rhg: add exit code to HgError::Abort()

My previous attempts to have rhg end with correct exit code was more of bug
hunting. I found cases which were failing and fixed them. But as one might
expect, more tests started failing.

Let's add exit code `HgError::Abort()` and make it users explicitly tell what
exit code they want.

Differential Revision: https://phab.mercurial-scm.org/D10838

rust/hg-core/src/exit_codes.rs

@@ -0,0 +1,19
+pub type ExitCode = i32;
+
+/// Successful exit
+pub const OK: ExitCode = 0;
+
+/// Generic abort
+pub const ABORT: ExitCode = 255;
+
+// Abort when there is a config related error
+pub const CONFIG_ERROR_ABORT: ExitCode = 30;
+
+// Abort when there is an error while parsing config
+pub const CONFIG_PARSE_ERROR_ABORT: ExitCode = 10;
+
+/// Generic something completed but did not succeed
+pub const UNSUCCESSFUL: ExitCode = 1;
+
+/// Command or feature not implemented by rhg
+pub const UNIMPLEMENTED: ExitCode = 252;

rust/hg-core/src/config/layer.rs

@@ -1,319 +1,323
 // layer.rs
 //
 // Copyright 2020
 //      Valentin Gatien-Baron,
 //      Raphaël Gomès <[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.
 
 use crate::errors::HgError;
+use crate::exit_codes::CONFIG_PARSE_ERROR_ABORT;
 use crate::utils::files::{get_bytes_from_path, get_path_from_bytes};
 use format_bytes::{format_bytes, write_bytes, DisplayBytes};
 use lazy_static::lazy_static;
 use regex::bytes::Regex;
 use std::collections::HashMap;
 use std::path::{Path, PathBuf};
 
 lazy_static! {
     static ref SECTION_RE: Regex = make_regex(r"^\[([^\[]+)\]");
     static ref ITEM_RE: Regex = make_regex(r"^([^=\s][^=]*?)\s*=\s*((.*\S)?)");
     /// Continuation whitespace
     static ref CONT_RE: Regex = make_regex(r"^\s+(\S|\S.*\S)\s*$");
     static ref EMPTY_RE: Regex = make_regex(r"^(;|#|\s*$)");
     static ref COMMENT_RE: Regex = make_regex(r"^(;|#)");
     /// A directive that allows for removing previous entries
     static ref UNSET_RE: Regex = make_regex(r"^%unset\s+(\S+)");
     /// A directive that allows for including other config files
     static ref INCLUDE_RE: Regex = make_regex(r"^%include\s+(\S|\S.*\S)\s*$");
 }
 
 /// All config values separated by layers of precedence.
 /// Each config source may be split in multiple layers if `%include` directives
 /// are used.
 /// TODO detail the general precedence
 #[derive(Clone)]
 pub struct ConfigLayer {
     /// Mapping of the sections to their items
     sections: HashMap<Vec<u8>, ConfigItem>,
     /// All sections (and their items/values) in a layer share the same origin
     pub origin: ConfigOrigin,
     /// Whether this layer comes from a trusted user or group
     pub trusted: bool,
 }
 
 impl ConfigLayer {
     pub fn new(origin: ConfigOrigin) -> Self {
         ConfigLayer {
             sections: HashMap::new(),
             trusted: true, // TODO check
             origin,
         }
     }
 
     /// Parse `--config` CLI arguments and return a layer if there’s any
     pub(crate) fn parse_cli_args(
         cli_config_args: impl IntoIterator<Item = impl AsRef<[u8]>>,
     ) -> Result<Option<Self>, ConfigError> {
         fn parse_one(arg: &[u8]) -> Option<(Vec<u8>, Vec<u8>, Vec<u8>)> {
             use crate::utils::SliceExt;
 
             let (section_and_item, value) = arg.split_2(b'=')?;
             let (section, item) = section_and_item.trim().split_2(b'.')?;
             Some((
                 section.to_owned(),
                 item.to_owned(),
                 value.trim().to_owned(),
             ))
         }
 
         let mut layer = Self::new(ConfigOrigin::CommandLine);
         for arg in cli_config_args {
             let arg = arg.as_ref();
             if let Some((section, item, value)) = parse_one(arg) {
                 layer.add(section, item, value, None);
             } else {
-                Err(HgError::abort(format!(
-                    "abort: malformed --config option: '{}' \
+                Err(HgError::abort(
+                    format!(
+                        "abort: malformed --config option: '{}' \
                     (use --config section.name=value)",
-                    String::from_utf8_lossy(arg),
-                )))?
+                        String::from_utf8_lossy(arg),
+                    ),
+                    CONFIG_PARSE_ERROR_ABORT,
+                ))?
             }
         }
         if layer.sections.is_empty() {
             Ok(None)
         } else {
             Ok(Some(layer))
         }
     }
 
     /// Returns whether this layer comes from `--config` CLI arguments
     pub(crate) fn is_from_command_line(&self) -> bool {
         if let ConfigOrigin::CommandLine = self.origin {
             true
         } else {
             false
         }
     }
 
     /// Add an entry to the config, overwriting the old one if already present.
     pub fn add(
         &mut self,
         section: Vec<u8>,
         item: Vec<u8>,
         value: Vec<u8>,
         line: Option<usize>,
     ) {
         self.sections
             .entry(section)
             .or_insert_with(|| HashMap::new())
             .insert(item, ConfigValue { bytes: value, line });
     }
 
     /// Returns the config value in `<section>.<item>` if it exists
     pub fn get(&self, section: &[u8], item: &[u8]) -> Option<&ConfigValue> {
         Some(self.sections.get(section)?.get(item)?)
     }
 
     /// Returns the keys defined in the given section
     pub fn iter_keys(&self, section: &[u8]) -> impl Iterator<Item = &[u8]> {
         self.sections
             .get(section)
             .into_iter()
             .flat_map(|section| section.keys().map(|vec| &**vec))
     }
 
     pub fn is_empty(&self) -> bool {
         self.sections.is_empty()
     }
 
     /// Returns a `Vec` of layers in order of precedence (so, in read order),
     /// recursively parsing the `%include` directives if any.
     pub fn parse(src: &Path, data: &[u8]) -> Result<Vec<Self>, ConfigError> {
         let mut layers = vec![];
 
         // Discard byte order mark if any
         let data = if data.starts_with(b"\xef\xbb\xbf") {
             &data[3..]
         } else {
             data
         };
 
