/*
 * Copyright (C) 1998, 1999, 2000  Internet Software Consortium.
 * 
 * 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 INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM 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.
 */

#include <config.h>

#include <errno.h>
#include <limits.h>
#include <time.h>

#include <sys/time.h>	/* Required for struct timeval on some platforms. */

#include <isc/string.h>
#include <isc/time.h>
#include <isc/util.h>

#define NS_PER_S	1000000000	/* Nanoseconds per second. */
#define NS_PER_US	1000		/* Nanoseconds per microsecond. */
#define US_PER_S	1000000		/* Microseconds per second. */

/*
 * All of the INSIST()s checks of nanoseconds < NS_PER_S are for 
 * consistency checking of the type. In lieu of magic numbers, it
 * is the best we've got.  The check is only performed on functions which
 * need an initialized type.
 */

/***
 *** Intervals
 ***/

static isc_interval_t zero_interval = { 0, 0 };
isc_interval_t *isc_interval_zero = &zero_interval;

void
isc_interval_set(isc_interval_t *i,
		 unsigned int seconds, unsigned int nanoseconds)
{

	/*
	 * Set 'i' to a value representing an interval of 'seconds' seconds
	 * and 'nanoseconds' nanoseconds, suitable for use in isc_time_add()
	 * and isc_time_subtract().
	 */

	REQUIRE(i != NULL);
	REQUIRE(nanoseconds < NS_PER_S);

	i->seconds = seconds;
	i->nanoseconds = nanoseconds;
}

isc_boolean_t
isc_interval_iszero(isc_interval_t *i) {

	/*
	 * Returns ISC_TRUE iff. 'i' is the zero interval.
	 */

	REQUIRE(i != NULL);
	INSIST(i->nanoseconds < NS_PER_S);

	if (i->seconds == 0 && i->nanoseconds == 0)
		return (ISC_TRUE);

	return (ISC_FALSE);
}


/***
 *** Absolute Times
 ***/

static isc_time_t epoch = { 0, 0 };
isc_time_t *isc_time_epoch = &epoch;

void
isc_time_set(isc_time_t *t, unsigned int seconds, unsigned int nanoseconds) {
	/*
	 * Set 't' to a particular number of seconds + nanoseconds since the
	 * epoch.
	 */
	REQUIRE(t != NULL);
	REQUIRE(nanoseconds < NS_PER_S);

	t->seconds = seconds;
	t->nanoseconds = nanoseconds;
}

void
isc_time_settoepoch(isc_time_t *t) {
	/*
	 * Set 't' to the time of the epoch.
	 */

	REQUIRE(t != NULL);

	t->seconds = 0;
	t->nanoseconds = 0;
}

isc_boolean_t
isc_time_isepoch(isc_time_t *t) {

	/*
	 * Returns ISC_TRUE iff. 't' is the epoch ("time zero").
	 */

	REQUIRE(t != NULL);
	INSIST(t->nanoseconds < NS_PER_S);

	if (t->seconds == 0 && t->nanoseconds == 0)
		return (ISC_TRUE);

	return (ISC_FALSE);
}

isc_result_t
isc_time_now(isc_time_t *t) {
	struct timeval tv;

	/*
	 * Set *t to the current absolute time.
	 */
	
	REQUIRE(t != NULL);
	
	if (gettimeofday(&tv, NULL) == -1) {
		UNEXPECTED_ERROR(__FILE__, __LINE__, strerror(errno));
		return (ISC_R_UNEXPECTED);
	}

	/*
	 * Does POSIX guarantee the signedness of tv_sec and tv_usec?  If not,
	 * then this test will generate warnings for platforms on which it is
	 * unsigned.  In any event, the chances of any of these problems
	 * happening are pretty much zero, but since the libisc library ensures
	 * certain things to be true ...
	 */
	if (tv.tv_sec < 0 || tv.tv_usec < 0 || tv.tv_usec >= US_PER_S)
		return (ISC_R_UNEXPECTED);

