std: Add more accessors for `Metadata` on Windows

This commit adds accessors for more fields in `fs::Metadata` on Windows
which weren't previously exposed. There's two sources of `fs::Metadata`
on Windows currently, one from `DirEntry` and one from a file itself.
These two sources of information don't actually have the same set of
fields exposed in their stat information, however. To handle this the
platform-specific accessors of Windows-specific information all return
`Option` to return `None` in the case a metadata comes from a
`DirEntry`, but they're guaranteed to return `Some` if it comes from a
file itself.

This is motivated by some changes in CraneStation/wasi-common#42, and
I'm curious how others feel about this platform-specific functionality!

1 files changed, 30 insertions, 0 deletions

diff --git a/src/libstd/sys/windows/ext/fs.rs b/src/libstd/sys/windows/ext/fs.rs
index 268a14ff0aa..23964dc5bd5 100644
--- a/src/libstd/sys/windows/ext/fs.rs
+++ b/src/libstd/sys/windows/ext/fs.rs
@@ -437,6 +437,33 @@ pub trait MetadataExt {
     /// ```
     #[stable(feature = "metadata_ext", since = "1.1.0")]
     fn file_size(&self) -> u64;
+
+    /// Returns the value of the `dwVolumeSerialNumber` field of this
+    /// metadata.
+    ///
+    /// This will return `None` if the `Metadata` instance was created from a
+    /// call to `DirEntry::metadata`. If this `Metadata` was created by using
+    /// `fs::metadata` or `File::metadata`, then this will return `Some`.
+    #[unstable(feature = "windows_by_handle", issue = "63010")]
+    fn volume_serial_number(&self) -> Option<u32>;
+
+    /// Returns the value of the `nNumberOfLinks` field of this
+    /// metadata.
+    ///
+    /// This will return `None` if the `Metadata` instance was created from a
+    /// call to `DirEntry::metadata`. If this `Metadata` was created by using
+    /// `fs::metadata` or `File::metadata`, then this will return `Some`.
+    #[unstable(feature = "windows_by_handle", issue = "63010")]
+    fn number_of_links(&self) -> Option<u32>;
+
+    /// Returns the value of the `nFileIndex{Low,High}` fields of this
+    /// metadata.
+    ///
+    /// This will return `None` if the `Metadata` instance was created from a
+    /// call to `DirEntry::metadata`. If this `Metadata` was created by using
+    /// `fs::metadata` or `File::metadata`, then this will return `Some`.
+    #[unstable(feature = "windows_by_handle", issue = "63010")]
+    fn file_index(&self) -> Option<u64>;
 }
 
 #[stable(feature = "metadata_ext", since = "1.1.0")]
@@ -446,6 +473,9 @@ impl MetadataExt for Metadata {
     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() }
+    fn volume_serial_number(&self) -> Option<u32> { self.as_inner().volume_serial_number() }
+    fn number_of_links(&self) -> Option<u32> { self.as_inner().number_of_links() }
+    fn file_index(&self) -> Option<u64> { self.as_inner().file_index() }
 }
 
 /// Windows-specific extensions to [`FileType`].