rhg: Set second_ambiguous as needed in post-status fixup

This fixes an intermittent bug that manifested only in test-revert.t,
and unfortunately not on CI. On a fast enough machine we could have:

1. A file is modified
2. `rhg status` writes an updated dirstate-v1
3. The same file is modified again

… all within the same integer second. Because the dirstate-v1 file format
does not store sub-second precision, step 2 must write the file’s mtime
as "unknown" because of the possibility of step 3.

However, most of the code now handles timestamps with nanosecond precision
in order to take advantage of it in dirstate-v2. `second_ambiguous` must
be set for timestamps that become ambiguous if sub-second precision is dropped
(such as through serialization in dirstate-v1 format).

Differential Revision: https://phab.mercurial-scm.org/D11889

rust/hg-core/src/dirstate/entry.rs

@@ -1,691 +1,707
 use crate::dirstate_tree::on_disk::DirstateV2ParseError;
 use crate::errors::HgError;
 use bitflags::bitflags;
 use std::convert::{TryFrom, TryInto};
 use std::fs;
 use std::io;
 use std::time::{SystemTime, UNIX_EPOCH};
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum EntryState {
     Normal,
     Added,
     Removed,
     Merged,
 }
 
 /// `size` and `mtime.seconds` are truncated to 31 bits.
 ///
 /// TODO: double-check status algorithm correctness for files
 /// larger than 2 GiB or modified after 2038.
 #[derive(Debug, Copy, Clone)]
 pub struct DirstateEntry {
     pub(crate) flags: Flags,
     mode_size: Option<(u32, u32)>,
     mtime: Option<TruncatedTimestamp>,
 }
 
 bitflags! {
     pub(crate) struct Flags: u8 {
         const WDIR_TRACKED = 1 << 0;
         const P1_TRACKED = 1 << 1;
         const P2_INFO = 1 << 2;
         const HAS_FALLBACK_EXEC = 1 << 3;
         const FALLBACK_EXEC = 1 << 4;
         const HAS_FALLBACK_SYMLINK = 1 << 5;
         const FALLBACK_SYMLINK = 1 << 6;
     }
 }
 
 /// A Unix timestamp with nanoseconds precision
 #[derive(Debug, Copy, Clone)]
 pub struct TruncatedTimestamp {
     truncated_seconds: u32,
     /// Always in the `0 .. 1_000_000_000` range.
     nanoseconds: u32,
     /// TODO this should be in DirstateEntry, but the current code needs
     /// refactoring to use DirstateEntry instead of TruncatedTimestamp for
     /// comparison.
     pub second_ambiguous: bool,
 }
 
 impl TruncatedTimestamp {
     /// Constructs from a timestamp potentially outside of the supported range,
     /// and truncate the seconds components to its lower 31 bits.
     ///
     /// Panics if the nanoseconds components is not in the expected range.
     pub fn new_truncate(
         seconds: i64,
         nanoseconds: u32,
         second_ambiguous: bool,
     ) -> Self {
         assert!(nanoseconds < NSEC_PER_SEC);
         Self {
             truncated_seconds: seconds as u32 & RANGE_MASK_31BIT,
             nanoseconds,
             second_ambiguous,
         }
     }
 
     /// Construct from components. Returns an error if they are not in the
     /// expcted range.
     pub fn from_already_truncated(
         truncated_seconds: u32,
         nanoseconds: u32,
         second_ambiguous: bool,
     ) -> Result<Self, DirstateV2ParseError> {
         if truncated_seconds & !RANGE_MASK_31BIT == 0
             && nanoseconds < NSEC_PER_SEC
         {
             Ok(Self {
                 truncated_seconds,
                 nanoseconds,
                 second_ambiguous,
             })
         } else {
             Err(DirstateV2ParseError)
         }
     }
 
+    /// Returns a `TruncatedTimestamp` for the modification time of `metadata`.
+    ///
+    /// Propagates errors from `std` on platforms where modification time
+    /// is not available at all.
     pub fn for_mtime_of(metadata: &fs::Metadata) -> io::Result<Self> {
         #[cfg(unix)]
         {
             use std::os::unix::fs::MetadataExt;
             let seconds = metadata.mtime();
             // i64 -> u32 with value always in the `0 .. NSEC_PER_SEC` range
             let nanoseconds = metadata.mtime_nsec().try_into().unwrap();
             Ok(Self::new_truncate(seconds, nanoseconds, false))
         }
         #[cfg(not(unix))]
         {
             metadata.modified().map(Self::from)
         }
     }
 