         // TODO check if it's trusted
         let mut current_layer = Self::new(ConfigOrigin::File(src.to_owned()));
 
         let mut lines_iter =
             data.split(|b| *b == b'\n').enumerate().peekable();
         let mut section = b"".to_vec();
 
         while let Some((index, bytes)) = lines_iter.next() {
             let line = Some(index + 1);
             if let Some(m) = INCLUDE_RE.captures(&bytes) {
                 let filename_bytes = &m[1];
                 let filename_bytes = crate::utils::expand_vars(filename_bytes);
                 // `Path::parent` only fails for the root directory,
                 // which `src` can’t be since we’ve managed to open it as a
                 // file.
                 let dir = src
                     .parent()
                     .expect("Path::parent fail on a file we’ve read");
                 // `Path::join` with an absolute argument correctly ignores the
                 // base path
                 let filename = dir.join(&get_path_from_bytes(&filename_bytes));
                 match std::fs::read(&filename) {
                     Ok(data) => {
                         layers.push(current_layer);
                         layers.extend(Self::parse(&filename, &data)?);
                         current_layer =
                             Self::new(ConfigOrigin::File(src.to_owned()));
                     }
                     Err(error) => {
                         if error.kind() != std::io::ErrorKind::NotFound {
                             return Err(ConfigParseError {
                                 origin: ConfigOrigin::File(src.to_owned()),
                                 line,
                                 message: format_bytes!(
                                     b"cannot include {} ({})",
                                     filename_bytes,
                                     format_bytes::Utf8(error)
                                 ),
                             }
                             .into());
                         }
                     }
                 }
             } else if let Some(_) = EMPTY_RE.captures(&bytes) {
             } else if let Some(m) = SECTION_RE.captures(&bytes) {
                 section = m[1].to_vec();
             } else if let Some(m) = ITEM_RE.captures(&bytes) {
                 let item = m[1].to_vec();
                 let mut value = m[2].to_vec();
                 loop {
                     match lines_iter.peek() {
                         None => break,
                         Some((_, v)) => {
                             if let Some(_) = COMMENT_RE.captures(&v) {
                             } else if let Some(_) = CONT_RE.captures(&v) {
                                 value.extend(b"\n");
                                 value.extend(&m[1]);
                             } else {
                                 break;
                             }
                         }
                     };
                     lines_iter.next();
                 }
                 current_layer.add(section.clone(), item, value, line);
             } else if let Some(m) = UNSET_RE.captures(&bytes) {
                 if let Some(map) = current_layer.sections.get_mut(&section) {
                     map.remove(&m[1]);
                 }
             } else {
                 let message = if bytes.starts_with(b" ") {
                     format_bytes!(b"unexpected leading whitespace: {}", bytes)
                 } else {
                     bytes.to_owned()
                 };
                 return Err(ConfigParseError {
                     origin: ConfigOrigin::File(src.to_owned()),
                     line,
                     message,
                 }
                 .into());
             }
         }
         if !current_layer.is_empty() {
             layers.push(current_layer);
         }
         Ok(layers)
     }
 }
 
 impl DisplayBytes for ConfigLayer {
     fn display_bytes(
         &self,
         out: &mut dyn std::io::Write,
     ) -> std::io::Result<()> {
         let mut sections: Vec<_> = self.sections.iter().collect();
         sections.sort_by(|e0, e1| e0.0.cmp(e1.0));
 
         for (section, items) in sections.into_iter() {
             let mut items: Vec<_> = items.into_iter().collect();
             items.sort_by(|e0, e1| e0.0.cmp(e1.0));
 
             for (item, config_entry) in items {
                 write_bytes!(
                     out,
                     b"{}.{}={} # {}\n",
                     section,
                     item,
                     &config_entry.bytes,
                     &self.origin,
                 )?
             }
         }
         Ok(())
     }
 }
 
 /// Mapping of section item to value.
 /// In the following:
 /// ```text
 /// [ui]
 /// paginate=no
 /// ```
 /// "paginate" is the section item and "no" the value.
 pub type ConfigItem = HashMap<Vec<u8>, ConfigValue>;
 
 #[derive(Clone, Debug, PartialEq)]
 pub struct ConfigValue {
     /// The raw bytes of the value (be it from the CLI, env or from a file)
     pub bytes: Vec<u8>,
     /// Only present if the value comes from a file, 1-indexed.
     pub line: Option<usize>,
 }
 
 #[derive(Clone, Debug)]
 pub enum ConfigOrigin {
     /// From a configuration file
     File(PathBuf),
     /// From a `--config` CLI argument
     CommandLine,
     /// From environment variables like `$PAGER` or `$EDITOR`
     Environment(Vec<u8>),
     /* TODO cli
      * TODO defaults (configitems.py)
      * TODO extensions
      * TODO Python resources?
      * Others? */
 }
 
 impl DisplayBytes for ConfigOrigin {
     fn display_bytes(
         &self,
         out: &mut dyn std::io::Write,
     ) -> std::io::Result<()> {
         match self {
             ConfigOrigin::File(p) => out.write_all(&get_bytes_from_path(p)),
             ConfigOrigin::CommandLine => out.write_all(b"--config"),
             ConfigOrigin::Environment(e) => write_bytes!(out, b"${}", e),
         }
     }
 }
 
 #[derive(Debug)]
 pub struct ConfigParseError {
     pub origin: ConfigOrigin,
     pub line: Option<usize>,
     pub message: Vec<u8>,
 }
 
 #[derive(Debug, derive_more::From)]
 pub enum ConfigError {
     Parse(ConfigParseError),
     Other(HgError),
 }
 
 fn make_regex(pattern: &'static str) -> Regex {
     Regex::new(pattern).expect("expected a valid regex")
 }

rust/hg-core/src/errors.rs

@@ -1,183 +1,194
 use crate::config::ConfigValueParseError;
+use crate::exit_codes;
 use std::fmt;
 
 /// Common error cases that can happen in many different APIs
 #[derive(Debug, derive_more::From)]
 pub enum HgError {
     IoError {
         error: std::io::Error,
         context: IoErrorContext,
     },
 
     /// A file under `.hg/` normally only written by Mercurial is not in the
     /// expected format. This indicates a bug in Mercurial, filesystem
     /// corruption, or hardware failure.
     ///
     /// The given string is a short explanation for users, not intended to be
     /// machine-readable.
     CorruptedRepository(String),
 
     /// The respository or requested operation involves a feature not
     /// supported by the Rust implementation. Falling back to the Python
     /// implementation may or may not work.
     ///
     /// The given string is a short explanation for users, not intended to be
     /// machine-readable.
     UnsupportedFeature(String),
 
