|
|
//! 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};
|
|
|
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 bytes_cast::unaligned::{I32Be, U32Be, U64Be};
|
|
|
use bytes_cast::BytesCast;
|
|
|
use std::borrow::Cow;
|
|
|
use std::convert::{TryFrom, TryInto};
|
|
|
|
|
|
/// 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)]
|
|
|
struct Node {
|
|
|
full_path: PathSlice,
|
|
|
|
|
|
/// In bytes from `self.full_path.start`
|
|
|
base_name_start: Size,
|
|
|
|
|
|
copy_source: OptPathSlice,
|
|
|
entry: OptEntry,
|
|
|
children: ChildNodes,
|
|
|
tracked_descendants_count: Size,
|
|
|
}
|
|
|
|
|
|
/// Either nothing if `state == b'\0'`, or a dirstate entry like in the v1
|
|
|
/// format
|
|
|
#[derive(BytesCast)]
|
|
|
#[repr(C)]
|
|
|
struct OptEntry {
|
|
|
state: u8,
|
|
|
mode: I32Be,
|
|
|
mtime: I32Be,
|
|
|
size: I32Be,
|
|
|
}
|
|
|
|
|
|
/// 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]>;
|
|
|
}
|
|
|
|
|
|
pub(super) fn read<'on_disk>(
|
|
|
on_disk: &'on_disk [u8],
|
|
|
) -> Result<(DirstateMap<'on_disk>, Option<DirstateParents>), DirstateError> {
|
|
|
if on_disk.is_empty() {
|
|
|
return Ok((DirstateMap::empty(on_disk), None));
|
|
|
}
|
|
|
let (header, _) = Header::from_bytes(on_disk)
|
|
|
.map_err(|_| HgError::corrupted("truncated dirstate-v2"))?;
|
|
|
let Header {
|
|
|
marker,
|
|
|
parents,
|
|
|
root,
|
|
|
nodes_with_entry_count,
|
|
|
nodes_with_copy_source_count,
|
|
|
} = header;
|
|
|
if marker != V2_FORMAT_MARKER {
|
|
|
return Err(HgError::corrupted("missing dirstated-v2 marker").into());
|
|
|
}
|
|
|
let dirstate_map = DirstateMap {
|
|
|
on_disk,
|
|
|
root: read_nodes(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 path<'on_disk>(
|
|
|
&self,
|
|
|
on_disk: &'on_disk [u8],
|
|
|
) -> Result<dirstate_map::NodeKey<'on_disk>, HgError> {
|
|
|
let full_path = read_hg_path(on_disk, self.full_path)?;
|
|
|
let base_name_start = usize::try_from(self.base_name_start.get())
|
|
|
// u32 -> usize, could only panic on a 16-bit CPU
|
|
|
.expect("dirstate-v2 base_name_start out of bounds");
|
|
|
if base_name_start < full_path.len() {
|
|
|
Ok(WithBasename::from_raw_parts(full_path, base_name_start))
|
|
|
} else {
|
|
|
Err(HgError::corrupted(
|
|
|
"dirstate-v2 base_name_start out of bounds",
|
|
|
))
|
|
|
}
|
|
|
}
|
|
|
|
|
|
pub(super) fn copy_source<'on_disk>(
|
|
|
&self,
|
|
|
on_disk: &'on_disk [u8],
|
|
|
) -> Result<Option<Cow<'on_disk, HgPath>>, HgError> {
|
|
|
Ok(if self.copy_source.start.get() != 0 {
|
|
|
Some(read_hg_path(on_disk, self.copy_source)?)
