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use std::path::PathBuf;
use gix_error::{ErrorExt, ExnResult, Message, ResultExt, message};
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,
}
}
}
/// Initialization
impl packed::Buffer {
fn open_with_backing(backing: packed::Backing, path: PathBuf, object_hash: gix_hash::Kind) -> ExnResult<Self> {
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(|()| {
gix_error::corruption("The header could not be parsed, even though first line started with '#'")
.raise_erased()
})?;
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..], object_hash)
.or_raise_erased(|| message("Could not iterate unsorted packed refs"))?
.collect::<Result<Vec<_>, _>>()
.or_erased()?;
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');
}
}
(packed::Backing::InMemory(serialized), 0)
} else {
(backing, offset)
}
};
Ok(packed::Buffer {
offset,
data: backing,
path,
object_hash,
})
}
/// Open the file at `path`, parsing object ids as `object_hash`, 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.
///
/// I/O failures include [metadata](gix_error::Exn::metadata()) `path` (native path), the packed-refs file.
pub fn open(
path: PathBuf,
use_memory_map_if_larger_than_bytes: u64,
object_hash: gix_hash::Kind,
) -> ExnResult<Self> {
let backing = (|| -> std::io::Result<packed::Backing> {
Ok(
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: Git replaces packed-refs rather than changing a mapped file in place.
#[expect(unsafe_code)]
unsafe {
memmap2::MmapOptions::new().map_copy_read_only(&std::fs::File::open(&path)?)?
},
)
},
)
})()
.or_raise_erased(|| Message::new("Could not open packed refs").with("path", path.as_path()))?;
Self::open_with_backing(backing, path, object_hash)
}
/// Open a buffer from `bytes`, which is the content of a typical `packed-refs` file, parsing object ids as
/// `object_hash`.
///
/// 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], object_hash: gix_hash::Kind) -> ExnResult<Self> {
let backing = packed::Backing::InMemory(bytes.into());
Self::open_with_backing(backing, PathBuf::from("<memory>"), object_hash)
}
}