//! Timestamps for files in Rust

//!

//! This library provides platform-agnostic inspection of the various timestamps

//! present in the standard `fs::Metadata` structure.

//!

//! # Installation

//!

//! Add this to your `Cargo.toml`:

//!

//! ```toml

//! [dependencies]

//! filetime = "0.2"

//! ```

//!

//! # Usage

//!

//! ```no_run

//! use std::fs;

//! use filetime::FileTime;

//!

//! let metadata = fs::metadata("foo.txt").unwrap();

//!

//! let mtime = FileTime::from_last_modification_time(&metadata);

//! println!("{}", mtime);

//!

//! let atime = FileTime::from_last_access_time(&metadata);

//! assert!(mtime < atime);

//!

//! // Inspect values that can be interpreted across platforms

//! println!("{}", mtime.unix_seconds());

//! println!("{}", mtime.nanoseconds());

//!

//! // Print the platform-specific value of seconds

//! println!("{}", mtime.seconds());

//! ```

use std::fmt;

use std::fs;

use std::io;

use std::path::Path;

use std::time::{Duration, SystemTime, UNIX_EPOCH};

cfg_if::cfg_if! {

    if #[cfg(target_os = "redox")] {

        #[path = "redox.rs"]

        mod imp;

    } else if #[cfg(windows)] {

        #[path = "windows.rs"]

        mod imp;

    } else if #[cfg(all(target_family = "wasm", not(target_os = "emscripten")))] {

        #[path = "wasm.rs"]

        mod imp;

    } else {

        #[path = "unix/mod.rs"]

        mod imp;

    }

}

/// A helper structure to represent a timestamp for a file.

///

/// The actual value contined within is platform-specific and does not have the

/// same meaning across platforms, but comparisons and stringification can be

/// significant among the same platform.

#[derive(Eq, PartialEq, Ord, PartialOrd, Debug, Copy, Clone, Hash)]

pub struct FileTime {

    seconds: i64,

    nanos: u32,

}

impl FileTime {

    /// Creates a new timestamp representing a 0 time.

    ///

    /// Useful for creating the base of a cmp::max chain of times.

    pub const fn zero() -> FileTime {

        FileTime {

            seconds: 0,

            nanos: 0,

        }

    }

    const fn emulate_second_only_system(self) -> FileTime {

        if cfg!(emulate_second_only_system) {

            FileTime {

                seconds: self.seconds,

                nanos: 0,

            }

        } else {

            self

        }

    }

    /// Creates a new timestamp representing the current system time.

    ///

    /// ```

    /// # use filetime::FileTime;

    /// #

    /// # fn example() -> std::io::Result<()> {

    /// #     let path = "";

    /// #

    /// filetime::set_file_mtime(path, FileTime::now())?;

    /// #

    /// #     Ok(())

    /// # }

    /// ```

    ///

    /// Equivalent to `FileTime::from_system_time(SystemTime::now())`.

    pub fn now() -> FileTime {

        FileTime::from_system_time(SystemTime::now())

    }

    /// Creates a new instance of `FileTime` with a number of seconds and

    /// nanoseconds relative to the Unix epoch, 1970-01-01T00:00:00Z.

    ///

    /// Negative seconds represent times before the Unix epoch, and positive

    /// values represent times after it. Nanos always count forwards in time.

    ///

    /// Note that this is typically the relative point that Unix time stamps are

    /// from, but on Windows the native time stamp is relative to January 1,

    /// 1601 so the return value of `seconds` from the returned `FileTime`

    /// instance may not be the same as that passed in.

    pub const fn from_unix_time(seconds: i64, nanos: u32) -> FileTime {

        FileTime {

            seconds: seconds + if cfg!(windows) { 11644473600 } else { 0 },

            nanos,

        }

        .emulate_second_only_system()

    }

    /// Creates a new timestamp from the last modification time listed in the

    /// specified metadata.

    ///

    /// The returned value corresponds to the `mtime` field of `stat` on Unix

    /// platforms and the `ftLastWriteTime` field on Windows platforms.

    pub fn from_last_modification_time(meta: &fs::Metadata) -> FileTime {

        imp::from_last_modification_time(meta).emulate_second_only_system()

    }

    /// Creates a new timestamp from the last access time listed in the

    /// specified metadata.

