/* 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 <sys/stat.h>

#include <unistd.h>

static uv_once_t once = UV_ONCE_INIT;

static int status;

int uv__random_readpath(const char* path, void* buf, size_t buflen) {

  struct stat s;

  size_t pos;

  ssize_t n;

  int fd;

  fd = uv__open_cloexec(path, O_RDONLY);

  if (fd < 0)

    return fd;

  if (fstat(fd, &s)) {

    uv__close(fd);

    return UV__ERR(errno);

  }

  if (!S_ISCHR(s.st_mode)) {

    uv__close(fd);

    return UV_EIO;

  }

  for (pos = 0; pos != buflen; pos += n) {

    do

      n = read(fd, (char*) buf + pos, buflen - pos);

    while (n == -1 && errno == EINTR);

    if (n == -1) {

      uv__close(fd);

      return UV__ERR(errno);

    }

    if (n == 0) {

      uv__close(fd);

      return UV_EIO;

    }

  }

  uv__close(fd);

  return 0;

}

static void uv__random_devurandom_init(void) {

  char c;

  /* Linux's random(4) man page suggests applications should read at least

   * once from /dev/random before switching to /dev/urandom in order to seed

   * the system RNG. Reads from /dev/random can of course block indefinitely

   * until entropy is available but that's the point.

   */

  status = uv__random_readpath("/dev/random", &c, 1);

}

int uv__random_devurandom(void* buf, size_t buflen) {

  uv_once(&once, uv__random_devurandom_init);

  if (status != 0)

    return status;

  return uv__random_readpath("/dev/urandom", buf, buflen);

}