std: Expose SystemTime accessors on fs::Metadata

These accessors are used to get at the last modification, last access, and
creation time of the underlying file. Currently not all platforms provide the
creation time, so that currently returns `Option`.

Author: alexcrichton

src/libstd/fs.rs

@@ -25,6 +25,7 @@ use sys::fs as fs_imp;
 use sys_common::io::read_to_end_uninitialized;
 use sys_common::{AsInnerMut, FromInner, AsInner, IntoInner};
 use vec::Vec;
+use time::SystemTime;
 
 /// A reference to an open file on the filesystem.
 ///
@@ -660,6 +661,52 @@ impl Metadata {
     pub fn permissions(&self) -> Permissions {
         Permissions(self.0.perm())
     }
+
+    /// Returns the last modification time listed in this metadata.
+    ///
+    /// The returned value corresponds to the `mtime` field of `stat` on Unix
+    /// platforms and the `ftLastWriteTime` field on Windows platforms.
+    ///
+    /// # Errors
+    ///
+    /// This field may not be available on all platforms, and will return an
+    /// `Err` on platforms where it is not available.
+    #[unstable(feature = "fs_time", issue = "31399")]
+    pub fn modified(&self) -> io::Result<SystemTime> {
+        self.0.modified().map(FromInner::from_inner)
+    }
+
+    /// Returns the last access time of this metadata.
+    ///
+    /// The returned value corresponds to the `atime` field of `stat` on Unix
+    /// platforms and the `ftLastAccessTime` field on Windows platforms.
+    ///
+    /// Note that not all platforms will keep this field update in a file's
+    /// metadata, for example Windows has an option to disable updating this
+    /// time when files are accessed and Linux similarly has `noatime`.
+    ///
+    /// # Errors
+    ///
+    /// This field may not be available on all platforms, and will return an
+    /// `Err` on platforms where it is not available.
+    #[unstable(feature = "fs_time", issue = "31399")]
+    pub fn accessed(&self) -> io::Result<SystemTime> {
+        self.0.accessed().map(FromInner::from_inner)
+    }
+
+    /// Returns the creation time listed in the this metadata.
+    ///
+    /// The returned value corresponds to the `birthtime` field of `stat` on
+    /// Unix platforms and the `ftCreationTime` field on Windows platforms.
+    ///
+    /// # Errors
+    ///
+    /// This field may not be available on all platforms, and will return an
+    /// `Err` on platforms where it is not available.
+    #[unstable(feature = "fs_time", issue = "31399")]
+    pub fn created(&self) -> io::Result<SystemTime> {
+        self.0.created().map(FromInner::from_inner)
+    }
 }
 
 impl AsInner<fs_imp::FileAttr> for Metadata {
@@ -2468,4 +2515,24 @@ mod tests {
         assert!(link.is_dir());
         assert!(d.exists());
     }
+
+    #[test]
+    fn metadata_access_times() {
+        let tmpdir = tmpdir();
+
+        let b = tmpdir.join("b");
+        File::create(&b).unwrap();
+
+        let a = check!(fs::metadata(&tmpdir.path()));
+        let b = check!(fs::metadata(&b));
+
+        assert_eq!(check!(a.accessed()), check!(a.accessed()));
+        assert_eq!(check!(a.modified()), check!(a.modified()));
+        assert_eq!(check!(b.accessed()), check!(b.modified()));
+
+        if cfg!(target_os = "macos") || cfg!(target_os = "windows") {
+            check!(a.created());
+            check!(b.created());
+        }
+    }
 }

src/libstd/sys/unix/fs.rs

@@ -22,6 +22,7 @@ use ptr;
 use sync::Arc;
 use sys::fd::FileDesc;
 use sys::platform::raw;
+use sys::time::SystemTime;
 use sys::{cvt, cvt_r};
 use sys_common::{AsInner, FromInner};
 