|
|
|
} else {
|
|
|
None
|
|
|
})
|
|
|
}
|
|
|
|
|
|
pub(super) fn entry(&self) -> Result<Option<DirstateEntry>, HgError> {
|
|
|
Ok(if self.entry.state != b'\0' {
|
|
|
Some(DirstateEntry {
|
|
|
state: self.entry.state.try_into()?,
|
|
|
mode: self.entry.mode.get(),
|
|
|
mtime: self.entry.mtime.get(),
|
|
|
size: self.entry.size.get(),
|
|
|
})
|
|
|
} else {
|
|
|
None
|
|
|
})
|
|
|
}
|
|
|
|
|
|
pub(super) fn to_in_memory_node<'on_disk>(
|
|
|
&self,
|
|
|
on_disk: &'on_disk [u8],
|
|
|
) -> Result<dirstate_map::Node<'on_disk>, HgError> {
|
|
|
Ok(dirstate_map::Node {
|
|
|
children: read_nodes(on_disk, self.children)?,
|
|
|
copy_source: self.copy_source(on_disk)?,
|
|
|
entry: self.entry()?,
|
|
|
tracked_descendants_count: self.tracked_descendants_count.get(),
|
|
|
})
|
|
|
}
|
|
|
}
|
|
|
|
|
|
fn read_nodes(
|
|
|
on_disk: &[u8],
|
|
|
slice: ChildNodes,
|
|
|
) -> Result<dirstate_map::ChildNodes, HgError> {
|
|
|
read_slice::<Node>(on_disk, slice)?
|
|
|
.iter()
|
|
|
.map(|node| {
|
|
|
Ok((node.path(on_disk)?, node.to_in_memory_node(on_disk)?))
|
|
|
})
|
|
|
.collect()
|
|
|
}
|
|
|
|
|
|
fn read_hg_path(on_disk: &[u8], slice: Slice) -> Result<Cow<HgPath>, HgError> {
|
|
|
let bytes = read_slice::<u8>(on_disk, slice)?;
|
|
|
Ok(Cow::Borrowed(HgPath::new(bytes)))
|
|
|
}
|
|
|
|
|
|
fn read_slice<T>(on_disk: &[u8], slice: Slice) -> Result<&[T], HgError>
|
|
|
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(|| {
|
|
|
HgError::corrupted("dirstate v2 slice is out of bounds")
|
|
|
})
|
|
|
}
|
|
|
|
|
|
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(&mut dirstate_map.root, &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(
|
|
|
nodes: &dirstate_map::ChildNodes,
|
|
|
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 = dirstate_map::Node::sorted(nodes);
|
|
|
|
|
|
// First accumulate serialized nodes in a `Vec`
|
|
|
let mut on_disk_nodes = Vec::with_capacity(nodes.len());
|
|
|
for (full_path, node) in nodes {
|
|
|
on_disk_nodes.push(Node {
|
|
|
children: write_nodes(&node.children, out)?,
|
|
|
tracked_descendants_count: node.tracked_descendants_count.into(),
|
|
|
full_path: write_slice::<u8>(
|
|
|
full_path.full_path().as_bytes(),
|
|
|
out,
|
|
|
),
|
|
|
base_name_start: u32::try_from(full_path.base_name_start())
|
|
|
// Could only panic for paths over 4 GiB
|
|
|
.expect("dirstate-v2 offset overflow")
|
|
|
.into(),
|
|
|
copy_source: if let Some(source) = &node.copy_source {
|
|
|
write_slice::<u8>(source.as_bytes(), out)
|
|
|
} else {
|
|
|
Slice {
|
|
|
start: 0.into(),
|
|
|
len: 0.into(),
|
|
|
}
|
|
|
},
|
|
|
entry: if let Some(entry) = &node.entry {
|
|
|
OptEntry {
|
|
|
state: entry.state.into(),
|
|
|
mode: entry.mode.into(),
|
|
|
mtime: entry.mtime.into(),
|
|
|
size: entry.size.into(),
|
|
|
}
|
|
|
} else {
|
|
|
OptEntry {
|
|
|
state: b'\0',
|
|
|
mode: 0.into(),
|
|
|
mtime: 0.into(),
|
|
|
size: 0.into(),
|
|
|
}
|
|
|
},
|
|
|
})
|
|
|
}
|
|
|
// … 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 }
|
|
|
}
|
|
|
|