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find.rs
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find.rs
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use std::{cmp::Ordering, collections::HashSet, fs, io::Read, path::PathBuf};
use git_features::zlib;
use crate::store_impls::loose::{hash_path, Store, HEADER_READ_UNCOMPRESSED_BYTES};
/// Returned by [`Store::try_find()`]
#[derive(thiserror::Error, Debug)]
#[allow(missing_docs)]
pub enum Error {
#[error("decompression of loose object at '{path}' failed")]
DecompressFile {
source: zlib::inflate::Error,
path: PathBuf,
},
#[error(transparent)]
Decode(#[from] git_object::decode::LooseHeaderDecodeError),
#[error("Could not {action} data at '{path}'")]
Io {
source: std::io::Error,
action: &'static str,
path: PathBuf,
},
}
/// Object lookup
impl Store {
const OPEN_ACTION: &'static str = "open";
/// Returns true if the given id is contained in our repository.
pub fn contains(&self, id: impl AsRef<git_hash::oid>) -> bool {
debug_assert_eq!(self.object_hash, id.as_ref().kind());
hash_path(id.as_ref(), self.path.clone()).is_file()
}
/// Given a `prefix`, find an object that matches it uniquely within this loose object
/// database as `Ok(Some(Ok(<oid>)))`.
/// If there is more than one object matching the object `Ok(Some(Err(()))` is returned.
///
/// Finally, if no object matches, the return value is `Ok(None)`.
///
/// The outer `Result` is to indicate errors during file system traversal.
///
/// Pass `candidates` to obtain the set of all object ids matching `prefix`, with the same return value as
/// one would have received if it remained `None`.
pub fn lookup_prefix(
&self,
prefix: git_hash::Prefix,
mut candidates: Option<&mut HashSet<git_hash::ObjectId>>,
) -> Result<Option<crate::find::PrefixLookupResult>, crate::loose::iter::Error> {
let single_directory_iter = crate::loose::Iter {
inner: git_features::fs::walkdir_new(&self.path.join(prefix.as_oid().to_hex_with_len(2).to_string()))
.min_depth(1)
.max_depth(1)
.follow_links(false)
.into_iter(),
hash_hex_len: prefix.as_oid().kind().len_in_hex(),
};
let mut candidate = None;
for oid in single_directory_iter {
let oid = match oid {
Ok(oid) => oid,
Err(err) => match err.io_error() {
Some(err) if err.kind() == std::io::ErrorKind::NotFound => return Ok(None),
None | Some(_) => return Err(err),
},
};
if prefix.cmp_oid(&oid) == Ordering::Equal {
match &mut candidates {
Some(candidates) => {
candidates.insert(oid);
}
None => {
if candidate.is_some() {
return Ok(Some(Err(())));
}
candidate = Some(oid);
}
}
}
}
match &mut candidates {
Some(candidates) => match candidates.len() {
0 => Ok(None),
1 => Ok(candidates.iter().next().cloned().map(Ok)),
_ => Ok(Some(Err(()))),
},
None => Ok(candidate.map(Ok)),
}
}
/// Return the object identified by the given [`ObjectId`][git_hash::ObjectId] if present in this database,
/// writing its raw data into the given `out` buffer.
///
/// Returns `Err` if there was an error locating or reading the object. Returns `Ok<None>` if
/// there was no such object.
pub fn try_find<'a>(
&self,
id: impl AsRef<git_hash::oid>,
out: &'a mut Vec<u8>,
) -> Result<Option<git_object::Data<'a>>, Error> {
debug_assert_eq!(self.object_hash, id.as_ref().kind());
match self.find_inner(id.as_ref(), out) {
Ok(obj) => Ok(Some(obj)),
Err(err) => match err {
Error::Io {
source: err,
action,
path,
} => {
if action == Self::OPEN_ACTION && err.kind() == std::io::ErrorKind::NotFound {
Ok(None)
} else {
Err(Error::Io {
source: err,
action,
path,
})
}
}
err => Err(err),
},
}
}
fn find_inner<'a>(&self, id: &git_hash::oid, buf: &'a mut Vec<u8>) -> Result<git_object::Data<'a>, Error> {
let path = hash_path(id, self.path.clone());
let mut inflate = zlib::Inflate::default();
let ((status, consumed_in, consumed_out), bytes_read) = {
let mut istream = fs::File::open(&path).map_err(|e| Error::Io {
source: e,
action: Self::OPEN_ACTION,
path: path.to_owned(),
})?;
buf.clear();
let bytes_read = istream.read_to_end(buf).map_err(|e| Error::Io {
source: e,
action: "read",
path: path.to_owned(),
})?;
buf.resize(bytes_read + HEADER_READ_UNCOMPRESSED_BYTES, 0);
let (input, output) = buf.split_at_mut(bytes_read);
(
inflate
.once(&input[..bytes_read], output)
.map_err(|e| Error::DecompressFile {
source: e,
path: path.to_owned(),
})?,
bytes_read,
)
};
assert_ne!(
status,
zlib::Status::BufError,
"Buffer errors might mean we encountered huge headers"
);
let decompressed_start = bytes_read;
let (kind, size, header_size) =
git_object::decode::loose_header(&buf[decompressed_start..decompressed_start + consumed_out])?;
if status == zlib::Status::StreamEnd {
let decompressed_body_bytes_sans_header =
decompressed_start + header_size..decompressed_start + consumed_out;
assert_eq!(
consumed_out,
size + header_size,
"At this point we have decompressed everything and given 'size' should match"
);
buf.copy_within(decompressed_body_bytes_sans_header, 0);
} else {
buf.resize(bytes_read + size + header_size, 0);
{
let (input, output) = buf.split_at_mut(bytes_read);
let num_decompressed_bytes = zlib::stream::inflate::read(
&mut &input[consumed_in..],
&mut inflate.state,
&mut output[consumed_out..],
)
.map_err(|e| Error::Io {
source: e,
action: "deflate",
path: path.to_owned(),
})?;
assert_eq!(
num_decompressed_bytes + consumed_out,
size + header_size,
"Object should have been decompressed entirely and match given 'size'"
);
};
buf.copy_within(decompressed_start + header_size.., 0);
}
buf.resize(size, 0);
Ok(git_object::Data { kind, data: buf })
}
}