rhg: add error message for paths outside the repository when cwd != root

This mirrors the Python implementation.

The relative path handling should probably be refactored into a util, but it
it out of scope for this change.

rust/rhg/src/commands/cat.rs

@@ -1,105 +1,114
 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 relative_path = working_directory
+            .strip_prefix(&cwd)
+            .unwrap_or(&working_directory);
         let stripped = normalized
             .strip_prefix(&working_directory)
-            // TODO: error message for path arguments outside of the repo
-            .map_err(|_| CommandError::abort(""))?;
+            .map_err(|_| {
+                CommandError::abort(format!(
+                    "abort: {} not under root '{}'\n(consider using '--cwd {}')",
+                    file,
+                    working_directory.display(),
+                    relative_path.display(),
+                ))
+            })?;
         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)
     }
 }