rust/rhg/src/error.rs

rhg: Parse system and user configuration at program start

… and pass it around up to `Repo::find`

Differential Revision: https://phab.mercurial-scm.org/D9962

use crate::ui::utf8_to_local;
use crate::ui::UiError;
use format_bytes::format_bytes;
use hg::config::{ConfigError, ConfigParseError};
use hg::errors::HgError;
use hg::repo::RepoFindError;
use hg::revlog::revlog::RevlogError;
use hg::utils::files::get_bytes_from_path;
use std::convert::From;

/// The kind of command error
#[derive(Debug)]
pub enum CommandError {
    /// Exit with an error message and "standard" failure exit code.
    Abort { message: Vec<u8> },

    /// A mercurial capability as not been implemented.
    ///
    /// There is no error message printed in this case.
    /// Instead, we exit with a specic status code and a wrapper script may
    /// fallback to Python-based Mercurial.
    Unimplemented,
}

impl CommandError {
    pub fn abort(message: impl AsRef<str>) -> Self {
        CommandError::Abort {
            // TODO: bytes-based (instead of Unicode-based) formatting
            // of error messages to handle non-UTF-8 filenames etc:
            // https://www.mercurial-scm.org/wiki/EncodingStrategy#Mixing_output
            message: utf8_to_local(message.as_ref()).into(),
        }
    }
}

impl From<HgError> for CommandError {
    fn from(error: HgError) -> Self {
        match error {
            HgError::UnsupportedFeature(_) => CommandError::Unimplemented,
            _ => CommandError::abort(error.to_string()),
        }
    }
}

impl From<UiError> for CommandError {
    fn from(_error: UiError) -> Self {
        // If we already failed writing to stdout or stderr,
        // writing an error message to stderr about it would be likely to fail
        // too.
        CommandError::abort("")
    }
}

impl From<RepoFindError> for CommandError {
    fn from(error: RepoFindError) -> Self {
        match error {
            RepoFindError::NotFoundInCurrentDirectoryOrAncestors {
                current_directory,
            } => CommandError::Abort {
                message: format_bytes!(
                    b"no repository found in '{}' (.hg not found)!",
                    get_bytes_from_path(current_directory)
                ),
            },
            RepoFindError::Other(error) => error.into(),
        }
    }
}

impl From<ConfigError> for CommandError {
    fn from(error: ConfigError) -> Self {
        match error {
            ConfigError::Parse(ConfigParseError {
                origin,
                line,
                bytes,
            }) => {
                let line_message = if let Some(line_number) = line {
                    format_bytes!(
                        b" at line {}",
                        line_number.to_string().into_bytes()
                    )
                } else {
                    Vec::new()
                };
                CommandError::Abort {
                    message: format_bytes!(
                        b"config parse error in {}{}: '{}'",
                        origin.to_bytes(),
                        line_message,
                        bytes
                    ),
                }
            }
            ConfigError::Other(error) => error.into(),
        }
    }
}

impl From<(RevlogError, &str)> for CommandError {
    fn from((err, rev): (RevlogError, &str)) -> CommandError {
        match err {
            RevlogError::InvalidRevision => CommandError::abort(format!(
                "invalid revision identifier {}",
                rev
            )),
            RevlogError::AmbiguousPrefix => CommandError::abort(format!(
                "ambiguous revision identifier {}",
                rev
            )),
            RevlogError::Other(error) => error.into(),
        }
    }
}