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use std::{convert::TryFrom, path::Path};
use crate::multi_index::{chunk, File, Version};
mod error {
use crate::multi_index::chunk;
/// The error returned by [File::at()][super::File::at()].
#[derive(Debug, thiserror::Error)]
#[allow(missing_docs)]
pub enum Error {
#[error("Could not open multi-index file at '{path}'")]
Io {
source: std::io::Error,
path: std::path::PathBuf,
},
#[error("{message}")]
Corrupt { message: &'static str },
#[error("Unsupported multi-index version: {version})")]
UnsupportedVersion { version: u8 },
#[error("Unsupported hash kind: {kind})")]
UnsupportedObjectHash { kind: u8 },
#[error(transparent)]
ChunkFileDecode(#[from] gix_chunk::file::decode::Error),
#[error(transparent)]
MissingChunk(#[from] gix_chunk::file::index::offset_by_kind::Error),
#[error(transparent)]
FileTooLarge(#[from] gix_chunk::file::index::data_by_kind::Error),
#[error("The multi-pack fan doesn't have the correct size of 256 * 4 bytes")]
MultiPackFanSize,
#[error(transparent)]
PackNames(#[from] chunk::index_names::decode::Error),
#[error("multi-index chunk {:?} has invalid size: {message}", String::from_utf8_lossy(.id))]
InvalidChunkSize { id: gix_chunk::Id, message: &'static str },
}
}
pub use error::Error;
/// Initialization
impl File {
/// Open the multi-index file at the given `path`.
pub fn at(path: impl AsRef<Path>) -> Result<Self, Error> {
Self::try_from(path.as_ref())
}
}
impl TryFrom<&Path> for File {
type Error = Error;
fn try_from(path: &Path) -> Result<Self, Self::Error> {
let data = crate::mmap::read_only(path).map_err(|source| Error::Io {
source,
path: path.to_owned(),
})?;
const TRAILER_LEN: usize = gix_hash::Kind::shortest().len_in_bytes(); /* trailing hash */
if data.len()
< Self::HEADER_LEN
+ gix_chunk::file::Index::size_for_entries(4 /*index names, fan, offsets, oids*/)
+ chunk::fanout::SIZE
+ TRAILER_LEN
{
return Err(Error::Corrupt {
message: "multi-index file is truncated and too short",
});
}
let (version, object_hash, num_chunks, num_indices) = {
let (signature, data) = data.split_at(4);
if signature != Self::SIGNATURE {
return Err(Error::Corrupt {
message: "Invalid signature",
});
}
let (version, data) = data.split_at(1);
let version = match version[0] {
1 => Version::V1,
version => return Err(Error::UnsupportedVersion { version }),
};
let (object_hash, data) = data.split_at(1);
let object_hash = gix_hash::Kind::try_from(object_hash[0])
.map_err(|unknown| Error::UnsupportedObjectHash { kind: unknown })?;
let (num_chunks, data) = data.split_at(1);
let num_chunks = num_chunks[0];
let (_num_base_files, data) = data.split_at(1); // TODO: handle base files once it's clear what this does
let (num_indices, _) = data.split_at(4);
let num_indices = crate::read_u32(num_indices);
(version, object_hash, num_chunks, num_indices)
};
let chunks = gix_chunk::file::Index::from_bytes(&data, Self::HEADER_LEN, num_chunks as u32)?;
let index_names = chunks.data_by_id(&data, chunk::index_names::ID)?;
let index_names = chunk::index_names::from_bytes(index_names, num_indices)?;
let fan = chunks.data_by_id(&data, chunk::fanout::ID)?;
let fan = chunk::fanout::from_bytes(fan).ok_or(Error::MultiPackFanSize)?;
let num_objects = fan[255];
let lookup = chunks.validated_usize_offset_by_id(chunk::lookup::ID, |offset| {
chunk::lookup::is_valid(&offset, object_hash, num_objects)
.then_some(offset)
.ok_or(Error::InvalidChunkSize {
id: chunk::lookup::ID,
message: "The chunk with alphabetically ordered object ids doesn't have the correct size",
})
})??;
let offsets = chunks.validated_usize_offset_by_id(chunk::offsets::ID, |offset| {
chunk::offsets::is_valid(&offset, num_objects)
.then_some(offset)
.ok_or(Error::InvalidChunkSize {
id: chunk::offsets::ID,
message: "The chunk with offsets into the pack doesn't have the correct size",
})
})??;
let large_offsets = chunks
.validated_usize_offset_by_id(chunk::large_offsets::ID, |offset| {
chunk::large_offsets::is_valid(&offset)
.then_some(offset)
.ok_or(Error::InvalidChunkSize {
id: chunk::large_offsets::ID,
message: "The chunk with large offsets into the pack doesn't have the correct size",
})
})
.ok()
.transpose()?;
let checksum_offset = chunks.highest_offset() as usize;
let trailer = &data[checksum_offset..];
if trailer.len() != object_hash.len_in_bytes() {
return Err(Error::Corrupt {
message:
"Trailing checksum didn't have the expected size or there were unknown bytes after the checksum.",
});
}
Ok(File {
data,
path: path.to_owned(),
version,
hash_len: object_hash.len_in_bytes(),
object_hash,
fan,
index_names,
lookup_ofs: lookup.start,
offsets_ofs: offsets.start,
large_offsets_ofs: large_offsets.map(|r| r.start),
num_objects,
num_indices,
})
}
}
|
