Rollup merge of #140459 - niklasf:feature/read-buf-at, r=tgross35

Add `read_buf` equivalents for positioned reads

Adds the following items under the ~~`read_buf` (rust-lang/rust#78485)~~ `read_buf_at` (rust-lang/rust#140771) feature:

 - `std::os::unix::fs::FileExt::read_buf_at`
 - `std::os::unix::fs::FileExt::read_buf_exact_at`
 - `std::os::windows::fs::FileExt::seek_read_buf`

try-job: `x86_64-msvc*`
try-job: `test-various*`
try-job: `dist-various*`

2 files changed, 8 insertions, 0 deletions

diff --git a/library/std/src/sys/fs/unix.rs b/library/std/src/sys/fs/unix.rs
index a89c3bbacfb..3b525406223 100644
--- a/library/std/src/sys/fs/unix.rs
+++ b/library/std/src/sys/fs/unix.rs
@@ -1463,6 +1463,10 @@ impl File {
         self.0.read_buf(cursor)
     }
 
+    pub fn read_buf_at(&self, cursor: BorrowedCursor<'_>, offset: u64) -> io::Result<()> {
+        self.0.read_buf_at(cursor, offset)
+    }
+
     pub fn read_vectored_at(&self, bufs: &mut [IoSliceMut<'_>], offset: u64) -> io::Result<usize> {
         self.0.read_vectored_at(bufs, offset)
     }
diff --git a/library/std/src/sys/fs/windows.rs b/library/std/src/sys/fs/windows.rs
index bac278f7c8f..ccfe410627f 100644
--- a/library/std/src/sys/fs/windows.rs
+++ b/library/std/src/sys/fs/windows.rs
@@ -605,6 +605,10 @@ impl File {
         self.handle.read_buf(cursor)
     }
 
+    pub fn read_buf_at(&self, cursor: BorrowedCursor<'_>, offset: u64) -> io::Result<()> {
+        self.handle.read_buf_at(cursor, offset)
+    }
+
     pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
         self.handle.write(buf)
     }