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123 lines
3.6 KiB
C
123 lines
3.6 KiB
C
/* Computing deadlines for timeouts.
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Copyright (C) 2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <net-internal.h>
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#include <assert.h>
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#include <limits.h>
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#include <stdio.h>
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#include <stdint.h>
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#include <time.h>
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struct deadline_current_time
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__deadline_current_time (void)
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{
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struct deadline_current_time result;
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if (__clock_gettime (CLOCK_MONOTONIC, &result.current) != 0)
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{
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struct timeval current_tv;
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if (__gettimeofday (¤t_tv, NULL) == 0)
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__libc_fatal ("Fatal error: gettimeofday system call failed\n");
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result.current.tv_sec = current_tv.tv_sec;
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result.current.tv_nsec = current_tv.tv_usec * 1000;
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}
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assert (result.current.tv_sec >= 0);
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return result;
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}
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/* A special deadline value for which __deadline_is_infinite is
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true. */
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static inline struct deadline
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infinite_deadline (void)
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{
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return (struct deadline) { { -1, -1 } };
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}
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struct deadline
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__deadline_from_timeval (struct deadline_current_time current,
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struct timeval tv)
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{
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assert (__is_timeval_valid_timeout (tv));
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/* Compute second-based deadline. Perform the addition in
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uintmax_t, which is unsigned, to simply overflow detection. */
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uintmax_t sec = current.current.tv_sec;
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sec += tv.tv_sec;
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if (sec < (uintmax_t) tv.tv_sec)
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return infinite_deadline ();
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/* Compute nanosecond deadline. */
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int nsec = current.current.tv_nsec + tv.tv_usec * 1000;
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if (nsec >= 1000 * 1000 * 1000)
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{
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/* Carry nanosecond overflow to seconds. */
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nsec -= 1000 * 1000 * 1000;
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if (sec + 1 < sec)
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return infinite_deadline ();
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++sec;
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}
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/* This uses a GCC extension, otherwise these casts for detecting
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overflow would not be defined. */
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if ((time_t) sec < 0 || sec != (uintmax_t) (time_t) sec)
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return infinite_deadline ();
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return (struct deadline) { { sec, nsec } };
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}
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int
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__deadline_to_ms (struct deadline_current_time current,
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struct deadline deadline)
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{
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if (__deadline_is_infinite (deadline))
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return INT_MAX;
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if (current.current.tv_sec > deadline.absolute.tv_sec
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|| (current.current.tv_sec == deadline.absolute.tv_sec
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&& current.current.tv_nsec >= deadline.absolute.tv_nsec))
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return 0;
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time_t sec = deadline.absolute.tv_sec - current.current.tv_sec;
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if (sec >= INT_MAX)
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/* This value will overflow below. */
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return INT_MAX;
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int nsec = deadline.absolute.tv_nsec - current.current.tv_nsec;
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if (nsec < 0)
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{
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/* Borrow from the seconds field. */
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assert (sec > 0);
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--sec;
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nsec += 1000 * 1000 * 1000;
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}
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/* Prepare for rounding up to milliseconds. */
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nsec += 999999;
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if (nsec > 1000 * 1000 * 1000)
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{
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assert (sec < INT_MAX);
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++sec;
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nsec -= 1000 * 1000 * 1000;
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}
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unsigned int msec = nsec / (1000 * 1000);
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if (sec > INT_MAX / 1000)
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return INT_MAX;
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msec += sec * 1000;
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if (msec > INT_MAX)
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return INT_MAX;
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return msec;
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}
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