rust/hg-core/src/narrow.rs

rust-dirstate: merge `dirstate_tree` module into `dirstate`

The historical reasonning for `dirstate_tree` existing in the first place is
that a new approach was needed for the tree-like dirstate and it was easier
to start somewhat fresh. Now that the former dirstate is (long) gone, we
can merge those two modules to avoid the confusion that even the module
creators sometimes get.

use std::path::Path;

use crate::{
    errors::HgError,
    exit_codes,
    filepatterns::parse_pattern_file_contents,
    matchers::{
        AlwaysMatcher, DifferenceMatcher, IncludeMatcher, Matcher,
        NeverMatcher,
    },
    repo::Repo,
    requirements::NARROW_REQUIREMENT,
    sparse::{self, SparseConfigError, SparseWarning},
};

/// The file in .hg/store/ that indicates which paths exit in the store
const FILENAME: &str = "narrowspec";
/// The file in .hg/ that indicates which paths exit in the dirstate
const DIRSTATE_FILENAME: &str = "narrowspec.dirstate";

/// Pattern prefixes that are allowed in narrow patterns. This list MUST
/// only contain patterns that are fast and safe to evaluate. Keep in mind
/// that patterns are supplied by clients and executed on remote servers
/// as part of wire protocol commands. That means that changes to this
/// data structure influence the wire protocol and should not be taken
/// lightly - especially removals.
pub const VALID_PREFIXES: [&str; 2] = ["path:", "rootfilesin:"];

/// Return the matcher for the current narrow spec, and all configuration
/// warnings to display.
pub fn matcher(
    repo: &Repo,
) -> Result<(Box<dyn Matcher + Sync>, Vec<SparseWarning>), SparseConfigError> {
    let mut warnings = vec![];
    if !repo.requirements().contains(NARROW_REQUIREMENT) {
        return Ok((Box::new(AlwaysMatcher), warnings));
    }
    // Treat "narrowspec does not exist" the same as "narrowspec file exists
    // and is empty".
    let store_spec = repo.store_vfs().try_read(FILENAME)?.unwrap_or_default();
    let working_copy_spec = repo
        .hg_vfs()
        .try_read(DIRSTATE_FILENAME)?
        .unwrap_or_default();
    if store_spec != working_copy_spec {
        return Err(HgError::abort(
            "abort: working copy's narrowspec is stale",
            exit_codes::STATE_ERROR,
            Some("run 'hg tracked --update-working-copy'".into()),
        )
        .into());
    }

    let config = sparse::parse_config(
        &store_spec,
        sparse::SparseConfigContext::Narrow,
    )?;

    warnings.extend(config.warnings);

    if !config.profiles.is_empty() {
        // TODO (from Python impl) maybe do something with profiles?
        return Err(SparseConfigError::IncludesInNarrow);
    }
    validate_patterns(&config.includes)?;
    validate_patterns(&config.excludes)?;

    if config.includes.is_empty() {
        return Ok((Box::new(NeverMatcher), warnings));
    }

    let (patterns, subwarnings) = parse_pattern_file_contents(
        &config.includes,
        Path::new(""),
        None,
        false,
        true,
    )?;
    warnings.extend(subwarnings.into_iter().map(From::from));

    let mut m: Box<dyn Matcher + Sync> =
        Box::new(IncludeMatcher::new(patterns)?);

    let (patterns, subwarnings) = parse_pattern_file_contents(
        &config.excludes,
        Path::new(""),
        None,
        false,
        true,
    )?;
    if !patterns.is_empty() {
        warnings.extend(subwarnings.into_iter().map(From::from));
        let exclude_matcher = Box::new(IncludeMatcher::new(patterns)?);
        m = Box::new(DifferenceMatcher::new(m, exclude_matcher));
    }

    Ok((m, warnings))
}

fn validate_patterns(patterns: &[u8]) -> Result<(), SparseConfigError> {
    for pattern in patterns.split(|c| *c == b'\n') {
        if pattern.is_empty() {
            continue;
        }
        for prefix in VALID_PREFIXES.iter() {
            if pattern.starts_with(prefix.as_bytes()) {
                return Ok(());
            }
        }
        return Err(SparseConfigError::InvalidNarrowPrefix(
            pattern.to_owned(),
        ));
    }
    Ok(())
}