use std::io; use gix_features::decode::{leb64, leb64_from_read}; use super::{BLOB, COMMIT, OFS_DELTA, REF_DELTA, TAG, TREE};use crate::data; /// The error returned by [data::Entry::from_bytes()].#[derive(Debug, thiserror::Error)]#[allow(missing_docs)]#[error("Object type {type_id} is unsupported")]pub struct Error { pub type_id: u8,} /// Decodingimpl data::Entry { /// Decode an entry from the given entry data `d`, providing the `pack_offset` to allow tracking the start of the entry data section. /// /// # Panics /// /// If we cannot understand the header, garbage data is likely to trigger this. pub fn from_bytes(d: &[u8], pack_offset: data::Offset, hash_len: usize) -> Result<data::Entry, Error> { let (type_id, size, mut consumed) = parse_header_info(d); use crate::data::entry::Header::*; let object = match type_id { OFS_DELTA => { let (distance, leb_bytes) = leb64(&d[consumed..]); let delta = OfsDelta { base_distance: distance, }; consumed += leb_bytes; delta } REF_DELTA => { let delta = RefDelta { base_id: gix_hash::ObjectId::from_bytes_or_panic(&d[consumed..][..hash_len]), }; consumed += hash_len; delta } BLOB => Blob, TREE => Tree, COMMIT => Commit, TAG => Tag, other => return Err(Error { type_id: other }), }; Ok(data::Entry { header: object, decompressed_size: size, data_offset: pack_offset + consumed as u64, }) } /// Instantiate an `Entry` from the reader `r`, providing the `pack_offset` to allow tracking the start of the entry data section. pub fn from_read(r: &mut dyn io::Read, pack_offset: data::Offset, hash_len: usize) -> io::Result<data::Entry> { let (type_id, size, mut consumed) = streaming_parse_header_info(r)?; use crate::data::entry::Header::*; let object = match type_id { OFS_DELTA => { let (distance, leb_bytes) = leb64_from_read(r)?; let delta = OfsDelta { base_distance: distance, }; consumed += leb_bytes; delta } REF_DELTA => { let mut buf = gix_hash::Kind::buf(); let hash = &mut buf[..hash_len]; r.read_exact(hash)?; #[allow(clippy::redundant_slicing)] let delta = RefDelta { base_id: gix_hash::ObjectId::from_bytes_or_panic(&hash[..]), }; consumed += hash_len; delta } BLOB => Blob, TREE => Tree, COMMIT => Commit, TAG => Tag, other => return Err(io::Error::other(format!("Object type {other} is unsupported"))), }; Ok(data::Entry { header: object, decompressed_size: size, data_offset: pack_offset + consumed as u64, }) }} #[inline]fn streaming_parse_header_info(read: &mut dyn io::Read) -> Result<(u8, u64, usize), io::Error> { let mut byte = [0u8; 1]; read.read_exact(&mut byte)?; let mut c = byte[0]; let mut i = 1; let type_id = (c >> 4) & 0b0000_0111; let mut size = u64::from(c) & 0b0000_1111; let mut s = 4; while c & 0b1000_0000 != 0 { read.read_exact(&mut byte)?; c = byte[0]; i += 1; size += u64::from(c & 0b0111_1111) << s; s += 7; } Ok((type_id, size, i))} /// Parses the header of a pack-entry, yielding object type id, decompressed object size, and consumed bytes#[inline]fn parse_header_info(data: &[u8]) -> (u8, u64, usize) { let mut c = data[0]; let mut i = 1; let type_id = (c >> 4) & 0b0000_0111; let mut size = u64::from(c) & 0b0000_1111; let mut s = 4; while c & 0b1000_0000 != 0 { c = data[i]; i += 1; size += u64::from(c & 0b0111_1111) << s; s += 7; } (type_id, size, i)}
use std::io;
use gix_features::decode::{leb64, leb64_from_read};
use super::{BLOB, COMMIT, OFS_DELTA, REF_DELTA, TAG, TREE};
use crate::data;
/// The error returned by [data::Entry::from_bytes()].