@@ -86,6 +87,67 @@ impl FileAttr {
     }
 }
 
+#[cfg(any(target_os = "ios", target_os = "macos"))]
+// FIXME: update SystemTime to store a timespec and don't lose precision
+impl FileAttr {
+    pub fn modified(&self) -> io::Result<SystemTime> {
+        Ok(SystemTime::from(libc::timeval {
+            tv_sec: self.stat.st_mtime,
+            tv_usec: (self.stat.st_mtime_nsec / 1000) as libc::suseconds_t,
+        }))
+    }
+
+    pub fn accessed(&self) -> io::Result<SystemTime> {
+        Ok(SystemTime::from(libc::timeval {
+            tv_sec: self.stat.st_atime,
+            tv_usec: (self.stat.st_atime_nsec / 1000) as libc::suseconds_t,
+        }))
+    }
+
+    pub fn created(&self) -> io::Result<SystemTime> {
+        Ok(SystemTime::from(libc::timeval {
+            tv_sec: self.stat.st_birthtime,
+            tv_usec: (self.stat.st_birthtime_nsec / 1000) as libc::suseconds_t,
+        }))
+    }
+}
+
+#[cfg(not(any(target_os = "ios", target_os = "macos")))]
+impl FileAttr {
+    pub fn modified(&self) -> io::Result<SystemTime> {
+        Ok(SystemTime::from(libc::timespec {
+            tv_sec: self.stat.st_mtime,
+            tv_nsec: self.stat.st_mtime_nsec as libc::c_long,
+        }))
+    }
+
+    pub fn accessed(&self) -> io::Result<SystemTime> {
+        Ok(SystemTime::from(libc::timespec {
+            tv_sec: self.stat.st_atime,
+            tv_nsec: self.stat.st_atime_nsec as libc::c_long,
+        }))
+    }
+
+    #[cfg(any(target_os = "bitrig",
+              target_os = "freebsd",
+              target_os = "openbsd"))]
+    pub fn created(&self) -> io::Result<SystemTime> {
+        Ok(SystemTime::from(libc::timespec {
+            tv_sec: self.stat.st_birthtime,
+            tv_nsec: self.stat.st_birthtime_nsec as libc::c_long,
+        }))
+    }
+
+    #[cfg(not(any(target_os = "bitrig",
+                  target_os = "freebsd",
+                  target_os = "openbsd")))]
+    pub fn created(&self) -> io::Result<SystemTime> {
+        Err(io::Error::new(io::ErrorKind::Other,
+                           "creation time is not available on this platform \
+                            currently"))
+    }
+}
+
 impl AsInner<raw::stat> for FileAttr {
     fn as_inner(&self) -> &raw::stat { &self.stat }
 }

src/libstd/sys/unix/time.rs

@@ -146,6 +146,12 @@ mod inner {
         }
     }
 
+    impl From<libc::timeval> for SystemTime {
+        fn from(t: libc::timeval) -> SystemTime {
+            SystemTime { t: t }
+        }
+    }
+
     impl PartialEq for SystemTime {
         fn eq(&self, other: &SystemTime) -> bool {
             self.t.tv_sec == other.t.tv_sec && self.t.tv_usec == other.t.tv_usec
@@ -282,6 +288,12 @@ mod inner {
         }
     }
 
+    impl From<libc::timespec> for SystemTime {
+        fn from(t: libc::timespec) -> SystemTime {
+            SystemTime { t: Timespec { t: t } }
+        }
+    }
+
     impl fmt::Debug for SystemTime {
         fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
             f.debug_struct("SystemTime")

