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Add and fix documentation on PushBytes's functions

This commit is contained in:
Antoni Spaanderman 2024-08-11 21:55:15 +02:00
parent 6dcb6f33fb
commit 71d760b3f2
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1 changed files with 18 additions and 13 deletions
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31
bitcoin/src/blockdata/script/push_bytes.rs
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@ -43,48 +43,53 @@ mod primitive {
pub struct PushBytes([u8]);
impl PushBytes {
/// Creates `&Self` without checking the length.
/// Creates `&PushBytes` without checking the length.
///
/// # Safety
///
/// The caller is responsible for checking that the length is less than the [`LIMIT`].
/// The caller is responsible for checking that the length is less than the 2^32.
unsafe fn from_slice_unchecked(bytes: &[u8]) -> &Self {
// SAFETY: The caller must guarantee that bytes.len() < 2^32.
// If that is the case the conversion is sound because &[u8] and &PushBytes
// have the same layout (because of #[repr(transparent)] on PushBytes).
&*(bytes as *const [u8] as *const PushBytes)
}
/// Creates `&mut Self` without checking the length.
/// Creates `&mut PushBytes` without checking the length.
///
/// # Safety
///
/// The caller is responsible for checking that the length is less than the [`LIMIT`].
/// The caller is responsible for checking that the length is less than the 2^32.
unsafe fn from_mut_slice_unchecked(bytes: &mut [u8]) -> &mut Self {
// SAFETY: The caller must guarantee that bytes.len() < 2^32.
// If that is the case the conversion is sound because &mut [u8] and &mut PushBytes
// have the same layout (because of #[repr(transparent)] on PushBytes).
&mut *(bytes as *mut [u8] as *mut PushBytes)
}
/// Creates an empty `PushBytes`.
/// Creates an empty `&PushBytes`.
pub fn empty() -> &'static Self {
// 0 < LIMIT
// SAFETY: 0 < 2^32.
unsafe { Self::from_slice_unchecked(&[]) }
}
/// Returns the underlying bytes.
pub fn as_bytes(&self) -> &[u8] { &self.0 }
/// Returns the underlying mutbale bytes.
/// Returns the underlying mutable bytes.
pub fn as_mut_bytes(&mut self) -> &mut [u8] { &mut self.0 }
}
macro_rules! delegate_index {
($($type:ty),* $(,)?) => {
$(
/// Script subslicing operation - read [slicing safety](#slicing-safety)!
impl Index<$type> for PushBytes {
type Output = Self;
#[inline]
#[track_caller]
fn index(&self, index: $type) -> &Self::Output {
// Slicing can not make slices longer
// SAFETY: Slicing can not make slices longer.
unsafe {
Self::from_slice_unchecked(&self.0[index])
}
@ -117,7 +122,7 @@ mod primitive {
fn try_from(bytes: &'a [u8]) -> Result<Self, Self::Error> {
check_limit(bytes.len())?;
// We've just checked the length
// SAFETY: We've just checked the length.
Ok(unsafe { PushBytes::from_slice_unchecked(bytes) })
}
}
@ -127,7 +132,7 @@ mod primitive {
fn try_from(bytes: &'a mut [u8]) -> Result<Self, Self::Error> {
check_limit(bytes.len())?;
// We've just checked the length
// SAFETY: We've just checked the length.
Ok(unsafe { PushBytes::from_mut_slice_unchecked(bytes) })
}
}
@ -139,7 +144,7 @@ mod primitive {
fn from(bytes: &'a [u8; $len]) -> Self {
// Check that the macro wasn't called with a wrong number.
const _: () = [(); 1][($len >= 0x100000000u64) as usize];
// We know the size of array statically and we checked macro input.
// SAFETY: We know the size of array statically and we checked macro input.
unsafe { PushBytes::from_slice_unchecked(bytes) }
}
}
@ -147,7 +152,7 @@ mod primitive {
impl<'a> From<&'a mut [u8; $len]> for &'a mut PushBytes {
fn from(bytes: &'a mut [u8; $len]) -> Self {
// Macro check already above, no need to duplicate.
// We know the size of array statically and we checked macro input.
// SAFETY: We know the size of array statically and we checked macro input.
unsafe { PushBytes::from_mut_slice_unchecked(bytes) }
}
}