revlog.rs
331 lines
| 9.8 KiB
| application/rls-services+xml
|
RustLexer
|
r46097 | use std::borrow::Cow; | ||
use std::fs::File; | ||||
use std::io::Read; | ||||
use std::ops::Deref; | ||||
use std::path::Path; | ||||
use byteorder::{BigEndian, ByteOrder}; | ||||
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r46102 | use crypto::digest::Digest; | ||
use crypto::sha1::Sha1; | ||||
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r46097 | use flate2::read::ZlibDecoder; | ||
use memmap::{Mmap, MmapOptions}; | ||||
use micro_timer::timed; | ||||
use zstd; | ||||
use super::index::Index; | ||||
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r46102 | use super::node::{NODE_BYTES_LENGTH, NULL_NODE_ID}; | ||
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r46097 | use super::patch; | ||
use crate::revlog::Revision; | ||||
pub enum RevlogError { | ||||
IoError(std::io::Error), | ||||
UnsuportedVersion(u16), | ||||
InvalidRevision, | ||||
Corrupted, | ||||
UnknowDataFormat(u8), | ||||
} | ||||
fn mmap_open(path: &Path) -> Result<Mmap, std::io::Error> { | ||||
let file = File::open(path)?; | ||||
let mmap = unsafe { MmapOptions::new().map(&file) }?; | ||||
Ok(mmap) | ||||
} | ||||
/// Read only implementation of revlog. | ||||
pub struct Revlog { | ||||
/// When index and data are not interleaved: bytes of the revlog index. | ||||
/// When index and data are interleaved: bytes of the revlog index and | ||||
/// data. | ||||
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r46175 | index: Index, | ||
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r46097 | /// When index and data are not interleaved: bytes of the revlog data | ||
data_bytes: Option<Box<dyn Deref<Target = [u8]> + Send>>, | ||||
} | ||||
impl Revlog { | ||||
/// Open a revlog index file. | ||||
/// | ||||
/// It will also open the associated data file if index and data are not | ||||
/// interleaved. | ||||
#[timed] | ||||
pub fn open(index_path: &Path) -> Result<Self, RevlogError> { | ||||
let index_mmap = | ||||
mmap_open(&index_path).map_err(RevlogError::IoError)?; | ||||
let version = get_version(&index_mmap); | ||||
if version != 1 { | ||||
return Err(RevlogError::UnsuportedVersion(version)); | ||||
} | ||||
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r46176 | let index = Index::new(Box::new(index_mmap))?; | ||
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r46097 | |||
// TODO load data only when needed // | ||||
// type annotation required | ||||
// won't recognize Mmap as Deref<Target = [u8]> | ||||
let data_bytes: Option<Box<dyn Deref<Target = [u8]> + Send>> = | ||||
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r46175 | if index.is_inline() { | ||
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r46097 | None | ||
} else { | ||||
let data_path = index_path.with_extension("d"); | ||||
let data_mmap = | ||||
mmap_open(&data_path).map_err(RevlogError::IoError)?; | ||||
Some(Box::new(data_mmap)) | ||||
}; | ||||
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r46175 | Ok(Revlog { index, data_bytes }) | ||
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r46097 | } | ||
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r46105 | /// Return number of entries of the `Revlog`. | ||
pub fn len(&self) -> usize { | ||||
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r46175 | self.index.len() | ||
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r46105 | } | ||
/// Returns `true` if the `Revlog` has zero `entries`. | ||||
pub fn is_empty(&self) -> bool { | ||||
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r46175 | self.index.is_empty() | ||
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r46105 | } | ||
/// Return the full data associated to a node. | ||||
#[timed] | ||||
pub fn get_node_rev(&self, node: &[u8]) -> Result<Revision, RevlogError> { | ||||
// This is brute force. But it is fast enough for now. | ||||
// Optimization will come later. | ||||
for rev in (0..self.len() as Revision).rev() { | ||||
let index_entry = | ||||
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r46175 | self.index.get_entry(rev).ok_or(RevlogError::Corrupted)?; | ||
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r46105 | if node == index_entry.hash() { | ||
return Ok(rev); | ||||
} | ||||
} | ||||
Err(RevlogError::InvalidRevision) | ||||
} | ||||
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r46097 | /// Return the full data associated to a revision. | ||
/// | ||||
/// All entries required to build the final data out of deltas will be | ||||
/// retrieved as needed, and the deltas will be applied to the inital | ||||
