rust-bitcoin-unsafe-fast/units/src/locktime/relative.rs

269 lines
8.5 KiB
Rust

// SPDX-License-Identifier: CC0-1.0
//! Provides [`Height`] and [`Time`] types used by the `rust-bitcoin` `relative::LockTime` type.
use core::fmt;
#[cfg(feature = "arbitrary")]
use arbitrary::{Arbitrary, Unstructured};
#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};
/// A relative lock time lock-by-blockheight value.
#[derive(Debug, Default, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct Height(u16);
impl Height {
/// Relative block height 0, can be included in any block.
pub const ZERO: Self = Height(0);
/// The minimum relative block height (0), can be included in any block.
pub const MIN: Self = Self::ZERO;
/// The maximum relative block height.
pub const MAX: Self = Height(u16::MAX);
/// Constructs a new [`Height`] using a count of blocks.
#[inline]
pub const fn from_height(blocks: u16) -> Self { Height(blocks) }
/// Returns the inner `u16` value.
#[inline]
#[must_use]
pub const fn value(self) -> u16 { self.0 }
/// Returns the `u32` value used to encode this locktime in an nSequence field or
/// argument to `OP_CHECKSEQUENCEVERIFY`.
#[inline]
pub const fn to_consensus_u32(self) -> u32 {
self.0 as u32 // cast safety: u32 is wider than u16 on all architectures
}
}
impl From<u16> for Height {
#[inline]
fn from(value: u16) -> Self { Height(value) }
}
crate::impl_parse_str_from_int_infallible!(Height, u16, from);
impl fmt::Display for Height {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::Display::fmt(&self.0, f) }
}
/// A relative lock time lock-by-blocktime value.
///
/// For BIP 68 relative lock-by-blocktime locks, time is measured in 512 second intervals.
#[derive(Debug, Default, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct Time(u16);
impl Time {
/// Relative block time 0, can be included in any block.
pub const ZERO: Self = Time(0);
/// The minimum relative block time (0), can be included in any block.
pub const MIN: Self = Time::ZERO;
/// The maximum relative block time (33,554,432 seconds or approx 388 days).
pub const MAX: Self = Time(u16::MAX);
/// Constructs a new [`Time`] using time intervals where each interval is equivalent to 512 seconds.
///
/// Encoding finer granularity of time for relative lock-times is not supported in Bitcoin.
#[inline]
pub const fn from_512_second_intervals(intervals: u16) -> Self { Time(intervals) }
/// Constructs a new [`Time`] from seconds, converting the seconds into 512 second interval with
/// truncating division.
///
/// # Errors
///
/// Will return an error if the input cannot be encoded in 16 bits.
#[inline]
#[rustfmt::skip] // moves comments to unrelated code
pub const fn from_seconds_floor(seconds: u32) -> Result<Self, TimeOverflowError> {
let interval = seconds / 512;
if interval <= u16::MAX as u32 { // infallible cast, needed by const code
Ok(Time::from_512_second_intervals(interval as u16)) // Cast checked above, needed by const code.
} else {
Err(TimeOverflowError { seconds })
}
}
/// Constructs a new [`Time`] from seconds, converting the seconds into 512 second intervals with
/// ceiling division.
///
/// # Errors
///
/// Will return an error if the input cannot be encoded in 16 bits.
#[inline]
#[rustfmt::skip] // moves comments to unrelated code
pub const fn from_seconds_ceil(seconds: u32) -> Result<Self, TimeOverflowError> {
if seconds <= u16::MAX as u32 * 512 {
let interval = (seconds + 511) / 512;
Ok(Time::from_512_second_intervals(interval as u16)) // Cast checked above, needed by const code.
} else {
Err(TimeOverflowError { seconds })
}
}
/// Returns the inner `u16` value.
#[inline]
#[must_use]
pub const fn value(self) -> u16 { self.0 }
/// Returns the `u32` value used to encode this locktime in an nSequence field or
/// argument to `OP_CHECKSEQUENCEVERIFY`.
#[inline]
pub const fn to_consensus_u32(self) -> u32 {
(1u32 << 22) | self.0 as u32 // cast safety: u32 is wider than u16 on all architectures
}
}
crate::impl_parse_str_from_int_infallible!(Time, u16, from_512_second_intervals);
impl fmt::Display for Time {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::Display::fmt(&self.0, f) }
}
/// Input time in seconds was too large to be encoded to a 16 bit 512 second interval.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct TimeOverflowError {
/// Time value in seconds that overflowed.
