view rust/hg-core/src/config/layer.rs @ 46243:63c923fd7fa8

setup: when possible, build and bundle man pages

This makes it so the manual pages are built as part of the Python
build, and includes them in any wheel generated. This should make
Python wheels a much more useful and complete way of distributing
Mercurial binaries.

Differential Revision: https://phab.mercurial-scm.org/D9640

// layer.rs
//
// Copyright 2020
//      Valentin Gatien-Baron,
//      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::utils::files::{
    get_bytes_from_path, get_path_from_bytes, read_whole_file,
};
use format_bytes::format_bytes;
use lazy_static::lazy_static;
use regex::bytes::Regex;
use std::collections::HashMap;
use std::io;
use std::path::{Path, PathBuf};

lazy_static! {
    static ref SECTION_RE: Regex = make_regex(r"^\[([^\[]+)\]");
    static ref ITEM_RE: Regex = make_regex(r"^([^=\s][^=]*?)\s*=\s*((.*\S)?)");
    /// Continuation whitespace
    static ref CONT_RE: Regex = make_regex(r"^\s+(\S|\S.*\S)\s*$");
    static ref EMPTY_RE: Regex = make_regex(r"^(;|#|\s*$)");
    static ref COMMENT_RE: Regex = make_regex(r"^(;|#)");
    /// A directive that allows for removing previous entries
    static ref UNSET_RE: Regex = make_regex(r"^%unset\s+(\S+)");
    /// A directive that allows for including other config files
    static ref INCLUDE_RE: Regex = make_regex(r"^%include\s+(\S|\S.*\S)\s*$");
}

/// All config values separated by layers of precedence.
/// Each config source may be split in multiple layers if `%include` directives
/// are used.
/// TODO detail the general precedence
#[derive(Clone)]
pub struct ConfigLayer {
    /// Mapping of the sections to their items
    sections: HashMap<Vec<u8>, ConfigItem>,
    /// All sections (and their items/values) in a layer share the same origin
    pub origin: ConfigOrigin,
    /// Whether this layer comes from a trusted user or group
    pub trusted: bool,
}

impl ConfigLayer {
    pub fn new(origin: ConfigOrigin) -> Self {
        ConfigLayer {
            sections: HashMap::new(),
            trusted: true, // TODO check
            origin,
        }
    }

    /// Add an entry to the config, overwriting the old one if already present.
    pub fn add(
        &mut self,
        section: Vec<u8>,
        item: Vec<u8>,
        value: Vec<u8>,
        line: Option<usize>,
    ) {
        self.sections
            .entry(section)
            .or_insert_with(|| HashMap::new())
            .insert(item, ConfigValue { bytes: value, line });
    }

    /// Returns the config value in `<section>.<item>` if it exists
    pub fn get(&self, section: &[u8], item: &[u8]) -> Option<&ConfigValue> {
        Some(self.sections.get(section)?.get(item)?)
    }

    pub fn is_empty(&self) -> bool {
        self.sections.is_empty()
    }

    /// Returns a `Vec` of layers in order of precedence (so, in read order),
    /// recursively parsing the `%include` directives if any.
    pub fn parse(src: &Path, data: &[u8]) -> Result<Vec<Self>, ConfigError> {
        let mut layers = vec![];

        // Discard byte order mark if any
        let data = if data.starts_with(b"\xef\xbb\xbf") {
            &data[3..]
        } else {
            data
        };

        // TODO check if it's trusted
        let mut current_layer = Self::new(ConfigOrigin::File(src.to_owned()));

        let mut lines_iter =
            data.split(|b| *b == b'\n').enumerate().peekable();
        let mut section = b"".to_vec();