-    /// Returns whether this timestamp is reliable as the "mtime" of a file.
+    /// Like `for_mtime_of`, but may return `None` or a value with
+    /// `second_ambiguous` set if the mtime is not "reliable".
     ///
     /// A modification time is reliable if it is older than `boundary` (or
     /// sufficiently in the future).
     ///
     /// Otherwise a concurrent modification might happens with the same mtime.
-    pub fn is_reliable_mtime(&self, boundary: &Self) -> bool {
+    pub fn for_reliable_mtime_of(
+        metadata: &fs::Metadata,
+        boundary: &Self,
+    ) -> io::Result<Option<Self>> {
+        let mut mtime = Self::for_mtime_of(metadata)?;
         // If the mtime of the ambiguous file is younger (or equal) to the
         // starting point of the `status` walk, we cannot garantee that
         // another, racy, write will not happen right after with the same mtime
         // and we cannot cache the information.
         //
         // However if the mtime is far away in the future, this is likely some
         // mismatch between the current clock and previous file system
         // operation. So mtime more than one days in the future are considered
         // fine.
-        if self.truncated_seconds == boundary.truncated_seconds {
-            self.nanoseconds != 0
+        let reliable = if mtime.truncated_seconds == boundary.truncated_seconds
+        {
+            mtime.second_ambiguous = true;
+            mtime.nanoseconds != 0
                 && boundary.nanoseconds != 0
-                && self.nanoseconds < boundary.nanoseconds
+                && mtime.nanoseconds < boundary.nanoseconds
         } else {
             // `truncated_seconds` is less than 2**31,
             // so this does not overflow `u32`:
             let one_day_later = boundary.truncated_seconds + 24 * 3600;
-            self.truncated_seconds < boundary.truncated_seconds
-                || self.truncated_seconds > one_day_later
+            mtime.truncated_seconds < boundary.truncated_seconds
+                || mtime.truncated_seconds > one_day_later
+        };
+        if reliable {
+            Ok(Some(mtime))
+        } else {
+            Ok(None)
         }
     }
 
     /// The lower 31 bits of the number of seconds since the epoch.
     pub fn truncated_seconds(&self) -> u32 {
         self.truncated_seconds
     }
 
     /// The sub-second component of this timestamp, in nanoseconds.
     /// Always in the `0 .. 1_000_000_000` range.
     ///
     /// This timestamp is after `(seconds, 0)` by this many nanoseconds.
     pub fn nanoseconds(&self) -> u32 {
         self.nanoseconds
     }
 
     /// Returns whether two timestamps are equal modulo 2**31 seconds.
     ///
     /// If this returns `true`, the original values converted from `SystemTime`
     /// or given to `new_truncate` were very likely equal. A false positive is
     /// possible if they were exactly a multiple of 2**31 seconds apart (around
     /// 68 years). This is deemed very unlikely to happen by chance, especially
     /// on filesystems that support sub-second precision.
     ///
     /// If someone is manipulating the modification times of some files to
     /// intentionally make `hg status` return incorrect results, not truncating
     /// wouldn’t help much since they can set exactly the expected timestamp.
     ///
     /// Sub-second precision is ignored if it is zero in either value.
     /// Some APIs simply return zero when more precision is not available.
     /// When comparing values from different sources, if only one is truncated
     /// in that way, doing a simple comparison would cause many false
     /// negatives.
     pub fn likely_equal(self, other: Self) -> bool {
         if self.truncated_seconds != other.truncated_seconds {
             false
         } else if self.nanoseconds == 0 || other.nanoseconds == 0 {
             if self.second_ambiguous {
                 false
             } else {
                 true
             }
         } else {
             self.nanoseconds == other.nanoseconds
         }
     }
 
     pub fn likely_equal_to_mtime_of(
         self,
         metadata: &fs::Metadata,
     ) -> io::Result<bool> {
         Ok(self.likely_equal(Self::for_mtime_of(metadata)?))
     }
 }
 
