|
|
//! The "version 2" disk representation of the dirstate
|
|
|
//!
|
|
|
//! # File format
|
|
|
//!
|
|
|
//! The file starts with a fixed-sized header, whose layout is defined by the
|
|
|
//! `Header` struct. Its `root` field contains the slice (offset and length) to
|
|
|
//! the nodes representing the files and directories at the root of the
|
|
|
//! repository. Each node is also fixed-size, defined by the `Node` struct.
|
|
|
//! Nodes in turn contain slices to variable-size paths, and to their own child
|
|
|
//! nodes (if any) for nested files and directories.
|
|
|
|
|
|
use crate::dirstate_tree::dirstate_map::{self, DirstateMap, NodeRef};
|
|
|
use crate::dirstate_tree::path_with_basename::WithBasename;
|
|
|
use crate::errors::HgError;
|
|
|
use crate::utils::hg_path::HgPath;
|
|
|
use crate::DirstateEntry;
|
|
|
use crate::DirstateError;
|
|
|
use crate::DirstateParents;
|
|
|
use crate::EntryState;
|
|
|
use bytes_cast::unaligned::{I32Be, I64Be, U32Be, U64Be};
|
|
|
use bytes_cast::BytesCast;
|
|
|
use std::borrow::Cow;
|
|
|
use std::convert::TryFrom;
|
|
|
use std::time::{Duration, SystemTime, UNIX_EPOCH};
|
|
|
|
|
|
/// Added at the start of `.hg/dirstate` when the "v2" format is used.
|
|
|
/// This a redundant sanity check more than an actual "magic number" since
|
|
|
/// `.hg/requires` already governs which format should be used.
|
|
|
pub const V2_FORMAT_MARKER: &[u8; 12] = b"dirstate-v2\n";
|
|
|
|
|
|
#[derive(BytesCast)]
|
|
|
#[repr(C)]
|
|
|
struct Header {
|
|
|
marker: [u8; V2_FORMAT_MARKER.len()],
|
|
|
|
|
|
/// `dirstatemap.parents()` in `mercurial/dirstate.py` relies on this
|
|
|
/// `parents` field being at this offset, immediately after `marker`.
|
|
|
parents: DirstateParents,
|
|
|
|
|
|
root: ChildNodes,
|
|
|
nodes_with_entry_count: Size,
|
|
|
nodes_with_copy_source_count: Size,
|
|
|
}
|
|
|
|
|
|
#[derive(BytesCast)]
|
|
|
#[repr(C)]
|
|
|
pub(super) struct Node {
|
|
|
full_path: PathSlice,
|
|
|
|
|
|
/// In bytes from `self.full_path.start`
|
|
|
base_name_start: Size,
|
|
|
|
|
|
copy_source: OptPathSlice,
|
|
|
children: ChildNodes,
|
|
|
pub(super) tracked_descendants_count: Size,
|
|
|
|
|
|
/// Dependending on the value of `state`:
|
|
|
///
|
|
|
/// * A null byte: `data` is not used.
|
|
|
///
|
|
|
/// * A `n`, `a`, `r`, or `m` ASCII byte: `state` and `data` together
|
|
|
/// represent a dirstate entry like in the v1 format.
|
|
|
///
|
|
|
/// * A `d` ASCII byte: the bytes of `data` should instead be interpreted
|
|
|
/// as the `Timestamp` for the mtime of a cached directory.
|
|
|
///
|
|
|
/// The presence of this state means that at some point, this path in
|
|
|
/// the working directory was observed:
|
|
|
///
|
|
|
/// - To be a directory
|
|
|
/// - With the modification time as given by `Timestamp`
|
|
|
/// - That timestamp was already strictly in the past when observed,
|
|
|
/// meaning that later changes cannot happen in the same clock tick
|
|
|
/// and must cause a different modification time (unless the system
|
|
|
/// clock jumps back and we get unlucky, which is not impossible but
|
|
|
/// but deemed unlikely enough).
|
|
|
/// - The directory did not contain any child entry that did not have a
|
|
|
/// corresponding dirstate node.
|
|
|
///
|
|
|
/// This means that if `std::fs::symlink_metadata` later reports the
|
|
|
/// same modification time, we don’t need to call `std::fs::read_dir`
|
|
|
/// again for this directory and can iterate child dirstate nodes
|
|
|
/// instead.
