rust/hg-core/src/repo.rs

run-tests: also send a message in the Keyboard interrupt case

The next patch will do something equivalent, so lets do the change in an
independant changeset first in case we need to bisect something in the future.

use crate::changelog::Changelog;
use crate::config::{Config, ConfigError, ConfigParseError};
use crate::dirstate::DirstateParents;
use crate::dirstate_tree::on_disk::Docket as DirstateDocket;
use crate::dirstate_tree::owning::OwningDirstateMap;
use crate::errors::HgResultExt;
use crate::errors::{HgError, IoResultExt};
use crate::exit_codes;
use crate::lock::{try_with_lock_no_wait, LockError};
use crate::manifest::{Manifest, Manifestlog};
use crate::revlog::filelog::Filelog;
use crate::revlog::revlog::RevlogError;
use crate::utils::files::get_path_from_bytes;
use crate::utils::hg_path::HgPath;
use crate::utils::SliceExt;
use crate::vfs::{is_dir, is_file, Vfs};
use crate::{requirements, NodePrefix};
use crate::{DirstateError, Revision};
use std::cell::{Ref, RefCell, RefMut};
use std::collections::HashSet;
use std::io::Seek;
use std::io::SeekFrom;
use std::io::Write as IoWrite;
use std::path::{Path, PathBuf};

/// A repository on disk
pub struct Repo {
    working_directory: PathBuf,
    dot_hg: PathBuf,
    store: PathBuf,
    requirements: HashSet<String>,
    config: Config,
    dirstate_parents: LazyCell<DirstateParents, HgError>,
    dirstate_data_file_uuid: LazyCell<Option<Vec<u8>>, HgError>,
    dirstate_map: LazyCell<OwningDirstateMap, DirstateError>,
    changelog: LazyCell<Changelog, HgError>,
    manifestlog: LazyCell<Manifestlog, HgError>,
}

#[derive(Debug, derive_more::From)]
pub enum RepoError {
    NotFound {
        at: PathBuf,
    },
    #[from]
    ConfigParseError(ConfigParseError),
    #[from]
    Other(HgError),
}

impl From<ConfigError> for RepoError {
    fn from(error: ConfigError) -> Self {
        match error {
            ConfigError::Parse(error) => error.into(),
            ConfigError::Other(error) => error.into(),
        }
    }
}

impl Repo {
    /// tries to find nearest repository root in current working directory or
    /// its ancestors
    pub fn find_repo_root() -> Result<PathBuf, RepoError> {
        let current_directory = crate::utils::current_dir()?;
        // ancestors() is inclusive: it first yields `current_directory`
        // as-is.
        for ancestor in current_directory.ancestors() {
            if is_dir(ancestor.join(".hg"))? {
                return Ok(ancestor.to_path_buf());
            }
        }
        return Err(RepoError::NotFound {
            at: current_directory,
        });
    }

    /// Find a repository, either at the given path (which must contain a `.hg`
    /// sub-directory) or by searching the current directory and its
    /// ancestors.
    ///
    /// A method with two very different "modes" like this usually a code smell
    /// to make two methods instead, but in this case an `Option` is what rhg
    /// sub-commands get from Clap for the `-R` / `--repository` CLI argument.
    /// Having two methods would just move that `if` to almost all callers.
    pub fn find(
        config: &Config,
        explicit_path: Option<PathBuf>,
    ) -> Result<Self, RepoError> {
        if let Some(root) = explicit_path {
            if is_dir(root.join(".hg"))? {
                Self::new_at_path(root.to_owned(), config)
            } else if is_file(&root)? {
                Err(HgError::unsupported("bundle repository").into())
            } else {
                Err(RepoError::NotFound {
                    at: root.to_owned(),
                })
            }
        } else {
            let root = Self::find_repo_root()?;
            Self::new_at_path(root, config)
        }
    }