    ///

    /// The returned value corresponds to the `atime` field of `stat` on Unix

    /// platforms and the `ftLastAccessTime` field on Windows platforms.

    pub fn from_last_access_time(meta: &fs::Metadata) -> FileTime {

        imp::from_last_access_time(meta).emulate_second_only_system()

    }

    /// Creates a new timestamp from the creation time listed in the specified

    /// metadata.

    ///

    /// The returned value corresponds to the `birthtime` field of `stat` on

    /// Unix platforms and the `ftCreationTime` field on Windows platforms. Note

    /// that not all Unix platforms have this field available and may return

    /// `None` in some circumstances.

    pub fn from_creation_time(meta: &fs::Metadata) -> Option<FileTime> {

        imp::from_creation_time(meta).map(|x| x.emulate_second_only_system())

    }

    /// Creates a new timestamp from the given SystemTime.

    ///

    /// Windows counts file times since 1601-01-01T00:00:00Z, and cannot

    /// represent times before this, but it's possible to create a SystemTime

    /// that does. This function will error if passed such a SystemTime.

    pub fn from_system_time(time: SystemTime) -> FileTime {

        let epoch = if cfg!(windows) {

            UNIX_EPOCH - Duration::from_secs(11644473600)

        } else {

            UNIX_EPOCH

        };

        time.duration_since(epoch)

            .map(|d| FileTime {

                seconds: d.as_secs() as i64,

                nanos: d.subsec_nanos(),

            })

            .unwrap_or_else(|e| {

                let until_epoch = e.duration();

                let (sec_offset, nanos) = if until_epoch.subsec_nanos() == 0 {

                    (0, 0)

                } else {

                    (-1, 1_000_000_000 - until_epoch.subsec_nanos())

                };

                FileTime {

                    seconds: -1 * until_epoch.as_secs() as i64 + sec_offset,

                    nanos,

                }

            })

            .emulate_second_only_system()

    }

    /// Returns the whole number of seconds represented by this timestamp.

    ///

    /// Note that this value's meaning is **platform specific**. On Unix

    /// platform time stamps are typically relative to January 1, 1970, but on

    /// Windows platforms time stamps are relative to January 1, 1601.

    pub const fn seconds(&self) -> i64 {

        self.seconds

    }

    /// Returns the whole number of seconds represented by this timestamp,

    /// relative to the Unix epoch start of January 1, 1970.

    ///

    /// Note that this does not return the same value as `seconds` for Windows

    /// platforms as seconds are relative to a different date there.

    pub const fn unix_seconds(&self) -> i64 {

        self.seconds - if cfg!(windows) { 11644473600 } else { 0 }

    }

    /// Returns the nanosecond precision of this timestamp.

    ///

    /// The returned value is always less than one billion and represents a

    /// portion of a second forward from the seconds returned by the `seconds`

    /// method.

    pub const fn nanoseconds(&self) -> u32 {

        self.nanos

    }

}

impl fmt::Display for FileTime {

    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {

        write!(f, "{}.{:09}s", self.seconds, self.nanos)

    }

}

impl From<SystemTime> for FileTime {

    fn from(time: SystemTime) -> FileTime {

        FileTime::from_system_time(time)

    }

}

/// Set the last access and modification times for a file on the filesystem.

///

/// This function will set the `atime` and `mtime` metadata fields for a file

/// on the local filesystem, returning any error encountered.

pub fn set_file_times<P>(p: P, atime: FileTime, mtime: FileTime) -> io::Result<()>

where

    P: AsRef<Path>,

{

    imp::set_file_times(p.as_ref(), atime, mtime)

}

/// Set the last access and modification times for a file handle.

///

/// This function will either or both of  the `atime` and `mtime` metadata

/// fields for a file handle , returning any error encountered. If `None` is

/// specified then the time won't be updated. If `None` is specified for both

/// options then no action is taken.

pub fn set_file_handle_times(

    f: &fs::File,

    atime: Option<FileTime>,

    mtime: Option<FileTime>,

) -> io::Result<()> {

    imp::set_file_handle_times(f, atime, mtime)

}

/// Set the last access and modification times for a file on the filesystem.

