hg-core: refactor rev parsing in operations::status_rev_rev

This is in preparation for a follow-up changeset that will implement
rhg status --change.

rust/rhg/src/commands/status.rs

@@ -1,832 +1,827
 // status.rs
 //
 // Copyright 2020, Georges Racinet <[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::error::CommandError;
 use crate::ui::{
     format_pattern_file_warning, print_narrow_sparse_warnings, relative_paths,
     RelativePaths, Ui,
 };
 use crate::utils::path_utils::RelativizePaths;
 use clap::Arg;
 use format_bytes::format_bytes;
 use hg::config::Config;
 use hg::dirstate::entry::{has_exec_bit, TruncatedTimestamp};
 use hg::dirstate::status::{
     BadMatch, DirstateStatus, StatusError, StatusOptions, StatusPath,
 };
 use hg::errors::{HgError, IoResultExt};
 use hg::filepatterns::{parse_pattern_args, PatternFileWarning};
 use hg::lock::LockError;
 use hg::matchers::{AlwaysMatcher, IntersectionMatcher};
 use hg::repo::Repo;
 use hg::revlog::manifest::Manifest;
 use hg::revlog::options::{default_revlog_options, RevlogOpenOptions};
 use hg::revlog::RevlogType;
 use hg::utils::debug::debug_wait_for_file;
 use hg::utils::files::{
     get_bytes_from_os_str, get_bytes_from_os_string, get_path_from_bytes,
 };
 use hg::utils::hg_path::{hg_path_to_path_buf, HgPath};
 use hg::Revision;
 use hg::{self, narrow, sparse};
 use log::info;
 use rayon::prelude::*;
 use std::borrow::Cow;
 use std::io;
 use std::mem::take;
 use std::path::PathBuf;
 
 pub const HELP_TEXT: &str = "
 Show changed files in the working directory
 
 This is a pure Rust version of `hg status`.
 
 Some options might be missing, check the list below.
 ";
 
 pub fn args() -> clap::Command {
     clap::command!("status")
         .alias("st")
         .about(HELP_TEXT)
         .arg(
             Arg::new("file")
                 .value_parser(clap::value_parser!(std::ffi::OsString))
                 .help("show only these files")
                 .action(clap::ArgAction::Append),
         )
         .arg(
             Arg::new("all")
                 .help("show status of all files")
                 .short('A')
                 .action(clap::ArgAction::SetTrue)
                 .long("all"),
         )
         .arg(
             Arg::new("modified")
                 .help("show only modified files")
                 .short('m')
                 .action(clap::ArgAction::SetTrue)
                 .long("modified"),
         )
         .arg(
             Arg::new("added")
                 .help("show only added files")
                 .short('a')
                 .action(clap::ArgAction::SetTrue)
                 .long("added"),
         )
         .arg(
             Arg::new("removed")
                 .help("show only removed files")
                 .short('r')
                 .action(clap::ArgAction::SetTrue)
                 .long("removed"),
         )
         .arg(
             Arg::new("clean")
                 .help("show only clean files")
                 .short('c')
                 .action(clap::ArgAction::SetTrue)
                 .long("clean"),
         )
         .arg(
             Arg::new("deleted")
                 .help("show only deleted files")
                 .short('d')
                 .action(clap::ArgAction::SetTrue)
                 .long("deleted"),
         )
         .arg(
             Arg::new("unknown")
                 .help("show only unknown (not tracked) files")
                 .short('u')
                 .action(clap::ArgAction::SetTrue)
                 .long("unknown"),
         )
         .arg(
             Arg::new("ignored")
                 .help("show only ignored files")
                 .short('i')
                 .action(clap::ArgAction::SetTrue)
                 .long("ignored"),
         )
         .arg(
             Arg::new("copies")
                 .help("show source of copied files (DEFAULT: ui.statuscopies)")
                 .short('C')
                 .action(clap::ArgAction::SetTrue)
                 .long("copies"),
         )
         .arg(
             Arg::new("no-copies")
                 .action(clap::ArgAction::SetTrue)
                 .long("no-copies")
                 .overrides_with("copies"),
         )
         .arg(
             Arg::new("print0")
                 .help("end filenames with NUL, for use with xargs")
                 .short('0')
                 .action(clap::ArgAction::SetTrue)
                 .long("print0"),
         )
         .arg(
             Arg::new("no-status")
                 .help("hide status prefix")
                 .short('n')
                 .action(clap::ArgAction::SetTrue)
                 .long("no-status"),
         )
         .arg(
             Arg::new("verbose")
                 .help("enable additional output")
                 .short('v')
                 .action(clap::ArgAction::SetTrue)
                 .long("verbose"),
         )
         .arg(
             Arg::new("rev")
                 .help("show difference from/to revision")
                 .long("rev")
                 .num_args(1)
                 .action(clap::ArgAction::Append)
                 .value_name("REV"),
         )
 }
 