|
|
|
state: u8,
|
|
|
data: Entry,
|
|
|
}
|
|
|
|
|
|
#[derive(BytesCast, Copy, Clone)]
|
|
|
#[repr(C)]
|
|
|
struct Entry {
|
|
|
mode: I32Be,
|
|
|
mtime: I32Be,
|
|
|
size: I32Be,
|
|
|
}
|
|
|
|
|
|
/// Duration since the Unix epoch
|
|
|
#[derive(BytesCast, Copy, Clone, PartialEq)]
|
|
|
#[repr(C)]
|
|
|
pub(super) struct Timestamp {
|
|
|
seconds: I64Be,
|
|
|
|
|
|
/// In `0 .. 1_000_000_000`.
|
|
|
///
|
|
|
/// This timestamp is later or earlier than `(seconds, 0)` by this many
|
|
|
/// nanoseconds, if `seconds` is non-negative or negative, respectively.
|
|
|
nanoseconds: U32Be,
|
|
|
}
|
|
|
|
|
|
/// Counted in bytes from the start of the file
|
|
|
///
|
|
|
/// NOTE: If we decide to never support `.hg/dirstate` files larger than 4 GiB
|
|
|
/// we could save space by using `U32Be` instead.
|
|
|
type Offset = U64Be;
|
|
|
|
|
|
/// Counted in number of items
|
|
|
///
|
|
|
/// NOTE: not supporting directories with more than 4 billion direct children,
|
|
|
/// or filenames more than 4 GiB.
|
|
|
type Size = U32Be;
|
|
|
|
|
|
/// Location of consecutive, fixed-size items.
|
|
|
///
|
|
|
/// An item can be a single byte for paths, or a struct with
|
|
|
/// `derive(BytesCast)`.
|
|
|
#[derive(BytesCast, Copy, Clone)]
|
|
|
#[repr(C)]
|
|
|
struct Slice {
|
|
|
start: Offset,
|
|
|
len: Size,
|
|
|
}
|
|
|
|
|
|
/// A contiguous sequence of `len` times `Node`, representing the child nodes
|
|
|
/// of either some other node or of the repository root.
|
|
|
///
|
|
|
/// Always sorted by ascending `full_path`, to allow binary search.
|
|
|
/// Since nodes with the same parent nodes also have the same parent path,
|
|
|
/// only the `base_name`s need to be compared during binary search.
|
|
|
type ChildNodes = Slice;
|
|
|
|
|
|
/// A `HgPath` of `len` bytes
|
|
|
type PathSlice = Slice;
|
|
|
|
|
|
/// Either nothing if `start == 0`, or a `HgPath` of `len` bytes
|
|
|
type OptPathSlice = Slice;
|
|
|
|
|
|
/// Make sure that size-affecting changes are made knowingly
|
|
|
fn _static_assert_size_of() {
|
|
|
let _ = std::mem::transmute::<Header, [u8; 72]>;
|
|
|
let _ = std::mem::transmute::<Node, [u8; 57]>;
|
|
|
}
|
|
|
|
|
|
/// Unexpected file format found in `.hg/dirstate` with the "v2" format.
|
|
|
///
|
|
|
/// This should only happen if Mercurial is buggy or a repository is corrupted.
