gnulib/m4/gc-random.m4

# gc-random.m4 serial 6
dnl Copyright (C) 2005-2020 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

AC_DEFUN([gl_GC_RANDOM],
[
  # Devices with randomness.
  # FIXME: Are these the best defaults?

  AC_REQUIRE([AC_CANONICAL_HOST])dnl

  case "$host_os" in
    *openbsd* | *mirbsd*)
      NAME_OF_RANDOM_DEVICE="/dev/srandom"
      NAME_OF_PSEUDO_RANDOM_DEVICE="/dev/prandom"
      NAME_OF_NONCE_DEVICE="/dev/urandom"
      ;;

    *netbsd*)
      NAME_OF_RANDOM_DEVICE="/dev/srandom"
      NAME_OF_PSEUDO_RANDOM_DEVICE="/dev/urandom"
      NAME_OF_NONCE_DEVICE="/dev/urandom"
      ;;

    *solaris* | *irix* | *dec-osf* )
      NAME_OF_RANDOM_DEVICE="/dev/random"
      NAME_OF_PSEUDO_RANDOM_DEVICE="/dev/random"
      NAME_OF_NONCE_DEVICE="/dev/random"
      ;;

    *)
      NAME_OF_RANDOM_DEVICE="/dev/random"
      NAME_OF_PSEUDO_RANDOM_DEVICE="/dev/urandom"
      NAME_OF_NONCE_DEVICE="/dev/urandom"
      ;;
  esac

  AC_MSG_CHECKING([device with (strong) random data...])
  AC_ARG_ENABLE([random-device],
        AS_HELP_STRING([--enable-random-device],
                [device with (strong) randomness (for Nettle)]),
        NAME_OF_RANDOM_DEVICE=$enableval)
  AC_MSG_RESULT([$NAME_OF_RANDOM_DEVICE])

  AC_MSG_CHECKING([device with pseudo random data...])
  AC_ARG_ENABLE([pseudo-random-device],
        AS_HELP_STRING([--enable-pseudo-random-device],
                [device with pseudo randomness (for Nettle)]),
        NAME_OF_PSEUDO_RANDOM_DEVICE=$enableval)
  AC_MSG_RESULT([$NAME_OF_PSEUDO_RANDOM_DEVICE])

  AC_MSG_CHECKING([device with unpredictable data for nonces...])
  AC_ARG_ENABLE([nonce-device],
        AS_HELP_STRING([--enable-nonce-device],
                [device with unpredictable nonces (for Nettle)]),
        NAME_OF_NONCE_DEVICE=$enableval)
  AC_MSG_RESULT([$NAME_OF_NONCE_DEVICE])

  if test "$cross_compiling" != yes; then
    if test "$NAME_OF_RANDOM_DEVICE" != "no"; then
      AC_CHECK_FILE([$NAME_OF_RANDOM_DEVICE],,
        AC_MSG_WARN([[Device '$NAME_OF_RANDOM_DEVICE' does not exist, consider to use --enable-random-device]]))
    fi
    if test "$NAME_OF_PSEUDO_RANDOM_DEVICE" != "no"; then
      AC_CHECK_FILE([$NAME_OF_PSEUDO_RANDOM_DEVICE],,
        AC_MSG_WARN([[Device '$NAME_OF_PSEUDO_RANDOM_DEVICE' does not exist, consider to use --enable-pseudo-random-device]]))
    fi
    if test "$NAME_OF_NONCE_DEVICE" != "no"; then
      AC_CHECK_FILE([$NAME_OF_NONCE_DEVICE],,
        AC_MSG_WARN([[Device '$NAME_OF_NONCE_DEVICE' does not exist, consider to use --enable-nonce-device]]))
    fi
  else
    AC_MSG_NOTICE([[Cross compiling, assuming random devices exists on the target host...]])
  fi

  # FIXME?: Open+read 42 bytes+close twice and compare data.  Should differ.

  AC_DEFINE_UNQUOTED([NAME_OF_RANDOM_DEVICE], ["$NAME_OF_RANDOM_DEVICE"],
                   [defined to the name of the (strong) random device])
  AC_DEFINE_UNQUOTED([NAME_OF_PSEUDO_RANDOM_DEVICE],
                         "$NAME_OF_PSEUDO_RANDOM_DEVICE",
                   [defined to the name of the pseudo random device])
  AC_DEFINE_UNQUOTED([NAME_OF_NONCE_DEVICE], ["$NAME_OF_NONCE_DEVICE"],
                   [defined to the name of the unpredictable nonce device])
])