/* Add two struct timespec values.
- Copyright (C) 2011-2012 Free Software Foundation, Inc.
+ Copyright (C) 2011-2016 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
/* Written by Paul Eggert. */
/* Return the sum of two timespec values A and B. On overflow, return
- an extremal value. This assumes 0 <= tv_nsec <= 999999999. */
+ an extremal value. This assumes 0 <= tv_nsec < TIMESPEC_RESOLUTION. */
#include <config.h>
#include "timespec.h"
struct timespec
timespec_add (struct timespec a, struct timespec b)
{
- struct timespec r;
time_t rs = a.tv_sec;
time_t bs = b.tv_sec;
int ns = a.tv_nsec + b.tv_nsec;
- int nsd = ns - 1000000000;
+ int nsd = ns - TIMESPEC_RESOLUTION;
int rns = ns;
+ time_t tmin = TYPE_MINIMUM (time_t);
+ time_t tmax = TYPE_MAXIMUM (time_t);
if (0 <= nsd)
{
rns = nsd;
- if (rs == TYPE_MAXIMUM (time_t))
- {
- if (0 <= bs)
- goto high_overflow;
- bs++;
- }
- else
+ if (bs < tmax)
+ bs++;
+ else if (rs < 0)
rs++;
+ else
+ goto high_overflow;
}
- if (INT_ADD_OVERFLOW (rs, bs))
+ /* INT_ADD_WRAPV is not appropriate since time_t might be unsigned.
+ In theory time_t might be narrower than int, so plain
+ INT_ADD_OVERFLOW does not suffice. */
+ if (! INT_ADD_OVERFLOW (rs, bs) && tmin <= rs + bs && rs + bs <= tmax)
+ rs += bs;
+ else
{
if (rs < 0)
{
- rs = TYPE_MINIMUM (time_t);
+ rs = tmin;
rns = 0;
}
else
{
high_overflow:
- rs = TYPE_MAXIMUM (time_t);
- rns = 999999999;
+ rs = tmax;
+ rns = TIMESPEC_RESOLUTION - 1;
}
}
- else
- rs += bs;
- r.tv_sec = rs;
- r.tv_nsec = rns;
- return r;
+ return make_timespec (rs, rns);
}