src/libstd/sys/windows/ext/fs.rs

@@ -196,9 +196,9 @@ pub trait MetadataExt {
 #[stable(feature = "metadata_ext", since = "1.1.0")]
 impl MetadataExt for Metadata {
     fn file_attributes(&self) -> u32 { self.as_inner().attrs() }
-    fn creation_time(&self) -> u64 { self.as_inner().created() }
-    fn last_access_time(&self) -> u64 { self.as_inner().accessed() }
-    fn last_write_time(&self) -> u64 { self.as_inner().modified() }
+    fn creation_time(&self) -> u64 { self.as_inner().created_u64() }
+    fn last_access_time(&self) -> u64 { self.as_inner().accessed_u64() }
+    fn last_write_time(&self) -> u64 { self.as_inner().modified_u64() }
     fn file_size(&self) -> u64 { self.as_inner().size() }
 }
 

src/libstd/sys/windows/fs.rs

@@ -20,6 +20,7 @@ use ptr;
 use slice;
 use sync::Arc;
 use sys::handle::Handle;
+use sys::time::SystemTime;
 use sys::{c, cvt};
 use sys_common::FromInner;
 
@@ -421,19 +422,39 @@ impl FileAttr {
         FileType::new(self.data.dwFileAttributes, self.reparse_tag)
     }
 
-    pub fn created(&self) -> u64 { self.to_u64(&self.data.ftCreationTime) }
-    pub fn accessed(&self) -> u64 { self.to_u64(&self.data.ftLastAccessTime) }
-    pub fn modified(&self) -> u64 { self.to_u64(&self.data.ftLastWriteTime) }
+    pub fn modified(&self) -> io::Result<SystemTime> {
+        Ok(SystemTime::from(self.data.ftLastWriteTime))
+    }
+
+    pub fn accessed(&self) -> io::Result<SystemTime> {
+        Ok(SystemTime::from(self.data.ftLastAccessTime))
+    }
 
-    fn to_u64(&self, ft: &c::FILETIME) -> u64 {
-        (ft.dwLowDateTime as u64) | ((ft.dwHighDateTime as u64) << 32)
+    pub fn created(&self) -> io::Result<SystemTime> {
+        Ok(SystemTime::from(self.data.ftCreationTime))
+    }
+
+    pub fn modified_u64(&self) -> u64 {
+        to_u64(&self.data.ftLastWriteTime)
+    }
+
+    pub fn accessed_u64(&self) -> u64 {
+        to_u64(&self.data.ftLastAccessTime)
+    }
+
+    pub fn created_u64(&self) -> u64 {
+        to_u64(&self.data.ftCreationTime)
     }
 
     fn is_reparse_point(&self) -> bool {
         self.data.dwFileAttributes & c::FILE_ATTRIBUTE_REPARSE_POINT != 0
     }
 }
 
+fn to_u64(ft: &c::FILETIME) -> u64 {
+    (ft.dwLowDateTime as u64) | ((ft.dwHighDateTime as u64) << 32)
+}
+
 impl FilePermissions {
     pub fn readonly(&self) -> bool {
         self.attrs & c::FILE_ATTRIBUTE_READONLY != 0

src/libstd/sys/windows/time.rs

@@ -166,6 +166,12 @@ impl fmt::Debug for SystemTime {
     }
 }
 
+impl From<c::FILETIME> for SystemTime {
+    fn from(t: c::FILETIME) -> SystemTime {
+        SystemTime { t: t }
+    }
+}
+
 fn dur2intervals(d: &Duration) -> i64 {
     d.as_secs().checked_mul(INTERVALS_PER_SEC).and_then(|i| {
         i.checked_add(d.subsec_nanos() as u64 / 100)

src/libstd/time/mod.rs

@@ -16,6 +16,7 @@ use error::Error;
 use fmt;
 use ops::{Add, Sub};
 use sys::time;
+use sys_common::FromInner;
 
 #[stable(feature = "time", since = "1.3.0")]
 pub use self::duration::Duration;
@@ -227,6 +228,12 @@ impl fmt::Display for SystemTimeError {
     }
 }
 
+impl FromInner<time::SystemTime> for SystemTime {
+    fn from_inner(time: time::SystemTime) -> SystemTime {
+        SystemTime(time)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::{Instant, SystemTime, Duration, UNIX_EPOCH};