    /// To be called after checking that `.hg` is a sub-directory
    fn new_at_path(
        working_directory: PathBuf,
        config: &Config,
    ) -> Result<Self, RepoError> {
        let dot_hg = working_directory.join(".hg");

        let mut repo_config_files = Vec::new();
        repo_config_files.push(dot_hg.join("hgrc"));
        repo_config_files.push(dot_hg.join("hgrc-not-shared"));

        let hg_vfs = Vfs { base: &dot_hg };
        let mut reqs = requirements::load_if_exists(hg_vfs)?;
        let relative =
            reqs.contains(requirements::RELATIVE_SHARED_REQUIREMENT);
        let shared =
            reqs.contains(requirements::SHARED_REQUIREMENT) || relative;

        // From `mercurial/localrepo.py`:
        //
        // if .hg/requires contains the sharesafe requirement, it means
        // there exists a `.hg/store/requires` too and we should read it
        // NOTE: presence of SHARESAFE_REQUIREMENT imply that store requirement
        // is present. We never write SHARESAFE_REQUIREMENT for a repo if store
        // is not present, refer checkrequirementscompat() for that
        //
        // However, if SHARESAFE_REQUIREMENT is not present, it means that the
        // repository was shared the old way. We check the share source
        // .hg/requires for SHARESAFE_REQUIREMENT to detect whether the
        // current repository needs to be reshared
        let share_safe = reqs.contains(requirements::SHARESAFE_REQUIREMENT);

        let store_path;
        if !shared {
            store_path = dot_hg.join("store");
        } else {
            let bytes = hg_vfs.read("sharedpath")?;
            let mut shared_path =
                get_path_from_bytes(bytes.trim_end_matches(|b| b == b'\n'))
                    .to_owned();
            if relative {
                shared_path = dot_hg.join(shared_path)
            }
            if !is_dir(&shared_path)? {
                return Err(HgError::corrupted(format!(
                    ".hg/sharedpath points to nonexistent directory {}",
                    shared_path.display()
                ))
                .into());
            }

            store_path = shared_path.join("store");

            let source_is_share_safe =
                requirements::load(Vfs { base: &shared_path })?
                    .contains(requirements::SHARESAFE_REQUIREMENT);

            if share_safe && !source_is_share_safe {
                return Err(match config
                    .get(b"share", b"safe-mismatch.source-not-safe")
                {
                    Some(b"abort") | None => HgError::abort(
                        "abort: share source does not support share-safe requirement\n\
                        (see `hg help config.format.use-share-safe` for more information)",
                        exit_codes::ABORT,
                    ),
                    _ => HgError::unsupported("share-safe downgrade"),
                }
                .into());
            } else if source_is_share_safe && !share_safe {
                return Err(
                    match config.get(b"share", b"safe-mismatch.source-safe") {
                        Some(b"abort") | None => HgError::abort(
                            "abort: version mismatch: source uses share-safe \
                            functionality while the current share does not\n\
                            (see `hg help config.format.use-share-safe` for more information)",
                        exit_codes::ABORT,
                        ),
                        _ => HgError::unsupported("share-safe upgrade"),
                    }
                    .into(),
                );
            }

            if share_safe {
                repo_config_files.insert(0, shared_path.join("hgrc"))
            }
        }
        if share_safe {
            reqs.extend(requirements::load(Vfs { base: &store_path })?);
        }

        let repo_config = if std::env::var_os("HGRCSKIPREPO").is_none() {
            config.combine_with_repo(&repo_config_files)?
        } else {
            config.clone()
        };

        let repo = Self {
            requirements: reqs,
            working_directory,
            store: store_path,
            dot_hg,
            config: repo_config,
            dirstate_parents: LazyCell::new(Self::read_dirstate_parents),
            dirstate_data_file_uuid: LazyCell::new(
                Self::read_dirstate_data_file_uuid,
            ),
            dirstate_map: LazyCell::new(Self::new_dirstate_map),
            changelog: LazyCell::new(Changelog::open),
            manifestlog: LazyCell::new(Manifestlog::open),
        };

        requirements::check(&repo)?;