/// This function does not follow symlink.

///

/// This function will set the `atime` and `mtime` metadata fields for a file

/// on the local filesystem, returning any error encountered.

pub fn set_symlink_file_times<P>(p: P, atime: FileTime, mtime: FileTime) -> io::Result<()>

where

    P: AsRef<Path>,

{

    imp::set_symlink_file_times(p.as_ref(), atime, mtime)

}

/// Set the last modification time for a file on the filesystem.

///

/// This function will set the `mtime` metadata field for a file on the local

/// filesystem, returning any error encountered.

///

/// # Platform support

///

/// Where supported this will attempt to issue just one syscall to update only

/// the `mtime`, but where not supported this may issue one syscall to learn the

/// existing `atime` so only the `mtime` can be configured.

pub fn set_file_mtime<P>(p: P, mtime: FileTime) -> io::Result<()>

where

    P: AsRef<Path>,

{

    imp::set_file_mtime(p.as_ref(), mtime)

}

/// Set the last access time for a file on the filesystem.

///

/// This function will set the `atime` metadata field for a file on the local

/// filesystem, returning any error encountered.

///

/// # Platform support

///

/// Where supported this will attempt to issue just one syscall to update only

/// the `atime`, but where not supported this may issue one syscall to learn the

/// existing `mtime` so only the `atime` can be configured.

pub fn set_file_atime<P>(p: P, atime: FileTime) -> io::Result<()>

where

    P: AsRef<Path>,

{

    imp::set_file_atime(p.as_ref(), atime)

}

#[cfg(test)]

mod tests {

    use super::{

        set_file_atime, set_file_handle_times, set_file_mtime, set_file_times,

        set_symlink_file_times, FileTime,

    };

    use std::fs::{self, File};

    use std::io;

    use std::path::Path;

    use std::time::{Duration, UNIX_EPOCH};

    use tempfile::Builder;

    #[cfg(unix)]

    fn make_symlink_file<P, Q>(src: P, dst: Q) -> io::Result<()>

    where

        P: AsRef<Path>,

        Q: AsRef<Path>,

    {

        use std::os::unix::fs::symlink;

        symlink(src, dst)

    }

    #[cfg(windows)]

    fn make_symlink_file<P, Q>(src: P, dst: Q) -> io::Result<()>

    where

        P: AsRef<Path>,

        Q: AsRef<Path>,

    {

        use std::os::windows::fs::symlink_file;

        symlink_file(src, dst)

    }

    #[cfg(unix)]

    fn make_symlink_dir<P, Q>(src: P, dst: Q) -> io::Result<()>

    where

        P: AsRef<Path>,

        Q: AsRef<Path>,

    {

        use std::os::unix::fs::symlink;

        symlink(src, dst)

    }

    #[cfg(windows)]

    fn make_symlink_dir<P, Q>(src: P, dst: Q) -> io::Result<()>

    where

        P: AsRef<Path>,

        Q: AsRef<Path>,

    {

        use std::os::windows::fs::symlink_dir;

        symlink_dir(src, dst)

    }

    #[test]

    #[cfg(windows)]

    fn from_unix_time_test() {

        let time = FileTime::from_unix_time(10, 100_000_000);

        assert_eq!(11644473610, time.seconds);

        assert_eq!(100_000_000, time.nanos);

        let time = FileTime::from_unix_time(-10, 100_000_000);

        assert_eq!(11644473590, time.seconds);

        assert_eq!(100_000_000, time.nanos);

        let time = FileTime::from_unix_time(-12_000_000_000, 0);

        assert_eq!(-355526400, time.seconds);

        assert_eq!(0, time.nanos);

    }

    #[test]

    #[cfg(not(windows))]

    fn from_unix_time_test() {

        let time = FileTime::from_unix_time(10, 100_000_000);

        assert_eq!(10, time.seconds);

        assert_eq!(100_000_000, time.nanos);

        let time = FileTime::from_unix_time(-10, 100_000_000);

        assert_eq!(-10, time.seconds);

        assert_eq!(100_000_000, time.nanos);

        let time = FileTime::from_unix_time(-12_000_000_000, 0);

        assert_eq!(-12_000_000_000, time.seconds);

        assert_eq!(0, time.nanos);

