sysdeps/unix/sysv/linux/getrandom.c

   1 /* Implementation of the getrandom system call.
   2    Copyright (C) 2016-2018 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <sys/random.h>
  20 #include <errno.h>
  21 #include <unistd.h>
  22 #include <sysdep-cancel.h>
  23
  24 #ifdef __NR_getrandom
  25 /* Write up to LENGTH bytes of randomness starting at BUFFER.
  26    Return the number of bytes written, or -1 on error.  */
  27 ssize_t
  28 getrandom (void *buffer, size_t length, unsigned int flags)
  29 {
  30   return SYSCALL_CANCEL (getrandom, buffer, length, flags);
  31 }
  32 #else
  33 /* Always provide a definition, even if the kernel headers lack the
  34    system call number. */
  35 ssize_t
  36 getrandom (void *buffer, size_t length, unsigned int flags)
  37 {
  38   /* Ideally, we would add a cancellation point here, but we currently
  39      cannot do so inside libc.  */
  40   __set_errno (ENOSYS);
  41   return -1;
  42 }
  43 #endif