/* Copyright libuv contributors. All rights reserved.

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to

 * deal in the Software without restriction, including without limitation the

 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or

 * sell copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS

 * IN THE SOFTWARE.

 */

#include "uv.h"

#include "internal.h"

#include <stddef.h>

#include <dlfcn.h>

typedef int (*uv__getentropy_cb)(void *, size_t);

static uv__getentropy_cb uv__getentropy;

static uv_once_t once = UV_ONCE_INIT;

static void uv__random_getentropy_init(void) {

  uv__getentropy = (uv__getentropy_cb) dlsym(RTLD_DEFAULT, "getentropy");

}

int uv__random_getentropy(void* buf, size_t buflen) {

  size_t pos;

  size_t stride;

  uv_once(&once, uv__random_getentropy_init);

  if (uv__getentropy == NULL)

    return UV_ENOSYS;

  /* getentropy() returns an error for requests > 256 bytes. */

  for (pos = 0, stride = 256; pos + stride < buflen; pos += stride)

    if (uv__getentropy((char *) buf + pos, stride))

      return UV__ERR(errno);

  if (uv__getentropy((char *) buf + pos, buflen - pos))

    return UV__ERR(errno);

  return 0;

}