/// snapshot to rebuild the final data. | ||||
#[timed] | ||||
pub fn get_rev_data(&self, rev: Revision) -> Result<Vec<u8>, RevlogError> { | ||||
// Todo return -> Cow | ||||
let mut entry = self.get_entry(rev)?; | ||||
let mut delta_chain = vec![]; | ||||
while let Some(base_rev) = entry.base_rev { | ||||
delta_chain.push(entry); | ||||
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r46177 | entry = | ||
self.get_entry(base_rev).or(Err(RevlogError::Corrupted))?; | ||||
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r46097 | } | ||
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r46102 | // TODO do not look twice in the index | ||
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r46175 | let index_entry = self | ||
.index | ||||
.get_entry(rev) | ||||
.ok_or(RevlogError::InvalidRevision)?; | ||||
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r46102 | |||
let data: Vec<u8> = if delta_chain.is_empty() { | ||||
entry.data()?.into() | ||||
} else { | ||||
Revlog::build_data_from_deltas(entry, &delta_chain)? | ||||
}; | ||||
if self.check_hash( | ||||
index_entry.p1(), | ||||
index_entry.p2(), | ||||
index_entry.hash(), | ||||
&data, | ||||
) { | ||||
Ok(data) | ||||
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r46097 | } else { | ||
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r46102 | Err(RevlogError::Corrupted) | ||
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r46097 | } | ||
} | ||||
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r46102 | /// Check the hash of some given data against the recorded hash. | ||
pub fn check_hash( | ||||
&self, | ||||
p1: Revision, | ||||
p2: Revision, | ||||
expected: &[u8], | ||||
data: &[u8], | ||||
) -> bool { | ||||
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r46175 | let e1 = self.index.get_entry(p1); | ||
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r46102 | let h1 = match e1 { | ||
Some(ref entry) => entry.hash(), | ||||
None => &NULL_NODE_ID, | ||||
}; | ||||
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r46175 | let e2 = self.index.get_entry(p2); | ||
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r46102 | let h2 = match e2 { | ||
Some(ref entry) => entry.hash(), | ||||
None => &NULL_NODE_ID, | ||||
}; | ||||
hash(data, &h1, &h2).as_slice() == expected | ||||
} | ||||
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r46097 | /// Build the full data of a revision out its snapshot | ||
/// and its deltas. | ||||
#[timed] | ||||
fn build_data_from_deltas( | ||||
snapshot: RevlogEntry, | ||||
deltas: &[RevlogEntry], | ||||
) -> Result<Vec<u8>, RevlogError> { | ||||
let snapshot = snapshot.data()?; | ||||
let deltas = deltas | ||||
.iter() | ||||
.rev() | ||||
.map(RevlogEntry::data) | ||||
.collect::<Result<Vec<Cow<'_, [u8]>>, RevlogError>>()?; | ||||
let patches: Vec<_> = | ||||
deltas.iter().map(|d| patch::PatchList::new(d)).collect(); | ||||
let patch = patch::fold_patch_lists(&patches); | ||||
Ok(patch.apply(&snapshot)) | ||||
} | ||||
/// Return the revlog data. | ||||
fn data(&self) -> &[u8] { | ||||
match self.data_bytes { | ||||
Some(ref data_bytes) => &data_bytes, | ||||
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r46175 | None => panic!( | ||
"forgot to load the data or trying to access inline data" | ||||
), | ||||
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r46097 | } | ||
} | ||||
/// Get an entry of the revlog. | ||||
fn get_entry(&self, rev: Revision) -> Result<RevlogEntry, RevlogError> { | ||||
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r46175 | let index_entry = self | ||
.index | ||||
.get_entry(rev) | ||||
.ok_or(RevlogError::InvalidRevision)?; | ||||
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r46097 | let start = index_entry.offset(); | ||
let end = start + index_entry.compressed_len(); | ||||
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r46175 | let data = if self.index.is_inline() { | ||
self.index.data(start, end) | ||||
} else { | ||||
&self.data()[start..end] | ||||
}; | ||||
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r46097 | let entry = RevlogEntry { | ||
rev, | ||||
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r46175 | bytes: data, | ||
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r46097 | compressed_len: index_entry.compressed_len(), | ||
uncompressed_len: index_entry.uncompressed_len(), | ||||
base_rev: if index_entry.base_revision() == rev { | ||||
None | ||||
} else { | ||||
Some(index_entry.base_revision()) | ||||
}, | ||||
}; | ||||
Ok(entry) | ||||
} | ||||
} | ||||