 fn parse_revpair(
     repo: &Repo,
     revs: Option<Vec<String>>,
 ) -> Result<Option<(Revision, Revision)>, CommandError> {
-    let revs = match revs {
-        None => return Ok(None),
-        Some(revs) => revs,
+    let Some(revs) = revs else {
+        return Ok(None);
     };
-    if revs.is_empty() {
-        return Ok(None);
+    match revs.as_slice() {
+        [] => Ok(None),
+        [rev1, rev2] => Ok(Some((
+            hg::revset::resolve_single(rev1, repo)?,
+            hg::revset::resolve_single(rev2, repo)?,
+        ))),
+        _ => Err(CommandError::unsupported("expected 0 or 2 --rev flags")),
     }
-    if revs.len() != 2 {
-        return Err(CommandError::unsupported("expected 0 or 2 --rev flags"));
-    }
-
-    let rev1 = &revs[0];
-    let rev2 = &revs[1];
-    let rev1 = hg::revset::resolve_single(rev1, repo)?;
-    let rev2 = hg::revset::resolve_single(rev2, repo)?;
-    Ok(Some((rev1, rev2)))
 }
 
 /// Pure data type allowing the caller to specify file states to display
 #[derive(Copy, Clone, Debug)]
 pub struct DisplayStates {
     pub modified: bool,
     pub added: bool,
     pub removed: bool,
     pub clean: bool,
     pub deleted: bool,
     pub unknown: bool,
     pub ignored: bool,
 }
 
 pub const DEFAULT_DISPLAY_STATES: DisplayStates = DisplayStates {
     modified: true,
     added: true,
     removed: true,
     clean: false,
     deleted: true,
     unknown: true,
     ignored: false,
 };
 
 pub const ALL_DISPLAY_STATES: DisplayStates = DisplayStates {
     modified: true,
     added: true,
     removed: true,
     clean: true,
     deleted: true,
     unknown: true,
     ignored: true,
 };
 
 impl DisplayStates {
     pub fn is_empty(&self) -> bool {
         !(self.modified
             || self.added
             || self.removed
             || self.clean
             || self.deleted
             || self.unknown
             || self.ignored)
     }
 }
 
 fn has_unfinished_merge(repo: &Repo) -> Result<bool, CommandError> {
     Ok(repo.dirstate_parents()?.is_merge())
 }
 
 fn has_unfinished_state(repo: &Repo) -> Result<bool, CommandError> {
     // These are all the known values for the [fname] argument of
     // [addunfinished] function in [state.py]
     let known_state_files: &[&str] = &[
         "bisect.state",
         "graftstate",
         "histedit-state",
         "rebasestate",
         "shelvedstate",
         "transplant/journal",
         "updatestate",
     ];
     if has_unfinished_merge(repo)? {
         return Ok(true);
     };
     for f in known_state_files {
         if repo.hg_vfs().join(f).exists() {
             return Ok(true);
         }
     }
     Ok(false)
 }
 
 pub fn run(invocation: &crate::CliInvocation) -> Result<(), CommandError> {
     // TODO: lift these limitations
     if invocation
         .config
         .get(b"commands", b"status.terse")
         .is_some()
     {
         return Err(CommandError::unsupported(
             "status.terse is not yet supported with rhg status",
         ));
     }
 
     let ui = invocation.ui;
     let config = invocation.config;
     let args = invocation.subcommand_args;
 
     let revs = args.get_many::<String>("rev");
     let print0 = args.get_flag("print0");
     let verbose = args.get_flag("verbose")
         || config.get_bool(b"ui", b"verbose")?
         || config.get_bool(b"commands", b"status.verbose")?;
     let verbose = verbose && !print0;
 
