rust/hg-core/src/dirstate.rs

dirstate: move the handling of special case within the dirstatemap

The dirstatemap is as well, if not better, suited to decided how to encode the
various case. So we move the associated code in the dirstatemap `addfile`
method.

This means the dirstate no longer need to know about the various magic value
used in the dirstate V1 format.

The pain of the messy API start to be quite palpable in Rust, we should clean
this up once the current large refactoring is dealt with.

Differential Revision: https://phab.mercurial-scm.org/D10963

// dirstate module
//
// Copyright 2019 Raphaël Gomès <[e-mail]>
//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.

use crate::dirstate_tree::on_disk::DirstateV2ParseError;
use crate::errors::HgError;
use crate::revlog::node::NULL_NODE;
use crate::revlog::Node;
use crate::utils::hg_path::{HgPath, HgPathBuf};
use crate::FastHashMap;
use bytes_cast::{unaligned, BytesCast};
use std::convert::TryFrom;

pub mod dirs_multiset;
pub mod dirstate_map;
pub mod parsers;
pub mod status;

#[derive(Debug, PartialEq, Clone, BytesCast)]
#[repr(C)]
pub struct DirstateParents {
    pub p1: Node,
    pub p2: Node,
}

impl DirstateParents {
    pub const NULL: Self = Self {
        p1: NULL_NODE,
        p2: NULL_NODE,
    };
}

/// The C implementation uses all signed types. This will be an issue
/// either when 4GB+ source files are commonplace or in 2038, whichever
/// comes first.
#[derive(Debug, PartialEq, Copy, Clone)]
pub struct DirstateEntry {
    pub state: EntryState,
    pub mode: i32,
    pub mtime: i32,
    pub size: i32,
}

impl DirstateEntry {
    pub fn is_non_normal(&self) -> bool {
        self.state != EntryState::Normal || self.mtime == MTIME_UNSET
    }

    pub fn is_from_other_parent(&self) -> bool {
        self.state == EntryState::Normal && self.size == SIZE_FROM_OTHER_PARENT
    }

    // TODO: other platforms
    #[cfg(unix)]
    pub fn mode_changed(
        &self,
        filesystem_metadata: &std::fs::Metadata,
    ) -> bool {
        use std::os::unix::fs::MetadataExt;
        const EXEC_BIT_MASK: u32 = 0o100;
        let dirstate_exec_bit = (self.mode as u32) & EXEC_BIT_MASK;
        let fs_exec_bit = filesystem_metadata.mode() & EXEC_BIT_MASK;
        dirstate_exec_bit != fs_exec_bit
    }
}

#[derive(BytesCast)]
#[repr(C)]
struct RawEntry {
    state: u8,
    mode: unaligned::I32Be,
    size: unaligned::I32Be,
    mtime: unaligned::I32Be,
    length: unaligned::I32Be,
}

pub const V1_RANGEMASK: i32 = 0x7FFFFFFF;

pub const MTIME_UNSET: i32 = -1;

/// A `DirstateEntry` with a size of `-2` means that it was merged from the
/// other parent. This allows revert to pick the right status back during a
/// merge.
pub const SIZE_FROM_OTHER_PARENT: i32 = -2;
/// A special value used for internal representation of special case in
/// dirstate v1 format.
pub const SIZE_NON_NORMAL: i32 = -1;

pub type StateMap = FastHashMap<HgPathBuf, DirstateEntry>;
pub type StateMapIter<'a> = Box<
    dyn Iterator<
            Item = Result<(&'a HgPath, DirstateEntry), DirstateV2ParseError>,
        > + Send
        + 'a,
>;

pub type CopyMap = FastHashMap<HgPathBuf, HgPathBuf>;
pub type CopyMapIter<'a> = Box<
    dyn Iterator<Item = Result<(&'a HgPath, &'a HgPath), DirstateV2ParseError>>
        + Send
        + 'a,
>;

#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub enum EntryState {
    Normal,
    Added,
    Removed,
    Merged,
    Unknown,
}

impl EntryState {
    pub fn is_tracked(self) -> bool {
        use EntryState::*;
        match self {
            Normal | Added | Merged => true,
            Removed | Unknown => false,
        }
    }
}

impl TryFrom<u8> for EntryState {
    type Error = HgError;

    fn try_from(value: u8) -> Result<Self, Self::Error> {
        match value {
            b'n' => Ok(EntryState::Normal),
            b'a' => Ok(EntryState::Added),
            b'r' => Ok(EntryState::Removed),
            b'm' => Ok(EntryState::Merged),
            b'?' => Ok(EntryState::Unknown),
            _ => Err(HgError::CorruptedRepository(format!(
                "Incorrect dirstate entry state {}",
                value
            ))),
        }
    }
}

impl Into<u8> for EntryState {
    fn into(self) -> u8 {
        match self {
            EntryState::Normal => b'n',
            EntryState::Added => b'a',
            EntryState::Removed => b'r',
            EntryState::Merged => b'm',
            EntryState::Unknown => b'?',
        }
    }
}