|
|
|
#[derive(Debug)]
|
|
|
pub struct DirstateV2ParseError;
|
|
|
|
|
|
impl From<DirstateV2ParseError> for HgError {
|
|
|
fn from(_: DirstateV2ParseError) -> Self {
|
|
|
HgError::corrupted("dirstate-v2 parse error")
|
|
|
}
|
|
|
}
|
|
|
|
|
|
impl From<DirstateV2ParseError> for crate::DirstateError {
|
|
|
fn from(error: DirstateV2ParseError) -> Self {
|
|
|
HgError::from(error).into()
|
|
|
}
|
|
|
}
|
|
|
|
|
|
pub(super) fn read<'on_disk>(
|
|
|
on_disk: &'on_disk [u8],
|
|
|
) -> Result<
|
|
|
(DirstateMap<'on_disk>, Option<DirstateParents>),
|
|
|
DirstateV2ParseError,
|
|
|
> {
|
|
|
if on_disk.is_empty() {
|
|
|
return Ok((DirstateMap::empty(on_disk), None));
|
|
|
}
|
|
|
let (header, _) =
|
|
|
Header::from_bytes(on_disk).map_err(|_| DirstateV2ParseError)?;
|
|
|
let Header {
|
|
|
marker,
|
|
|
parents,
|
|
|
root,
|
|
|
nodes_with_entry_count,
|
|
|
nodes_with_copy_source_count,
|
|
|
} = header;
|
|
|
if marker != V2_FORMAT_MARKER {
|
|
|
return Err(DirstateV2ParseError);
|
|
|
}
|
|
|
let dirstate_map = DirstateMap {
|
|
|
on_disk,
|
|
|
root: dirstate_map::ChildNodes::OnDisk(read_slice::<Node>(
|
|
|
on_disk, *root,
|
|
|
)?),
|
|
|
nodes_with_entry_count: nodes_with_entry_count.get(),
|
|
|
nodes_with_copy_source_count: nodes_with_copy_source_count.get(),
|
|
|
};
|
|
|
let parents = Some(parents.clone());
|
|
|
Ok((dirstate_map, parents))
|
|
|
}
|
|
|
|
|
|
impl Node {
|
|
|
pub(super) fn full_path<'on_disk>(
|
|
|
&self,
|
|
|
on_disk: &'on_disk [u8],
|
|
|
) -> Result<&'on_disk HgPath, DirstateV2ParseError> {
|
|
|
read_hg_path(on_disk, self.full_path)
|
|
|
}
|
|
|
|
|
|
pub(super) fn base_name_start<'on_disk>(
|
|
|
&self,
|
|
|
) -> Result<usize, DirstateV2ParseError> {
|
|
|
let start = self.base_name_start.get();
|
|
|
if start < self.full_path.len.get() {
|
|
|
let start = usize::try_from(start)
|
|
|
// u32 -> usize, could only panic on a 16-bit CPU
|
|
|
.expect("dirstate-v2 base_name_start out of bounds");
|
|
|
Ok(start)
|
|
|
} else {
|
|
|
Err(DirstateV2ParseError)
|
|
|
}
|
|
|
}
|
|
|
|
|
|
pub(super) fn base_name<'on_disk>(
|
|
|
&self,
|
|
|
on_disk: &'on_disk [u8],
|
|
|
) -> Result<&'on_disk HgPath, DirstateV2ParseError> {
|
|
|
let full_path = self.full_path(on_disk)?;
|
|
|
let base_name_start = self.base_name_start()?;
|
|
|
Ok(HgPath::new(&full_path.as_bytes()[base_name_start..]))
|
|
|
}
|
|
|
|
|
|
pub(super) fn path<'on_disk>(
|
|
|
&self,
|
|
|
on_disk: &'on_disk [u8],
|
|
|
) -> Result<dirstate_map::NodeKey<'on_disk>, DirstateV2ParseError> {
|
|
|
Ok(WithBasename::from_raw_parts(
|
|
|
Cow::Borrowed(self.full_path(on_disk)?),
|
|
|
self.base_name_start()?,
|
|
|
))
|
|
|
}
|
|
|
|
|
|
pub(super) fn has_copy_source<'on_disk>(&self) -> bool {
|
|
|
self.copy_source.start.get() != 0
|
|
|
}
|
|
|
|
|
|
pub(super) fn copy_source<'on_disk>(
|
|
|
&self,
|
|
|
on_disk: &'on_disk [u8],
|
|
|
) -> Result<Option<&'on_disk HgPath>, DirstateV2ParseError> {
|
|
|
Ok(if self.has_copy_source() {
|
|
|
Some(read_hg_path(on_disk, self.copy_source)?)