#[derive(Debug, thiserror::Error)]
#[allow(missing_docs)]
#[error("Object type {type_id} is unsupported")]
pub struct Error {
pub type_id: u8,
}
/// Decoding
impl data::Entry {
/// Decode an entry from the given entry data `d`, providing the `pack_offset` to allow tracking the start of the entry data section.
///
/// # Panics
///
/// If we cannot understand the header, garbage data is likely to trigger this.
pub fn from_bytes(d: &[u8], pack_offset: data::Offset, hash_len: usize) -> Result<data::Entry, Error> {
let (type_id, size, mut consumed) = parse_header_info(d);
use crate::data::entry::Header::*;
let object = match type_id {
OFS_DELTA => {
let (distance, leb_bytes) = leb64(&d[consumed..]);
let delta = OfsDelta {
base_distance: distance,
};
consumed += leb_bytes;
delta
}
REF_DELTA => {
let delta = RefDelta {
base_id: gix_hash::ObjectId::from_bytes_or_panic(&d[consumed..][..hash_len]),
};
consumed += hash_len;
delta
}
BLOB => Blob,
TREE => Tree,
COMMIT => Commit,
TAG => Tag,
other => return Err(Error { type_id: other }),
};
Ok(data::Entry {
header: object,
decompressed_size: size,
data_offset: pack_offset + consumed as u64,
})
}
/// Instantiate an `Entry` from the reader `r`, providing the `pack_offset` to allow tracking the start of the entry data section.
pub fn from_read(r: &mut dyn io::Read, pack_offset: data::Offset, hash_len: usize) -> io::Result<data::Entry> {
let (type_id, size, mut consumed) = streaming_parse_header_info(r)?;
use crate::data::entry::Header::*;
let object = match type_id {
OFS_DELTA => {
let (distance, leb_bytes) = leb64_from_read(r)?;
let delta = OfsDelta {
base_distance: distance,
};
consumed += leb_bytes;
delta
}
REF_DELTA => {
let mut buf = gix_hash::Kind::buf();
let hash = &mut buf[..hash_len];
r.read_exact(hash)?;
#[allow(clippy::redundant_slicing)]
let delta = RefDelta {
base_id: gix_hash::ObjectId::from_bytes_or_panic(&hash[..]),
};
consumed += hash_len;
delta
}
BLOB => Blob,
TREE => Tree,
COMMIT => Commit,
TAG => Tag,
other => return Err(io::Error::other(format!("Object type {other} is unsupported"))),
};
Ok(data::Entry {
header: object,
decompressed_size: size,
data_offset: pack_offset + consumed as u64,
})
}
}
#[inline]
fn streaming_parse_header_info(read: &mut dyn io::Read) -> Result<(u8, u64, usize), io::Error> {
let mut byte = [0u8; 1];
read.read_exact(&mut byte)?;
let mut c = byte[0];
let mut i = 1;
let type_id = (c >> 4) & 0b0000_0111;
let mut size = u64::from(c) & 0b0000_1111;
let mut s = 4;
while c & 0b1000_0000 != 0 {
read.read_exact(&mut byte)?;
c = byte[0];
i += 1;
size += u64::from(c & 0b0111_1111) << s;
s += 7;
}
Ok((type_id, size, i))
}
/// Parses the header of a pack-entry, yielding object type id, decompressed object size, and consumed bytes
#[inline]
fn parse_header_info(data: &[u8]) -> (u8, u64, usize) {
let mut c = data[0];
let mut i = 1;
let type_id = (c >> 4) & 0b0000_0111;
let mut size = u64::from(c) & 0b0000_1111;
let mut s = 4;
while c & 0b1000_0000 != 0 {
c = data[i];
i += 1;
size += u64::from(c & 0b0111_1111) << s;
s += 7;
}
(type_id, size, i)
}