/// The revlog entry's bytes and the necessary informations to extract | ||||
/// the entry's data. | ||||
#[derive(Debug)] | ||||
pub struct RevlogEntry<'a> { | ||||
rev: Revision, | ||||
bytes: &'a [u8], | ||||
compressed_len: usize, | ||||
uncompressed_len: usize, | ||||
base_rev: Option<Revision>, | ||||
} | ||||
impl<'a> RevlogEntry<'a> { | ||||
/// Extract the data contained in the entry. | ||||
pub fn data(&self) -> Result<Cow<'_, [u8]>, RevlogError> { | ||||
if self.bytes.is_empty() { | ||||
return Ok(Cow::Borrowed(&[])); | ||||
} | ||||
match self.bytes[0] { | ||||
// Revision data is the entirety of the entry, including this | ||||
// header. | ||||
b'\0' => Ok(Cow::Borrowed(self.bytes)), | ||||
// Raw revision data follows. | ||||
b'u' => Ok(Cow::Borrowed(&self.bytes[1..])), | ||||
// zlib (RFC 1950) data. | ||||
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r46169 | b'x' => Ok(Cow::Owned(self.uncompressed_zlib_data()?)), | ||
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r46097 | // zstd data. | ||
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r46169 | b'\x28' => Ok(Cow::Owned(self.uncompressed_zstd_data()?)), | ||
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r46097 | format_type => Err(RevlogError::UnknowDataFormat(format_type)), | ||
} | ||||
} | ||||
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r46169 | fn uncompressed_zlib_data(&self) -> Result<Vec<u8>, RevlogError> { | ||
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r46097 | let mut decoder = ZlibDecoder::new(self.bytes); | ||
if self.is_delta() { | ||||
let mut buf = Vec::with_capacity(self.compressed_len); | ||||
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r46169 | decoder | ||
.read_to_end(&mut buf) | ||||
.or(Err(RevlogError::Corrupted))?; | ||||
Ok(buf) | ||||
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r46097 | } else { | ||
let mut buf = vec![0; self.uncompressed_len]; | ||||
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r46169 | decoder | ||
.read_exact(&mut buf) | ||||
.or(Err(RevlogError::Corrupted))?; | ||||
Ok(buf) | ||||
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r46097 | } | ||
} | ||||
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r46169 | fn uncompressed_zstd_data(&self) -> Result<Vec<u8>, RevlogError> { | ||
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r46097 | if self.is_delta() { | ||
let mut buf = Vec::with_capacity(self.compressed_len); | ||||
zstd::stream::copy_decode(self.bytes, &mut buf) | ||||
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r46169 | .or(Err(RevlogError::Corrupted))?; | ||
Ok(buf) | ||||
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r46097 | } else { | ||
let mut buf = vec![0; self.uncompressed_len]; | ||||
let len = zstd::block::decompress_to_buffer(self.bytes, &mut buf) | ||||
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r46169 | .or(Err(RevlogError::Corrupted))?; | ||
if len != self.uncompressed_len { | ||||
Err(RevlogError::Corrupted) | ||||
} else { | ||||
Ok(buf) | ||||
} | ||||
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r46097 | } | ||
} | ||||
/// Tell if the entry is a snapshot or a delta | ||||
/// (influences on decompression). | ||||
fn is_delta(&self) -> bool { | ||||
self.base_rev.is_some() | ||||
} | ||||
} | ||||
/// Format version of the revlog. | ||||
pub fn get_version(index_bytes: &[u8]) -> u16 { | ||||
BigEndian::read_u16(&index_bytes[2..=3]) | ||||
} | ||||
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r46102 | /// Calculate the hash of a revision given its data and its parents. | ||
fn hash(data: &[u8], p1_hash: &[u8], p2_hash: &[u8]) -> Vec<u8> { | ||||
let mut hasher = Sha1::new(); | ||||
let (a, b) = (p1_hash, p2_hash); | ||||
if a > b { | ||||
hasher.input(b); | ||||
hasher.input(a); | ||||
} else { | ||||
hasher.input(a); | ||||
hasher.input(b); | ||||
} | ||||
hasher.input(data); | ||||
let mut hash = vec![0; NODE_BYTES_LENGTH]; | ||||
hasher.result(&mut hash); | ||||
hash | ||||
} | ||||
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r46097 | #[cfg(test)] | ||
mod tests { | ||||
use super::*; | ||||
use super::super::index::IndexEntryBuilder; | ||||
#[test] | ||||
fn version_test() { | ||||
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r46175 | let bytes = IndexEntryBuilder::new() | ||
.is_first(true) | ||||
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r46097 | .with_version(1) | ||
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r46175 | .build(); | ||
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r46097 | |||
assert_eq!(get_version(&bytes), 1) | ||||
} | ||||
} | ||||