Mercurial > hg
view rust/hg-core/src/revlog/revlog.rs @ 49210:cc92ad0e8185 stable
rhg: correctly handle the case where diffs are encoded relative to nullrev
returning a valid entry for nullrev fix chain that delta against nullrev.
author | Arseniy Alekseyev <aalekseyev@janestreet.com> |
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date | Sun, 22 May 2022 14:21:59 +0200 |
parents | e91aa800ae5b |
children | 13dfad0f9f7a |
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use std::borrow::Cow; use std::convert::TryFrom; use std::io::Read; use std::ops::Deref; use std::path::Path; use flate2::read::ZlibDecoder; use micro_timer::timed; use sha1::{Digest, Sha1}; use zstd; use super::index::Index; use super::node::{NodePrefix, NODE_BYTES_LENGTH, NULL_NODE}; use super::nodemap; use super::nodemap::{NodeMap, NodeMapError}; use super::nodemap_docket::NodeMapDocket; use super::patch; use crate::errors::HgError; use crate::repo::Repo; use crate::revlog::Revision; use crate::{Node, NULL_REVISION}; const REVISION_FLAG_CENSORED: u16 = 1 << 15; const REVISION_FLAG_ELLIPSIS: u16 = 1 << 14; const REVISION_FLAG_EXTSTORED: u16 = 1 << 13; const REVISION_FLAG_HASCOPIESINFO: u16 = 1 << 12; // Keep this in sync with REVIDX_KNOWN_FLAGS in // mercurial/revlogutils/flagutil.py const REVIDX_KNOWN_FLAGS: u16 = REVISION_FLAG_CENSORED | REVISION_FLAG_ELLIPSIS | REVISION_FLAG_EXTSTORED | REVISION_FLAG_HASCOPIESINFO; const NULL_REVLOG_ENTRY_FLAGS: u16 = 0; #[derive(derive_more::From)] pub enum RevlogError { InvalidRevision, /// Working directory is not supported WDirUnsupported, /// Found more than one entry whose ID match the requested prefix AmbiguousPrefix, #[from] Other(HgError), } impl From<NodeMapError> for RevlogError { fn from(error: NodeMapError) -> Self { match error { NodeMapError::MultipleResults => RevlogError::AmbiguousPrefix, NodeMapError::RevisionNotInIndex(_) => RevlogError::corrupted(), } } } fn corrupted() -> HgError { HgError::corrupted("corrupted revlog") } impl RevlogError { fn corrupted() -> Self { RevlogError::Other(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<Box<dyn Deref<Target = [u8]> + Send>>, /// When present on disk: the persistent nodemap for this revlog nodemap: Option<nodemap::NodeTree>, } 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<Path>, data_path: Option<&Path>, ) -> Result<Self, HgError> { let index_path = index_path.as_ref(); let index = { match repo.store_vfs().mmap_open_opt(&index_path)? { None => Index::new(Box::new(vec![])), Some(index_mmap) => { let index = Index::new(Box::new(index_mmap))?; Ok(index) } } }?; let default_data_path = index_path.with_extension("d"); // type annotation required // won't recognize Mmap as Deref<Target = [u8]> let data_bytes: Option<Box<dyn Deref<Target = [u8]> + 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)?; Some(Box::new(data_mmap)) }; let nodemap = if index.is_inline() { None } else { 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() } /// Returns the node ID for the given revision number, if it exists in this /// revlog pub fn node_from_rev(&self, rev: Revision) -> Option<&Node> { if rev == NULL_REVISION { return Some(&NULL_NODE); } Some(self.index.get_entry(rev)?.hash()) } /// Return the revision number for the given node ID, if it exists in this /// revlog #[timed] pub fn rev_from_node( &self, node: NodePrefix, ) -> Result<Revision, RevlogError> { if node.is_prefix_of(&NULL_NODE) { return Ok(NULL_REVISION); } if let Some(nodemap) = &self.nodemap { return nodemap .find_bin(&self.index, node)? .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(HgError::corrupted( "revlog references a revision not in the index", ))?; 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) } /// Returns whether the given revision exists in this revlog. pub fn has_rev(&self, rev: Revision) -> bool { self.index.get_entry(rev).is_some() } /// 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<Cow<[u8]>, RevlogError> { if rev == NULL_REVISION { return Ok(Cow::Borrowed(&[])); }; Ok(self.get_entry(rev)?.data()?) } /// 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()) == 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<Vec<u8>, HgError> { let snapshot = snapshot.data_chunk()?; let deltas = deltas .iter() .rev() .map(RevlogEntry::data_chunk) .collect::<Result<Vec<_>, _>>()?; 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" ), } } pub fn make_null_entry(&self) -> RevlogEntry { RevlogEntry { revlog: self, rev: NULL_REVISION, bytes: b"", compressed_len: 0, uncompressed_len: 0, base_rev_or_base_of_delta_chain: None, p1: NULL_REVISION, p2: NULL_REVISION, flags: NULL_REVLOG_ENTRY_FLAGS, hash: NULL_NODE, } } /// Get an entry of the revlog. pub fn get_entry( &self, rev: Revision, ) -> Result<RevlogEntry, RevlogError> { if rev == NULL_REVISION { return Ok(self.make_null_entry()); } let index_entry = self .index .get_entry(rev) .ok_or(RevlogError::InvalidRevision)?; let start = index_entry.offset(); let end = start + index_entry.compressed_len() as usize; let data = if self.index.is_inline() { self.index.data(start, end) } else { &self.data()[start..end] }; let entry = RevlogEntry { revlog: self, rev, bytes: data, compressed_len: index_entry.compressed_len(), uncompressed_len: index_entry.uncompressed_len(), base_rev_or_base_of_delta_chain: if index_entry .base_revision_or_base_of_delta_chain() == rev { None } else { Some(index_entry.base_revision_or_base_of_delta_chain()) }, p1: index_entry.p1(), p2: index_entry.p2(), flags: index_entry.flags(), hash: *index_entry.hash(), }; Ok(entry) } /// when resolving internal references within revlog, any errors /// should be reported as corruption, instead of e.g. "invalid revision" fn get_entry_internal( &self, rev: Revision, ) -> Result<RevlogEntry, HgError> { return self.get_entry(rev).map_err(|_| corrupted()); } } /// The revlog entry's bytes and the necessary informations to extract /// the entry's data. #[derive(Clone)] pub struct RevlogEntry<'a> { revlog: &'a Revlog, rev: Revision, bytes: &'a [u8], compressed_len: u32, uncompressed_len: i32, base_rev_or_base_of_delta_chain: Option<Revision>, p1: Revision, p2: Revision, flags: u16, hash: Node, } impl<'a> RevlogEntry<'a> { pub fn revision(&self) -> Revision { self.rev } pub fn uncompressed_len(&self) -> Option<u32> { u32::try_from(self.uncompressed_len).ok() } pub fn has_p1(&self) -> bool { self.p1 != NULL_REVISION } pub fn is_cencored(&self) -> bool { (self.flags & REVISION_FLAG_CENSORED) != 0 } pub fn has_length_affecting_flag_processor(&self) -> bool { // Relevant Python code: revlog.size() // note: ELLIPSIS is known to not change the content (self.flags & (REVIDX_KNOWN_FLAGS ^ REVISION_FLAG_ELLIPSIS)) != 0 } /// The data for this entry, after resolving deltas if any. pub fn data(&self) -> Result<Cow<'a, [u8]>, HgError> { let mut entry = self.clone(); let mut delta_chain = vec![]; // The meaning of `base_rev_or_base_of_delta_chain` depends on // generaldelta. See the doc on `ENTRY_DELTA_BASE` in // `mercurial/revlogutils/constants.py` and the code in // [_chaininfo] and in [index_deltachain]. let uses_generaldelta = self.revlog.index.uses_generaldelta(); while let Some(base_rev) = entry.base_rev_or_base_of_delta_chain { let base_rev = if uses_generaldelta { base_rev } else { entry.rev - 1 }; delta_chain.push(entry); entry = self.revlog.get_entry_internal(base_rev)?; } let data = if delta_chain.is_empty() { entry.data_chunk()? } else { Revlog::build_data_from_deltas(entry, &delta_chain)?.into() }; if self.revlog.check_hash( self.p1, self.p2, self.hash.as_bytes(), &data, ) { Ok(data) } else { Err(corrupted()) } } /// Extract the data contained in the entry. /// This may be a delta. (See `is_delta`.) fn data_chunk(&self) -> Result<Cow<'a, [u8]>, HgError> { 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()?)), // A proper new format should have had a repo/store requirement. _format_type => Err(corrupted()), } } fn uncompressed_zlib_data(&self) -> Result<Vec<u8>, HgError> { let mut decoder = ZlibDecoder::new(self.bytes); if self.is_delta() { let mut buf = Vec::with_capacity(self.compressed_len as usize); decoder.read_to_end(&mut buf).map_err(|_| corrupted())?; Ok(buf) } else { let cap = self.uncompressed_len.max(0) as usize; let mut buf = vec![0; cap]; decoder.read_exact(&mut buf).map_err(|_| corrupted())?; Ok(buf) } } fn uncompressed_zstd_data(&self) -> Result<Vec<u8>, HgError> { if self.is_delta() { let mut buf = Vec::with_capacity(self.compressed_len as usize); zstd::stream::copy_decode(self.bytes, &mut buf) .map_err(|_| corrupted())?; Ok(buf) } else { let cap = self.uncompressed_len.max(0) as usize; let mut buf = vec![0; cap]; let len = zstd::block::decompress_to_buffer(self.bytes, &mut buf) .map_err(|_| corrupted())?; if len != self.uncompressed_len as usize { Err(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_or_base_of_delta_chain.is_some() } } /// Calculate the hash of a revision given its data and its parents. fn hash( data: &[u8], p1_hash: &[u8], p2_hash: &[u8], ) -> [u8; NODE_BYTES_LENGTH] { let mut hasher = Sha1::new(); let (a, b) = (p1_hash, p2_hash); if a > b { hasher.update(b); hasher.update(a); } else { hasher.update(a); hasher.update(b); } hasher.update(data); *hasher.finalize().as_ref() }