|
|
|
} else {
|
|
|
None
|
|
|
})
|
|
|
}
|
|
|
|
|
|
pub(super) fn node_data(
|
|
|
&self,
|
|
|
) -> Result<dirstate_map::NodeData, DirstateV2ParseError> {
|
|
|
let entry = |state| {
|
|
|
dirstate_map::NodeData::Entry(self.entry_with_given_state(state))
|
|
|
};
|
|
|
|
|
|
match self.state {
|
|
|
b'\0' => Ok(dirstate_map::NodeData::None),
|
|
|
b'd' => Ok(dirstate_map::NodeData::CachedDirectory {
|
|
|
mtime: *self.data.as_timestamp(),
|
|
|
}),
|
|
|
b'n' => Ok(entry(EntryState::Normal)),
|
|
|
b'a' => Ok(entry(EntryState::Added)),
|
|
|
b'r' => Ok(entry(EntryState::Removed)),
|
|
|
b'm' => Ok(entry(EntryState::Merged)),
|
|
|
_ => Err(DirstateV2ParseError),
|
|
|
}
|
|
|
}
|
|
|
|
|
|
pub(super) fn cached_directory_mtime(&self) -> Option<&Timestamp> {
|
|
|
if self.state == b'd' {
|
|
|
Some(self.data.as_timestamp())
|
|
|
} else {
|
|
|
None
|
|
|
}
|
|
|
}
|
|
|
|
|
|
pub(super) fn state(
|
|
|
&self,
|
|
|
) -> Result<Option<EntryState>, DirstateV2ParseError> {
|
|
|
match self.state {
|
|
|
b'\0' | b'd' => Ok(None),
|
|
|
b'n' => Ok(Some(EntryState::Normal)),
|
|
|
b'a' => Ok(Some(EntryState::Added)),
|
|
|
b'r' => Ok(Some(EntryState::Removed)),
|
|
|
b'm' => Ok(Some(EntryState::Merged)),
|
|
|
_ => Err(DirstateV2ParseError),
|
|
|
}
|
|
|
}
|
|
|
|
|
|
fn entry_with_given_state(&self, state: EntryState) -> DirstateEntry {
|
|
|
DirstateEntry {
|
|
|
state,
|
|
|
mode: self.data.mode.get(),
|
|
|
mtime: self.data.mtime.get(),
|
|
|
size: self.data.size.get(),
|
|
|
}
|
|
|
}
|
|
|
|
|
|
pub(super) fn entry(
|
|
|
&self,
|
|
|
) -> Result<Option<DirstateEntry>, DirstateV2ParseError> {
|
|
|
Ok(self
|
|
|
.state()?
|
|
|
.map(|state| self.entry_with_given_state(state)))
|
|
|
}
|
|
|
|
|
|
pub(super) fn children<'on_disk>(
|
|
|
&self,
|
|
|
on_disk: &'on_disk [u8],
|
|
|
) -> Result<&'on_disk [Node], DirstateV2ParseError> {
|
|
|
read_slice::<Node>(on_disk, self.children)
|
|
|
}
|
|
|
|
|
|
pub(super) fn to_in_memory_node<'on_disk>(
|
|
|
&self,
|
|
|
on_disk: &'on_disk [u8],
|
|
|
) -> Result<dirstate_map::Node<'on_disk>, DirstateV2ParseError> {
|
|
|
Ok(dirstate_map::Node {
|
|
|
children: dirstate_map::ChildNodes::OnDisk(
|
|
|
self.children(on_disk)?,
|
|
|
),
|
|
|
copy_source: self.copy_source(on_disk)?.map(Cow::Borrowed),
|
|
|
data: self.node_data()?,
|
|
|
tracked_descendants_count: self.tracked_descendants_count.get(),
|
|
|
})
|
|
|
}
|
|
|
}
|
|
|
|
|
|
impl Entry {
|
|
|
fn from_timestamp(timestamp: Timestamp) -> Self {
|
|
|
// Safety: both types implement the `ByteCast` trait, so we could
|
|
|
// safely use `as_bytes` and `from_bytes` to do this conversion. Using
|
|
|
// `transmute` instead makes the compiler check that the two types
|
|
|
// have the same size, which eliminates the error case of
|
|
|
// `from_bytes`.
