use std::{convert::TryInto, fmt}; use crate::{ObjectId, SIZE_OF_SHA1_DIGEST}; /// A borrowed reference to a hash identifying objects.////// # Future Proofing////// In case we wish to support multiple hashes with the same length we cannot discriminate/// using the slice length anymore. To make that work, we will use the high bits of the/// internal `bytes` slice length (a fat pointer, pointing to data and its length in bytes)/// to encode additional information. Before accessing or returning the bytes, a new adjusted/// slice will be constructed, while the high bits will be used to help resolving the/// hash `[`kind()`][oid::kind()]`./// We expect to have quite a few bits available for such 'conflict resolution' as most hashes aren't longer/// than 64 bytes.#[derive(PartialEq, Eq, Hash, Ord, PartialOrd)]#[repr(transparent)]#[allow(non_camel_case_types)]#[cfg_attr(feature = "serde1", derive(serde::Serialize))]pub struct oid { bytes: [u8],} /// A utility able to format itself with the given amount of characters in hex#[derive(PartialEq, Eq, Hash, Ord, PartialOrd)]pub struct HexDisplay<'a> { inner: &'a oid, hex_len: usize,} impl<'a> fmt::Display for HexDisplay<'a> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { let mut hex = crate::Kind::hex_buf(); let max_len = self.inner.hex_to_buf(hex.as_mut()); let hex = std::str::from_utf8(&hex[..self.hex_len.min(max_len)]).expect("ascii only in hex"); f.write_str(hex) }} impl fmt::Debug for oid { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> std::fmt::Result { write!( f, "{}({})", match self.kind() { crate::Kind::Sha1 => "Sha1", }, self.to_hex(), ) }} #[derive(Debug, thiserror::Error)]pub enum Error { #[error("Cannot instantiate git hash from a digest of length {0}")] InvalidByteSliceLength(usize),} /// Conversionimpl oid { /// Try to create a shared object id from a slice of bytes representing a hash `digest` #[inline] pub fn try_from_bytes(digest: &[u8]) -> Result<&Self, Error> { match digest.len() { 20 => Ok( #[allow(unsafe_code)] unsafe { &*(digest as *const [u8] as *const oid) }, ), len => Err(Error::InvalidByteSliceLength(len)), } } /// Create an OID from the input `value` slice without performing any safety check. /// Use only once sure that `value` is a hash of valid length. pub fn from_bytes_unchecked(value: &[u8]) -> &Self { Self::from_bytes(value) } /// Only from code that statically assures correct sizes using array conversions pub(crate) fn from_bytes(value: &[u8]) -> &Self { #[allow(unsafe_code)] unsafe { &*(value as *const [u8] as *const oid) } }} /// Accessimpl oid { /// The kind of hash used for this Digest #[inline] pub fn kind(&self) -> crate::Kind { crate::Kind::from_len_in_bytes(self.bytes.len()) } /// The first byte of the hash, commonly used to partition a set of `Id`s #[inline] pub fn first_byte(&self) -> u8 { self.bytes[0] } /// Interpret this object id as raw byte slice. #[inline] pub fn as_bytes(&self) -> &[u8] { &self.bytes } /// Return a type which can display itself in hexadecimal form with the `len` amount of characters. #[inline] pub fn to_hex_with_len(&self, len: usize) -> HexDisplay<'_> { HexDisplay { inner: self, hex_len: len, } } /// Return a type which displays this oid as hex in full. #[inline] pub fn to_hex(&self) -> HexDisplay<'_> { HexDisplay { inner: self, hex_len: self.bytes.len() * 2, } }} /// Sha1 specific methodsimpl oid { /// Write ourselves to the `out` in hexadecimal notation, returning the