        Ok(repo)
    }

    pub fn working_directory_path(&self) -> &Path {
        &self.working_directory
    }

    pub fn requirements(&self) -> &HashSet<String> {
        &self.requirements
    }

    pub fn config(&self) -> &Config {
        &self.config
    }

    /// For accessing repository files (in `.hg`), except for the store
    /// (`.hg/store`).
    pub fn hg_vfs(&self) -> Vfs<'_> {
        Vfs { base: &self.dot_hg }
    }

    /// For accessing repository store files (in `.hg/store`)
    pub fn store_vfs(&self) -> Vfs<'_> {
        Vfs { base: &self.store }
    }

    /// For accessing the working copy
    pub fn working_directory_vfs(&self) -> Vfs<'_> {
        Vfs {
            base: &self.working_directory,
        }
    }

    pub fn try_with_wlock_no_wait<R>(
        &self,
        f: impl FnOnce() -> R,
    ) -> Result<R, LockError> {
        try_with_lock_no_wait(self.hg_vfs(), "wlock", f)
    }

    pub fn has_dirstate_v2(&self) -> bool {
        self.requirements
            .contains(requirements::DIRSTATE_V2_REQUIREMENT)
    }

    pub fn has_sparse(&self) -> bool {
        self.requirements.contains(requirements::SPARSE_REQUIREMENT)
    }

    pub fn has_narrow(&self) -> bool {
        self.requirements.contains(requirements::NARROW_REQUIREMENT)
    }

    fn dirstate_file_contents(&self) -> Result<Vec<u8>, HgError> {
        Ok(self
            .hg_vfs()
            .read("dirstate")
            .io_not_found_as_none()?
            .unwrap_or(Vec::new()))
    }

    pub fn dirstate_parents(&self) -> Result<DirstateParents, HgError> {
        Ok(*self.dirstate_parents.get_or_init(self)?)
    }

    fn read_dirstate_parents(&self) -> Result<DirstateParents, HgError> {
        let dirstate = self.dirstate_file_contents()?;
        let parents = if dirstate.is_empty() {
            if self.has_dirstate_v2() {
                self.dirstate_data_file_uuid.set(None);
            }
            DirstateParents::NULL
        } else if self.has_dirstate_v2() {
            let docket =
                crate::dirstate_tree::on_disk::read_docket(&dirstate)?;
            self.dirstate_data_file_uuid
                .set(Some(docket.uuid.to_owned()));
            docket.parents()
        } else {
            crate::dirstate::parsers::parse_dirstate_parents(&dirstate)?
                .clone()
        };
        self.dirstate_parents.set(parents);
        Ok(parents)
    }

    fn read_dirstate_data_file_uuid(
        &self,
    ) -> Result<Option<Vec<u8>>, HgError> {
        assert!(
            self.has_dirstate_v2(),
            "accessing dirstate data file ID without dirstate-v2"
        );
        let dirstate = self.dirstate_file_contents()?;
        if dirstate.is_empty() {
            self.dirstate_parents.set(DirstateParents::NULL);
            Ok(None)
        } else {
            let docket =
                crate::dirstate_tree::on_disk::read_docket(&dirstate)?;
            self.dirstate_parents.set(docket.parents());
            Ok(Some(docket.uuid.to_owned()))
        }
    }

    fn new_dirstate_map(&self) -> Result<OwningDirstateMap, DirstateError> {
        let dirstate_file_contents = self.dirstate_file_contents()?;
        if dirstate_file_contents.is_empty() {
            self.dirstate_parents.set(DirstateParents::NULL);
            if self.has_dirstate_v2() {
                self.dirstate_data_file_uuid.set(None);
            }
            Ok(OwningDirstateMap::new_empty(Vec::new()))
        } else if self.has_dirstate_v2() {
            let docket = crate::dirstate_tree::on_disk::read_docket(
                &dirstate_file_contents,
            )?;
            self.dirstate_parents.set(docket.parents());
            self.dirstate_data_file_uuid
                .set(Some(docket.uuid.to_owned()));
            let data_size = docket.data_size();
            let metadata = docket.tree_metadata();
            if let Some(data_mmap) = self
                .hg_vfs()
                .mmap_open(docket.data_filename())
                .io_not_found_as_none()?
            {
                OwningDirstateMap::new_v2(data_mmap, data_size, metadata)
            } else {
                OwningDirstateMap::new_v2(Vec::new(), data_size, metadata)
            }
        } else {
            let (map, parents) =
                OwningDirstateMap::new_v1(dirstate_file_contents)?;
            self.dirstate_parents.set(parents);
            Ok(map)
        }
    }