     /// Operation cannot proceed for some other reason.
     ///
-    /// The given string is a short explanation for users, not intended to be
+    /// The message is a short explanation for users, not intended to be
     /// machine-readable.
-    Abort(String),
+    Abort {
+        message: String,
+        detailed_exit_code: exit_codes::ExitCode,
+    },
 
     /// A configuration value is not in the expected syntax.
     ///
     /// These errors can happen in many places in the code because values are
     /// parsed lazily as the file-level parser does not know the expected type
     /// and syntax of each value.
     #[from]
     ConfigValueParseError(ConfigValueParseError),
 }
 
 /// Details about where an I/O error happened
 #[derive(Debug)]
 pub enum IoErrorContext {
     ReadingFile(std::path::PathBuf),
     WritingFile(std::path::PathBuf),
     RemovingFile(std::path::PathBuf),
     RenamingFile {
         from: std::path::PathBuf,
         to: std::path::PathBuf,
     },
     /// `std::fs::canonicalize`
     CanonicalizingPath(std::path::PathBuf),
     /// `std::env::current_dir`
     CurrentDir,
     /// `std::env::current_exe`
     CurrentExe,
 }
 
 impl HgError {
     pub fn corrupted(explanation: impl Into<String>) -> Self {
         // TODO: capture a backtrace here and keep it in the error value
         // to aid debugging?
         // https://doc.rust-lang.org/std/backtrace/struct.Backtrace.html
         HgError::CorruptedRepository(explanation.into())
     }
 
     pub fn unsupported(explanation: impl Into<String>) -> Self {
         HgError::UnsupportedFeature(explanation.into())
     }
-    pub fn abort(explanation: impl Into<String>) -> Self {
-        HgError::Abort(explanation.into())
+
+    pub fn abort(
+        explanation: impl Into<String>,
+        exit_code: exit_codes::ExitCode,
+    ) -> Self {
+        HgError::Abort {
+            message: explanation.into(),
+            detailed_exit_code: exit_code,
+        }
     }
 }
 
 // TODO: use `DisplayBytes` instead to show non-Unicode filenames losslessly?
 impl fmt::Display for HgError {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
-            HgError::Abort(explanation) => write!(f, "{}", explanation),
+            HgError::Abort { message, .. } => write!(f, "{}", message),
             HgError::IoError { error, context } => {
                 write!(f, "abort: {}: {}", context, error)
             }
             HgError::CorruptedRepository(explanation) => {
                 write!(f, "abort: {}", explanation)
             }
             HgError::UnsupportedFeature(explanation) => {
                 write!(f, "unsupported feature: {}", explanation)
             }
             HgError::ConfigValueParseError(error) => error.fmt(f),
         }
     }
 }
 
 // TODO: use `DisplayBytes` instead to show non-Unicode filenames losslessly?
 impl fmt::Display for IoErrorContext {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
             IoErrorContext::ReadingFile(path) => {
                 write!(f, "when reading {}", path.display())
             }
             IoErrorContext::WritingFile(path) => {
                 write!(f, "when writing {}", path.display())
             }
             IoErrorContext::RemovingFile(path) => {
                 write!(f, "when removing {}", path.display())
             }
             IoErrorContext::RenamingFile { from, to } => write!(
                 f,
                 "when renaming {} to {}",
                 from.display(),
                 to.display()
             ),
             IoErrorContext::CanonicalizingPath(path) => {
                 write!(f, "when canonicalizing {}", path.display())
             }
             IoErrorContext::CurrentDir => {
                 write!(f, "error getting current working directory")
             }
             IoErrorContext::CurrentExe => {
                 write!(f, "error getting current executable")
             }
         }
     }
 }
 
 pub trait IoResultExt<T> {
     /// Annotate a possible I/O error as related to a reading a file at the
     /// given path.
     ///
     /// This allows printing something like “File not found when reading
     /// example.txt” instead of just “File not found”.
     ///
     /// Converts a `Result` with `std::io::Error` into one with `HgError`.
     fn when_reading_file(self, path: &std::path::Path) -> Result<T, HgError>;
 
     fn with_context(
         self,
         context: impl FnOnce() -> IoErrorContext,
     ) -> Result<T, HgError>;
 }
 
 impl<T> IoResultExt<T> for std::io::Result<T> {
     fn when_reading_file(self, path: &std::path::Path) -> Result<T, HgError> {
         self.with_context(|| IoErrorContext::ReadingFile(path.to_owned()))
     }
 
     fn with_context(
         self,
         context: impl FnOnce() -> IoErrorContext,
     ) -> Result<T, HgError> {
         self.map_err(|error| HgError::IoError {
             error,
             context: context(),
         })
     }
 }
 
 pub trait HgResultExt<T> {
     /// Handle missing files separately from other I/O error cases.
     ///
     /// Wraps the `Ok` type in an `Option`:
     ///
     /// * `Ok(x)` becomes `Ok(Some(x))`
     /// * An I/O "not found" error becomes `Ok(None)`
     /// * Other errors are unchanged
     fn io_not_found_as_none(self) -> Result<Option<T>, HgError>;
 }
 
 impl<T> HgResultExt<T> for Result<T, HgError> {
     fn io_not_found_as_none(self) -> Result<Option<T>, HgError> {
         match self {
             Ok(x) => Ok(Some(x)),
             Err(HgError::IoError { error, .. })
                 if error.kind() == std::io::ErrorKind::NotFound =>
             {
                 Ok(None)
             }
             Err(other_error) => Err(other_error),
         }
     }
 }

rust/hg-core/src/lib.rs

@@ -1,132 +1,133
 // Copyright 2018-2020 Georges Racinet <[e-mail]>
 //           and Mercurial contributors
 //
 // This software may be used and distributed according to the terms of the
 // GNU General Public License version 2 or any later version.
 
