52 lines
1.5 KiB
Go
52 lines
1.5 KiB
Go
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package models
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// Helper time methods since parsing time can easily overflow and we only support a
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// specific time range.
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import (
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"fmt"
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"math"
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"time"
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)
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var (
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// MaxNanoTime is the maximum time that can be represented via int64 nanoseconds since the epoch.
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MaxNanoTime = time.Unix(0, math.MaxInt64).UTC()
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// MinNanoTime is the minumum time that can be represented via int64 nanoseconds since the epoch.
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MinNanoTime = time.Unix(0, math.MinInt64).UTC()
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// ErrTimeOutOfRange gets returned when time is out of the representable range using int64 nanoseconds since the epoch.
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ErrTimeOutOfRange = fmt.Errorf("time outside range %s - %s", MinNanoTime, MaxNanoTime)
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)
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// SafeCalcTime safely calculates the time given. Will return error if the time is outside the
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// supported range.
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func SafeCalcTime(timestamp int64, precision string) (time.Time, error) {
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mult := GetPrecisionMultiplier(precision)
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if t, ok := safeSignedMult(timestamp, mult); ok {
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return time.Unix(0, t).UTC(), nil
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}
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return time.Time{}, ErrTimeOutOfRange
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}
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// CheckTime checks that a time is within the safe range.
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func CheckTime(t time.Time) error {
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if t.Before(MinNanoTime) || t.After(MaxNanoTime) {
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return ErrTimeOutOfRange
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}
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return nil
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}
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// Perform the multiplication and check to make sure it didn't overflow.
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func safeSignedMult(a, b int64) (int64, bool) {
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if a == 0 || b == 0 || a == 1 || b == 1 {
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return a * b, true
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}
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if a == math.MinInt64 || b == math.MaxInt64 {
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return 0, false
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}
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c := a * b
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return c, c/b == a
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}
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