rust/chg/src/clientext.rs

interfaces: introduce and use a protocol class for the `charencoding` module

See f2832de2a46c for details when this was done for the `bdiff` module.

This lets us dump the hack where the `pure` implementation was imported during
the type checking phase to provide signatures for the module methods it
provides.  Now the protocol classes are starting to shine, because these methods
are provided by `pure.charencoding` and `cext.parsers`, and references to
`cffi.charencoding` and `cext.charencoding` are forwarded to them as appropriate
by the `policy` module.  But none of that matters, as long as the module
returned provides the listed methods.

The interface was copy/pasted from the `pure` module, but `jsonescapeu8fallback`
is omitted because it is accessed from the `pure` module directly when the
escaping fails in the primary module's `jsonescapeu8()`.

// Copyright 2018 Yuya Nishihara <[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.

//! cHg extensions to command server client.

use bytes::{BufMut, BytesMut};
use std::ffi::OsStr;
use std::io;
use std::mem;
use std::os::unix::ffi::OsStrExt;
use std::os::unix::io::AsRawFd;
use std::path::Path;
use tokio_hglib::UnixClient;

use crate::attachio;
use crate::message::{self, Instruction, ServerSpec};
use crate::runcommand;
use crate::uihandler::SystemHandler;

/// Command-server client that also supports cHg extensions.
pub struct ChgClient {
    client: UnixClient,
}

impl ChgClient {
    /// Connects to a command server listening at the specified socket path.
    pub async fn connect(path: impl AsRef<Path>) -> io::Result<Self> {
        let client = UnixClient::connect(path).await?;
        Ok(ChgClient { client })
    }

    /// Server capabilities, encoding, etc.
    pub fn server_spec(&self) -> &ServerSpec {
        self.client.server_spec()
    }

    /// Attaches the client file descriptors to the server.
    pub async fn attach_io(
        &mut self,
        stdin: &impl AsRawFd,
        stdout: &impl AsRawFd,
        stderr: &impl AsRawFd,
    ) -> io::Result<()> {
        attachio::attach_io(
            self.client.borrow_protocol_mut(),
            stdin,
            stdout,
            stderr,
        )
        .await
    }

    /// Changes the working directory of the server.
    pub async fn set_current_dir(
        &mut self,
        dir: impl AsRef<Path>,
    ) -> io::Result<()> {
        let dir_bytes = dir.as_ref().as_os_str().as_bytes().to_owned();
        self.client
            .borrow_protocol_mut()
            .send_command_with_args("chdir", dir_bytes)
            .await
    }

    /// Updates the environment variables of the server.
    pub async fn set_env_vars_os(
        &mut self,
        vars: impl IntoIterator<Item = (impl AsRef<OsStr>, impl AsRef<OsStr>)>,
    ) -> io::Result<()> {
        self.client
            .borrow_protocol_mut()
            .send_command_with_args("setenv", message::pack_env_vars_os(vars))
            .await
    }

    /// Changes the process title of the server.
    pub async fn set_process_name(
        &mut self,
        name: impl AsRef<OsStr>,
    ) -> io::Result<()> {
        let name_bytes = name.as_ref().as_bytes().to_owned();
        self.client
            .borrow_protocol_mut()
            .send_command_with_args("setprocname", name_bytes)
            .await
    }

    /// Changes the umask of the server process.
    pub async fn set_umask(&mut self, mask: u32) -> io::Result<()> {
        let mut mask_bytes = BytesMut::with_capacity(mem::size_of_val(&mask));
        mask_bytes.put_u32(mask);
        self.client
            .borrow_protocol_mut()
            .send_command_with_args("setumask2", mask_bytes)
            .await
    }

    /// Runs the specified Mercurial command with cHg extension.
    pub async fn run_command_chg(
        &mut self,
        handler: &mut impl SystemHandler,
        args: impl IntoIterator<Item = impl AsRef<OsStr>>,
    ) -> io::Result<i32> {
        runcommand::run_command(
            self.client.borrow_protocol_mut(),
            handler,
            message::pack_args_os(args),
        )
        .await
    }

    /// Validates if the server can run Mercurial commands with the expected
    /// configuration.
    ///
    /// The `args` should contain early command arguments such as `--config`
    /// and `-R`.
    ///
    /// Client-side environment must be sent prior to this request, by
    /// `set_current_dir()` and `set_env_vars_os()`.
    pub async fn validate(
        &mut self,
        args: impl IntoIterator<Item = impl AsRef<OsStr>>,
    ) -> io::Result<Vec<Instruction>> {
        let data = self
            .client
            .borrow_protocol_mut()
            .query_with_args("validate", message::pack_args_os(args))
            .await?;
        message::parse_instructions(data)
    }
}