	/*
	 * Ensure the tv_sec value fits in t->seconds. 
	 */
	if (sizeof(tv.tv_sec) > sizeof(t->seconds) &&
	    ((tv.tv_sec | (unsigned int)-1) ^ (unsigned int)-1) != 0)
		return (ISC_R_RANGE);

	t->seconds = tv.tv_sec;
	t->nanoseconds = tv.tv_usec * NS_PER_US;

	return (ISC_R_SUCCESS);
}

isc_result_t
isc_time_nowplusinterval(isc_time_t *t, isc_interval_t *i) {
	struct timeval tv;

	/*
	 * Set *t to the current absolute time + i.
	 */
	
	REQUIRE(t != NULL);
	REQUIRE(i != NULL);
	INSIST(i->nanoseconds < NS_PER_S);

	if (gettimeofday(&tv, NULL) == -1) {
		UNEXPECTED_ERROR(__FILE__, __LINE__, strerror(errno));
		return (ISC_R_UNEXPECTED);
	}

	/*
	 * Does POSIX guarantee the signedness of tv_sec and tv_usec?  If not,
	 * then this test will generate warnings for platforms on which it is
	 * unsigned.  In any event, the chances of any of these problems
	 * happening are pretty much zero, but since the libisc library ensures
	 * certain things to be true ...
	 */
	if (tv.tv_sec < 0 || tv.tv_usec < 0 || tv.tv_usec >= US_PER_S)
		return (ISC_R_UNEXPECTED);

	/*
	 * Ensure the resulting seconds value fits in the size of an
	 * unsigned int.  (It is written this way as a slight optimization;
	 * note that even if both values == INT_MAX, then when added
	 * and getting another 1 added below the result is UINT_MAX.)
	 */
	if ((tv.tv_sec > INT_MAX || i->seconds > INT_MAX) &&
	    ((long long)tv.tv_sec + i->seconds > UINT_MAX))
		return (ISC_R_RANGE);

	t->seconds = tv.tv_sec + i->seconds;
	t->nanoseconds = tv.tv_usec * NS_PER_US + i->nanoseconds;
	if (t->nanoseconds > NS_PER_S) {
		t->seconds++;
		t->nanoseconds -= NS_PER_S;
	}

	return (ISC_R_SUCCESS);
}

int
isc_time_compare(isc_time_t *t1, isc_time_t *t2) {

	/*
	 * Compare the times referenced by 't1' and 't2'
	 */

	REQUIRE(t1 != NULL && t2 != NULL);
	INSIST(t1->nanoseconds < NS_PER_S && t2->nanoseconds < NS_PER_S);

	if (t1->seconds < t2->seconds)
		return (-1);
	if (t1->seconds > t2->seconds)
		return (1);
	if (t1->nanoseconds < t2->nanoseconds)
		return (-1);
	if (t1->nanoseconds > t2->nanoseconds)
		return (1);
	return (0);
}

isc_result_t
isc_time_add(isc_time_t *t, isc_interval_t *i, isc_time_t *result) {
	/*
	 * Add 't' to 'i', storing the result in 'result'.
	 */

	REQUIRE(t != NULL && i != NULL && result != NULL);
	INSIST(t->nanoseconds < NS_PER_S && i->nanoseconds < NS_PER_S);

	/*
	 * Ensure the resulting seconds value fits in the size of an
	 * unsigned int.  (It is written this way as a slight optimization;
	 * note that even if both values == INT_MAX, then when added
	 * and getting another 1 added below the result is UINT_MAX.)
	 */
	if ((t->seconds > INT_MAX || i->seconds > INT_MAX) &&
	    ((long long)t->seconds + i->seconds > UINT_MAX))
		return (ISC_R_RANGE);

	result->seconds = t->seconds + i->seconds;
	result->nanoseconds = t->nanoseconds + i->nanoseconds;
	if (result->nanoseconds > NS_PER_S) {
		result->seconds++;
		result->nanoseconds -= NS_PER_S;
	}

	return (ISC_R_SUCCESS);
}

isc_result_t
isc_time_subtract(isc_time_t *t, isc_interval_t *i, isc_time_t *result) {
	/*
	 * Subtract 'i' from 't', storing the result in 'result'.
	 */

