annotate rust/rhg/src/error.rs @ 49149:006688e36e12 stable

rhg: use `Command::exec` instead of `Command::status`

`rhg` is supposed to be a transparent executable, using a subprocess defeats
that purpose. See inline comments for more details.

This also introduces the `which` crate to check if the fallback executable
actually exists to help debugging (plain `execve` doesn't give much
information).

The error code 253 is used to signify that the fallback is not found, but may
mean in the future that it is otherwise invalid if we start being more
specific.

Differential Revision: https://phab.mercurial-scm.org/D12578

use crate::ui::utf8_to_local;
use crate::ui::UiError;
use crate::NoRepoInCwdError;
use format_bytes::format_bytes;
use hg::config::{ConfigError, ConfigParseError, ConfigValueParseError};
use hg::dirstate_tree::on_disk::DirstateV2ParseError;
use hg::errors::HgError;
use hg::exit_codes;
use hg::repo::RepoError;
use hg::revlog::revlog::RevlogError;
use hg::utils::files::get_bytes_from_path;
use hg::{DirstateError, DirstateMapError, StatusError};
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>,
        detailed_exit_code: exit_codes::ExitCode,
    },

    /// Exit with a failure exit code but no message.
    Unsuccessful,

    /// Encountered something (such as a CLI argument, repository layout, …)
    /// not supported by this version of `rhg`. Depending on configuration
    /// `rhg` may attempt to silently fall back to Python-based `hg`, which
    /// may or may not support this feature.
    UnsupportedFeature { message: Vec<u8> },
    /// The fallback executable does not exist (or has some other problem if
    /// we end up being more precise about broken fallbacks).
    InvalidFallback { path: Vec<u8>, err: String },
}

impl CommandError {
    pub fn abort(message: impl AsRef<str>) -> Self {
        CommandError::abort_with_exit_code(message, exit_codes::ABORT)
    }

    pub fn abort_with_exit_code(
        message: impl AsRef<str>,
        detailed_exit_code: exit_codes::ExitCode,
    ) -> 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(),
            detailed_exit_code: detailed_exit_code,
        }
    }

    pub fn unsupported(message: impl AsRef<str>) -> Self {
        CommandError::UnsupportedFeature {
            message: utf8_to_local(message.as_ref()).into(),
        }
    }
}

/// For now we don’t differenciate between invalid CLI args and valid for `hg`
/// but not supported yet by `rhg`.
impl From<clap::Error> for CommandError {
    fn from(error: clap::Error) -> Self {
        CommandError::unsupported(error.to_string())
    }
}

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

impl From<ConfigValueParseError> for CommandError {
    fn from(error: ConfigValueParseError) -> Self {
        CommandError::abort_with_exit_code(
            error.to_string(),
            exit_codes::CONFIG_ERROR_ABORT,
        )
    }
}

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<RepoError> for CommandError {
    fn from(error: RepoError) -> Self {
        match error {
            RepoError::NotFound { at } => CommandError::Abort {
                message: format_bytes!(
                    b"abort: repository {} not found",
                    get_bytes_from_path(at)
                ),
                detailed_exit_code: exit_codes::ABORT,
            },
            RepoError::ConfigParseError(error) => error.into(),
            RepoError::Other(error) => error.into(),
        }
    }
}

impl<'a> From<&'a NoRepoInCwdError> for CommandError {
    fn from(error: &'a NoRepoInCwdError) -> Self {
        let NoRepoInCwdError { cwd } = error;
        CommandError::Abort {
            message: format_bytes!(
                b"abort: no repository found in '{}' (.hg not found)!",
                get_bytes_from_path(cwd)
            ),
            detailed_exit_code: exit_codes::ABORT,
        }
    }
}

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

impl From<ConfigParseError> for CommandError {
    fn from(error: ConfigParseError) -> Self {
        let ConfigParseError {
            origin,
            line,
            message,
        } = error;
        let line_message = if let Some(line_number) = line {
            format_bytes!(b":{}", line_number.to_string().into_bytes())
        } else {
            Vec::new()
        };
        CommandError::Abort {
            message: format_bytes!(
                b"config error at {}{}: {}",
                origin,
                line_message,
                message
            ),
            detailed_exit_code: exit_codes::CONFIG_ERROR_ABORT,
        }
    }
}

impl From<(RevlogError, &str)> for CommandError {
    fn from((err, rev): (RevlogError, &str)) -> CommandError {
        match err {
            RevlogError::WDirUnsupported => CommandError::abort(
                "abort: working directory revision cannot be specified",
            ),
            RevlogError::InvalidRevision => CommandError::abort(format!(
                "abort: invalid revision identifier: {}",
                rev
            )),
            RevlogError::AmbiguousPrefix => CommandError::abort(format!(
                "abort: ambiguous revision identifier: {}",
                rev
            )),
            RevlogError::Other(error) => error.into(),
        }
    }
}

impl From<StatusError> for CommandError {
    fn from(error: StatusError) -> Self {
        CommandError::abort(format!("{}", error))
    }
}

impl From<DirstateMapError> for CommandError {
    fn from(error: DirstateMapError) -> Self {
        CommandError::abort(format!("{}", error))
    }
}

impl From<DirstateError> for CommandError {
    fn from(error: DirstateError) -> Self {
        match error {
            DirstateError::Common(error) => error.into(),
            DirstateError::Map(error) => error.into(),
        }
    }
}

impl From<DirstateV2ParseError> for CommandError {
    fn from(error: DirstateV2ParseError) -> Self {
        HgError::from(error).into()
    }
}