    pub fn dirstate_map(
        &self,
    ) -> Result<Ref<OwningDirstateMap>, DirstateError> {
        self.dirstate_map.get_or_init(self)
    }

    pub fn dirstate_map_mut(
        &self,
    ) -> Result<RefMut<OwningDirstateMap>, DirstateError> {
        self.dirstate_map.get_mut_or_init(self)
    }

    pub fn changelog(&self) -> Result<Ref<Changelog>, HgError> {
        self.changelog.get_or_init(self)
    }

    pub fn changelog_mut(&self) -> Result<RefMut<Changelog>, HgError> {
        self.changelog.get_mut_or_init(self)
    }

    pub fn manifestlog(&self) -> Result<Ref<Manifestlog>, HgError> {
        self.manifestlog.get_or_init(self)
    }

    pub fn manifestlog_mut(&self) -> Result<RefMut<Manifestlog>, HgError> {
        self.manifestlog.get_mut_or_init(self)
    }

    /// Returns the manifest of the *changeset* with the given node ID
    pub fn manifest_for_node(
        &self,
        node: impl Into<NodePrefix>,
    ) -> Result<Manifest, RevlogError> {
        self.manifestlog()?.data_for_node(
            self.changelog()?
                .data_for_node(node.into())?
                .manifest_node()?
                .into(),
        )
    }

    /// Returns the manifest of the *changeset* with the given revision number
    pub fn manifest_for_rev(
        &self,
        revision: Revision,
    ) -> Result<Manifest, RevlogError> {
        self.manifestlog()?.data_for_node(
            self.changelog()?
                .data_for_rev(revision)?
                .manifest_node()?
                .into(),
        )
    }

    pub fn has_subrepos(&self) -> Result<bool, DirstateError> {
        if let Some(entry) = self.dirstate_map()?.get(HgPath::new(".hgsub"))? {
            Ok(entry.state().is_tracked())
        } else {
            Ok(false)
        }
    }

    pub fn filelog(&self, path: &HgPath) -> Result<Filelog, HgError> {
        Filelog::open(self, path)
    }

    /// Write to disk any updates that were made through `dirstate_map_mut`.
    ///
    /// The "wlock" must be held while calling this.
    /// See for example `try_with_wlock_no_wait`.
    ///
    /// TODO: have a `WritableRepo` type only accessible while holding the
    /// lock?
    pub fn write_dirstate(&self) -> Result<(), DirstateError> {
        let map = self.dirstate_map()?;
        // TODO: Maintain a `DirstateMap::dirty` flag, and return early here if
        // it’s unset
        let parents = self.dirstate_parents()?;
        let (packed_dirstate, old_uuid_to_remove) = if self.has_dirstate_v2() {
            let uuid_opt = self.dirstate_data_file_uuid.get_or_init(self)?;
            let uuid_opt = uuid_opt.as_ref();
            let can_append = uuid_opt.is_some();
            let (data, tree_metadata, append, old_data_size) =
                map.pack_v2(can_append)?;

