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/* Copyright (c) 2008, 2009, 2010, 2011, 2013 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <config.h>
#include "entropy.h"
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include "socket-util.h"
#include "vlog.h"
VLOG_DEFINE_THIS_MODULE(entropy);
static const char urandom[] = "/dev/urandom";
/* Initializes 'buffer' with 'n' bytes of high-quality random numbers. Returns
* 0 if successful, otherwise a positive errno value or EOF on error. */
int
get_entropy(void *buffer, size_t n)
{
size_t bytes_read;
int error;
int fd;
fd = open(urandom, O_RDONLY);
if (fd < 0) {
VLOG_ERR("%s: open failed (%s)", urandom, ovs_strerror(errno));
return errno ? errno : EINVAL;
}
error = read_fully(fd, buffer, n, &bytes_read);
close(fd);
if (error) {
VLOG_ERR("%s: read error (%s)", urandom, ovs_retval_to_string(error));
}
return error;
}
/* Initializes 'buffer' with 'n' bytes of high-quality random numbers. Exits
* if an error occurs. */
void
get_entropy_or_die(void *buffer, size_t n)
{
int error = get_entropy(buffer, n);
if (error) {
VLOG_FATAL("%s: read error (%s)",
urandom, ovs_retval_to_string(error));
}
}
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