|
|
|
unsafe { std::mem::transmute::<Timestamp, Entry>(timestamp) }
|
|
|
}
|
|
|
|
|
|
fn as_timestamp(&self) -> &Timestamp {
|
|
|
// Safety: same as above in `from_timestamp`
|
|
|
unsafe { &*(self as *const Entry as *const Timestamp) }
|
|
|
}
|
|
|
}
|
|
|
|
|
|
impl Timestamp {
|
|
|
pub fn seconds(&self) -> i64 {
|
|
|
self.seconds.get()
|
|
|
}
|
|
|
}
|
|
|
|
|
|
impl From<SystemTime> for Timestamp {
|
|
|
fn from(system_time: SystemTime) -> Self {
|
|
|
let (secs, nanos) = match system_time.duration_since(UNIX_EPOCH) {
|
|
|
Ok(duration) => {
|
|
|
(duration.as_secs() as i64, duration.subsec_nanos())
|
|
|
}
|
|
|
Err(error) => {
|
|
|
let negative = error.duration();
|
|
|
(-(negative.as_secs() as i64), negative.subsec_nanos())
|
|
|
}
|
|
|
};
|
|
|
Timestamp {
|
|
|
seconds: secs.into(),
|
|
|
nanoseconds: nanos.into(),
|
|
|
}
|
|
|
}
|
|
|
}
|
|
|
|
|
|
impl From<&'_ Timestamp> for SystemTime {
|
|
|
fn from(timestamp: &'_ Timestamp) -> Self {
|
|
|
let secs = timestamp.seconds.get();
|
|
|
let nanos = timestamp.nanoseconds.get();
|
|
|
if secs >= 0 {
|
|
|
UNIX_EPOCH + Duration::new(secs as u64, nanos)
|
|
|
} else {
|
|
|
UNIX_EPOCH - Duration::new((-secs) as u64, nanos)
|
|
|
}
|
|
|
}
|
|
|
}
|
|
|
|
|
|
fn read_hg_path(
|
|
|
on_disk: &[u8],
|
|
|
slice: Slice,
|
|
|
) -> Result<&HgPath, DirstateV2ParseError> {
|
|
|
let bytes = read_slice::<u8>(on_disk, slice)?;
|
|
|
Ok(HgPath::new(bytes))
|
|
|
}
|
|
|
|
|
|
fn read_slice<T>(
|
|
|
on_disk: &[u8],
|
|
|
slice: Slice,
|
|
|
) -> Result<&[T], DirstateV2ParseError>
|
|
|
where
|
|
|
T: BytesCast,
|
|
|
{
|
|
|
// Either `usize::MAX` would result in "out of bounds" error since a single
|
|
|
// `&[u8]` cannot occupy the entire addess space.
|
|
|
let start = usize::try_from(slice.start.get()).unwrap_or(std::usize::MAX);
|
|
|
let len = usize::try_from(slice.len.get()).unwrap_or(std::usize::MAX);
|
|
|
on_disk
|
|
|
.get(start..)
|
|
|
.and_then(|bytes| T::slice_from_bytes(bytes, len).ok())
|
|
|
.map(|(slice, _rest)| slice)
|
|
|
.ok_or_else(|| DirstateV2ParseError)
|
|
|
}
|
|
|
|
|
|
pub(super) fn write(
|
|
|
dirstate_map: &mut DirstateMap,
|
|
|
parents: DirstateParents,
|
|
|
) -> Result<Vec<u8>, DirstateError> {
|
|
|
let header_len = std::mem::size_of::<Header>();
|
|
|
|
|
|
// This ignores the space for paths, and for nodes without an entry.
|
|
|
// TODO: better estimate? Skip the `Vec` and write to a file directly?
|
|
|
let size_guess = header_len
|
|
|
+ std::mem::size_of::<Node>()
|
|
|
* dirstate_map.nodes_with_entry_count as usize;
|
|
|
let mut out = Vec::with_capacity(size_guess);
|
|
|
|
|
|
// Keep space for the header. We’ll fill it out at the end when we know the
|
|
|
// actual offset for the root nodes.
|
|
|
out.resize(header_len, 0_u8);
|
|
|
|
|
|
let root =
|
|
|
write_nodes(dirstate_map, dirstate_map.root.as_ref(), &mut out)?;
|
|
|
|
|
|
let header = Header {
|
|
|
marker: *V2_FORMAT_MARKER,
|
|
|
parents: parents,
|
|
|
root,
|
|
|
nodes_with_entry_count: dirstate_map.nodes_with_entry_count.into(),
|
|
|
nodes_with_copy_source_count: dirstate_map
|
|
|
.nodes_with_copy_source_count
|
|
|
.into(),
|
|
|
};
|
|
|
out[..header_len].copy_from_slice(header.as_bytes());
|
|
|
Ok(out)
|
|
|
}
|
|
|
|
|
|
fn write_nodes(
|
|
|
dirstate_map: &DirstateMap,
|
|
|
nodes: dirstate_map::ChildNodesRef,
|
|
|
out: &mut Vec<u8>,
|
|
|
) -> Result<ChildNodes, DirstateError> {
|
|
|
// `dirstate_map::ChildNodes` is a `HashMap` with undefined iteration
|
|
|
// order. Sort to enable binary search in the written file.