 impl From<SystemTime> for TruncatedTimestamp {
     fn from(system_time: SystemTime) -> Self {
         // On Unix, `SystemTime` is a wrapper for the `timespec` C struct:
         // https://www.gnu.org/software/libc/manual/html_node/Time-Types.html#index-struct-timespec
         // We want to effectively access its fields, but the Rust standard
         // library does not expose them. The best we can do is:
         let seconds;
         let nanoseconds;
         match system_time.duration_since(UNIX_EPOCH) {
             Ok(duration) => {
                 seconds = duration.as_secs() as i64;
                 nanoseconds = duration.subsec_nanos();
             }
             Err(error) => {
                 // `system_time` is before `UNIX_EPOCH`.
                 // We need to undo this algorithm:
                 // https://github.com/rust-lang/rust/blob/6bed1f0bc3cc50c10aab26d5f94b16a00776b8a5/library/std/src/sys/unix/time.rs#L40-L41
                 let negative = error.duration();
                 let negative_secs = negative.as_secs() as i64;
                 let negative_nanos = negative.subsec_nanos();
                 if negative_nanos == 0 {
                     seconds = -negative_secs;
                     nanoseconds = 0;
                 } else {
                     // For example if `system_time` was 4.3 seconds before
                     // the Unix epoch we get a Duration that represents
                     // `(-4, -0.3)` but we want `(-5, +0.7)`:
                     seconds = -1 - negative_secs;
                     nanoseconds = NSEC_PER_SEC - negative_nanos;
                 }
             }
         };
         Self::new_truncate(seconds, nanoseconds, false)
     }
 }
 
 const NSEC_PER_SEC: u32 = 1_000_000_000;
 pub const RANGE_MASK_31BIT: u32 = 0x7FFF_FFFF;
 
 pub const MTIME_UNSET: i32 = -1;
 
 /// A `DirstateEntry` with a size of `-2` means that it was merged from the
 /// other parent. This allows revert to pick the right status back during a
 /// merge.
 pub const SIZE_FROM_OTHER_PARENT: i32 = -2;
 /// A special value used for internal representation of special case in
 /// dirstate v1 format.
 pub const SIZE_NON_NORMAL: i32 = -1;
 
 impl DirstateEntry {
     pub fn from_v2_data(
         wdir_tracked: bool,
         p1_tracked: bool,
         p2_info: bool,
         mode_size: Option<(u32, u32)>,
         mtime: Option<TruncatedTimestamp>,
         fallback_exec: Option<bool>,
         fallback_symlink: Option<bool>,
     ) -> Self {
         if let Some((mode, size)) = mode_size {
             // TODO: return an error for out of range values?
             assert!(mode & !RANGE_MASK_31BIT == 0);
             assert!(size & !RANGE_MASK_31BIT == 0);
         }
         let mut flags = Flags::empty();
         flags.set(Flags::WDIR_TRACKED, wdir_tracked);
         flags.set(Flags::P1_TRACKED, p1_tracked);
         flags.set(Flags::P2_INFO, p2_info);
         if let Some(exec) = fallback_exec {
             flags.insert(Flags::HAS_FALLBACK_EXEC);
             if exec {
                 flags.insert(Flags::FALLBACK_EXEC);
             }
         }
         if let Some(exec) = fallback_symlink {
             flags.insert(Flags::HAS_FALLBACK_SYMLINK);
             if exec {
                 flags.insert(Flags::FALLBACK_SYMLINK);
             }
         }
         Self {
             flags,
             mode_size,
             mtime,
         }
     }
 
     pub fn from_v1_data(
         state: EntryState,
         mode: i32,
         size: i32,
         mtime: i32,
     ) -> Self {
         match state {
             EntryState::Normal => {
                 if size == SIZE_FROM_OTHER_PARENT {
                     Self {
                         // might be missing P1_TRACKED
                         flags: Flags::WDIR_TRACKED | Flags::P2_INFO,
                         mode_size: None,
                         mtime: None,
                     }
                 } else if size == SIZE_NON_NORMAL {
                     Self {
                         flags: Flags::WDIR_TRACKED | Flags::P1_TRACKED,
                         mode_size: None,
                         mtime: None,
                     }
                 } else if mtime == MTIME_UNSET {
                     // TODO: return an error for negative values?
                     let mode = u32::try_from(mode).unwrap();
                     let size = u32::try_from(size).unwrap();
                     Self {
                         flags: Flags::WDIR_TRACKED | Flags::P1_TRACKED,
                         mode_size: Some((mode, size)),
                         mtime: None,
                     }
                 } else {
                     // TODO: return an error for negative values?
                     let mode = u32::try_from(mode).unwrap();
                     let size = u32::try_from(size).unwrap();
                     let mtime = u32::try_from(mtime).unwrap();
                     let mtime = TruncatedTimestamp::from_already_truncated(
                         mtime, 0, false,
                     )
                     .unwrap();
                     Self {
                         flags: Flags::WDIR_TRACKED | Flags::P1_TRACKED,
                         mode_size: Some((mode, size)),
                         mtime: Some(mtime),
                     }
                 }
             }
             EntryState::Added => Self {
                 flags: Flags::WDIR_TRACKED,
                 mode_size: None,
                 mtime: None,
             },
             EntryState::Removed => Self {
                 flags: if size == SIZE_NON_NORMAL {
                     Flags::P1_TRACKED | Flags::P2_INFO
                 } else if size == SIZE_FROM_OTHER_PARENT {
                     // We don’t know if P1_TRACKED should be set (file history)
                     Flags::P2_INFO
                 } else {
                     Flags::P1_TRACKED
                 },
                 mode_size: None,
                 mtime: None,
             },
             EntryState::Merged => Self {
                 flags: Flags::WDIR_TRACKED
                     | Flags::P1_TRACKED // might not be true because of rename ?
                     | Flags::P2_INFO, // might not be true because of rename ?
                 mode_size: None,
                 mtime: None,
             },
         }
     }
 
