <= 256) 35 for (;;) 36 { 37 ssize_t bytes; 38 if (length == 0) 39 return 0; 40 while ((bytes = getrandom (buf, length, 0)) < 0) 41 if (errno != EINTR) 42 return -1; 43 if (bytes == 0) 44 break; 45 buf += bytes; 46 length -= bytes; 47 } 48 49 errno = EIO; 50 return -1; 51 }