view rust/hg-core/src/repo.rs @ 47410:ebdef6283798

rhg: read [paths] for `--repository` value

hg parses `-R` and `--repository` CLI arguments "early" in order to know which
local repository to load config from. (Config can then affect whether or how to
fall back.)

The value of of those arguments can be not only a filesystem path, but also an
alias configured in the `[paths]` section. This part was missing in rhg and
this patch implements that.

The current patch still lacks functionality to read config of current repository
if we are not at root of repo. That will be fixed in upcoming patches.

A new crate `home` is added to get path of home directory.

Differential Revision: https://phab.mercurial-scm.org/D10296

use crate::config::{Config, ConfigError, ConfigParseError};
use crate::errors::{HgError, IoErrorContext, IoResultExt};
use crate::requirements;
use crate::utils::files::get_path_from_bytes;
use crate::utils::SliceExt;
use memmap::{Mmap, MmapOptions};
use std::collections::HashSet;
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,
}

#[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(),
        }
    }
}

/// Filesystem access abstraction for the contents of a given "base" diretory
#[derive(Clone, Copy)]
pub struct Vfs<'a> {
    pub(crate) base: &'a Path,
}

impl Repo {
    /// 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 root.join(".hg").is_dir() {
                Self::new_at_path(root.to_owned(), config)
            } else if root.is_file() {
                Err(HgError::unsupported("bundle repository").into())
            } else {
                Err(RepoError::NotFound {
                    at: root.to_owned(),
                })
            }
        } else {
            let current_directory = crate::utils::current_dir()?;
            // ancestors() is inclusive: it first yields `current_directory`
            // as-is.
            for ancestor in current_directory.ancestors() {
                if ancestor.join(".hg").is_dir() {
                    return Self::new_at_path(ancestor.to_owned(), config);
                }
            }
            Err(RepoError::NotFound {
                at: current_directory,
            })
        }
    }

    /// 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_newlines()).to_owned();
            if relative {
                shared_path = dot_hg.join(shared_path)
            }
            if !shared_path.is_dir() {
                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)",
                    ),
                    _ => 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)",
                        ),
                        _ => 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,
        };

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

    pub fn dirstate_parents(
        &self,
    ) -> Result<crate::dirstate::DirstateParents, HgError> {
        let dirstate = self.hg_vfs().mmap_open("dirstate")?;
        if dirstate.is_empty() {
            return Ok(crate::dirstate::DirstateParents::NULL);
        }
        let parents = if self.has_dirstate_v2() {
            crate::dirstate_tree::on_disk::parse_dirstate_parents(&dirstate)?
        } else {
            crate::dirstate::parsers::parse_dirstate_parents(&dirstate)?
        };
        Ok(parents.clone())
    }
}

impl Vfs<'_> {
    pub fn join(&self, relative_path: impl AsRef<Path>) -> PathBuf {
        self.base.join(relative_path)
    }

    pub fn read(
        &self,
        relative_path: impl AsRef<Path>,
    ) -> Result<Vec<u8>, HgError> {
        let path = self.join(relative_path);
        std::fs::read(&path).when_reading_file(&path)
    }

    pub fn mmap_open(
        &self,
        relative_path: impl AsRef<Path>,
    ) -> Result<Mmap, HgError> {
        let path = self.base.join(relative_path);
        let file = std::fs::File::open(&path).when_reading_file(&path)?;
        // TODO: what are the safety requirements here?
        let mmap = unsafe { MmapOptions::new().map(&file) }
            .when_reading_file(&path)?;
        Ok(mmap)
    }

    pub fn rename(
        &self,
        relative_from: impl AsRef<Path>,
        relative_to: impl AsRef<Path>,
    ) -> Result<(), HgError> {
        let from = self.join(relative_from);
        let to = self.join(relative_to);
        std::fs::rename(&from, &to)
            .with_context(|| IoErrorContext::RenamingFile { from, to })
    }
}