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use crate::store_impl::packed;
impl AsRef<[u8]> for packed::Buffer {
fn as_ref(&self) -> &[u8] {
&self.data.as_ref()[self.offset..]
}
}
impl AsRef<[u8]> for packed::Backing {
fn as_ref(&self) -> &[u8] {
match self {
packed::Backing::InMemory(data) => data,
packed::Backing::Mapped(map) => map,
}
}
}
///
pub mod open {
use std::path::PathBuf;
use crate::store_impl::packed;
/// Initialization
impl packed::Buffer {
fn open_with_backing(
backing: packed::Backing,
path: PathBuf,
hash_kind: gix_hash::Kind,
) -> Result<Self, Error> {
let (backing, offset) = {
let (offset, sorted) = {
let mut input = backing.as_ref();
if *input.first().unwrap_or(&b' ') == b'#' {
let header = packed::decode::header(&mut input).map_err(|_| Error::HeaderParsing)?;
let offset = backing.as_ref().len() - input.len();
(offset, header.sorted)
} else {
(0, false)
}
};
if !sorted {
// this implementation is likely slower than what git does, but it's less code, too.
let mut entries =
packed::Iter::new(&backing.as_ref()[offset..], hash_kind)?.collect::<Result<Vec<_>, _>>()?;
entries.sort_by_key(|e| e.name.as_bstr());
let mut serialized = Vec::<u8>::new();
for entry in entries {
serialized.extend_from_slice(entry.target);
serialized.push(b' ');
serialized.extend_from_slice(entry.name.as_bstr());
serialized.push(b'\n');
if let Some(object) = entry.object {
serialized.push(b'^');
serialized.extend_from_slice(object);
serialized.push(b'\n');
}
}
(Backing::InMemory(serialized), 0)
} else {
(backing, offset)
}
};
Ok(packed::Buffer {
offset,
data: backing,
path,
hash_kind,
})
}
/// Open the file at `path`, parsing object ids as `hash_kind`, and map it into memory if the file size is larger
/// than `use_memory_map_if_larger_than_bytes`.
///
/// In order to allow fast lookups and optimizations, the contents of the packed refs must be sorted.
/// If that's not the case, they will be sorted on the fly with the data being written into a memory buffer.
pub fn open(
path: PathBuf,
use_memory_map_if_larger_than_bytes: u64,
hash_kind: gix_hash::Kind,
) -> Result<Self, Error> {
let backing = if std::fs::metadata(&path)?.len() <= use_memory_map_if_larger_than_bytes {
packed::Backing::InMemory(std::fs::read(&path)?)
} else {
packed::Backing::Mapped(
// SAFETY: we have to take the risk of somebody changing the file underneath. Git never writes into the same file.
#[allow(unsafe_code)]
unsafe {
memmap2::MmapOptions::new().map_copy_read_only(&std::fs::File::open(&path)?)?
},
)
};
Self::open_with_backing(backing, path, hash_kind)
}
/// Open a buffer from `bytes`, which is the content of a typical `packed-refs` file, parsing object ids as
/// `hash_kind`.
///
/// In order to allow fast lookups and optimizations, the contents of the packed refs must be sorted.
/// If that's not the case, they will be sorted on the fly.
pub fn from_bytes(bytes: &[u8], hash_kind: gix_hash::Kind) -> Result<Self, Error> {
let backing = packed::Backing::InMemory(bytes.into());
Self::open_with_backing(backing, PathBuf::from("<memory>"), hash_kind)
}
}
mod error {
use crate::packed;
/// The error returned by [`open()`][super::packed::Buffer::open()].
#[derive(Debug, thiserror::Error)]
#[allow(missing_docs)]
pub enum Error {
#[error("The packed-refs file did not have a header or wasn't sorted and could not be iterated")]
Iter(#[from] packed::iter::Error),
#[error("The header could not be parsed, even though first line started with '#'")]
HeaderParsing,
#[error("The buffer could not be opened or read")]
Io(#[from] std::io::Error),
}
}
pub use error::Error;
use crate::packed::Backing;
}