     let all = args.get_flag("all");
     let display_states = if all {
         // TODO when implementing `--quiet`: it excludes clean files
         // from `--all`
         ALL_DISPLAY_STATES
     } else {
         let requested = DisplayStates {
             modified: args.get_flag("modified"),
             added: args.get_flag("added"),
             removed: args.get_flag("removed"),
             clean: args.get_flag("clean"),
             deleted: args.get_flag("deleted"),
             unknown: args.get_flag("unknown"),
             ignored: args.get_flag("ignored"),
         };
         if requested.is_empty() {
             DEFAULT_DISPLAY_STATES
         } else {
             requested
         }
     };
     let no_status = args.get_flag("no-status");
     let list_copies = if args.get_flag("copies") {
         true
     } else if args.get_flag("no-copies") {
         false
     } else {
         config.get_bool(b"ui", b"statuscopies")?
     };
     let list_copies = (list_copies || all) && !no_status;
 
     let repo = invocation.repo?;
     let revpair = parse_revpair(repo, revs.map(|i| i.cloned().collect()))?;
 
     if verbose && has_unfinished_state(repo)? {
         return Err(CommandError::unsupported(
             "verbose status output is not supported by rhg (and is needed because we're in an unfinished operation)",
         ));
     }
 
     let mut dmap = repo.dirstate_map_mut()?;
 
     let check_exec = hg::checkexec::check_exec(repo.working_directory_path());
 
     let options = StatusOptions {
         check_exec,
         list_clean: display_states.clean,
         list_unknown: display_states.unknown,
         list_ignored: display_states.ignored,
         list_copies,
         collect_traversed_dirs: false,
     };
 
     type StatusResult<'a> =
         Result<(DirstateStatus<'a>, Vec<PatternFileWarning>), StatusError>;
 
     let relative_status = config
         .get_option(b"commands", b"status.relative")?
         .expect("commands.status.relative should have a default value");
 
     let relativize_paths = relative_status || {
         // See in Python code with `getuipathfn` usage in `commands.py`.
         let legacy_relative_behavior = args.contains_id("file");
         match relative_paths(invocation.config)? {
             RelativePaths::Legacy => legacy_relative_behavior,
             RelativePaths::Bool(v) => v,
         }
     };
 
     let mut output = DisplayStatusPaths {
         ui,
         no_status,
         relativize: if relativize_paths {
             Some(RelativizePaths::new(repo)?)
         } else {
             None
         },
         print0,
     };
 
     let after_status = |res: StatusResult| -> Result<_, CommandError> {
         let (mut ds_status, pattern_warnings) = res?;
         for warning in pattern_warnings {
             ui.write_stderr(&format_pattern_file_warning(&warning, repo))?;
         }
 
         for (path, error) in take(&mut ds_status.bad) {
             let error = match error {
                 BadMatch::OsError(code) => {
                     std::io::Error::from_raw_os_error(code).to_string()
                 }
                 BadMatch::BadType(ty) => {
                     format!("unsupported file type (type is {})", ty)
                 }
             };
             ui.write_stderr(&format_bytes!(
                 b"{}: {}\n",
                 path.as_bytes(),
                 error.as_bytes()
             ))?
         }
         if !ds_status.unsure.is_empty() {
             info!(
                 "Files to be rechecked by retrieval from filelog: {:?}",
                 ds_status.unsure.iter().map(|s| &s.path).collect::<Vec<_>>()
             );
         }
         let mut fixup = Vec::new();
         if !ds_status.unsure.is_empty()
             && (display_states.modified || display_states.clean)
         {
             let p1 = repo.dirstate_parents()?.p1;
             let manifest = repo.manifest_for_node(p1)?;
             let working_directory_vfs = repo.working_directory_vfs();
             let store_vfs = repo.store_vfs();
             let filelog_open_options = default_revlog_options(
                 repo.config(),
                 repo.requirements(),
                 RevlogType::Filelog,
             )?;
             let res: Vec<_> = take(&mut ds_status.unsure)
                 .into_par_iter()
                 .map(|to_check| {
                     // The compiler seems to get a bit confused with complex
                     // inference when using a parallel iterator + map
                     // + map_err + collect, so let's just inline some of the
                     // logic.
                     match unsure_is_modified(
                         &working_directory_vfs,
                         &store_vfs,
                         check_exec,
                         &manifest,
                         &to_check.path,
                         filelog_open_options,
                     ) {
                         Err(HgError::IoError { .. }) => {
                             // IO errors most likely stem from the file being
                             // deleted even though we know it's in the
                             // dirstate.
                             Ok((to_check, UnsureOutcome::Deleted))
                         }
                         Ok(outcome) => Ok((to_check, outcome)),
                         Err(e) => Err(e),
                     }
                 })
                 .collect::<Result<_, _>>()?;
             for (status_path, outcome) in res.into_iter() {
                 match outcome {
                     UnsureOutcome::Clean => {
                         if display_states.clean {
                             ds_status.clean.push(status_path.clone());
                         }
                         fixup.push(status_path.path.into_owned())
                     }
                     UnsureOutcome::Modified => {
                         if display_states.modified {
                             ds_status.modified.push(status_path);
                         }
                     }
                     UnsureOutcome::Deleted => {
                         if display_states.deleted {
                             ds_status.deleted.push(status_path);
                         }
                     }
                 }
             }
         }
 
