1  /* Test of getting random bytes.
       2     Copyright (C) 2020-2022 Free Software Foundation, Inc.
       3  
       4     This program is free software: you can redistribute it and/or modify
       5     it under the terms of the GNU General Public License as published by
       6     the Free Software Foundation, either version 3 of the License, or
       7     (at your option) any later version.
       8  
       9     This program is distributed in the hope that it will be useful,
      10     but WITHOUT ANY WARRANTY; without even the implied warranty of
      11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      12     GNU General Public License for more details.
      13  
      14     You should have received a copy of the GNU General Public License
      15     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      16  
      17  /* Written by Bruno Haible.  */
      18  
      19  #include <config.h>
      20  
      21  #include <sys/random.h>
      22  
      23  #include "signature.h"
      24  SIGNATURE_CHECK (getrandom, ssize_t, (void *, size_t, unsigned int));
      25  
      26  #include <errno.h>
      27  #include <string.h>
      28  
      29  #include "macros.h"
      30  
      31  int
      32  main (void)
      33  {
      34    char buf1[8];
      35    char buf2[8];
      36    char large_buf[100000];
      37    ssize_t ret;
      38  
      39    /* Check that different calls produce different results (with a high
      40       probability).  */
      41    ret = getrandom (buf1, sizeof (buf1), 0);
      42    if (ret < 0)
      43      ASSERT (errno == ENOSYS);
      44    else
      45      {
      46        ret = getrandom (buf2, sizeof (buf2), 0);
      47        if (ret < 0)
      48          ASSERT (errno == ENOSYS);
      49        else
      50          {
      51            /* It is very unlikely that two calls to getrandom produce the
      52               same results.  */
      53            ASSERT (memcmp (buf1, buf2, sizeof (buf1)) != 0);
      54          }
      55      }
      56  
      57    /* Likewise with the "truly random" number generator.  */
      58    ret = getrandom (buf1, sizeof (buf1), GRND_RANDOM);
      59    if (ret < 0)
      60      ASSERT (errno == ENOSYS);
      61    else
      62      {
      63        ret = getrandom (buf2, sizeof (buf2), GRND_RANDOM);
      64        if (ret < 0)
      65          ASSERT (errno == ENOSYS);
      66        else
      67          {
      68            /* It is very unlikely that two calls to getrandom produce the
      69               same results.  */
      70            ASSERT (memcmp (buf1, buf2, sizeof (buf1)) != 0);
      71          }
      72      }
      73  
      74    /* Check that GRND_NONBLOCK works.  */
      75    ret = getrandom (large_buf, sizeof (large_buf), GRND_RANDOM | GRND_NONBLOCK);
      76    ASSERT (ret <= (ssize_t) sizeof (large_buf));
      77    /* It is very unlikely that so many truly random bytes were ready.  */
      78    if (ret < 0)
      79      ASSERT (errno == ENOSYS || errno == EAGAIN
      80              || errno == EINVAL /* Solaris */);
      81    else
      82      ASSERT (ret > 0);
      83  
      84    if (getrandom (buf1, 1, 0) < 1)
      85      if (getrandom (buf1, 1, GRND_RANDOM) < 1)
      86        {
      87          fputs ("Skipping test: getrandom is ineffective\n", stderr);
      88          return 77;
      89        }
      90  
      91    return 0;
      92  }