view rust/rhg/src/commands/cat.rs @ 48575:e91aa800ae5b

rhg: desambiguate status without decompressing filelog if possible

When status is unsure based on `stat()` and the dirstate if a file is clean
or modified, we need to compare it against the filelog.

This comparison can skip looking at contents if the lengths differ.
This changeset optimize this further to deduce what we can about the length
if the filelog without decompressing it or resolving deltas.

Differential Revision: https://phab.mercurial-scm.org/D11965

use crate::error::CommandError;
use clap::Arg;
use format_bytes::format_bytes;
use hg::operations::cat;
use hg::utils::hg_path::HgPathBuf;
use micro_timer::timed;
use std::convert::TryFrom;

pub const HELP_TEXT: &str = "
Output the current or given revision of files
";

pub fn args() -> clap::App<'static, 'static> {
    clap::SubCommand::with_name("cat")
        .arg(
            Arg::with_name("rev")
                .help("search the repository as it is in REV")
                .short("-r")
                .long("--rev")
                .value_name("REV")
                .takes_value(true),
        )
        .arg(
            clap::Arg::with_name("files")
                .required(true)
                .multiple(true)
                .empty_values(false)
                .value_name("FILE")
                .help("Files to output"),
        )
        .about(HELP_TEXT)
}

#[timed]
pub fn run(invocation: &crate::CliInvocation) -> Result<(), CommandError> {
    let cat_enabled_default = true;
    let cat_enabled = invocation.config.get_option(b"rhg", b"cat")?;
    if !cat_enabled.unwrap_or(cat_enabled_default) {
        return Err(CommandError::unsupported(
            "cat is disabled in rhg (enable it with 'rhg.cat = true' \
            or enable fallback with 'rhg.on-unsupported = fallback')",
        ));
    }

    let rev = invocation.subcommand_args.value_of("rev");
    let file_args = match invocation.subcommand_args.values_of("files") {
        Some(files) => files.collect(),
        None => vec![],
    };

    let repo = invocation.repo?;
    let cwd = hg::utils::current_dir()?;
    let working_directory = repo.working_directory_path();
    let working_directory = cwd.join(working_directory); // Make it absolute

    let mut files = vec![];
    for file in file_args.iter() {
        if file.starts_with("set:") {
            let message = "fileset";
            return Err(CommandError::unsupported(message));
        }

        let normalized = cwd.join(&file);
        // TODO: actually normalize `..` path segments etc?
        let dotted = normalized.components().any(|c| c.as_os_str() == "..");
        if file == &"." || dotted {
            let message = "`..` or `.` path segment";
            return Err(CommandError::unsupported(message));
        }
        let stripped = normalized
            .strip_prefix(&working_directory)
            // TODO: error message for path arguments outside of the repo
            .map_err(|_| CommandError::abort(""))?;
        let hg_file = HgPathBuf::try_from(stripped.to_path_buf())
            .map_err(|e| CommandError::abort(e.to_string()))?;
        files.push(hg_file);
    }
    let files = files.iter().map(|file| file.as_ref()).collect();
    // TODO probably move this to a util function like `repo.default_rev` or
    // something when it's used somewhere else
    let rev = match rev {
        Some(r) => r.to_string(),
        None => format!("{:x}", repo.dirstate_parents()?.p1),
    };

    let output = cat(&repo, &rev, files).map_err(|e| (e, rev.as_str()))?;
    for (_file, contents) in output.results {
        invocation.ui.write_stdout(&contents)?;
    }
    if !output.missing.is_empty() {
        let short = format!("{:x}", output.node.short()).into_bytes();
        for path in &output.missing {
            invocation.ui.write_stderr(&format_bytes!(
                b"{}: no such file in rev {}\n",
                path.as_bytes(),
                short
            ))?;
        }
    }
    if output.found_any {
        Ok(())
    } else {
        Err(CommandError::Unsuccessful)
    }
}