 mod ancestors;
 pub mod dagops;
 pub mod errors;
 pub use ancestors::{AncestorsIterator, LazyAncestors, MissingAncestors};
 pub mod dirstate;
 pub mod dirstate_tree;
 pub mod discovery;
+pub mod exit_codes;
 pub mod requirements;
 pub mod testing; // unconditionally built, for use from integration tests
 pub use dirstate::{
     dirs_multiset::{DirsMultiset, DirsMultisetIter},
     dirstate_map::DirstateMap,
     parsers::{pack_dirstate, parse_dirstate, PARENT_SIZE},
     status::{
         status, BadMatch, BadType, DirstateStatus, HgPathCow, StatusError,
         StatusOptions,
     },
     CopyMap, CopyMapIter, DirstateEntry, DirstateParents, EntryState,
     StateMap, StateMapIter,
 };
 pub mod copy_tracing;
 mod filepatterns;
 pub mod matchers;
 pub mod repo;
 pub mod revlog;
 pub use revlog::*;
 pub mod config;
 pub mod logging;
 pub mod operations;
 pub mod revset;
 pub mod utils;
 
 use crate::utils::hg_path::{HgPathBuf, HgPathError};
 pub use filepatterns::{
     parse_pattern_syntax, read_pattern_file, IgnorePattern,
     PatternFileWarning, PatternSyntax,
 };
 use std::collections::HashMap;
 use std::fmt;
 use twox_hash::RandomXxHashBuilder64;
 
 /// This is a contract between the `micro-timer` crate and us, to expose
 /// the `log` crate as `crate::log`.
 use log;
 
 pub type LineNumber = usize;
 
 /// Rust's default hasher is too slow because it tries to prevent collision
 /// attacks. We are not concerned about those: if an ill-minded person has
 /// write access to your repository, you have other issues.
 pub type FastHashMap<K, V> = HashMap<K, V, RandomXxHashBuilder64>;
 
 #[derive(Debug, PartialEq)]
 pub enum DirstateMapError {
     PathNotFound(HgPathBuf),
     EmptyPath,
     InvalidPath(HgPathError),
 }
 
 impl fmt::Display for DirstateMapError {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
             DirstateMapError::PathNotFound(_) => {
                 f.write_str("expected a value, found none")
             }
             DirstateMapError::EmptyPath => {
                 f.write_str("Overflow in dirstate.")
             }
             DirstateMapError::InvalidPath(path_error) => path_error.fmt(f),
         }
     }
 }
 
 #[derive(Debug, derive_more::From)]
 pub enum DirstateError {
     Map(DirstateMapError),
     Common(errors::HgError),
 }
 
 impl fmt::Display for DirstateError {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
             DirstateError::Map(error) => error.fmt(f),
             DirstateError::Common(error) => error.fmt(f),
         }
     }
 }
 
 #[derive(Debug, derive_more::From)]
 pub enum PatternError {
     #[from]
     Path(HgPathError),
     UnsupportedSyntax(String),
     UnsupportedSyntaxInFile(String, String, usize),
     TooLong(usize),
     #[from]
     IO(std::io::Error),
     /// Needed a pattern that can be turned into a regex but got one that
     /// can't. This should only happen through programmer error.
     NonRegexPattern(IgnorePattern),
 }
 
 impl fmt::Display for PatternError {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
             PatternError::UnsupportedSyntax(syntax) => {
                 write!(f, "Unsupported syntax {}", syntax)
             }
             PatternError::UnsupportedSyntaxInFile(syntax, file_path, line) => {
                 write!(
                     f,
                     "{}:{}: unsupported syntax {}",
                     file_path, line, syntax
                 )
             }
             PatternError::TooLong(size) => {
                 write!(f, "matcher pattern is too long ({} bytes)", size)
             }
             PatternError::IO(error) => error.fmt(f),
             PatternError::Path(error) => error.fmt(f),
             PatternError::NonRegexPattern(pattern) => {
                 write!(f, "'{:?}' cannot be turned into a regex", pattern)
             }
         }
     }
 }

rust/hg-core/src/repo.rs

@@ -1,284 +1,287
 use crate::config::{Config, ConfigError, ConfigParseError};
 use crate::errors::{HgError, IoErrorContext, IoResultExt};
+use crate::exit_codes;
 use crate::requirements;
 use crate::utils::files::get_path_from_bytes;
 use crate::utils::SliceExt;
 use memmap::{Mmap, MmapOptions};
 use std::collections::HashSet;
 use std::path::{Path, PathBuf};
 
 /// A repository on disk
 pub struct Repo {
     working_directory: PathBuf,
     dot_hg: PathBuf,
     store: PathBuf,
     requirements: HashSet<String>,
     config: Config,
 }
 
 #[derive(Debug, derive_more::From)]
 pub enum RepoError {
     NotFound {
         at: PathBuf,
     },
     #[from]
     ConfigParseError(ConfigParseError),
     #[from]
     Other(HgError),
 }
 
 impl From<ConfigError> for RepoError {
     fn from(error: ConfigError) -> Self {
         match error {
             ConfigError::Parse(error) => error.into(),
             ConfigError::Other(error) => error.into(),
         }
     }
 }
 
 /// Filesystem access abstraction for the contents of a given "base" diretory
 #[derive(Clone, Copy)]
 pub struct Vfs<'a> {
     pub(crate) base: &'a Path,
 }
 
 impl Repo {
     /// tries to find nearest repository root in current working directory or
     /// its ancestors
     pub fn find_repo_root() -> Result<PathBuf, RepoError> {
         let current_directory = crate::utils::current_dir()?;
         // ancestors() is inclusive: it first yields `current_directory`
         // as-is.
         for ancestor in current_directory.ancestors() {
             if ancestor.join(".hg").is_dir() {
                 return Ok(ancestor.to_path_buf());
             }
         }
         return Err(RepoError::NotFound {
             at: current_directory,
         });
     }
 
     /// Find a repository, either at the given path (which must contain a `.hg`
     /// sub-directory) or by searching the current directory and its
     /// ancestors.
     ///
     /// A method with two very different "modes" like this usually a code smell
     /// to make two methods instead, but in this case an `Option` is what rhg
     /// sub-commands get from Clap for the `-R` / `--repository` CLI argument.
     /// Having two methods would just move that `if` to almost all callers.
     pub fn find(
         config: &Config,
         explicit_path: Option<PathBuf>,
     ) -> Result<Self, RepoError> {
         if let Some(root) = explicit_path {
             if root.join(".hg").is_dir() {
                 Self::new_at_path(root.to_owned(), config)
             } else if root.is_file() {
                 Err(HgError::unsupported("bundle repository").into())
             } else {
                 Err(RepoError::NotFound {
                     at: root.to_owned(),
                 })
             }
         } else {
             let root = Self::find_repo_root()?;
             Self::new_at_path(root, config)
         }
     }
 
