doze.c

[詳解]

/*++
/* NAME
/*  doze 3
/* SUMMARY
/*  take a nap
/* SYNOPSIS
/*  #include <iostuff.h>
/*
/*  void    doze(microseconds)
/*  unsigned microseconds;
/* DESCRIPTION
/*  doze() sleeps for the specified number of microseconds. It is
/*  a simple alternative for systems that lack usleep().
/* DIAGNOSTICS
/*  All errors are fatal.
/* LICENSE
/* .ad
/* .fi
/*  The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*  Wietse Venema
/*  IBM T.J. Watson Research
/*  P.O. Box 704
/*  Yorktown Heights, NY 10598, USA
/*--*/

/* System library. */

#include "sys_defs.h"
#include <sys/time.h>
#include <unistd.h>
#include <errno.h>
#ifdef USE_SYS_SELECT_H
#include <sys/select.h>
#endif

/* Utility library. */

#include <msg.h>
#include <iostuff.h>

/* doze - sleep a while */

void    doze(unsigned delay)
{
    struct timeval tv;

#define MILLION 1000000

    tv.tv_sec = delay / MILLION;
    tv.tv_usec = delay % MILLION;
    while (select(0, (fd_set *) 0, (fd_set *) 0, (fd_set *) 0, &tv) < 0)
    if (errno != EINTR)
        msg_fatal("doze: select: %m");
}

#ifdef TEST

#include <stdlib.h>

int     main(int argc, char **argv)
{
    unsigned delay;

    if (argc != 2 || (delay = atol(argv[1])) == 0)
    msg_fatal("usage: %s microseconds", argv[0]);
    doze(delay);
    exit(0);
}

#endif