     /// Creates a new entry in "removed" state.
     ///
     /// `size` is expected to be zero, `SIZE_NON_NORMAL`, or
     /// `SIZE_FROM_OTHER_PARENT`
     pub fn new_removed(size: i32) -> Self {
         Self::from_v1_data(EntryState::Removed, 0, size, 0)
     }
 
     pub fn tracked(&self) -> bool {
         self.flags.contains(Flags::WDIR_TRACKED)
     }
 
     pub fn p1_tracked(&self) -> bool {
         self.flags.contains(Flags::P1_TRACKED)
     }
 
     fn in_either_parent(&self) -> bool {
         self.flags.intersects(Flags::P1_TRACKED | Flags::P2_INFO)
     }
 
     pub fn removed(&self) -> bool {
         self.in_either_parent() && !self.flags.contains(Flags::WDIR_TRACKED)
     }
 
     pub fn p2_info(&self) -> bool {
         self.flags.contains(Flags::WDIR_TRACKED | Flags::P2_INFO)
     }
 
     pub fn added(&self) -> bool {
         self.flags.contains(Flags::WDIR_TRACKED) && !self.in_either_parent()
     }
 
     pub fn maybe_clean(&self) -> bool {
         if !self.flags.contains(Flags::WDIR_TRACKED) {
             false
         } else if !self.flags.contains(Flags::P1_TRACKED) {
             false
         } else if self.flags.contains(Flags::P2_INFO) {
             false
         } else {
             true
         }
     }
 
     pub fn any_tracked(&self) -> bool {
         self.flags.intersects(
             Flags::WDIR_TRACKED | Flags::P1_TRACKED | Flags::P2_INFO,
         )
     }
 
     /// Returns `(wdir_tracked, p1_tracked, p2_info, mode_size, mtime)`
     pub(crate) fn v2_data(
         &self,
     ) -> (
         bool,
         bool,
         bool,
         Option<(u32, u32)>,
         Option<TruncatedTimestamp>,
         Option<bool>,
         Option<bool>,
     ) {
         if !self.any_tracked() {
             // TODO: return an Option instead?
             panic!("Accessing v1_state of an untracked DirstateEntry")
         }
         let wdir_tracked = self.flags.contains(Flags::WDIR_TRACKED);
         let p1_tracked = self.flags.contains(Flags::P1_TRACKED);
         let p2_info = self.flags.contains(Flags::P2_INFO);
         let mode_size = self.mode_size;
         let mtime = self.mtime;
         (
             wdir_tracked,
             p1_tracked,
             p2_info,
             mode_size,
             mtime,
             self.get_fallback_exec(),
             self.get_fallback_symlink(),
         )
     }
 
     fn v1_state(&self) -> EntryState {
         if !self.any_tracked() {
             // TODO: return an Option instead?
             panic!("Accessing v1_state of an untracked DirstateEntry")
         }
         if self.removed() {
             EntryState::Removed
         } else if self
             .flags
             .contains(Flags::WDIR_TRACKED | Flags::P1_TRACKED | Flags::P2_INFO)
         {
             EntryState::Merged
         } else if self.added() {
             EntryState::Added
         } else {
             EntryState::Normal
         }
     }
 