     /// To be called after checking that `.hg` is a sub-directory
     fn new_at_path(
         working_directory: PathBuf,
         config: &Config,
     ) -> Result<Self, RepoError> {
         let dot_hg = working_directory.join(".hg");
 
         let mut repo_config_files = Vec::new();
         repo_config_files.push(dot_hg.join("hgrc"));
         repo_config_files.push(dot_hg.join("hgrc-not-shared"));
 
         let hg_vfs = Vfs { base: &dot_hg };
         let mut reqs = requirements::load_if_exists(hg_vfs)?;
         let relative =
             reqs.contains(requirements::RELATIVE_SHARED_REQUIREMENT);
         let shared =
             reqs.contains(requirements::SHARED_REQUIREMENT) || relative;
 
         // From `mercurial/localrepo.py`:
         //
         // if .hg/requires contains the sharesafe requirement, it means
         // there exists a `.hg/store/requires` too and we should read it
         // NOTE: presence of SHARESAFE_REQUIREMENT imply that store requirement
         // is present. We never write SHARESAFE_REQUIREMENT for a repo if store
         // is not present, refer checkrequirementscompat() for that
         //
         // However, if SHARESAFE_REQUIREMENT is not present, it means that the
         // repository was shared the old way. We check the share source
         // .hg/requires for SHARESAFE_REQUIREMENT to detect whether the
         // current repository needs to be reshared
         let share_safe = reqs.contains(requirements::SHARESAFE_REQUIREMENT);
 
         let store_path;
         if !shared {
             store_path = dot_hg.join("store");
         } else {
             let bytes = hg_vfs.read("sharedpath")?;
             let mut shared_path =
                 get_path_from_bytes(bytes.trim_end_newlines()).to_owned();
             if relative {
                 shared_path = dot_hg.join(shared_path)
             }
             if !shared_path.is_dir() {
                 return Err(HgError::corrupted(format!(
                     ".hg/sharedpath points to nonexistent directory {}",
                     shared_path.display()
                 ))
                 .into());
             }
 
             store_path = shared_path.join("store");
 
             let source_is_share_safe =
                 requirements::load(Vfs { base: &shared_path })?
                     .contains(requirements::SHARESAFE_REQUIREMENT);
 
             if share_safe && !source_is_share_safe {
                 return Err(match config
                     .get(b"share", b"safe-mismatch.source-not-safe")
                 {
                     Some(b"abort") | None => HgError::abort(
                         "abort: share source does not support share-safe requirement\n\
                         (see `hg help config.format.use-share-safe` for more information)",
+                        exit_codes::ABORT,
                     ),
                     _ => HgError::unsupported("share-safe downgrade"),
                 }
                 .into());
             } else if source_is_share_safe && !share_safe {
                 return Err(
                     match config.get(b"share", b"safe-mismatch.source-safe") {
                         Some(b"abort") | None => HgError::abort(
                             "abort: version mismatch: source uses share-safe \
                             functionality while the current share does not\n\
                             (see `hg help config.format.use-share-safe` for more information)",
+                        exit_codes::ABORT,
                         ),
                         _ => HgError::unsupported("share-safe upgrade"),
                     }
                     .into(),
                 );
             }
 
             if share_safe {
                 repo_config_files.insert(0, shared_path.join("hgrc"))
             }
         }
         if share_safe {
             reqs.extend(requirements::load(Vfs { base: &store_path })?);
         }
 
         let repo_config = if std::env::var_os("HGRCSKIPREPO").is_none() {
             config.combine_with_repo(&repo_config_files)?
         } else {
             config.clone()
         };
 
         let repo = Self {
             requirements: reqs,
             working_directory,
             store: store_path,
             dot_hg,
             config: repo_config,
         };
 
         requirements::check(&repo)?;
 
         Ok(repo)
     }
 
     pub fn working_directory_path(&self) -> &Path {
         &self.working_directory
     }
 
     pub fn requirements(&self) -> &HashSet<String> {
         &self.requirements
     }
 
     pub fn config(&self) -> &Config {
         &self.config
     }
 
     /// For accessing repository files (in `.hg`), except for the store
     /// (`.hg/store`).
     pub fn hg_vfs(&self) -> Vfs<'_> {
         Vfs { base: &self.dot_hg }
     }
 
     /// For accessing repository store files (in `.hg/store`)
     pub fn store_vfs(&self) -> Vfs<'_> {
         Vfs { base: &self.store }
     }
 
     /// For accessing the working copy
     pub fn working_directory_vfs(&self) -> Vfs<'_> {
         Vfs {
             base: &self.working_directory,
         }
     }
 
     pub fn has_dirstate_v2(&self) -> bool {
         self.requirements
             .contains(requirements::DIRSTATE_V2_REQUIREMENT)
     }
 
     pub fn dirstate_parents(
         &self,
     ) -> Result<crate::dirstate::DirstateParents, HgError> {
         let dirstate = self.hg_vfs().mmap_open("dirstate")?;
         if dirstate.is_empty() {
             return Ok(crate::dirstate::DirstateParents::NULL);
         }
         let parents = if self.has_dirstate_v2() {
             crate::dirstate_tree::on_disk::parse_dirstate_parents(&dirstate)?
         } else {
             crate::dirstate::parsers::parse_dirstate_parents(&dirstate)?
         };
         Ok(parents.clone())
     }
 }
 
 impl Vfs<'_> {
     pub fn join(&self, relative_path: impl AsRef<Path>) -> PathBuf {
         self.base.join(relative_path)
     }
 
     pub fn read(
         &self,
         relative_path: impl AsRef<Path>,
     ) -> Result<Vec<u8>, HgError> {
         let path = self.join(relative_path);
         std::fs::read(&path).when_reading_file(&path)
     }
 
     pub fn mmap_open(
         &self,
         relative_path: impl AsRef<Path>,
     ) -> Result<Mmap, HgError> {
         let path = self.base.join(relative_path);
         let file = std::fs::File::open(&path).when_reading_file(&path)?;
         // TODO: what are the safety requirements here?
         let mmap = unsafe { MmapOptions::new().map(&file) }
             .when_reading_file(&path)?;
         Ok(mmap)
     }
 
     pub fn rename(
         &self,
         relative_from: impl AsRef<Path>,
         relative_to: impl AsRef<Path>,
     ) -> Result<(), HgError> {
         let from = self.join(relative_from);
         let to = self.join(relative_to);
         std::fs::rename(&from, &to)
             .with_context(|| IoErrorContext::RenamingFile { from, to })
     }
 }

rust/rhg/src/error.rs

@@ -1,195 +1,195
-use crate::exitcode;
 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::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: exitcode::ExitCode,
+        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> },
 }
 
