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/* Computing deadlines for timeouts.
Copyright (C) 2017-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <net-internal.h>
#include <assert.h>
#include <limits.h>
#include <stdio.h>
#include <stdint.h>
#include <time.h>
struct deadline_current_time
__deadline_current_time (void)
{
struct deadline_current_time result;
if (__clock_gettime (CLOCK_MONOTONIC, &result.current) != 0)
__clock_gettime (CLOCK_REALTIME, &result.current);
assert (result.current.tv_sec >= 0);
return result;
}
/* A special deadline value for which __deadline_is_infinite is
true. */
static inline struct deadline
infinite_deadline (void)
{
return (struct deadline) { { -1, -1 } };
}
struct deadline
__deadline_from_timeval (struct deadline_current_time current,
struct timeval tv)
{
assert (__is_timeval_valid_timeout (tv));
/* Compute second-based deadline. Perform the addition in
uintmax_t, which is unsigned, to simply overflow detection. */
uintmax_t sec = current.current.tv_sec;
sec += tv.tv_sec;
if (sec < (uintmax_t) tv.tv_sec)
return infinite_deadline ();
/* Compute nanosecond deadline. */
int nsec = current.current.tv_nsec + tv.tv_usec * 1000;
if (nsec >= 1000 * 1000 * 1000)
{
/* Carry nanosecond overflow to seconds. */
nsec -= 1000 * 1000 * 1000;
if (sec + 1 < sec)
return infinite_deadline ();
++sec;
}
/* This uses a GCC extension, otherwise these casts for detecting
overflow would not be defined. */
if ((time_t) sec < 0 || sec != (uintmax_t) (time_t) sec)
return infinite_deadline ();
return (struct deadline) { { sec, nsec } };
}
int
__deadline_to_ms (struct deadline_current_time current,
struct deadline deadline)
{
if (__deadline_is_infinite (deadline))
return INT_MAX;
if (current.current.tv_sec > deadline.absolute.tv_sec
|| (current.current.tv_sec == deadline.absolute.tv_sec
&& current.current.tv_nsec >= deadline.absolute.tv_nsec))
return 0;
time_t sec = deadline.absolute.tv_sec - current.current.tv_sec;
if (sec >= INT_MAX)
/* This value will overflow below. */
return INT_MAX;
int nsec = deadline.absolute.tv_nsec - current.current.tv_nsec;
if (nsec < 0)
{
/* Borrow from the seconds field. */
assert (sec > 0);
--sec;
nsec += 1000 * 1000 * 1000;
}
/* Prepare for rounding up to milliseconds. */
nsec += 999999;
if (nsec > 1000 * 1000 * 1000)
{
assert (sec < INT_MAX);
++sec;
nsec -= 1000 * 1000 * 1000;
}
unsigned int msec = nsec / (1000 * 1000);
if (sec > INT_MAX / 1000)
return INT_MAX;
msec += sec * 1000;
if (msec > INT_MAX)
return INT_MAX;
return msec;
}
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