1/* Copyright (C) 2000-2022 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public License as
6 published by the Free Software Foundation; either version 2.1 of the
7 License, or (at your option) any later version.
8
9 The GNU C Library 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 GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; see the file COPYING.LIB. If
16 not, see <https://www.gnu.org/licenses/>. */
17
18#include <errno.h>
19#include <pthread.h>
20#include <time.h>
21
22#include "posix-timer.h"
23
24
25/* Set timer TIMERID to VALUE, returning old value in OVLAUE. */
26int
27timer_settime (timer_t timerid, int flags, const struct itimerspec *value,
28 struct itimerspec *ovalue)
29{
30 struct timer_node *timer;
31 struct thread_node *thread = NULL;
32 struct timespec now;
33 int have_now = 0, need_wakeup = 0;
34 int retval = -1;
35
36 timer = timer_id2ptr (timerid);
37 if (timer == NULL)
38 {
39 __set_errno (EINVAL);
40 goto bail;
41 }
42
43 if (! valid_nanoseconds (ns: value->it_interval.tv_nsec)
44 || ! valid_nanoseconds (ns: value->it_value.tv_nsec))
45 {
46 __set_errno (EINVAL);
47 goto bail;
48 }
49
50 /* Will need to know current time since this is a relative timer;
51 might as well make the system call outside of the lock now! */
52
53 if ((flags & TIMER_ABSTIME) == 0)
54 {
55 __clock_gettime (timer->clock, &now);
56 have_now = 1;
57 }
58
59 pthread_mutex_lock (mutex: &__timer_mutex);
60 timer_addref (timer);
61
62 /* One final check of timer validity; this one is possible only
63 until we have the mutex, because it accesses the inuse flag. */
64
65 if (! timer_valid(timer))
66 {
67 __set_errno (EINVAL);
68 goto unlock_bail;
69 }
70
71 if (ovalue != NULL)
72 {
73 ovalue->it_interval = timer->value.it_interval;
74
75 if (timer->armed)
76 {
77 if (! have_now)
78 {
79 pthread_mutex_unlock (mutex: &__timer_mutex);
80 __clock_gettime (timer->clock, &now);
81 have_now = 1;
82 pthread_mutex_lock (mutex: &__timer_mutex);
83 timer_addref (timer);
84 }
85
86 timespec_sub (diff: &ovalue->it_value, left: &timer->expirytime, right: &now);
87 }
88 else
89 {
90 ovalue->it_value.tv_sec = 0;
91 ovalue->it_value.tv_nsec = 0;
92 }
93 }
94
95 timer->value = *value;
96
97 list_unlink_ip (list: &timer->links);
98 timer->armed = 0;
99
100 thread = timer->thread;
101
102 /* A value of { 0, 0 } causes the timer to be stopped. */
103 if (value->it_value.tv_sec != 0
104 || __builtin_expect (value->it_value.tv_nsec != 0, 1))
105 {
106 if ((flags & TIMER_ABSTIME) != 0)
107 /* The user specified the expiration time. */
108 timer->expirytime = value->it_value;
109 else
110 timespec_add (sum: &timer->expirytime, left: &now, right: &value->it_value);
111
112 /* Only need to wake up the thread if timer is inserted
113 at the head of the queue. */
114 if (thread != NULL)
115 need_wakeup = __timer_thread_queue_timer (thread, insert: timer);
116 timer->armed = 1;
117 }
118
119 retval = 0;
120
121unlock_bail:
122 timer_delref (timer);
123 pthread_mutex_unlock (mutex: &__timer_mutex);
124
125bail:
126 if (thread != NULL && need_wakeup)
127 __timer_thread_wakeup (thread);
128
129 return retval;
130}
131

source code of glibc/rt/timer_settime.c