     fn v1_mode(&self) -> i32 {
         if let Some((mode, _size)) = self.mode_size {
             i32::try_from(mode).unwrap()
         } else {
             0
         }
     }
 
     fn v1_size(&self) -> i32 {
         if !self.any_tracked() {
             // TODO: return an Option instead?
             panic!("Accessing v1_size of an untracked DirstateEntry")
         }
         if self.removed()
             && self.flags.contains(Flags::P1_TRACKED | Flags::P2_INFO)
         {
             SIZE_NON_NORMAL
         } else if self.flags.contains(Flags::P2_INFO) {
             SIZE_FROM_OTHER_PARENT
         } else if self.removed() {
             0
         } else if self.added() {
             SIZE_NON_NORMAL
         } else if let Some((_mode, size)) = self.mode_size {
             i32::try_from(size).unwrap()
         } else {
             SIZE_NON_NORMAL
         }
     }
 
     fn v1_mtime(&self) -> i32 {
         if !self.any_tracked() {
             // TODO: return an Option instead?
             panic!("Accessing v1_mtime of an untracked DirstateEntry")
         }
         if self.removed() {
             0
         } else if self.flags.contains(Flags::P2_INFO) {
             MTIME_UNSET
         } else if !self.flags.contains(Flags::P1_TRACKED) {
             MTIME_UNSET
         } else if let Some(mtime) = self.mtime {
             if mtime.second_ambiguous {
                 MTIME_UNSET
             } else {
                 i32::try_from(mtime.truncated_seconds()).unwrap()
             }
         } else {
             MTIME_UNSET
         }
     }
 
     // TODO: return `Option<EntryState>`? None when `!self.any_tracked`
     pub fn state(&self) -> EntryState {
         self.v1_state()
     }
 
     // TODO: return Option?
     pub fn mode(&self) -> i32 {
         self.v1_mode()
     }
 
     // TODO: return Option?
     pub fn size(&self) -> i32 {
         self.v1_size()
     }
 
     // TODO: return Option?
     pub fn mtime(&self) -> i32 {
         self.v1_mtime()
     }
 
     pub fn get_fallback_exec(&self) -> Option<bool> {
         if self.flags.contains(Flags::HAS_FALLBACK_EXEC) {
             Some(self.flags.contains(Flags::FALLBACK_EXEC))
         } else {
             None
         }
     }
 
     pub fn set_fallback_exec(&mut self, value: Option<bool>) {
         match value {
             None => {
                 self.flags.remove(Flags::HAS_FALLBACK_EXEC);
                 self.flags.remove(Flags::FALLBACK_EXEC);
             }
             Some(exec) => {
                 self.flags.insert(Flags::HAS_FALLBACK_EXEC);
                 if exec {
                     self.flags.insert(Flags::FALLBACK_EXEC);
                 }
             }
         }
     }
 
     pub fn get_fallback_symlink(&self) -> Option<bool> {
         if self.flags.contains(Flags::HAS_FALLBACK_SYMLINK) {
             Some(self.flags.contains(Flags::FALLBACK_SYMLINK))
         } else {
             None
         }
     }
 
     pub fn set_fallback_symlink(&mut self, value: Option<bool>) {
         match value {
             None => {
                 self.flags.remove(Flags::HAS_FALLBACK_SYMLINK);
                 self.flags.remove(Flags::FALLBACK_SYMLINK);
             }
             Some(symlink) => {
                 self.flags.insert(Flags::HAS_FALLBACK_SYMLINK);
                 if symlink {
                     self.flags.insert(Flags::FALLBACK_SYMLINK);
                 }
             }
         }
     }
 
     pub fn truncated_mtime(&self) -> Option<TruncatedTimestamp> {
         self.mtime
     }
 
     pub fn drop_merge_data(&mut self) {
         if self.flags.contains(Flags::P2_INFO) {
             self.flags.remove(Flags::P2_INFO);
             self.mode_size = None;
             self.mtime = None;
         }
     }
 
     pub fn set_possibly_dirty(&mut self) {
         self.mtime = None
     }
 
     pub fn set_clean(
         &mut self,
         mode: u32,
         size: u32,
         mtime: TruncatedTimestamp,
     ) {
         let size = size & RANGE_MASK_31BIT;
         self.flags.insert(Flags::WDIR_TRACKED | Flags::P1_TRACKED);
         self.mode_size = Some((mode, size));
         self.mtime = Some(mtime);
     }
 
     pub fn set_tracked(&mut self) {
         self.flags.insert(Flags::WDIR_TRACKED);
         // `set_tracked` is replacing various `normallookup` call. So we mark
         // the files as needing lookup
         //
         // Consider dropping this in the future in favor of something less
         // broad.
         self.mtime = None;
     }
 
     pub fn set_untracked(&mut self) {
         self.flags.remove(Flags::WDIR_TRACKED);
         self.mode_size = None;
         self.mtime = None;
     }
 