         let dirstate_write_needed = ds_status.dirty;
         let filesystem_time_at_status_start =
             ds_status.filesystem_time_at_status_start;
 
         output.output(display_states, ds_status)?;
 
         Ok((
             fixup,
             dirstate_write_needed,
             filesystem_time_at_status_start,
         ))
     };
 
     let (narrow_matcher, narrow_warnings) = narrow::matcher(repo)?;
     let (sparse_matcher, sparse_warnings) = sparse::matcher(repo)?;
     let matcher = match (repo.has_narrow(), repo.has_sparse()) {
         (true, true) => {
             Box::new(IntersectionMatcher::new(narrow_matcher, sparse_matcher))
         }
         (true, false) => narrow_matcher,
         (false, true) => sparse_matcher,
         (false, false) => Box::new(AlwaysMatcher),
     };
     let matcher = match args.get_many::<std::ffi::OsString>("file") {
         None => matcher,
         Some(files) => {
             let patterns: Vec<Vec<u8>> = files
                 .filter(|s| !s.is_empty())
                 .map(get_bytes_from_os_str)
                 .collect();
             for file in &patterns {
                 if file.starts_with(b"set:") {
                     return Err(CommandError::unsupported("fileset"));
                 }
             }
             let cwd = hg::utils::current_dir()?;
             let root = repo.working_directory_path();
             let ignore_patterns = parse_pattern_args(patterns, &cwd, root)?;
             let files_matcher =
                 hg::matchers::PatternMatcher::new(ignore_patterns)?;
             Box::new(IntersectionMatcher::new(
                 Box::new(files_matcher),
                 matcher,
             ))
         }
     };
     print_narrow_sparse_warnings(
         &narrow_warnings,
         &sparse_warnings,
         ui,
         repo,
     )?;
 
     if let Some((rev1, rev2)) = revpair {
         let mut ds_status = DirstateStatus::default();
         if list_copies {
             return Err(CommandError::unsupported(
                 "status --rev --rev with copy information is not implemented yet",
             ));
         }
 
         let stat = hg::operations::status_rev_rev_no_copies(
             repo, rev1, rev2, matcher,
         )?;
         for entry in stat.iter() {
             let (path, status) = entry?;
             let path = StatusPath {
                 path: Cow::Borrowed(path),
                 copy_source: None,
             };
             match status {
                 hg::operations::DiffStatus::Removed => {
                     if display_states.removed {
                         ds_status.removed.push(path)
                     }
                 }
                 hg::operations::DiffStatus::Added => {
                     if display_states.added {
                         ds_status.added.push(path)
                     }
                 }
                 hg::operations::DiffStatus::Modified => {
                     if display_states.modified {
                         ds_status.modified.push(path)
                     }
                 }
                 hg::operations::DiffStatus::Matching => {
                     if display_states.clean {
                         ds_status.clean.push(path)
                     }
                 }
             }
         }
         output.output(display_states, ds_status)?;
         return Ok(());
     }
 
     let (fixup, mut dirstate_write_needed, filesystem_time_at_status_start) =
         dmap.with_status(
             matcher.as_ref(),
             repo.working_directory_path().to_owned(),
             ignore_files(repo, config),
             options,
             after_status,
         )?;
 
     // Development config option to test write races
     if let Err(e) =
         debug_wait_for_file(config, "status.pre-dirstate-write-file")
     {
         ui.write_stderr(e.as_bytes()).ok();
     }
 
     if (fixup.is_empty() || filesystem_time_at_status_start.is_none())
         && !dirstate_write_needed
     {
         // Nothing to update
         return Ok(());
     }
 