|
|
|
let nodes = nodes.sorted();
|
|
|
|
|
|
// First accumulate serialized nodes in a `Vec`
|
|
|
let mut on_disk_nodes = Vec::with_capacity(nodes.len());
|
|
|
for node in nodes {
|
|
|
let children = write_nodes(
|
|
|
dirstate_map,
|
|
|
node.children(dirstate_map.on_disk)?,
|
|
|
out,
|
|
|
)?;
|
|
|
let full_path = node.full_path(dirstate_map.on_disk)?;
|
|
|
let full_path = write_slice::<u8>(full_path.as_bytes(), out);
|
|
|
let copy_source =
|
|
|
if let Some(source) = node.copy_source(dirstate_map.on_disk)? {
|
|
|
write_slice::<u8>(source.as_bytes(), out)
|
|
|
} else {
|
|
|
Slice {
|
|
|
start: 0.into(),
|
|
|
len: 0.into(),
|
|
|
}
|
|
|
};
|
|
|
on_disk_nodes.push(match node {
|
|
|
NodeRef::InMemory(path, node) => {
|
|
|
let (state, data) = match &node.data {
|
|
|
dirstate_map::NodeData::Entry(entry) => (
|
|
|
entry.state.into(),
|
|
|
Entry {
|
|
|
mode: entry.mode.into(),
|
|
|
mtime: entry.mtime.into(),
|
|
|
size: entry.size.into(),
|
|
|
},
|
|
|
),
|
|
|
dirstate_map::NodeData::CachedDirectory { mtime } => {
|
|
|
(b'd', Entry::from_timestamp(*mtime))
|
|
|
}
|
|
|
dirstate_map::NodeData::None => (
|
|
|
b'\0',
|
|
|
Entry {
|
|
|
mode: 0.into(),
|
|
|
mtime: 0.into(),
|
|
|
size: 0.into(),
|
|
|
},
|
|
|
),
|
|
|
};
|
|
|
Node {
|
|
|
children,
|
|
|
copy_source,
|
|
|
full_path,
|
|
|
base_name_start: u32::try_from(path.base_name_start())
|
|
|
// Could only panic for paths over 4 GiB
|
|
|
.expect("dirstate-v2 offset overflow")
|
|
|
.into(),
|
|
|
tracked_descendants_count: node
|
|
|
.tracked_descendants_count
|
|
|
.into(),
|
|
|
state,
|
|
|
data,
|
|
|
}
|
|
|
}
|
|
|
NodeRef::OnDisk(node) => Node {
|
|
|
children,
|
|
|
copy_source,
|
|
|
full_path,
|
|
|
..*node
|
|
|
},
|
|
|
})
|
|
|
}
|
|
|
// … so we can write them contiguously
|
|
|
Ok(write_slice::<Node>(&on_disk_nodes, out))
|
|
|
}
|
|
|
|
|
|
fn write_slice<T>(slice: &[T], out: &mut Vec<u8>) -> Slice
|
|
|
where
|
|
|
T: BytesCast,
|
|
|
{
|
|
|
let start = u64::try_from(out.len())
|
|
|
// Could only panic on a 128-bit CPU with a dirstate over 16 EiB
|
|
|
.expect("dirstate-v2 offset overflow")
|
|
|
.into();
|
|
|
let len = u32::try_from(slice.len())
|
|
|
// Could only panic for paths over 4 GiB or nodes with over 4 billions
|
|
|
// child nodes
|
|
|
.expect("dirstate-v2 offset overflow")
|
|
|
.into();
|
|
|
out.extend(slice.as_bytes());
|
|
|
Slice { start, len }
|
|
|
}
|
|
|
|