 impl CommandError {
     pub fn abort(message: impl AsRef<str>) -> Self {
-        CommandError::abort_with_exit_code(message, exitcode::ABORT)
+        CommandError::abort_with_exit_code(message, exit_codes::ABORT)
     }
 
     pub fn abort_with_exit_code(
         message: impl AsRef<str>,
-        detailed_exit_code: exitcode::ExitCode,
+        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)
             }
             _ => CommandError::abort(error.to_string()),
         }
     }
 }
 
 impl From<ConfigValueParseError> for CommandError {
     fn from(error: ConfigValueParseError) -> Self {
         CommandError::abort_with_exit_code(
             error.to_string(),
-            exitcode::CONFIG_ERROR_ABORT,
+            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: exitcode::ABORT,
+                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: exitcode::ABORT,
+            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: exitcode::CONFIG_ERROR_ABORT,
+            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(),
         }
     }
 }

rust/rhg/src/main.rs

@@ -1,588 +1,588
 extern crate log;
 use crate::ui::Ui;
 use clap::App;
 use clap::AppSettings;
 use clap::Arg;
 use clap::ArgMatches;
 use format_bytes::{format_bytes, join};
 use hg::config::{Config, ConfigSource};
+use hg::exit_codes;
 use hg::repo::{Repo, RepoError};
 use hg::utils::files::{get_bytes_from_os_str, get_path_from_bytes};
 use hg::utils::SliceExt;
 use std::ffi::OsString;
 use std::path::PathBuf;
 use std::process::Command;
 
 mod blackbox;
 mod error;
-mod exitcode;
 mod ui;
 use error::CommandError;
 
 fn main_with_result(
     process_start_time: &blackbox::ProcessStartTime,
     ui: &ui::Ui,
     repo: Result<&Repo, &NoRepoInCwdError>,
     config: &Config,
 ) -> Result<(), CommandError> {
     check_extensions(config)?;
 
     let app = App::new("rhg")
         .global_setting(AppSettings::AllowInvalidUtf8)
         .global_setting(AppSettings::DisableVersion)
         .setting(AppSettings::SubcommandRequired)
         .setting(AppSettings::VersionlessSubcommands)
         .arg(
             Arg::with_name("repository")
                 .help("repository root directory")
                 .short("-R")
                 .long("--repository")
                 .value_name("REPO")
                 .takes_value(true)
                 // Both ok: `hg -R ./foo log` or `hg log -R ./foo`
                 .global(true),
         )
         .arg(
             Arg::with_name("config")
                 .help("set/override config option (use 'section.name=value')")
                 .long("--config")
                 .value_name("CONFIG")
                 .takes_value(true)
                 .global(true)
                 // Ok: `--config section.key1=val --config section.key2=val2`
                 .multiple(true)
                 // Not ok: `--config section.key1=val section.key2=val2`
                 .number_of_values(1),
         )
         .arg(
             Arg::with_name("cwd")
                 .help("change working directory")
                 .long("--cwd")
                 .value_name("DIR")
                 .takes_value(true)
                 .global(true),
         )
         .version("0.0.1");
     let app = add_subcommand_args(app);
 
     let matches = app.clone().get_matches_safe()?;
 
     let (subcommand_name, subcommand_matches) = matches.subcommand();
     let run = subcommand_run_fn(subcommand_name)
         .expect("unknown subcommand name from clap despite AppSettings::SubcommandRequired");
     let subcommand_args = subcommand_matches
         .expect("no subcommand arguments from clap despite AppSettings::SubcommandRequired");
 
     let invocation = CliInvocation {
         ui,
         subcommand_args,
         config,
         repo,
     };
     let blackbox = blackbox::Blackbox::new(&invocation, process_start_time)?;
     blackbox.log_command_start();
     let result = run(&invocation);
     blackbox.log_command_end(exit_code(
         &result,
         // TODO: show a warning or combine with original error if `get_bool`
         // returns an error
         config
             .get_bool(b"ui", b"detailed-exit-code")
             .unwrap_or(false),
     ));
     result
 }
 
 fn main() {
     // Run this first, before we find out if the blackbox extension is even
     // enabled, in order to include everything in-between in the duration
     // measurements. Reading config files can be slow if they’re on NFS.
     let process_start_time = blackbox::ProcessStartTime::now();
 
     env_logger::init();
     let ui = ui::Ui::new();
 
     let early_args = EarlyArgs::parse(std::env::args_os());
 
     let initial_current_dir = early_args.cwd.map(|cwd| {
         let cwd = get_path_from_bytes(&cwd);
         std::env::current_dir()
             .and_then(|initial| {
                 std::env::set_current_dir(cwd)?;
                 Ok(initial)
             })
             .unwrap_or_else(|error| {
                 exit(
                     &None,
                     &ui,
                     OnUnsupported::Abort,
                     Err(CommandError::abort(format!(
                         "abort: {}: '{}'",
                         error,
                         cwd.display()
                     ))),
                     false,
                 )
             })
     });
 
     let mut non_repo_config =
         Config::load_non_repo().unwrap_or_else(|error| {
             // Normally this is decided based on config, but we don’t have that
             // available. As of this writing config loading never returns an
             // "unsupported" error but that is not enforced by the type system.
             let on_unsupported = OnUnsupported::Abort;
 
             exit(
                 &initial_current_dir,
                 &ui,
                 on_unsupported,
                 Err(error.into()),
                 false,
             )
         });
 
     non_repo_config
         .load_cli_args_config(early_args.config)
         .unwrap_or_else(|error| {
             exit(
                 &initial_current_dir,
                 &ui,
                 OnUnsupported::from_config(&ui, &non_repo_config),
                 Err(error.into()),
                 non_repo_config
                     .get_bool(b"ui", b"detailed-exit-code")
                     .unwrap_or(false),
             )
         });
 