     // Update the dirstate on disk if we can
     let with_lock_result =
         repo.try_with_wlock_no_wait(|| -> Result<(), CommandError> {
             if let Some(mtime_boundary) = filesystem_time_at_status_start {
                 for hg_path in fixup {
                     use std::os::unix::fs::MetadataExt;
                     let fs_path = hg_path_to_path_buf(&hg_path)
                         .expect("HgPath conversion");
                     // Specifically do not reuse `fs_metadata` from
                     // `unsure_is_clean` which was needed before reading
                     // contents. Here we access metadata again after reading
                     // content, in case it changed in the meantime.
                     let metadata_res = repo
                         .working_directory_vfs()
                         .symlink_metadata(&fs_path);
                     let fs_metadata = match metadata_res {
                         Ok(meta) => meta,
                         Err(err) => match err {
                             HgError::IoError { .. } => {
                                 // The file has probably been deleted. In any
                                 // case, it was in the dirstate before, so
                                 // let's ignore the error.
                                 continue;
                             }
                             _ => return Err(err.into()),
                         },
                     };
                     if let Some(mtime) =
                         TruncatedTimestamp::for_reliable_mtime_of(
                             &fs_metadata,
                             &mtime_boundary,
                         )
                         .when_reading_file(&fs_path)?
                     {
                         let mode = fs_metadata.mode();
                         let size = fs_metadata.len();
                         dmap.set_clean(&hg_path, mode, size as u32, mtime)?;
                         dirstate_write_needed = true
                     }
                 }
             }
             drop(dmap); // Avoid "already mutably borrowed" RefCell panics
             if dirstate_write_needed {
                 repo.write_dirstate()?
             }
             Ok(())
         });
     match with_lock_result {
         Ok(closure_result) => closure_result?,
         Err(LockError::AlreadyHeld) => {
             // Not updating the dirstate is not ideal but not critical:
             // don’t keep our caller waiting until some other Mercurial
             // process releases the lock.
             log::info!("not writing dirstate from `status`: lock is held")
         }
         Err(LockError::Other(HgError::IoError { error, .. }))
             if error.kind() == io::ErrorKind::PermissionDenied
                 || match error.raw_os_error() {
                     None => false,
                     Some(errno) => libc::EROFS == errno,
                 } =>
         {
             // `hg status` on a read-only repository is fine
         }
         Err(LockError::Other(error)) => {
             // Report other I/O errors
             Err(error)?
         }
     }
     Ok(())
 }
 
 fn ignore_files(repo: &Repo, config: &Config) -> Vec<PathBuf> {
     let mut ignore_files = Vec::new();
     let repo_ignore = repo.working_directory_vfs().join(".hgignore");
     if repo_ignore.exists() {
         ignore_files.push(repo_ignore)
     }
     for (key, value) in config.iter_section(b"ui") {
         if key == b"ignore" || key.starts_with(b"ignore.") {
             let path = get_path_from_bytes(value);
             let path = shellexpand::path::full_with_context_no_errors(
                 path,
                 home::home_dir,
                 |s| std::env::var(s).ok(),
             );
             let joined = repo.working_directory_path().join(path);
             ignore_files.push(joined);
         }
     }
     ignore_files
 }
 
 struct DisplayStatusPaths<'a> {
     ui: &'a Ui,
     no_status: bool,
     relativize: Option<RelativizePaths>,
     print0: bool,
 }
 
 impl DisplayStatusPaths<'_> {
     // Probably more elegant to use a Deref or Borrow trait rather than
     // harcode HgPathBuf, but probably not really useful at this point
     fn display(
         &self,
         status_prefix: &[u8],
         label: &'static str,
         mut paths: Vec<StatusPath<'_>>,
     ) -> Result<(), CommandError> {
         paths.sort_unstable();
         // TODO: get the stdout lock once for the whole loop
         // instead of in each write
         for StatusPath { path, copy_source } in paths {
             let relative_path;
             let relative_source;
             let (path, copy_source) = if let Some(relativize) =
                 &self.relativize
             {
                 relative_path = relativize.relativize(&path);
                 relative_source =
                     copy_source.as_ref().map(|s| relativize.relativize(s));
                 (&*relative_path, relative_source.as_deref())
             } else {
                 (path.as_bytes(), copy_source.as_ref().map(|s| s.as_bytes()))
             };
             // TODO: Add a way to use `write_bytes!` instead of `format_bytes!`
             // in order to stream to stdout instead of allocating an
             // itermediate `Vec<u8>`.
             if !self.no_status {
                 self.ui.write_stdout_labelled(status_prefix, label)?
             }
             let linebreak = if self.print0 { b"\x00" } else { b"\n" };
             self.ui.write_stdout_labelled(
                 &format_bytes!(b"{}{}", path, linebreak),
                 label,
             )?;
             if let Some(source) = copy_source {
                 let label = "status.copied";
                 self.ui.write_stdout_labelled(
                     &format_bytes!(b"  {}{}", source, linebreak),
                     label,
                 )?
             }
         }
         Ok(())
     }
 