            // Reuse the uuid, or generate a new one, keeping the old for
            // deletion.
            let (uuid, old_uuid) = match uuid_opt {
                Some(uuid) => {
                    let as_str = std::str::from_utf8(uuid)
                        .map_err(|_| {
                            HgError::corrupted(
                                "non-UTF-8 dirstate data file ID",
                            )
                        })?
                        .to_owned();
                    if append {
                        (as_str, None)
                    } else {
                        (DirstateDocket::new_uid(), Some(as_str))
                    }
                }
                None => (DirstateDocket::new_uid(), None),
            };

            let data_filename = format!("dirstate.{}", uuid);
            let data_filename = self.hg_vfs().join(data_filename);
            let mut options = std::fs::OpenOptions::new();
            options.write(true);

            // Why are we not using the O_APPEND flag when appending?
            //
            // - O_APPEND makes it trickier to deal with garbage at the end of
            //   the file, left by a previous uncommitted transaction. By
            //   starting the write at [old_data_size] we make sure we erase
            //   all such garbage.
            //
            // - O_APPEND requires to special-case 0-byte writes, whereas we
            //   don't need that.
            //
            // - Some OSes have bugs in implementation O_APPEND:
            //   revlog.py talks about a Solaris bug, but we also saw some ZFS
            //   bug: https://github.com/openzfs/zfs/pull/3124,
            //   https://github.com/openzfs/zfs/issues/13370
            //
            if !append {
                options.create_new(true);
            }

            let data_size = (|| {
                // TODO: loop and try another random ID if !append and this
                // returns `ErrorKind::AlreadyExists`? Collision chance of two
                // random IDs is one in 2**32
                let mut file = options.open(&data_filename)?;
                if append {
                    file.seek(SeekFrom::Start(old_data_size as u64))?;
                }
                file.write_all(&data)?;
                file.flush()?;
                file.seek(SeekFrom::Current(0))
            })()
            .when_writing_file(&data_filename)?;

            let packed_dirstate = DirstateDocket::serialize(
                parents,
                tree_metadata,
                data_size,
                uuid.as_bytes(),
            )
            .map_err(|_: std::num::TryFromIntError| {
                HgError::corrupted("overflow in dirstate docket serialization")
            })?;

            (packed_dirstate, old_uuid)
        } else {
            (map.pack_v1(parents)?, None)
        };

        let vfs = self.hg_vfs();
        vfs.atomic_write("dirstate", &packed_dirstate)?;
        if let Some(uuid) = old_uuid_to_remove {
            // Remove the old data file after the new docket pointing to the
            // new data file was written.
            vfs.remove_file(format!("dirstate.{}", uuid))?;
        }
        Ok(())
    }
}

/// Lazily-initialized component of `Repo` with interior mutability
///
/// This differs from `OnceCell` in that the value can still be "deinitialized"
/// later by setting its inner `Option` to `None`.
struct LazyCell<T, E> {
    value: RefCell<Option<T>>,
    // `Fn`s that don’t capture environment are zero-size, so this box does
    // not allocate:
    init: Box<dyn Fn(&Repo) -> Result<T, E>>,
}

impl<T, E> LazyCell<T, E> {
    fn new(init: impl Fn(&Repo) -> Result<T, E> + 'static) -> Self {
        Self {
            value: RefCell::new(None),
            init: Box::new(init),
        }
    }

    fn set(&self, value: T) {
        *self.value.borrow_mut() = Some(value)
    }

    fn get_or_init(&self, repo: &Repo) -> Result<Ref<T>, E> {
        let mut borrowed = self.value.borrow();
        if borrowed.is_none() {
            drop(borrowed);
            // Only use `borrow_mut` if it is really needed to avoid panic in
            // case there is another outstanding borrow but mutation is not
            // needed.
            *self.value.borrow_mut() = Some((self.init)(repo)?);
            borrowed = self.value.borrow()
        }
        Ok(Ref::map(borrowed, |option| option.as_ref().unwrap()))
    }

    fn get_mut_or_init(&self, repo: &Repo) -> Result<RefMut<T>, E> {
        let mut borrowed = self.value.borrow_mut();
        if borrowed.is_none() {
            *borrowed = Some((self.init)(repo)?);
        }
        Ok(RefMut::map(borrowed, |option| option.as_mut().unwrap()))
    }
}