1  /* Pausing execution of the current thread.
       2     Copyright (C) 2009-2023 Free Software Foundation, Inc.
       3     Written by Eric Blake <ebb9@byu.net>, 2009.
       4  
       5     This file is free software: you can redistribute it and/or modify
       6     it under the terms of the GNU Lesser General Public License as
       7     published by the Free Software Foundation; either version 2.1 of the
       8     License, or (at your option) any later version.
       9  
      10     This file is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      13     GNU Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public License
      16     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      17  
      18  /* This file is _intentionally_ light-weight.  Rather than using
      19     select or nanosleep, both of which drag in external libraries on
      20     some platforms, this merely rounds up to the nearest second if
      21     usleep() does not exist.  If sub-second resolution is important,
      22     then use a more powerful interface to begin with.  */
      23  
      24  #include <config.h>
      25  
      26  /* Specification.  */
      27  #include <unistd.h>
      28  
      29  #include <errno.h>
      30  
      31  #if defined _WIN32 && ! defined __CYGWIN__
      32  # define WIN32_LEAN_AND_MEAN  /* avoid including junk */
      33  # include <windows.h>
      34  #endif
      35  
      36  #ifndef HAVE_USLEEP
      37  # define HAVE_USLEEP 0
      38  #endif
      39  
      40  /* Sleep for MICRO microseconds, which can be greater than 1 second.
      41     Return -1 and set errno to EINVAL on range error (about 4295
      42     seconds), or 0 on success.  Interaction with SIGALARM is
      43     unspecified.  */
      44  
      45  int
      46  usleep (useconds_t micro)
      47  #undef usleep
      48  {
      49  #if defined _WIN32 && ! defined __CYGWIN__
      50    unsigned int milliseconds = micro / 1000;
      51    if (sizeof milliseconds < sizeof micro && micro / 1000 != milliseconds)
      52      {
      53        errno = EINVAL;
      54        return -1;
      55      }
      56    if (micro % 1000)
      57      milliseconds++;
      58    Sleep (milliseconds);
      59    return 0;
      60  #else
      61    unsigned int seconds = micro / 1000000;
      62    if (sizeof seconds < sizeof micro && micro / 1000000 != seconds)
      63      {
      64        errno = EINVAL;
      65        return -1;
      66      }
      67    if (!HAVE_USLEEP && micro % 1000000)
      68      seconds++;
      69    while ((seconds = sleep (seconds)) != 0);
      70  
      71  # if !HAVE_USLEEP
      72  #  define usleep(x) 0
      73  # endif
      74    return usleep (micro % 1000000);
      75  #endif
      76  }