rust: don't swallow valuable error information
This helps when diagnosing corruption, and is in general good practice. The
information is here, valuable and can be used easily.
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::revlog::Revision;
use crate::vfs::Vfs;
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(Debug, 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(rev) => RevlogError::corrupted(
format!("nodemap point to revision {} not in index", rev),
),
}
}
}
fn corrupted<S: AsRef<str>>(context: S) -> HgError {
HgError::corrupted(format!("corrupted revlog, {}", context.as_ref()))
}
impl RevlogError {
fn corrupted<S: AsRef<str>>(context: S) -> Self {
RevlogError::Other(corrupted(context))
}
}
/// 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(
store_vfs: &Vfs,
index_path: impl AsRef<Path>,
data_path: Option<&Path>,
use_nodemap: bool,
) -> Result<Self, HgError> {
let index_path = index_path.as_ref();
let index = {
match 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 = store_vfs.mmap_open(data_path)?;
Some(Box::new(data_mmap))
};
let nodemap = if index.is_inline() {
None
} else if !use_nodemap {
None
} else {
NodeMapDocket::read_from_file(store_vfs, 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> {
self.get_entry(rev)
.map_err(|_| corrupted(format!("revision {} out of range", rev)))
}
}
/// 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 node(&self) -> &Node {
&self.hash
}
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 p1_entry(&self) -> Result<Option<RevlogEntry>, RevlogError> {
if self.p1 == NULL_REVISION {
Ok(None)
} else {
Ok(Some(self.revlog.get_entry(self.p1)?))
}
}
pub fn p2_entry(&self) -> Result<Option<RevlogEntry>, RevlogError> {
if self.p2 == NULL_REVISION {
Ok(None)
} else {
Ok(Some(self.revlog.get_entry(self.p2)?))
}
}
pub fn p1(&self) -> Option<Revision> {
if self.p1 == NULL_REVISION {
None
} else {
Some(self.p1)
}
}
pub fn p2(&self) -> Option<Revision> {
if self.p2 == NULL_REVISION {
None
} else {
Some(self.p2)
}
}
pub fn is_censored(&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 rawdata(&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()
};
Ok(data)
}
fn check_data(
&self,
data: Cow<'a, [u8]>,
) -> Result<Cow<'a, [u8]>, HgError> {
if self.revlog.check_hash(
self.p1,
self.p2,
self.hash.as_bytes(),
&data,
) {
Ok(data)
} else {
Err(corrupted(format!(
"hash check failed for revision {}",
self.rev
)))
}
}
pub fn data(&self) -> Result<Cow<'a, [u8]>, HgError> {
let data = self.rawdata()?;
if self.is_censored() {
return Err(HgError::CensoredNodeError);
}
self.check_data(data)
}
/// 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(format!(
"unknown compression header '{}'",
format_type
))),
}
}
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(|e| corrupted(e.to_string()))?;
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(|e| corrupted(e.to_string()))?;
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(|e| corrupted(e.to_string()))?;
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(|e| corrupted(e.to_string()))?;
if len != self.uncompressed_len as usize {
Err(corrupted("uncompressed length does not match"))
} 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()
}
#[cfg(test)]
mod tests {
use super::*;
use crate::index::{IndexEntryBuilder, INDEX_ENTRY_SIZE};
use itertools::Itertools;
#[test]
fn test_empty() {
let temp = tempfile::tempdir().unwrap();
let vfs = Vfs { base: temp.path() };
std::fs::write(temp.path().join("foo.i"), b"").unwrap();
let revlog = Revlog::open(&vfs, "foo.i", None, false).unwrap();
assert!(revlog.is_empty());
assert_eq!(revlog.len(), 0);
assert!(revlog.get_entry(0).is_err());
assert!(!revlog.has_rev(0));
}
#[test]
fn test_inline() {
let temp = tempfile::tempdir().unwrap();
let vfs = Vfs { base: temp.path() };
let node0 = Node::from_hex("2ed2a3912a0b24502043eae84ee4b279c18b90dd")
.unwrap();
let node1 = Node::from_hex("b004912a8510032a0350a74daa2803dadfb00e12")
.unwrap();
let node2 = Node::from_hex("dd6ad206e907be60927b5a3117b97dffb2590582")
.unwrap();
let entry0_bytes = IndexEntryBuilder::new()
.is_first(true)
.with_version(1)
.with_inline(true)
.with_offset(INDEX_ENTRY_SIZE)
.with_node(node0)
.build();
let entry1_bytes = IndexEntryBuilder::new()
.with_offset(INDEX_ENTRY_SIZE)
.with_node(node1)
.build();
let entry2_bytes = IndexEntryBuilder::new()
.with_offset(INDEX_ENTRY_SIZE)
.with_p1(0)
.with_p2(1)
.with_node(node2)
.build();
let contents = vec![entry0_bytes, entry1_bytes, entry2_bytes]
.into_iter()
.flatten()
.collect_vec();
std::fs::write(temp.path().join("foo.i"), contents).unwrap();
let revlog = Revlog::open(&vfs, "foo.i", None, false).unwrap();
let entry0 = revlog.get_entry(0).ok().unwrap();
assert_eq!(entry0.revision(), 0);
assert_eq!(*entry0.node(), node0);
assert!(!entry0.has_p1());
assert_eq!(entry0.p1(), None);
assert_eq!(entry0.p2(), None);
let p1_entry = entry0.p1_entry().unwrap();
assert!(p1_entry.is_none());
let p2_entry = entry0.p2_entry().unwrap();
assert!(p2_entry.is_none());
let entry1 = revlog.get_entry(1).ok().unwrap();
assert_eq!(entry1.revision(), 1);
assert_eq!(*entry1.node(), node1);
assert!(!entry1.has_p1());
assert_eq!(entry1.p1(), None);
assert_eq!(entry1.p2(), None);
let p1_entry = entry1.p1_entry().unwrap();
assert!(p1_entry.is_none());
let p2_entry = entry1.p2_entry().unwrap();
assert!(p2_entry.is_none());
let entry2 = revlog.get_entry(2).ok().unwrap();
assert_eq!(entry2.revision(), 2);
assert_eq!(*entry2.node(), node2);
assert!(entry2.has_p1());
assert_eq!(entry2.p1(), Some(0));
assert_eq!(entry2.p2(), Some(1));
let p1_entry = entry2.p1_entry().unwrap();
assert!(p1_entry.is_some());
assert_eq!(p1_entry.unwrap().revision(), 0);
let p2_entry = entry2.p2_entry().unwrap();
assert!(p2_entry.is_some());
assert_eq!(p2_entry.unwrap().revision(), 1);
}
}