	REQUIRE(t != NULL && i != NULL && result != NULL);
	INSIST(t->nanoseconds < NS_PER_S && i->nanoseconds < NS_PER_S);

	if ((unsigned int)t->seconds < i->seconds ||
	    ((unsigned int)t->seconds == i->seconds &&
	     t->nanoseconds < i->nanoseconds))
	    return (ISC_R_RANGE);

	result->seconds = t->seconds - i->seconds;
	if (t->nanoseconds >= i->nanoseconds)
		result->nanoseconds = t->nanoseconds - i->nanoseconds;
	else {
		result->nanoseconds = NS_PER_S - i->nanoseconds +
			t->nanoseconds;
		result->seconds--;
	}

	return (ISC_R_SUCCESS);
}

isc_uint64_t
isc_time_microdiff(isc_time_t *t1, isc_time_t *t2) {
	isc_uint64_t i1, i2, i3;

	REQUIRE(t1 != NULL && t2 != NULL);
	INSIST(t1->nanoseconds < NS_PER_S && t2->nanoseconds < NS_PER_S);

	i1 = (isc_uint64_t)t1->seconds * NS_PER_S + t1->nanoseconds;
	i2 = (isc_uint64_t)t2->seconds * NS_PER_S + t2->nanoseconds;

	if (i1 <= i2)
		return (0);

	i3 = i1 - i2;

	/*
	 * Convert to microseconds.
	 */
	i3 = (i1 - i2) / NS_PER_US;

	return (i3);
}

isc_uint32_t
isc_time_seconds(isc_time_t *t) {
	REQUIRE(t != NULL);
	INSIST(t->nanoseconds < NS_PER_S);

	return ((isc_uint32_t)t->seconds);
}

isc_result_t
isc_time_secondsastimet(isc_time_t *t, time_t *secondsp) {
	isc_uint64_t i;
	time_t seconds;

	REQUIRE(t != NULL);
	INSIST(t->nanoseconds < NS_PER_S);

	/*
	 * Ensure that the number of seconds represented by t->seconds
	 * can be represented by a time_t.  Since t->seconds is an unsigned
	 * int and since time_t is mostly opaque, this is trickier than
	 * it seems.  (This standardized opaqueness of time_t is *very*
	 * frustrating; time_t is not even limited to being an integral
	 * type.)
	 *
	 * The mission, then, is to avoid generating any kind of warning
	 * about "signed versus unsigned" while trying to determine if the
	 * the unsigned int t->seconds is out range for tv_sec, which is
	 * pretty much only true if time_t is a signed integer of the same
	 * size as the return value of isc_time_seconds. 
	 *
	 * The use of a 64 bit integer takes advantage of C's conversion rules
	 * to either zero fill or sign extend the widened type.
	 */
	seconds = (time_t)t->seconds;

	INSIST(sizeof(unsigned int) == sizeof(isc_uint32_t));
	INSIST(sizeof(time_t) >= sizeof(isc_uint32_t));

	if (sizeof(time_t) == sizeof(isc_uint32_t) &&	       /* Same size. */
	    (time_t)0.5 != 0.5 &&	       /* Not a floating point type. */
	    (i = (time_t)-1) != 4294967295u &&		       /* Is signed. */
	    (seconds & (1 << (sizeof(time_t) * 8 - 1))) != 0) {	/* Negative. */
		/*
		 * This is here to shut up the IRIX compiler:
		 *	variable "i" was set but never used
		 * when the value of i *was* used in the third test.
		 * (Let's hope the compiler got the actual test right.)
		 */
		UNUSED(i);
		return (ISC_R_RANGE);
	}

	*secondsp = seconds;

	return (ISC_R_SUCCESS);
}

isc_uint32_t
isc_time_nanoseconds(isc_time_t *t) {
	REQUIRE(t != NULL);

	ENSURE(t->nanoseconds < NS_PER_S);

	return ((isc_uint32_t)t->nanoseconds);
}