    }

    #[test]

    #[cfg(windows)]

    fn from_system_time_test() {

        let time = FileTime::from_system_time(UNIX_EPOCH + Duration::from_secs(10));

        assert_eq!(11644473610, time.seconds);

        assert_eq!(0, time.nanos);

        let time = FileTime::from_system_time(UNIX_EPOCH - Duration::from_secs(10));

        assert_eq!(11644473590, time.seconds);

        assert_eq!(0, time.nanos);

        let time = FileTime::from_system_time(UNIX_EPOCH - Duration::from_millis(1100));

        assert_eq!(11644473598, time.seconds);

        assert_eq!(900_000_000, time.nanos);

        let time = FileTime::from_system_time(UNIX_EPOCH - Duration::from_secs(12_000_000_000));

        assert_eq!(-355526400, time.seconds);

        assert_eq!(0, time.nanos);

    }

    #[test]

    #[cfg(not(windows))]

    fn from_system_time_test() {

        let time = FileTime::from_system_time(UNIX_EPOCH + Duration::from_secs(10));

        assert_eq!(10, time.seconds);

        assert_eq!(0, time.nanos);

        let time = FileTime::from_system_time(UNIX_EPOCH - Duration::from_secs(10));

        assert_eq!(-10, time.seconds);

        assert_eq!(0, time.nanos);

        let time = FileTime::from_system_time(UNIX_EPOCH - Duration::from_millis(1100));

        assert_eq!(-2, time.seconds);

        assert_eq!(900_000_000, time.nanos);

        let time = FileTime::from_system_time(UNIX_EPOCH - Duration::from_secs(12_000_000));

        assert_eq!(-12_000_000, time.seconds);

        assert_eq!(0, time.nanos);

    }

    #[test]

    fn set_file_times_test() -> io::Result<()> {

        let td = Builder::new().prefix("filetime").tempdir()?;

        let path = td.path().join("foo.txt");

        let mut f = File::create(&path)?;

        let metadata = fs::metadata(&path)?;

        let mtime = FileTime::from_last_modification_time(&metadata);

        let atime = FileTime::from_last_access_time(&metadata);

        set_file_times(&path, atime, mtime)?;

        let new_mtime = FileTime::from_unix_time(10_000, 0);

        set_file_times(&path, atime, new_mtime)?;

        let metadata = fs::metadata(&path)?;

        let mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, new_mtime, "modification should be updated");

        // Update just mtime

        let new_mtime = FileTime::from_unix_time(20_000, 0);

        set_file_handle_times(&mut f, None, Some(new_mtime))?;

        let metadata = f.metadata()?;

        let mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, new_mtime, "modification time should be updated");

        let new_atime = FileTime::from_last_access_time(&metadata);

        assert_eq!(atime, new_atime, "accessed time should not be updated");

        // Update just atime

        let new_atime = FileTime::from_unix_time(30_000, 0);

        set_file_handle_times(&mut f, Some(new_atime), None)?;

        let metadata = f.metadata()?;

        let mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, new_mtime, "modification time should not be updated");

        let atime = FileTime::from_last_access_time(&metadata);

        assert_eq!(atime, new_atime, "accessed time should be updated");

        let spath = td.path().join("bar.txt");

        make_symlink_file(&path, &spath)?;

        let metadata = fs::symlink_metadata(&spath)?;

        let smtime = FileTime::from_last_modification_time(&metadata);

        set_file_times(&spath, atime, mtime)?;

        let metadata = fs::metadata(&path)?;

        let cur_mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, cur_mtime);

        let metadata = fs::symlink_metadata(&spath)?;

        let cur_mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(smtime, cur_mtime);

        set_file_times(&spath, atime, new_mtime)?;

        let metadata = fs::metadata(&path)?;

        let mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, new_mtime);

        let metadata = fs::symlink_metadata(&spath)?;

        let mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, smtime);