     if let Some(repo_path_bytes) = &early_args.repo {
         lazy_static::lazy_static! {
             static ref SCHEME_RE: regex::bytes::Regex =
                 // Same as `_matchscheme` in `mercurial/util.py`
                 regex::bytes::Regex::new("^[a-zA-Z0-9+.\\-]+:").unwrap();
         }
         if SCHEME_RE.is_match(&repo_path_bytes) {
             exit(
                 &initial_current_dir,
                 &ui,
                 OnUnsupported::from_config(&ui, &non_repo_config),
                 Err(CommandError::UnsupportedFeature {
                     message: format_bytes!(
                         b"URL-like --repository {}",
                         repo_path_bytes
                     ),
                 }),
                 // TODO: show a warning or combine with original error if
                 // `get_bool` returns an error
                 non_repo_config
                     .get_bool(b"ui", b"detailed-exit-code")
                     .unwrap_or(false),
             )
         }
     }
     let repo_arg = early_args.repo.unwrap_or(Vec::new());
     let repo_path: Option<PathBuf> = {
         if repo_arg.is_empty() {
             None
         } else {
             let local_config = {
                 if std::env::var_os("HGRCSKIPREPO").is_none() {
                     // TODO: handle errors from find_repo_root
                     if let Ok(current_dir_path) = Repo::find_repo_root() {
                         let config_files = vec![
                             ConfigSource::AbsPath(
                                 current_dir_path.join(".hg/hgrc"),
                             ),
                             ConfigSource::AbsPath(
                                 current_dir_path.join(".hg/hgrc-not-shared"),
                             ),
                         ];
                         // TODO: handle errors from
                         // `load_from_explicit_sources`
                         Config::load_from_explicit_sources(config_files).ok()
                     } else {
                         None
                     }
                 } else {
                     None
                 }
             };
 
             let non_repo_config_val = {
                 let non_repo_val = non_repo_config.get(b"paths", &repo_arg);
                 match &non_repo_val {
                     Some(val) if val.len() > 0 => home::home_dir()
                         .unwrap_or_else(|| PathBuf::from("~"))
                         .join(get_path_from_bytes(val))
                         .canonicalize()
                         // TODO: handle error and make it similar to python
                         // implementation maybe?
                         .ok(),
                     _ => None,
                 }
             };
 
             let config_val = match &local_config {
                 None => non_repo_config_val,
                 Some(val) => {
                     let local_config_val = val.get(b"paths", &repo_arg);
                     match &local_config_val {
                         Some(val) if val.len() > 0 => {
                             // presence of a local_config assures that
                             // current_dir
                             // wont result in an Error
                             let canpath = hg::utils::current_dir()
                                 .unwrap()
                                 .join(get_path_from_bytes(val))
                                 .canonicalize();
                             canpath.ok().or(non_repo_config_val)
                         }
                         _ => non_repo_config_val,
                     }
                 }
             };
             config_val.or(Some(get_path_from_bytes(&repo_arg).to_path_buf()))
         }
     };
 
     let repo_result = match Repo::find(&non_repo_config, repo_path.to_owned())
     {
         Ok(repo) => Ok(repo),
         Err(RepoError::NotFound { at }) if repo_path.is_none() => {
             // Not finding a repo is not fatal yet, if `-R` was not given
             Err(NoRepoInCwdError { cwd: at })
         }
         Err(error) => exit(
             &initial_current_dir,
             &ui,
             OnUnsupported::from_config(&ui, &non_repo_config),
             Err(error.into()),
             // TODO: show a warning or combine with original error if
             // `get_bool` returns an error
             non_repo_config
                 .get_bool(b"ui", b"detailed-exit-code")
                 .unwrap_or(false),
         ),
     };
 
     let config = if let Ok(repo) = &repo_result {
         repo.config()
     } else {
         &non_repo_config
     };
     let on_unsupported = OnUnsupported::from_config(&ui, config);
 
     let result = main_with_result(
         &process_start_time,
         &ui,
         repo_result.as_ref(),
         config,
     );
     exit(
         &initial_current_dir,
         &ui,
         on_unsupported,
         result,
         // TODO: show a warning or combine with original error if `get_bool`
         // returns an error
         config
             .get_bool(b"ui", b"detailed-exit-code")
             .unwrap_or(false),
     )
 }
 
 fn exit_code(
     result: &Result<(), CommandError>,
     use_detailed_exit_code: bool,
 ) -> i32 {
     match result {
-        Ok(()) => exitcode::OK,
+        Ok(()) => exit_codes::OK,
         Err(CommandError::Abort {
             message: _,
             detailed_exit_code,
         }) => {
             if use_detailed_exit_code {
                 *detailed_exit_code
             } else {
-                exitcode::ABORT
+                exit_codes::ABORT
             }
         }
-        Err(CommandError::Unsuccessful) => exitcode::UNSUCCESSFUL,
+        Err(CommandError::Unsuccessful) => exit_codes::UNSUCCESSFUL,
 
         // Exit with a specific code and no error message to let a potential
         // wrapper script fallback to Python-based Mercurial.
         Err(CommandError::UnsupportedFeature { .. }) => {
-            exitcode::UNIMPLEMENTED
+            exit_codes::UNIMPLEMENTED
         }
     }
 }
 
 fn exit(
     initial_current_dir: &Option<PathBuf>,
     ui: &Ui,
     mut on_unsupported: OnUnsupported,
     result: Result<(), CommandError>,
     use_detailed_exit_code: bool,
 ) -> ! {
     if let (
         OnUnsupported::Fallback { executable },
         Err(CommandError::UnsupportedFeature { .. }),
     ) = (&on_unsupported, &result)
     {
         let mut args = std::env::args_os();
         let executable_path = get_path_from_bytes(&executable);
         let this_executable = args.next().expect("exepcted argv[0] to exist");
         if executable_path == &PathBuf::from(this_executable) {
             // Avoid spawning infinitely many processes until resource
             // exhaustion.
             let _ = ui.write_stderr(&format_bytes!(
                 b"Blocking recursive fallback. The 'rhg.fallback-executable = {}' config \
                 points to `rhg` itself.\n",
                 executable
             ));
             on_unsupported = OnUnsupported::Abort
         } else {
             // `args` is now `argv[1..]` since we’ve already consumed `argv[0]`
             let mut command = Command::new(executable_path);
             command.args(args);
             if let Some(initial) = initial_current_dir {
                 command.current_dir(initial);
             }
             let result = command.status();
             match result {
                 Ok(status) => std::process::exit(
-                    status.code().unwrap_or(exitcode::ABORT),
+                    status.code().unwrap_or(exit_codes::ABORT),
                 ),
                 Err(error) => {
                     let _ = ui.write_stderr(&format_bytes!(
                         b"tried to fall back to a '{}' sub-process but got error {}\n",
                         executable, format_bytes::Utf8(error)
                     ));
                     on_unsupported = OnUnsupported::Abort
                 }
             }
         }
     }
     exit_no_fallback(ui, on_unsupported, result, use_detailed_exit_code)
 }
 
