summaryrefslogtreecommitdiff
path: root/lib/nanosleep.c
blob: 97d60d864f85ad85bbae55c7b2f3c6a371746415 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
/* Provide a replacement for the POSIX nanosleep function.
   Copyright (C) 1999, 2000, 2002, 2004, 2005 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

/* written by Jim Meyering */

#include <config.h>

/* Undefine nanosleep here so any prototype is not redefined to be a
   prototype for rpl_nanosleep. (they'd conflict e.g., on alpha-dec-osf3.2)  */
#undef nanosleep

#include <stdbool.h>
#include <stdio.h>
#include <sys/types.h>
#include <signal.h>

#include <errno.h>

#include <unistd.h>

#include "timespec.h"

/* Some systems (MSDOS) don't have SIGCONT.
   Using SIGTERM here turns the signal-handling code below
   into a no-op on such systems. */
#ifndef SIGCONT
# define SIGCONT SIGTERM
#endif

#if ! HAVE_SIGINTERRUPT
# define siginterrupt(sig, flag) /* empty */
#endif

static sig_atomic_t volatile suspended;

/* Handle SIGCONT. */

static void
sighandler (int sig)
{
  suspended = 1;
}

/* FIXME: comment */

static void
my_usleep (const struct timespec *ts_delay)
{
  struct timeval tv_delay;
  tv_delay.tv_sec = ts_delay->tv_sec;
  tv_delay.tv_usec = (ts_delay->tv_nsec + 999) / 1000;
  if (tv_delay.tv_usec == 1000000)
    {
      tv_delay.tv_sec++;
      tv_delay.tv_usec = 0;
    }
  select (0, NULL, NULL, NULL, &tv_delay);
}

/* FIXME: comment */

int
rpl_nanosleep (const struct timespec *requested_delay,
	       struct timespec *remaining_delay)
{
  static bool initialized;

  /* set up sig handler */
  if (! initialized)
    {
#ifdef SA_NOCLDSTOP
      struct sigaction oldact, newact;
      newact.sa_handler = sighandler;
      sigemptyset (&newact.sa_mask);
      newact.sa_flags = 0;

      sigaction (SIGCONT, NULL, &oldact);
      if (oldact.sa_handler != SIG_IGN)
	sigaction (SIGCONT, &newact, NULL);
#else
      if (signal (SIGCONT, SIG_IGN) != SIG_IGN)
	{
	  signal (SIGCONT, sighandler);
	  siginterrupt (SIGCONT, 1);
	}
#endif
      initialized = true;
    }

  suspended = 0;

  my_usleep (requested_delay);

  if (suspended)
    {
      /* Calculate time remaining.  */
      /* FIXME: the code in sleep doesn't use this, so there's no
	 rush to implement it.  */

      errno = EINTR;
    }

  /* FIXME: Restore sig handler?  */

  return suspended;
}