getrandom.c 1.5 KB

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  1. /* Implementation of the getrandom system call.
  2. Copyright (C) 2016-2019 Free Software Foundation, Inc.
  3. This file is part of the GNU C Library.
  4. The GNU C Library is free software; you can redistribute it and/or
  5. modify it under the terms of the GNU Lesser General Public
  6. License as published by the Free Software Foundation; either
  7. version 2.1 of the License, or (at your option) any later version.
  8. The GNU C Library is distributed in the hope that it will be useful,
  9. but WITHOUT ANY WARRANTY; without even the implied warranty of
  10. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  11. Lesser General Public License for more details.
  12. You should have received a copy of the GNU Lesser General Public
  13. License along with the GNU C Library; if not, see
  14. <http://www.gnu.org/licenses/>. */
  15. #include <sys/random.h>
  16. #include <errno.h>
  17. #include <unistd.h>
  18. #include <sysdep-cancel.h>
  19. #ifdef __NR_getrandom
  20. /* Write up to LENGTH bytes of randomness starting at BUFFER.
  21. Return the number of bytes written, or -1 on error. */
  22. ssize_t
  23. getrandom (void *buffer, size_t length, unsigned int flags)
  24. {
  25. return SYSCALL_CANCEL (getrandom, buffer, length, flags);
  26. }
  27. #else
  28. /* Always provide a definition, even if the kernel headers lack the
  29. system call number. */
  30. ssize_t
  31. getrandom (void *buffer, size_t length, unsigned int flags)
  32. {
  33. /* Ideally, we would add a cancellation point here, but we currently
  34. cannot do so inside libc. */
  35. __set_errno (ENOSYS);
  36. return -1;
  37. }
  38. #endif