amount of written bytes. /// /// **Panics** if the buffer isn't big enough to hold twice as many bytes as the current binary size. #[inline] #[must_use] pub fn hex_to_buf(&self, buf: &mut [u8]) -> usize { let num_hex_bytes = self.bytes.len() * 2; hex::encode_to_slice(&self.bytes, &mut buf[..num_hex_bytes]).expect("to count correctly"); num_hex_bytes } /// Write ourselves to `out` in hexadecimal notation #[inline] pub fn write_hex_to(&self, mut out: impl std::io::Write) -> std::io::Result<()> { let mut hex = crate::Kind::hex_buf(); let hex_len = self.hex_to_buf(&mut hex); out.write_all(&hex[..hex_len]) } /// Returns a Sha1 digest with all bytes being initialized to zero. #[inline] pub(crate) fn null_sha1() -> &'static Self { oid::from_bytes([0u8; SIZE_OF_SHA1_DIGEST].as_ref()) }} impl AsRef<oid> for &oid { fn as_ref(&self) -> &oid { self }} impl ToOwned for oid { type Owned = crate::ObjectId; fn to_owned(&self) -> Self::Owned { match self.kind() { crate::Kind::Sha1 => crate::ObjectId::Sha1(self.bytes.try_into().expect("no bug in hash detection")), } }} impl<'a> From<&'a [u8; SIZE_OF_SHA1_DIGEST]> for &'a oid { fn from(v: &'a [u8; SIZE_OF_SHA1_DIGEST]) -> Self { oid::from_bytes(v.as_ref()) }} impl fmt::Display for &oid { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { for b in self.as_bytes() { write!(f, "{b:02x}")?; } Ok(()) }} impl PartialEq<crate::ObjectId> for &oid { fn eq(&self, other: &ObjectId) -> bool { *self == other.as_ref() }} /// Manually created from a version that uses a slice, and we forcefully try to convert it into a borrowed array of the desired size/// Could be improved by fitting this into serde/// Unfortunately the serde::Deserialize derive wouldn't work for borrowed arrays.#[cfg(feature = "serde1")]impl<'de: 'a, 'a> serde::Deserialize<'de> for &'a oid { fn deserialize<D>(deserializer: D) -> Result<Self, <D as serde::Deserializer<'de>>::Error> where D: serde::Deserializer<'de>, { struct __Visitor<'de: 'a, 'a> { marker: std::marker::PhantomData<&'a oid>, lifetime: std::marker::PhantomData<&'de ()>, } impl<'de: 'a, 'a> serde::de::Visitor<'de> for __Visitor<'de, 'a> { type Value = &'a oid; fn expecting(&self, __formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { std::fmt::Formatter::write_str(__formatter, "tuple struct Digest") } #[inline] fn visit_newtype_struct<__E>(self, __e: __E) -> std::result::Result<Self::Value, __E::Error> where __E: serde::Deserializer<'de>, { let __field0: &'a [u8] = match <&'a [u8] as serde::Deserialize>::deserialize(__e) { Ok(__val) => __val, Err(__err) => { return Err(__err); } }; Ok(oid::try_from_bytes(__field0).expect("hash of known length")) } #[inline] fn visit_seq<__A>(self, mut __seq: __A) -> std::result::Result<Self::Value, __A::Error> where __A: serde::de::SeqAccess<'de>, { let __field0 = match match serde::de::SeqAccess::next_element::<&'a [u8]>(&mut __seq) { Ok(__val) => __val, Err(__err) => { return Err(__err); } } { Some(__value) => __value, None => { return Err(serde::de::Error::invalid_length( 0usize, &"tuple struct Digest with 1 element", )); } }; Ok(oid::try_from_bytes(__field0).expect("hash of known length")) } } serde::Deserializer::deserialize_newtype_struct( deserializer, "Digest", __Visitor { marker: std::marker::PhantomData::<&'a oid>, lifetime: std::marker::PhantomData, }, ) }}
use std::{convert::TryInto, fmt};
use crate::{ObjectId, SIZE_OF_SHA1_DIGEST};
/// A borrowed reference to a hash identifying objects.