        Ok(())

    }

    #[test]

    fn set_dir_times_test() -> io::Result<()> {

        let td = Builder::new().prefix("filetime").tempdir()?;

        let path = td.path().join("foo");

        fs::create_dir(&path)?;

        let metadata = fs::metadata(&path)?;

        let mtime = FileTime::from_last_modification_time(&metadata);

        let atime = FileTime::from_last_access_time(&metadata);

        set_file_times(&path, atime, mtime)?;

        let new_mtime = FileTime::from_unix_time(10_000, 0);

        set_file_times(&path, atime, new_mtime)?;

        let metadata = fs::metadata(&path)?;

        let mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, new_mtime, "modification should be updated");

        // Update just mtime

        let new_mtime = FileTime::from_unix_time(20_000, 0);

        set_file_mtime(&path, new_mtime)?;

        let metadata = fs::metadata(&path)?;

        let mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, new_mtime, "modification time should be updated");

        let new_atime = FileTime::from_last_access_time(&metadata);

        assert_eq!(atime, new_atime, "accessed time should not be updated");

        // Update just atime

        let new_atime = FileTime::from_unix_time(30_000, 0);

        set_file_atime(&path, new_atime)?;

        let metadata = fs::metadata(&path)?;

        let mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, new_mtime, "modification time should not be updated");

        let atime = FileTime::from_last_access_time(&metadata);

        assert_eq!(atime, new_atime, "accessed time should be updated");

        let spath = td.path().join("bar");

        make_symlink_dir(&path, &spath)?;

        let metadata = fs::symlink_metadata(&spath)?;

        let smtime = FileTime::from_last_modification_time(&metadata);

        set_file_times(&spath, atime, mtime)?;

        let metadata = fs::metadata(&path)?;

        let cur_mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, cur_mtime);

        let metadata = fs::symlink_metadata(&spath)?;

        let cur_mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(smtime, cur_mtime);

        set_file_times(&spath, atime, new_mtime)?;

        let metadata = fs::metadata(&path)?;

        let mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, new_mtime);

        let metadata = fs::symlink_metadata(&spath)?;

        let mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, smtime);

        Ok(())

    }

    #[test]

    fn set_file_times_pre_unix_epoch_test() {

        let td = Builder::new().prefix("filetime").tempdir().unwrap();

        let path = td.path().join("foo.txt");

        File::create(&path).unwrap();

        let metadata = fs::metadata(&path).unwrap();

        let mtime = FileTime::from_last_modification_time(&metadata);

        let atime = FileTime::from_last_access_time(&metadata);

        set_file_times(&path, atime, mtime).unwrap();

        let new_mtime = FileTime::from_unix_time(-10_000, 0);

        if cfg!(target_os = "aix") {

            // On AIX, os checks if the unix timestamp is valid.

            let result = set_file_times(&path, atime, new_mtime);

            assert!(result.is_err());

            assert!(result.err().unwrap().kind() == std::io::ErrorKind::InvalidInput);

        } else {

            set_file_times(&path, atime, new_mtime).unwrap();

            let metadata = fs::metadata(&path).unwrap();

            let mtime = FileTime::from_last_modification_time(&metadata);

            assert_eq!(mtime, new_mtime);

        }

    }

    #[test]

    #[cfg(windows)]

    fn set_file_times_pre_windows_epoch_test() {

        let td = Builder::new().prefix("filetime").tempdir().unwrap();

        let path = td.path().join("foo.txt");

        File::create(&path).unwrap();

        let metadata = fs::metadata(&path).unwrap();

        let mtime = FileTime::from_last_modification_time(&metadata);

        let atime = FileTime::from_last_access_time(&metadata);

        set_file_times(&path, atime, mtime).unwrap();

        let new_mtime = FileTime::from_unix_time(-12_000_000_000, 0);

        assert!(set_file_times(&path, atime, new_mtime).is_err());

    }

    #[test]

    fn set_symlink_file_times_test() {

        let td = Builder::new().prefix("filetime").tempdir().unwrap();

        let path = td.path().join("foo.txt");