     /// Returns `(state, mode, size, mtime)` for the puprose of serialization
     /// in the dirstate-v1 format.
     ///
     /// This includes marker values such as `mtime == -1`. In the future we may
     /// want to not represent these cases that way in memory, but serialization
     /// will need to keep the same format.
     pub fn v1_data(&self) -> (u8, i32, i32, i32) {
         (
             self.v1_state().into(),
             self.v1_mode(),
             self.v1_size(),
             self.v1_mtime(),
         )
     }
 
     pub(crate) fn is_from_other_parent(&self) -> bool {
         self.state() == EntryState::Normal
             && self.size() == SIZE_FROM_OTHER_PARENT
     }
 
     // TODO: other platforms
     #[cfg(unix)]
     pub fn mode_changed(
         &self,
         filesystem_metadata: &std::fs::Metadata,
     ) -> bool {
         let dirstate_exec_bit = (self.mode() as u32 & EXEC_BIT_MASK) != 0;
         let fs_exec_bit = has_exec_bit(filesystem_metadata);
         dirstate_exec_bit != fs_exec_bit
     }
 
     /// Returns a `(state, mode, size, mtime)` tuple as for
     /// `DirstateMapMethods::debug_iter`.
     pub fn debug_tuple(&self) -> (u8, i32, i32, i32) {
         (self.state().into(), self.mode(), self.size(), self.mtime())
     }
 }
 
 impl EntryState {
     pub fn is_tracked(self) -> bool {
         use EntryState::*;
         match self {
             Normal | Added | Merged => true,
             Removed => false,
         }
     }
 }
 
 impl TryFrom<u8> for EntryState {
     type Error = HgError;
 
     fn try_from(value: u8) -> Result<Self, Self::Error> {
         match value {
             b'n' => Ok(EntryState::Normal),
             b'a' => Ok(EntryState::Added),
             b'r' => Ok(EntryState::Removed),
             b'm' => Ok(EntryState::Merged),
             _ => Err(HgError::CorruptedRepository(format!(
                 "Incorrect dirstate entry state {}",
                 value
             ))),
         }
     }
 }
 
 impl Into<u8> for EntryState {
     fn into(self) -> u8 {
         match self {
             EntryState::Normal => b'n',
             EntryState::Added => b'a',
             EntryState::Removed => b'r',
             EntryState::Merged => b'm',
         }
     }
 }
 
 const EXEC_BIT_MASK: u32 = 0o100;
 
 pub fn has_exec_bit(metadata: &std::fs::Metadata) -> bool {
     // TODO: How to handle executable permissions on Windows?
     use std::os::unix::fs::MetadataExt;
     (metadata.mode() & EXEC_BIT_MASK) != 0
 }

rust/rhg/src/commands/status.rs

@@ -1,474 +1,478
 // 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::Ui;
 use crate::utils::path_utils::relativize_paths;
 use clap::{Arg, SubCommand};
 use format_bytes::format_bytes;
 use hg;
 use hg::config::Config;
 use hg::dirstate::has_exec_bit;
 use hg::dirstate::TruncatedTimestamp;
 use hg::dirstate::RANGE_MASK_31BIT;
 use hg::errors::{HgError, IoResultExt};
 use hg::lock::LockError;
 use hg::manifest::Manifest;
 use hg::matchers::AlwaysMatcher;
 use hg::repo::Repo;
 use hg::utils::files::get_bytes_from_os_string;
 use hg::utils::hg_path::{hg_path_to_path_buf, HgPath};
 use hg::{HgPathCow, StatusOptions};
 use log::{info, warn};
 use std::io;
 