///
/// # Future Proofing
///
/// In case we wish to support multiple hashes with the same length we cannot discriminate
/// using the slice length anymore. To make that work, we will use the high bits of the
/// internal `bytes` slice length (a fat pointer, pointing to data and its length in bytes)
/// to encode additional information. Before accessing or returning the bytes, a new adjusted
/// slice will be constructed, while the high bits will be used to help resolving the
/// hash `[`kind()`][oid::kind()]`.
/// We expect to have quite a few bits available for such 'conflict resolution' as most hashes aren't longer
/// than 64 bytes.
#[derive(PartialEq, Eq, Hash, Ord, PartialOrd)]
#[repr(transparent)]
#[allow(non_camel_case_types)]
#[cfg_attr(feature = "serde1", derive(serde::Serialize))]
pub struct oid {
bytes: [u8],
}
/// A utility able to format itself with the given amount of characters in hex
#[derive(PartialEq, Eq, Hash, Ord, PartialOrd)]
pub struct HexDisplay<'a> {
inner: &'a oid,
hex_len: usize,
}
impl<'a> fmt::Display for HexDisplay<'a> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut hex = crate::Kind::hex_buf();
let max_len = self.inner.hex_to_buf(hex.as_mut());
let hex = std::str::from_utf8(&hex[..self.hex_len.min(max_len)]).expect("ascii only in hex");
f.write_str(hex)
}
}
impl fmt::Debug for oid {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> std::fmt::Result {
write!(
f,
"{}({})",
match self.kind() {
crate::Kind::Sha1 => "Sha1",
},
self.to_hex(),
)
}
}
#[derive(Debug, thiserror::Error)]
pub enum Error {
#[error("Cannot instantiate git hash from a digest of length {0}")]
InvalidByteSliceLength(usize),
}
/// Conversion
impl oid {
/// Try to create a shared object id from a slice of bytes representing a hash `digest`
#[inline]
pub fn try_from_bytes(digest: &[u8]) -> Result<&Self, Error> {
match digest.len() {
20 => Ok(
#[allow(unsafe_code)]
unsafe {
&*(digest as *const [u8] as *const oid)
},
),
len => Err(Error::InvalidByteSliceLength(len)),
}
}
/// Create an OID from the input `value` slice without performing any safety check.
/// Use only once sure that `value` is a hash of valid length.
pub fn from_bytes_unchecked(value: &[u8]) -> &Self {
Self::from_bytes(value)
}
/// Only from code that statically assures correct sizes using array conversions
pub(crate) fn from_bytes(value: &[u8]) -> &Self {
#[allow(unsafe_code)]
unsafe {
&*(value as *const [u8] as *const oid)
}
}
}
/// Access
impl oid {
/// The kind of hash used for this Digest
#[inline]
pub fn kind(&self) -> crate::Kind {
crate::Kind::from_len_in_bytes(self.bytes.len())
}
/// The first byte of the hash, commonly used to partition a set of `Id`s
#[inline]
pub fn first_byte(&self) -> u8 {
self.bytes[0]
}
/// Interpret this object id as raw byte slice.
#[inline]
pub fn as_bytes(&self) -> &[u8] {
&self.bytes
}
/// Return a type which can display itself in hexadecimal form with the `len` amount of characters.
#[inline]
pub fn to_hex_with_len(&self, len: usize) -> HexDisplay<'_> {
HexDisplay {
inner: self,
hex_len: len,
}
}
/// Return a type which displays this oid as hex in full.
#[inline]
pub fn to_hex(&self) -> HexDisplay<'_> {
HexDisplay {
inner: self,
hex_len: self.bytes.len() * 2,
}
}
}
/// Sha1 specific methods
impl oid {
/// Write ourselves to the `out` in hexadecimal notation, returning the amount of written bytes.
///
/// **Panics** if the buffer isn't big enough to hold twice as many bytes as the current binary size.
