use std::borrow::Cow; use std::io::Read; use std::ops::Deref; use std::path::Path; use byteorder::{BigEndian, ByteOrder}; use crypto::digest::Digest; use crypto::sha1::Sha1; use flate2::read::ZlibDecoder; use micro_timer::timed; use zstd; use super::index::Index; use super::node::{NodePrefixRef, NODE_BYTES_LENGTH, NULL_NODE}; use super::nodemap; use super::nodemap::NodeMap; use super::nodemap_docket::NodeMapDocket; use super::patch; use crate::repo::Repo; use crate::revlog::Revision; pub enum RevlogError { IoError(std::io::Error), UnsuportedVersion(u16), InvalidRevision, /// Found more than one entry whose ID match the requested prefix AmbiguousPrefix, Corrupted, UnknowDataFormat(u8), } impl From for RevlogError { fn from(_: bytes_cast::FromBytesError) -> Self { RevlogError::Corrupted } } /// 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. index: Index, /// When index and data are not interleaved: bytes of the revlog data data_bytes: Option + Send>>, /// When present on disk: the persistent nodemap for this revlog nodemap: Option, } 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( repo: &Repo, index_path: impl AsRef, data_path: Option<&Path>, ) -> Result { let index_path = index_path.as_ref(); let index_mmap = repo .store_vfs() .mmap_open(&index_path) .map_err(RevlogError::IoError)?; let version = get_version(&index_mmap); if version != 1 { return Err(RevlogError::UnsuportedVersion(version)); } let index = Index::new(Box::new(index_mmap))?; let default_data_path = index_path.with_extension("d"); // type annotation required // won't recognize Mmap as Deref let data_bytes: Option + Send>> = if index.is_inline() { None } else { let data_path = data_path.unwrap_or(&default_data_path); let data_mmap = repo .store_vfs() .mmap_open(data_path) .map_err(RevlogError::IoError)?; Some(Box::new(data_mmap)) }; let nodemap = NodeMapDocket::read_from_file(repo, index_path)?.map( |(docket, data)| { nodemap::NodeTree::load_bytes( Box::new(data), docket.data_length, ) }, ); Ok(Revlog { index, data_bytes, nodemap, }) } /// Return number of entries of the `Revlog`. pub fn len(&self) -> usize { self.index.len() } /// Returns `true` if the `Revlog` has zero `entries`. pub fn is_empty(&self) -> bool { self.index.is_empty() } /// Return the full data associated to a node. #[timed] pub fn get_node_rev( &self, node: NodePrefixRef, ) -> Result { if let Some(nodemap) = &self.nodemap { return nodemap .find_bin(&self.index, node) // TODO: propagate details of this error: .map_err(|_| RevlogError::Corrupted)? .ok_or(RevlogError::InvalidRevision); } // Fallback to linear scan when a persistent nodemap is not present. // This happens when the persistent-nodemap experimental feature is not // enabled, or for small revlogs. // // TODO: consider building a non-persistent nodemap in memory to // optimize these cases. let mut found_by_prefix = None; for rev in (0..self.len() as Revision).rev() { let index_entry = self.index.get_entry(rev).ok_or(RevlogError::Corrupted)?; if node == *index_entry.hash() { return Ok(rev); } if node.is_prefix_of(index_entry.hash()) { if found_by_prefix.is_some() { return Err(RevlogError::AmbiguousPrefix); } found_by_prefix = Some(rev) } } found_by_prefix.ok_or(RevlogError::InvalidRevision) } /// 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, 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); entry = self.get_entry(base_rev).or(Err(RevlogError::Corrupted))?; } // TODO do not look twice in the index let index_entry = self .index .get_entry(rev) .ok_or(RevlogError::InvalidRevision)?; let data: Vec = 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().as_bytes(), &data, ) { Ok(data) } else { Err(RevlogError::Corrupted) } } /// 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 { let e1 = self.index.get_entry(p1); let h1 = match e1 { Some(ref entry) => entry.hash(), None => &NULL_NODE, }; let e2 = self.index.get_entry(p2); let h2 = match e2 { Some(ref entry) => entry.hash(), None => &NULL_NODE, }; hash(data, h1.as_bytes(), h2.as_bytes()).as_slice() == expected } /// Build the full data of a revision out its snapshot /// and its deltas. #[timed] fn build_data_from_deltas( snapshot: RevlogEntry, deltas: &[RevlogEntry], ) -> Result, RevlogError> { let snapshot = snapshot.data()?; let deltas = deltas .iter() .rev() .map(RevlogEntry::data) .collect::>, 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, None => panic!( "forgot to load the data or trying to access inline data" ), } } /// Get an entry of the revlog. fn get_entry(&self, rev: Revision) -> Result { let index_entry = self .index .get_entry(rev) .ok_or(RevlogError::InvalidRevision)?; let start = index_entry.offset(); let end = start + index_entry.compressed_len(); let data = if self.index.is_inline() { self.index.data(start, end) } else { &self.data()[start..end] }; let entry = RevlogEntry { rev, bytes: data, 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, } impl<'a> RevlogEntry<'a> { /// Extract the data contained in the entry. pub fn data(&self) -> Result, 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. b'x' => Ok(Cow::Owned(self.uncompressed_zlib_data()?)), // zstd data. b'\x28' => Ok(Cow::Owned(self.uncompressed_zstd_data()?)), format_type => Err(RevlogError::UnknowDataFormat(format_type)), } } fn uncompressed_zlib_data(&self) -> Result, RevlogError> { let mut decoder = ZlibDecoder::new(self.bytes); if self.is_delta() { let mut buf = Vec::with_capacity(self.compressed_len); decoder .read_to_end(&mut buf) .or(Err(RevlogError::Corrupted))?; Ok(buf) } else { let mut buf = vec![0; self.uncompressed_len]; decoder .read_exact(&mut buf) .or(Err(RevlogError::Corrupted))?; Ok(buf) } } fn uncompressed_zstd_data(&self) -> Result, RevlogError> { if self.is_delta() { let mut buf = Vec::with_capacity(self.compressed_len); zstd::stream::copy_decode(self.bytes, &mut buf) .or(Err(RevlogError::Corrupted))?; Ok(buf) } else { let mut buf = vec![0; self.uncompressed_len]; let len = zstd::block::decompress_to_buffer(self.bytes, &mut buf) .or(Err(RevlogError::Corrupted))?; if len != self.uncompressed_len { Err(RevlogError::Corrupted) } else { Ok(buf) } } } /// 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]) } /// Calculate the hash of a revision given its data and its parents. fn hash(data: &[u8], p1_hash: &[u8], p2_hash: &[u8]) -> Vec { 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 } #[cfg(test)] mod tests { use super::*; use super::super::index::IndexEntryBuilder; #[test] fn version_test() { let bytes = IndexEntryBuilder::new() .is_first(true) .with_version(1) .build(); assert_eq!(get_version(&bytes), 1) } }