isc/unix/time.c

	time.c revision 9c3531d72aeaad6c5f01efe6a1c82023e1379e4d
/*
 * Copyright (C) 1998-2000  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.
 */

/* $Id: time.c,v 1.26 2000/06/22 21:58:50 tale Exp $ */

#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 the 64 bit integer ``i'' takes advantage of C's
     * conversion rules to either zero fill or sign extend the widened
     * type.
     *
     * Solaris 5.6 gives this warning about the left shift:
     *  warning: integer overflow detected: op "<<"
     * if the U(nsigned) qualifier is not on the 1.
     */
    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 &
         (1U << (sizeof(time_t) * CHAR_BIT - 1))) != 0) {   /* Negative. */
        /*
         * This UNUSED() 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);
}