        File::create(&path).unwrap();

        let metadata = fs::metadata(&path).unwrap();

        let mtime = FileTime::from_last_modification_time(&metadata);

        let atime = FileTime::from_last_access_time(&metadata);

        set_symlink_file_times(&path, atime, mtime).unwrap();

        let new_mtime = FileTime::from_unix_time(10_000, 0);

        set_symlink_file_times(&path, atime, new_mtime).unwrap();

        let metadata = fs::metadata(&path).unwrap();

        let mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, new_mtime);

        let spath = td.path().join("bar.txt");

        make_symlink_file(&path, &spath).unwrap();

        let metadata = fs::symlink_metadata(&spath).unwrap();

        let smtime = FileTime::from_last_modification_time(&metadata);

        let satime = FileTime::from_last_access_time(&metadata);

        set_symlink_file_times(&spath, smtime, satime).unwrap();

        let metadata = fs::metadata(&path).unwrap();

        let mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, new_mtime);

        let new_smtime = FileTime::from_unix_time(20_000, 0);

        set_symlink_file_times(&spath, atime, new_smtime).unwrap();

        let metadata = fs::metadata(&spath).unwrap();

        let mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, new_mtime);

        let metadata = fs::symlink_metadata(&spath).unwrap();

        let mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, new_smtime);

    }

    #[test]

    fn set_symlink_dir_times_test() {

        let td = Builder::new().prefix("filetime").tempdir().unwrap();

        let path = td.path().join("foo");

        fs::create_dir(&path).unwrap();

        let metadata = fs::metadata(&path).unwrap();

        let mtime = FileTime::from_last_modification_time(&metadata);

        let atime = FileTime::from_last_access_time(&metadata);

        set_symlink_file_times(&path, atime, mtime).unwrap();

        let new_mtime = FileTime::from_unix_time(10_000, 0);

        set_symlink_file_times(&path, atime, new_mtime).unwrap();

        let metadata = fs::metadata(&path).unwrap();

        let mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, new_mtime);

        let spath = td.path().join("bar");

        make_symlink_dir(&path, &spath).unwrap();

        let metadata = fs::symlink_metadata(&spath).unwrap();

        let smtime = FileTime::from_last_modification_time(&metadata);

        let satime = FileTime::from_last_access_time(&metadata);

        set_symlink_file_times(&spath, smtime, satime).unwrap();

        let metadata = fs::metadata(&path).unwrap();

        let mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, new_mtime);

        let new_smtime = FileTime::from_unix_time(20_000, 0);

        set_symlink_file_times(&spath, atime, new_smtime).unwrap();

        let metadata = fs::metadata(&spath).unwrap();

        let mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, new_mtime);

        let metadata = fs::symlink_metadata(&spath).unwrap();

        let mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, new_smtime);

    }

    #[test]

    fn set_single_time_test() {

        use super::{set_file_atime, set_file_mtime};

        let td = Builder::new().prefix("filetime").tempdir().unwrap();

        let path = td.path().join("foo.txt");

        File::create(&path).unwrap();

        let metadata = fs::metadata(&path).unwrap();

        let mtime = FileTime::from_last_modification_time(&metadata);

        let atime = FileTime::from_last_access_time(&metadata);

        set_file_times(&path, atime, mtime).unwrap();

        let new_mtime = FileTime::from_unix_time(10_000, 0);

        set_file_mtime(&path, new_mtime).unwrap();

        let metadata = fs::metadata(&path).unwrap();

        let mtime = FileTime::from_last_modification_time(&metadata);

        assert_eq!(mtime, new_mtime, "modification time should be updated");

        assert_eq!(

            atime,

            FileTime::from_last_access_time(&metadata),

            "access time should not be updated",

        );

        let new_atime = FileTime::from_unix_time(20_000, 0);

        set_file_atime(&path, new_atime).unwrap();

        let metadata = fs::metadata(&path).unwrap();

        let atime = FileTime::from_last_access_time(&metadata);

        assert_eq!(atime, new_atime, "access time should be updated");

        assert_eq!(

            mtime,

            FileTime::from_last_modification_time(&metadata),

            "modification time should not be updated"

        );

    }

}