 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::App<'static, 'static> {
     SubCommand::with_name("status")
         .alias("st")
         .about(HELP_TEXT)
         .arg(
             Arg::with_name("all")
                 .help("show status of all files")
                 .short("-A")
                 .long("--all"),
         )
         .arg(
             Arg::with_name("modified")
                 .help("show only modified files")
                 .short("-m")
                 .long("--modified"),
         )
         .arg(
             Arg::with_name("added")
                 .help("show only added files")
                 .short("-a")
                 .long("--added"),
         )
         .arg(
             Arg::with_name("removed")
                 .help("show only removed files")
                 .short("-r")
                 .long("--removed"),
         )
         .arg(
             Arg::with_name("clean")
                 .help("show only clean files")
                 .short("-c")
                 .long("--clean"),
         )
         .arg(
             Arg::with_name("deleted")
                 .help("show only deleted files")
                 .short("-d")
                 .long("--deleted"),
         )
         .arg(
             Arg::with_name("unknown")
                 .help("show only unknown (not tracked) files")
                 .short("-u")
                 .long("--unknown"),
         )
         .arg(
             Arg::with_name("ignored")
                 .help("show only ignored files")
                 .short("-i")
                 .long("--ignored"),
         )
         .arg(
             Arg::with_name("no-status")
                 .help("hide status prefix")
                 .short("-n")
                 .long("--no-status"),
         )
 }
 
 /// 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)
     }
 }
 
 pub fn run(invocation: &crate::CliInvocation) -> Result<(), CommandError> {
     let status_enabled_default = false;
     let status_enabled = invocation.config.get_option(b"rhg", b"status")?;
     if !status_enabled.unwrap_or(status_enabled_default) {
         return Err(CommandError::unsupported(
             "status is experimental in rhg (enable it with 'rhg.status = true' \
             or enable fallback with 'rhg.on-unsupported = fallback')"
         ));
     }
 
     // TODO: lift these limitations
     if invocation.config.get_bool(b"ui", b"tweakdefaults")? {
         return Err(CommandError::unsupported(
             "ui.tweakdefaults is not yet supported with rhg status",
         ));
     }
     if invocation.config.get_bool(b"ui", b"statuscopies")? {
         return Err(CommandError::unsupported(
             "ui.statuscopies is not yet supported with rhg status",
         ));
     }
     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 display_states = if args.is_present("all") {
         // TODO when implementing `--quiet`: it excludes clean files
         // from `--all`
         ALL_DISPLAY_STATES
     } else {
         let requested = DisplayStates {
             modified: args.is_present("modified"),
             added: args.is_present("added"),
             removed: args.is_present("removed"),
             clean: args.is_present("clean"),
             deleted: args.is_present("deleted"),
             unknown: args.is_present("unknown"),
             ignored: args.is_present("ignored"),
         };
         if requested.is_empty() {
             DEFAULT_DISPLAY_STATES
         } else {
             requested
         }
     };
     let no_status = args.is_present("no-status");
 
     let repo = invocation.repo?;
 
     if repo.has_sparse() || repo.has_narrow() {
         return Err(CommandError::unsupported(
             "rhg status is not supported for sparse checkouts or narrow clones yet"
         ));
     }
 
     let mut dmap = repo.dirstate_map_mut()?;
 
     let options = StatusOptions {
         // we're currently supporting file systems with exec flags only
         // anyway
         check_exec: true,
         list_clean: display_states.clean,
         list_unknown: display_states.unknown,
         list_ignored: display_states.ignored,
         collect_traversed_dirs: false,
     };
     let ignore_file = repo.working_directory_vfs().join(".hgignore"); // TODO hardcoded
     let (mut ds_status, pattern_warnings) = dmap.status(
         &AlwaysMatcher,
         repo.working_directory_path().to_owned(),
         vec![ignore_file],
         options,
     )?;
     if !pattern_warnings.is_empty() {
         warn!("Pattern warnings: {:?}", &pattern_warnings);
     }
 