     fn output(
         &mut self,
         display_states: DisplayStates,
         ds_status: DirstateStatus,
     ) -> Result<(), CommandError> {
         if display_states.modified {
             self.display(b"M ", "status.modified", ds_status.modified)?;
         }
         if display_states.added {
             self.display(b"A ", "status.added", ds_status.added)?;
         }
         if display_states.removed {
             self.display(b"R ", "status.removed", ds_status.removed)?;
         }
         if display_states.deleted {
             self.display(b"! ", "status.deleted", ds_status.deleted)?;
         }
         if display_states.unknown {
             self.display(b"? ", "status.unknown", ds_status.unknown)?;
         }
         if display_states.ignored {
             self.display(b"I ", "status.ignored", ds_status.ignored)?;
         }
         if display_states.clean {
             self.display(b"C ", "status.clean", ds_status.clean)?;
         }
         Ok(())
     }
 }
 
 /// Outcome of the additional check for an ambiguous tracked file
 enum UnsureOutcome {
     /// The file is actually clean
     Clean,
     /// The file has been modified
     Modified,
     /// The file was deleted on disk (or became another type of fs entry)
     Deleted,
 }
 
 /// Check if a file is modified by comparing actual repo store and file system.
 ///
 /// This meant to be used for those that the dirstate cannot resolve, due
 /// to time resolution limits.
 fn unsure_is_modified(
     working_directory_vfs: &hg::vfs::VfsImpl,
     store_vfs: &hg::vfs::VfsImpl,
     check_exec: bool,
     manifest: &Manifest,
     hg_path: &HgPath,
     revlog_open_options: RevlogOpenOptions,
 ) -> Result<UnsureOutcome, HgError> {
     let vfs = working_directory_vfs;
     let fs_path = hg_path_to_path_buf(hg_path).expect("HgPath conversion");
     let fs_metadata = vfs.symlink_metadata(&fs_path)?;
     let is_symlink = fs_metadata.file_type().is_symlink();
 
     let entry = manifest
         .find_by_path(hg_path)?
         .expect("ambgious file not in p1");
 
     // TODO: Also account for `FALLBACK_SYMLINK` and `FALLBACK_EXEC` from the
     // dirstate
     let fs_flags = if is_symlink {
         Some(b'l')
     } else if check_exec && has_exec_bit(&fs_metadata) {
         Some(b'x')
     } else {
         None
     };
 
     let entry_flags = if check_exec {
         entry.flags
     } else if entry.flags.map(|f| f.into()) == Some(b'x') {
         None
     } else {
         entry.flags
     };
 
     if entry_flags.map(|f| f.into()) != fs_flags {
         return Ok(UnsureOutcome::Modified);
     }
     let filelog = hg::revlog::filelog::Filelog::open_vfs(
         store_vfs,
         hg_path,
         revlog_open_options,
     )?;
     let fs_len = fs_metadata.len();
     let file_node = entry.node_id()?;
     let filelog_entry = filelog.entry_for_node(file_node).map_err(|_| {
         HgError::corrupted(format!(
             "filelog {:?} missing node {:?} from manifest",
             hg_path, file_node
         ))
     })?;
     if filelog_entry.file_data_len_not_equal_to(fs_len) {
         // No need to read file contents:
         // it cannot be equal if it has a different length.
         return Ok(UnsureOutcome::Modified);
     }
 
     let p1_filelog_data = filelog_entry.data()?;
     let p1_contents = p1_filelog_data.file_data()?;
     if p1_contents.len() as u64 != fs_len {
         // No need to read file contents:
         // it cannot be equal if it has a different length.
         return Ok(UnsureOutcome::Modified);
     }
 
     let fs_contents = if is_symlink {
         get_bytes_from_os_string(vfs.read_link(fs_path)?.into_os_string())
     } else {
         vfs.read(fs_path)?
     };
 
     Ok(if p1_contents != &*fs_contents {
         UnsureOutcome::Modified
     } else {
         UnsureOutcome::Clean
     })
 }