// Private because we maintain an invariant that the `seconds` value does actually overflow.
pub(crate) seconds: u32,
}
impl TimeOverflowError {
/// Constructs a new `TimeOverflowError` using `seconds`.
///
/// # Panics
///
/// If `seconds` would not actually overflow a `u16`.
pub fn new(seconds: u32) -> Self {
assert!(u16::try_from((seconds + 511) / 512).is_err());
Self { seconds }
}
}
impl fmt::Display for TimeOverflowError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(
f,
"{} seconds is too large to be encoded to a 16 bit 512 second interval",
self.seconds
)
}
}
#[cfg(feature = "std")]
impl std::error::Error for TimeOverflowError {}
#[cfg(feature = "arbitrary")]
impl<'a> Arbitrary<'a> for Height {
fn arbitrary(u: &mut Unstructured<'a>) -> arbitrary::Result<Self> {
let choice = u.int_in_range(0..=2)?;
match choice {
0 => Ok(Height::MIN),
1 => Ok(Height::MAX),
_ => Ok(Height::from_height(u16::arbitrary(u)?)),
}
}
}
#[cfg(feature = "arbitrary")]
impl<'a> Arbitrary<'a> for Time {
fn arbitrary(u: &mut Unstructured<'a>) -> arbitrary::Result<Self> {
let choice = u.int_in_range(0..=2)?;
match choice {
0 => Ok(Time::MIN),
1 => Ok(Time::MAX),
_ => Ok(Time::from_512_second_intervals(u16::arbitrary(u)?)),
}
}
}
#[cfg(test)]
mod tests {
#[cfg(feature = "serde")]
use internals::serde_round_trip;
use super::*;
const MAXIMUM_ENCODABLE_SECONDS: u32 = u16::MAX as u32 * 512;
#[test]
fn sanity_check() {
assert_eq!(Height::MAX.to_consensus_u32(), u32::from(u16::MAX));
assert_eq!(Time::from_512_second_intervals(100).value(), 100u16);
assert_eq!(Time::from_512_second_intervals(100).to_consensus_u32(), 4_194_404u32); // 0x400064
}
#[test]
fn from_seconds_ceil_success() {
let actual = Time::from_seconds_ceil(100).unwrap();
let expected = Time(1_u16);
assert_eq!(actual, expected);
}
#[test]
fn from_seconds_ceil_with_maximum_encodable_seconds_success() {
let actual = Time::from_seconds_ceil(MAXIMUM_ENCODABLE_SECONDS).unwrap();
let expected = Time(u16::MAX);
assert_eq!(actual, expected);
}
#[test]
fn from_seconds_ceil_causes_time_overflow_error() {
let result = Time::from_seconds_ceil(MAXIMUM_ENCODABLE_SECONDS + 1);
assert!(result.is_err());
}
#[test]
fn from_seconds_floor_success() {
let actual = Time::from_seconds_floor(100).unwrap();
let expected = Time(0_u16);
assert_eq!(actual, expected);
}
#[test]
fn from_seconds_floor_with_exact_interval() {
let actual = Time::from_seconds_floor(512).unwrap();
let expected = Time(1_u16);
assert_eq!(actual, expected);
}
#[test]
fn from_seconds_floor_with_maximum_encodable_seconds_success() {
let actual = Time::from_seconds_floor(MAXIMUM_ENCODABLE_SECONDS + 511).unwrap();
let expected = Time(u16::MAX);
assert_eq!(actual, expected);
}
#[test]
fn from_seconds_floor_causes_time_overflow_error() {
let result = Time::from_seconds_floor(MAXIMUM_ENCODABLE_SECONDS + 512);
assert!(result.is_err());
}
#[test]
#[cfg(feature = "serde")]
pub fn encode_decode_height() {
serde_round_trip!(Height::ZERO);
serde_round_trip!(Height::MIN);
serde_round_trip!(Height::MAX);
}
#[test]
#[cfg(feature = "serde")]
pub fn encode_decode_time() {
serde_round_trip!(Time::ZERO);
serde_round_trip!(Time::MIN);
serde_round_trip!(Time::MAX);
}
}