 fn exit_no_fallback(
     ui: &Ui,
     on_unsupported: OnUnsupported,
     result: Result<(), CommandError>,
     use_detailed_exit_code: bool,
 ) -> ! {
     match &result {
         Ok(_) => {}
         Err(CommandError::Unsuccessful) => {}
         Err(CommandError::Abort {
             message,
             detailed_exit_code: _,
         }) => {
             if !message.is_empty() {
                 // Ignore errors when writing to stderr, we’re already exiting
                 // with failure code so there’s not much more we can do.
                 let _ = ui.write_stderr(&format_bytes!(b"{}\n", message));
             }
         }
         Err(CommandError::UnsupportedFeature { message }) => {
             match on_unsupported {
                 OnUnsupported::Abort => {
                     let _ = ui.write_stderr(&format_bytes!(
                         b"unsupported feature: {}\n",
                         message
                     ));
                 }
                 OnUnsupported::AbortSilent => {}
                 OnUnsupported::Fallback { .. } => unreachable!(),
             }
         }
     }
     std::process::exit(exit_code(&result, use_detailed_exit_code))
 }
 
 macro_rules! subcommands {
     ($( $command: ident )+) => {
         mod commands {
             $(
                 pub mod $command;
             )+
         }
 
         fn add_subcommand_args<'a, 'b>(app: App<'a, 'b>) -> App<'a, 'b> {
             app
             $(
                 .subcommand(commands::$command::args())
             )+
         }
 
         pub type RunFn = fn(&CliInvocation) -> Result<(), CommandError>;
 
         fn subcommand_run_fn(name: &str) -> Option<RunFn> {
             match name {
                 $(
                     stringify!($command) => Some(commands::$command::run),
                 )+
                 _ => None,
             }
         }
     };
 }
 
 subcommands! {
     cat
     debugdata
     debugrequirements
     files
     root
     config
     status
 }
 
 pub struct CliInvocation<'a> {
     ui: &'a Ui,
     subcommand_args: &'a ArgMatches<'a>,
     config: &'a Config,
     /// References inside `Result` is a bit peculiar but allow
     /// `invocation.repo?` to work out with `&CliInvocation` since this
     /// `Result` type is `Copy`.
     repo: Result<&'a Repo, &'a NoRepoInCwdError>,
 }
 
 struct NoRepoInCwdError {
     cwd: PathBuf,
 }
 
 /// CLI arguments to be parsed "early" in order to be able to read
 /// configuration before using Clap. Ideally we would also use Clap for this,
 /// see <https://github.com/clap-rs/clap/discussions/2366>.
 ///
 /// These arguments are still declared when we do use Clap later, so that Clap
 /// does not return an error for their presence.
 struct EarlyArgs {
     /// Values of all `--config` arguments. (Possibly none)
     config: Vec<Vec<u8>>,
     /// Value of the `-R` or `--repository` argument, if any.
     repo: Option<Vec<u8>>,
     /// Value of the `--cwd` argument, if any.
     cwd: Option<Vec<u8>>,
 }
 
 impl EarlyArgs {
     fn parse(args: impl IntoIterator<Item = OsString>) -> Self {
         let mut args = args.into_iter().map(get_bytes_from_os_str);
         let mut config = Vec::new();
         let mut repo = None;
         let mut cwd = None;
         // Use `while let` instead of `for` so that we can also call
         // `args.next()` inside the loop.
         while let Some(arg) = args.next() {
             if arg == b"--config" {
                 if let Some(value) = args.next() {
                     config.push(value)
                 }
             } else if let Some(value) = arg.drop_prefix(b"--config=") {
                 config.push(value.to_owned())
             }
 
             if arg == b"--cwd" {
                 if let Some(value) = args.next() {
                     cwd = Some(value)
                 }
             } else if let Some(value) = arg.drop_prefix(b"--cwd=") {
                 cwd = Some(value.to_owned())
             }
 
             if arg == b"--repository" || arg == b"-R" {
                 if let Some(value) = args.next() {
                     repo = Some(value)
                 }
             } else if let Some(value) = arg.drop_prefix(b"--repository=") {
                 repo = Some(value.to_owned())
             } else if let Some(value) = arg.drop_prefix(b"-R") {
                 repo = Some(value.to_owned())
             }
         }
         Self { config, repo, cwd }
     }
 }
 
 /// What to do when encountering some unsupported feature.
 ///
 /// See `HgError::UnsupportedFeature` and `CommandError::UnsupportedFeature`.
 enum OnUnsupported {
     /// Print an error message describing what feature is not supported,
     /// and exit with code 252.
     Abort,
     /// Silently exit with code 252.
     AbortSilent,
     /// Try running a Python implementation
     Fallback { executable: Vec<u8> },
 }
 
 impl OnUnsupported {
     const DEFAULT: Self = OnUnsupported::Abort;
 
     fn from_config(ui: &Ui, config: &Config) -> Self {
         match config
             .get(b"rhg", b"on-unsupported")
             .map(|value| value.to_ascii_lowercase())
             .as_deref()
         {
             Some(b"abort") => OnUnsupported::Abort,
             Some(b"abort-silent") => OnUnsupported::AbortSilent,
             Some(b"fallback") => OnUnsupported::Fallback {
                 executable: config
                     .get(b"rhg", b"fallback-executable")
                     .unwrap_or_else(|| {
                         exit_no_fallback(
                             ui,
                             Self::Abort,
                             Err(CommandError::abort(
                                 "abort: 'rhg.on-unsupported=fallback' without \
                                 'rhg.fallback-executable' set."
                             )),
                             false,
                         )
                     })
                     .to_owned(),
             },
             None => Self::DEFAULT,
             Some(_) => {
                 // TODO: warn about unknown config value
                 Self::DEFAULT
             }
         }
     }
 }
 
 const SUPPORTED_EXTENSIONS: &[&[u8]] = &[b"blackbox", b"share"];
 
 fn check_extensions(config: &Config) -> Result<(), CommandError> {
     let enabled = config.get_section_keys(b"extensions");
 
     let mut unsupported = enabled;
     for supported in SUPPORTED_EXTENSIONS {
         unsupported.remove(supported);
     }
 
     if let Some(ignored_list) =
         config.get_simple_list(b"rhg", b"ignored-extensions")
     {
         for ignored in ignored_list {
             unsupported.remove(ignored);
         }
     }
 
     if unsupported.is_empty() {
         Ok(())
     } else {
         Err(CommandError::UnsupportedFeature {
             message: format_bytes!(
                 b"extensions: {} (consider adding them to 'rhg.ignored-extensions' config)",
                 join(unsupported, b", ")
             ),
         })
     }
 }