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
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
|
/* xnanosleep.c -- a more convenient interface to nanosleep
Copyright (C) 2002, 2003, 2004 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
/* Mostly written (for sleep.c) by Paul Eggert.
Factored out (creating this file) by Jim Meyering. */
#if HAVE_CONFIG_H
# include <config.h>
#endif
#include "xnanosleep.h"
#include <limits.h>
#include <stdbool.h>
#include <stdio.h>
#include <assert.h>
#include <errno.h>
#include <sys/types.h>
#include <time.h>
/* The extra casts work around common compiler bugs. */
#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
/* The outer cast is needed to work around a bug in Cray C 5.0.3.0.
It is necessary at least when t == time_t. */
#define TYPE_MINIMUM(t) ((t) (TYPE_SIGNED (t) \
? ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1) : (t) 0))
#define TYPE_MAXIMUM(t) ((t) (~ (t) 0 - TYPE_MINIMUM (t)))
#ifndef TIME_T_MAX
# define TIME_T_MAX TYPE_MAXIMUM (time_t)
#endif
#include "timespec.h"
#include "xalloc.h"
/* Subtract the `struct timespec' values X and Y by computing X - Y.
If the difference is negative or zero, return false.
Otherwise, return true and store the difference in DIFF.
X and Y must have valid ts_nsec values, in the range 0 to 999999999.
If the difference would overflow, store the maximum possible difference. */
static bool
timespec_subtract (struct timespec *diff,
struct timespec const *x, struct timespec const *y)
{
time_t sec = x->tv_sec - y->tv_sec;
long int nsec = x->tv_nsec - y->tv_nsec;
if (x->tv_sec < y->tv_sec)
return false;
if (sec < 0)
{
/* The difference has overflowed. */
sec = TIME_T_MAX;
nsec = 999999999;
}
else if (sec == 0 && nsec <= 0)
return false;
if (nsec < 0)
{
sec--;
nsec += 1000000000;
}
diff->tv_sec = sec;
diff->tv_nsec = nsec;
return true;
}
/* Sleep until the time (call it WAKE_UP_TIME) specified as
SECONDS seconds after the time this function is called.
SECONDS must be non-negative. If SECONDS is so large that
it is not representable as a `struct timespec', then use
the maximum value for that interval. Return -1 on failure
(setting errno), 0 on success. */
int
xnanosleep (double seconds)
{
bool overflow;
double ns;
struct timespec ts_start;
struct timespec ts_sleep;
struct timespec ts_stop;
assert (0 <= seconds);
if (gettime (&ts_start) != 0)
return -1;
/* Separate whole seconds from nanoseconds.
Be careful to detect any overflow. */
ts_sleep.tv_sec = seconds;
ns = 1e9 * (seconds - ts_sleep.tv_sec);
overflow = ! (ts_sleep.tv_sec <= seconds && 0 <= ns && ns <= 1e9);
ts_sleep.tv_nsec = ns;
/* Round up to the next whole number, if necessary, so that we
always sleep for at least the requested amount of time. Assuming
the default rounding mode, we don't have to worry about the
rounding error when computing 'ns' above, since the error won't
cause 'ns' to drop below an integer boundary. */
ts_sleep.tv_nsec += (ts_sleep.tv_nsec < ns);
/* Normalize the interval length. nanosleep requires this. */
if (1000000000 <= ts_sleep.tv_nsec)
{
time_t t = ts_sleep.tv_sec + 1;
/* Detect integer overflow. */
overflow |= (t < ts_sleep.tv_sec);
ts_sleep.tv_sec = t;
ts_sleep.tv_nsec -= 1000000000;
}
/* Compute the time until which we should sleep. */
ts_stop.tv_sec = ts_start.tv_sec + ts_sleep.tv_sec;
ts_stop.tv_nsec = ts_start.tv_nsec + ts_sleep.tv_nsec;
if (1000000000 <= ts_stop.tv_nsec)
{
++ts_stop.tv_sec;
ts_stop.tv_nsec -= 1000000000;
}
/* Detect integer overflow. */
overflow |= (ts_stop.tv_sec < ts_start.tv_sec
|| (ts_stop.tv_sec == ts_start.tv_sec
&& ts_stop.tv_nsec < ts_start.tv_nsec));
if (overflow)
{
/* Fix ts_sleep and ts_stop, which may be garbage due to overflow. */
ts_sleep.tv_sec = ts_stop.tv_sec = TIME_T_MAX;
ts_sleep.tv_nsec = ts_stop.tv_nsec = 999999999;
}
while (nanosleep (&ts_sleep, NULL) != 0)
{
if (errno != EINTR || gettime (&ts_start) != 0)
return -1;
/* POSIX.1-2001 requires that when a process is suspended, then
resumed, nanosleep (A, B) returns -1, sets errno to EINTR,
and sets *B to the time remaining at the point of resumption.
However, some versions of the Linux kernel incorrectly return
the time remaining at the point of suspension. Work around
this bug by computing the remaining time here, rather than by
relying on nanosleep's computation. */
if (! timespec_subtract (&ts_sleep, &ts_stop, &ts_start))
break;
}
return 0;
}
|
