getdns/src/compat/gettimeofday.c

73 lines
2.0 KiB
C

/*
* Copyright (c) 2016 Christian Huitema <huitema@huitema.net>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* Numerous places in the code make reference to the Unix/Linux
* "gettimeofday()" function, which is not available in the standard
* windows libraries. This code provides a compatible implementation.
*/
#include "config.h"
#ifdef GETDNS_ON_WINDOWS
int gettimeofday(struct timeval* tv, struct timezone* tz)
{
FILETIME ft;
uint64_t now = 0;
/*
* The GetSystemTimeAsFileTime API returns the number
* of 100-nanosecond intervals since January 1, 1601 (UTC),
* in FILETIME format.
*/
GetSystemTimeAsFileTime(&ft);
/*
* Convert to plain 64 bit format, without making
* assumptions about the FILETIME structure alignment.
*/
now |= ft.dwHighDateTime;
now <<= 32;
now |= ft.dwLowDateTime;
/*
* Convert units from 100ns to 1us
*/
now /= 10;
/*
* Account for microseconds elapsed between 1601 and 1970.
*/
now -= 11644473600000000ULL;
if (tv != NULL)
{
uint64_t sec = now / 1000000;
uint64_t usec = now % 1000000;
tv->tv_sec = (long)sec;
tv->tv_usec = (long)usec;
}
if (tz != NULL)
{
/*
* TODO: implement a timezone retrieval function.
* Not urgent, since the GetDNS code always set this parameter to NULL.
*/
return -1;
}
return 0;
}
#endif /* GETDNS_ON_WINDOWS */