#[inline]
#[must_use]
pub fn hex_to_buf(&self, buf: &mut [u8]) -> usize {
let num_hex_bytes = self.bytes.len() * 2;
hex::encode_to_slice(&self.bytes, &mut buf[..num_hex_bytes]).expect("to count correctly");
num_hex_bytes
}
/// Write ourselves to `out` in hexadecimal notation
#[inline]
pub fn write_hex_to(&self, mut out: impl std::io::Write) -> std::io::Result<()> {
let mut hex = crate::Kind::hex_buf();
let hex_len = self.hex_to_buf(&mut hex);
out.write_all(&hex[..hex_len])
}
/// Returns a Sha1 digest with all bytes being initialized to zero.
#[inline]
pub(crate) fn null_sha1() -> &'static Self {
oid::from_bytes([0u8; SIZE_OF_SHA1_DIGEST].as_ref())
}
}
impl AsRef<oid> for &oid {
fn as_ref(&self) -> &oid {
self
}
}
impl ToOwned for oid {
type Owned = crate::ObjectId;
fn to_owned(&self) -> Self::Owned {
match self.kind() {
crate::Kind::Sha1 => crate::ObjectId::Sha1(self.bytes.try_into().expect("no bug in hash detection")),
}
}
}
impl<'a> From<&'a [u8; SIZE_OF_SHA1_DIGEST]> for &'a oid {
fn from(v: &'a [u8; SIZE_OF_SHA1_DIGEST]) -> Self {
oid::from_bytes(v.as_ref())
}
}
impl fmt::Display for &oid {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
for b in self.as_bytes() {
write!(f, "{b:02x}")?;
}
Ok(())
}
}
impl PartialEq<crate::ObjectId> for &oid {
fn eq(&self, other: &ObjectId) -> bool {
*self == other.as_ref()
}
}
/// Manually created from a version that uses a slice, and we forcefully try to convert it into a borrowed array of the desired size
/// Could be improved by fitting this into serde
/// Unfortunately the serde::Deserialize derive wouldn't work for borrowed arrays.
#[cfg(feature = "serde1")]
impl<'de: 'a, 'a> serde::Deserialize<'de> for &'a oid {
fn deserialize<D>(deserializer: D) -> Result<Self, <D as serde::Deserializer<'de>>::Error>
where
D: serde::Deserializer<'de>,
{
struct __Visitor<'de: 'a, 'a> {
marker: std::marker::PhantomData<&'a oid>,
lifetime: std::marker::PhantomData<&'de ()>,
}
impl<'de: 'a, 'a> serde::de::Visitor<'de> for __Visitor<'de, 'a> {
type Value = &'a oid;
fn expecting(&self, __formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
std::fmt::Formatter::write_str(__formatter, "tuple struct Digest")
}
#[inline]
fn visit_newtype_struct<__E>(self, __e: __E) -> std::result::Result<Self::Value, __E::Error>
where
__E: serde::Deserializer<'de>,
{
let __field0: &'a [u8] = match <&'a [u8] as serde::Deserialize>::deserialize(__e) {
Ok(__val) => __val,
Err(__err) => {
return Err(__err);
}
};
Ok(oid::try_from_bytes(__field0).expect("hash of known length"))
}
#[inline]
fn visit_seq<__A>(self, mut __seq: __A) -> std::result::Result<Self::Value, __A::Error>
where
__A: serde::de::SeqAccess<'de>,
{
let __field0 = match match serde::de::SeqAccess::next_element::<&'a [u8]>(&mut __seq) {
Ok(__val) => __val,
Err(__err) => {
return Err(__err);
}
} {
Some(__value) => __value,
None => {
return Err(serde::de::Error::invalid_length(
0usize,
&"tuple struct Digest with 1 element",
));
}
};
Ok(oid::try_from_bytes(__field0).expect("hash of known length"))
}
}
serde::Deserializer::deserialize_newtype_struct(
deserializer,
"Digest",
__Visitor {
marker: std::marker::PhantomData::<&'a oid>,
lifetime: std::marker::PhantomData,
},
)
}
}