        while let Some((index, bytes)) = lines_iter.next() {
            if let Some(m) = INCLUDE_RE.captures(&bytes) {
                let filename_bytes = &m[1];
                let filename_to_include = get_path_from_bytes(&filename_bytes);
                match read_include(&src, &filename_to_include) {
                    (include_src, Ok(data)) => {
                        layers.push(current_layer);
                        layers.extend(Self::parse(&include_src, &data)?);
                        current_layer =
                            Self::new(ConfigOrigin::File(src.to_owned()));
                    }
                    (_, Err(e)) => {
                        return Err(ConfigError::IncludeError {
                            path: filename_to_include.to_owned(),
                            io_error: e,
                        })
                    }
                }
            } else if let Some(_) = EMPTY_RE.captures(&bytes) {
            } else if let Some(m) = SECTION_RE.captures(&bytes) {
                section = m[1].to_vec();
            } else if let Some(m) = ITEM_RE.captures(&bytes) {
                let item = m[1].to_vec();
                let mut value = m[2].to_vec();
                loop {
                    match lines_iter.peek() {
                        None => break,
                        Some((_, v)) => {
                            if let Some(_) = COMMENT_RE.captures(&v) {
                            } else if let Some(_) = CONT_RE.captures(&v) {
                                value.extend(b"\n");
                                value.extend(&m[1]);
                            } else {
                                break;
                            }
                        }
                    };
                    lines_iter.next();
                }
                current_layer.add(
                    section.clone(),
                    item,
                    value,
                    Some(index + 1),
                );
            } else if let Some(m) = UNSET_RE.captures(&bytes) {
                if let Some(map) = current_layer.sections.get_mut(&section) {
                    map.remove(&m[1]);
                }
            } else {
                return Err(ConfigError::Parse {
                    origin: ConfigOrigin::File(src.to_owned()),
                    line: Some(index + 1),
                    bytes: bytes.to_owned(),
                });
            }
        }
        if !current_layer.is_empty() {
            layers.push(current_layer);
        }
        Ok(layers)
    }
}

impl std::fmt::Debug for ConfigLayer {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let mut sections: Vec<_> = self.sections.iter().collect();
        sections.sort_by(|e0, e1| e0.0.cmp(e1.0));

        for (section, items) in sections.into_iter() {
            let mut items: Vec<_> = items.into_iter().collect();
            items.sort_by(|e0, e1| e0.0.cmp(e1.0));

            for (item, config_entry) in items {
                writeln!(
                    f,
                    "{}",
                    String::from_utf8_lossy(&format_bytes!(
                        b"{}.{}={} # {}",
                        section,
                        item,
                        &config_entry.bytes,
                        &self.origin.to_bytes(),
                    ))
                )?
            }
        }
        Ok(())
    }
}

/// Mapping of section item to value.
/// In the following:
/// ```text
/// [ui]
/// paginate=no
/// ```
/// "paginate" is the section item and "no" the value.
pub type ConfigItem = HashMap<Vec<u8>, ConfigValue>;

#[derive(Clone, Debug, PartialEq)]
pub struct ConfigValue {
    /// The raw bytes of the value (be it from the CLI, env or from a file)
    pub bytes: Vec<u8>,
    /// Only present if the value comes from a file, 1-indexed.
    pub line: Option<usize>,
}

#[derive(Clone, Debug)]
pub enum ConfigOrigin {
    /// The value comes from a configuration file
    File(PathBuf),
    /// The value comes from the environment like `$PAGER` or `$EDITOR`
    Environment(Vec<u8>),
    /* TODO cli
     * TODO defaults (configitems.py)
     * TODO extensions
     * TODO Python resources?
     * Others? */
}

impl ConfigOrigin {
    /// TODO use some kind of dedicated trait?
    pub fn to_bytes(&self) -> Vec<u8> {
        match self {
            ConfigOrigin::File(p) => get_bytes_from_path(p),
            ConfigOrigin::Environment(e) => e.to_owned(),
        }
    }
}

#[derive(Debug)]
pub enum ConfigError {
    Parse {
        origin: ConfigOrigin,
        line: Option<usize>,
        bytes: Vec<u8>,
    },
    /// Failed to include a sub config file
    IncludeError {
        path: PathBuf,
        io_error: std::io::Error,
    },
    /// Any IO error that isn't expected
    IO(std::io::Error),
}

impl From<std::io::Error> for ConfigError {
    fn from(e: std::io::Error) -> Self {
        Self::IO(e)
    }
}

fn make_regex(pattern: &'static str) -> Regex {
    Regex::new(pattern).expect("expected a valid regex")
}

/// Includes are relative to the file they're defined in, unless they're
/// absolute.
fn read_include(
    old_src: &Path,
    new_src: &Path,
) -> (PathBuf, io::Result<Vec<u8>>) {
    if new_src.is_absolute() {
        (new_src.to_path_buf(), read_whole_file(&new_src))
    } else {
        let dir = old_src.parent().unwrap();
        let new_src = dir.join(&new_src);
        (new_src.to_owned(), read_whole_file(&new_src))
    }
}