From fa5143f942e1ea9b487fc9cc336077d16964f64b Mon Sep 17 00:00:00 2001
From: est31 <MTest31@outlook.com>
Date: Wed, 22 Feb 2023 17:44:50 +0100
Subject: [PATCH 1/2] Use the inner stream_len impl instead of using the Seek
 default

This is useful if stream_len is overridden by the Seek implementation
of the inner member.
---
 library/std/src/io/buffered/bufreader.rs |  4 ++++
 library/std/src/io/buffered/bufwriter.rs |  4 ++++
 library/std/src/io/impls.rs              | 10 ++++++++++
 3 files changed, 18 insertions(+)

diff --git a/library/std/src/io/buffered/bufreader.rs b/library/std/src/io/buffered/bufreader.rs
index 4f339a18a480e..0b64d4ab4434b 100644
--- a/library/std/src/io/buffered/bufreader.rs
+++ b/library/std/src/io/buffered/bufreader.rs
@@ -489,6 +489,10 @@ impl<R: Seek> Seek for BufReader<R> {
             )
         })
     }
+
+    fn stream_len(&mut self) -> io::Result<u64> {
+        self.inner.stream_len()
+    }
 }
 
 impl<T> SizeHint for BufReader<T> {
diff --git a/library/std/src/io/buffered/bufwriter.rs b/library/std/src/io/buffered/bufwriter.rs
index 6acb937e78479..d7697db878c9b 100644
--- a/library/std/src/io/buffered/bufwriter.rs
+++ b/library/std/src/io/buffered/bufwriter.rs
@@ -661,6 +661,10 @@ impl<W: Write + Seek> Seek for BufWriter<W> {
         self.flush_buf()?;
         self.get_mut().seek(pos)
     }
+
+    fn stream_len(&mut self) -> io::Result<u64> {
+        self.inner.stream_len()
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
diff --git a/library/std/src/io/impls.rs b/library/std/src/io/impls.rs
index e5048dcc8acd9..bcbf978432b3b 100644
--- a/library/std/src/io/impls.rs
+++ b/library/std/src/io/impls.rs
@@ -93,6 +93,11 @@ impl<S: Seek + ?Sized> Seek for &mut S {
     fn stream_position(&mut self) -> io::Result<u64> {
         (**self).stream_position()
     }
+
+    #[inline]
+    fn stream_len(&mut self) -> io::Result<u64> {
+        (**self).stream_len()
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<B: BufRead + ?Sized> BufRead for &mut B {
@@ -197,6 +202,11 @@ impl<S: Seek + ?Sized> Seek for Box<S> {
     fn stream_position(&mut self) -> io::Result<u64> {
         (**self).stream_position()
     }
+
+    #[inline]
+    fn stream_len(&mut self) -> io::Result<u64> {
+        (**self).stream_len()
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<B: BufRead + ?Sized> BufRead for Box<B> {

From 811d5b47827776a3b8966ba88ed733524f1288f8 Mon Sep 17 00:00:00 2001
From: est31 <MTest31@outlook.com>
Date: Wed, 22 Feb 2023 17:45:53 +0100
Subject: [PATCH 2/2] Make stream_len atomic for File

---
 library/std/src/fs.rs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/library/std/src/fs.rs b/library/std/src/fs.rs
index c550378e7d6b7..1c63280fb0ca6 100644
--- a/library/std/src/fs.rs
+++ b/library/std/src/fs.rs
@@ -795,6 +795,11 @@ impl Seek for File {
     fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
         self.inner.seek(pos)
     }
+
+    fn stream_len(&mut self) -> io::Result<u64> {
+        let file_attr = self.inner.file_attr()?;
+        Ok(file_attr.size())
+    }
 }
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Read for &File {
@@ -851,6 +856,10 @@ impl Seek for &File {
     fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
         self.inner.seek(pos)
     }
+    fn stream_len(&mut self) -> io::Result<u64> {
+        let file_attr = self.inner.file_attr()?;
+        Ok(file_attr.size())
+    }
 }
 
 impl OpenOptions {