     if !ds_status.bad.is_empty() {
         warn!("Bad matches {:?}", &(ds_status.bad))
     }
     if !ds_status.unsure.is_empty() {
         info!(
             "Files to be rechecked by retrieval from filelog: {:?}",
             &ds_status.unsure
         );
     }
     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).map_err(|e| {
             CommandError::from((e, &*format!("{:x}", p1.short())))
         })?;
         for to_check in ds_status.unsure {
             if unsure_is_modified(repo, &manifest, &to_check)? {
                 if display_states.modified {
                     ds_status.modified.push(to_check);
                 }
             } else {
                 if display_states.clean {
                     ds_status.clean.push(to_check.clone());
                 }
                 fixup.push(to_check.into_owned())
             }
         }
     }
     if display_states.modified {
         display_status_paths(
             ui,
             repo,
             config,
             no_status,
             &mut ds_status.modified,
             b"M",
         )?;
     }
     if display_states.added {
         display_status_paths(
             ui,
             repo,
             config,
             no_status,
             &mut ds_status.added,
             b"A",
         )?;
     }
     if display_states.removed {
         display_status_paths(
             ui,
             repo,
             config,
             no_status,
             &mut ds_status.removed,
             b"R",
         )?;
     }
     if display_states.deleted {
         display_status_paths(
             ui,
             repo,
             config,
             no_status,
             &mut ds_status.deleted,
             b"!",
         )?;
     }
     if display_states.unknown {
         display_status_paths(
             ui,
             repo,
             config,
             no_status,
             &mut ds_status.unknown,
             b"?",
         )?;
     }
     if display_states.ignored {
         display_status_paths(
             ui,
             repo,
             config,
             no_status,
             &mut ds_status.ignored,
             b"I",
         )?;
     }
     if display_states.clean {
         display_status_paths(
             ui,
             repo,
             config,
             no_status,
             &mut ds_status.clean,
             b"C",
         )?;
     }
 
     let mut dirstate_write_needed = ds_status.dirty;
     let filesystem_time_at_status_start = ds_status
         .filesystem_time_at_status_start
         .map(TruncatedTimestamp::from);
 
     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 fs_metadata = repo
                         .working_directory_vfs()
                         .symlink_metadata(&fs_path)?;
-                    let mtime = TruncatedTimestamp::for_mtime_of(&fs_metadata)
-                        .when_reading_file(&fs_path)?;
-                    if mtime.is_reliable_mtime(&mtime_boundary) {
+                    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() as u32 & RANGE_MASK_31BIT;
                         let mut entry = dmap
                             .get(&hg_path)?
                             .expect("ambiguous file not in dirstate");
                         entry.set_clean(mode, size, mtime);
                         dmap.add_file(&hg_path, entry)?;
                         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.
         }
         Err(LockError::Other(HgError::IoError { error, .. }))
             if error.kind() == io::ErrorKind::PermissionDenied =>
         {
             // `hg status` on a read-only repository is fine
         }
         Err(LockError::Other(error)) => {
             // Report other I/O errors
             Err(error)?
         }
     }
     Ok(())
 }
 
 // Probably more elegant to use a Deref or Borrow trait rather than
 // harcode HgPathBuf, but probably not really useful at this point
 fn display_status_paths(
     ui: &Ui,
     repo: &Repo,
     config: &Config,
     no_status: bool,
     paths: &mut [HgPathCow],
     status_prefix: &[u8],
 ) -> Result<(), CommandError> {
     paths.sort_unstable();
     let mut relative: bool = config.get_bool(b"ui", b"relative-paths")?;
     relative = config
         .get_option(b"commands", b"status.relative")?
         .unwrap_or(relative);
     let print_path = |path: &[u8]| {
         // TODO optim, probably lots of unneeded copies here, especially
         // if out stream is buffered
         if no_status {
             ui.write_stdout(&format_bytes!(b"{}\n", path))
         } else {
             ui.write_stdout(&format_bytes!(b"{} {}\n", status_prefix, path))
         }
     };
 
     if relative && !ui.plain() {
         relativize_paths(repo, paths.iter().map(Ok), |path| {
             print_path(&path)
         })?;
     } else {
         for path in paths {
             print_path(path.as_bytes())?
         }
     }
     Ok(())
 }
 
 /// 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(
     repo: &Repo,
     manifest: &Manifest,
     hg_path: &HgPath,
 ) -> Result<bool, HgError> {
     let vfs = repo.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();
     // TODO: Also account for `FALLBACK_SYMLINK` and `FALLBACK_EXEC` from the
     // dirstate
     let fs_flags = if is_symlink {
         Some(b'l')
     } else if has_exec_bit(&fs_metadata) {
         Some(b'x')
     } else {
         None
     };
 
     let entry = manifest
         .find_file(hg_path)?
         .expect("ambgious file not in p1");
     if entry.flags != fs_flags {
         return Ok(true);
     }
     let filelog = repo.filelog(hg_path)?;
     let filelog_entry =
         filelog.data_for_node(entry.node_id()?).map_err(|_| {
             HgError::corrupted("filelog missing node from manifest")
         })?;
     let contents_in_p1 = filelog_entry.data()?;
 
     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(contents_in_p1 != &*fs_contents)
 }