Feature request, move part of std::io into core::io to be used by rust-libc such as relibc

Get libstd io to be portable.

And makes platform dependent IoSliceMut can be customized by the user
And give the default impl for windows/posix.

Author: lygstate

library/std/src/io/buffered.rs

@@ -1,17 +1,13 @@
-//! Buffering wrappers for I/O traits
 
-#[cfg(test)]
-mod tests;
+//! Buffering wrappers for I/O traits
 
-use crate::io::prelude::*;
+use core::prelude::v1::*;
+use io::prelude::*;
 
-use crate::cmp;
-use crate::error;
-use crate::fmt;
-use crate::io::{
-    self, Error, ErrorKind, Initializer, IoSlice, IoSliceMut, SeekFrom, DEFAULT_BUF_SIZE,
-};
-use crate::memchr;
+use core::cmp;
+use core::fmt;
+use io::{self, Initializer, DEFAULT_BUF_SIZE, Error, ErrorKind, SeekFrom, IoSlice, IoSliceMut};
+use io::memchr;
 
 /// The `BufReader<R>` struct adds buffering to any reader.
 ///
@@ -52,7 +48,6 @@ use crate::memchr;
 ///     Ok(())
 /// }
 /// ```
-#[stable(feature = "rust1", since = "1.0.0")]
 pub struct BufReader<R> {
     inner: R,
     buf: Box<[u8]>,
@@ -76,7 +71,6 @@ impl<R: Read> BufReader<R> {
     ///     Ok(())
     /// }
     /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn new(inner: R) -> BufReader<R> {
         BufReader::with_capacity(DEFAULT_BUF_SIZE, inner)
     }
@@ -97,7 +91,6 @@ impl<R: Read> BufReader<R> {
     ///     Ok(())
     /// }
     /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn with_capacity(capacity: usize, inner: R) -> BufReader<R> {
         unsafe {
             let mut buffer = Vec::with_capacity(capacity);
@@ -127,7 +120,6 @@ impl<R> BufReader<R> {
     ///     Ok(())
     /// }
     /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn get_ref(&self) -> &R {
         &self.inner
     }
@@ -150,7 +142,6 @@ impl<R> BufReader<R> {
     ///     Ok(())
     /// }
     /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn get_mut(&mut self) -> &mut R {
         &mut self.inner
     }
@@ -178,7 +169,6 @@ impl<R> BufReader<R> {
     ///     Ok(())
     /// }
     /// ```
-    #[stable(feature = "bufreader_buffer", since = "1.37.0")]
     pub fn buffer(&self) -> &[u8] {
         &self.buf[self.pos..self.cap]
     }
@@ -201,7 +191,6 @@ impl<R> BufReader<R> {
     ///     Ok(())
     /// }
     /// ```
-    #[stable(feature = "buffered_io_capacity", since = "1.46.0")]
     pub fn capacity(&self) -> usize {
         self.buf.len()
     }
@@ -225,7 +214,6 @@ impl<R> BufReader<R> {
     ///     Ok(())
     /// }
     /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn into_inner(self) -> R {
         self.inner
     }
@@ -243,7 +231,6 @@ impl<R: Seek> BufReader<R> {
     /// the buffer will not be flushed, allowing for more efficient seeks.
     /// This method does not return the location of the underlying reader, so the caller
     /// must track this information themselves if it is required.
-    #[unstable(feature = "bufreader_seek_relative", issue = "31100")]
     pub fn seek_relative(&mut self, offset: i64) -> io::Result<()> {
         let pos = self.pos as u64;
         if offset < 0 {
@@ -263,7 +250,6 @@ impl<R: Seek> BufReader<R> {
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
 impl<R: Read> Read for BufReader<R> {
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
         // If we don't have any buffered data and we're doing a massive read
@@ -305,7 +291,6 @@ impl<R: Read> Read for BufReader<R> {
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
 impl<R: Read> BufRead for BufReader<R> {
     fn fill_buf(&mut self) -> io::Result<&[u8]> {
         // If we've reached the end of our internal buffer then we need to fetch
@@ -325,7 +310,6 @@ impl<R: Read> BufRead for BufReader<R> {
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
 impl<R> fmt::Debug for BufReader<R>
 where
     R: fmt::Debug,
@@ -338,7 +322,6 @@ where
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
 impl<R: Seek> Seek for BufReader<R> {
     /// Seek to an offset, in bytes, in the underlying reader.
     ///
@@ -492,10 +475,9 @@ impl<R: Seek> Seek for BufReader<R> {
 /// [`TcpStream::write`]: Write::write
 /// [`TcpStream`]: crate::net::TcpStream
 /// [`flush`]: Write::flush
-#[stable(feature = "rust1", since = "1.0.0")]
 pub struct BufWriter<W: Write> {
     inner: Option<W>,
-    buf: Vec<u8>,
+    pub buf: Vec<u8>,
     // #30888: If the inner writer panics in a call to write, we don't want to
     // write the buffered data a second time in BufWriter's destructor. This
     // flag tells the Drop impl if it should skip the flush.
@@ -527,7 +509,6 @@ pub struct BufWriter<W: Write> {
 /// };
 /// ```
 #[derive(Debug)]
-#[stable(feature = "rust1", since = "1.0.0")]
 pub struct IntoInnerError<W>(W, Error);
 
 impl<W: Write> BufWriter<W> {
@@ -542,7 +523,6 @@ impl<W: Write> BufWriter<W> {
     ///
     /// let mut buffer = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
     /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn new(inner: W) -> BufWriter<W> {
         BufWriter::with_capacity(DEFAULT_BUF_SIZE, inner)
     }
@@ -560,7 +540,6 @@ impl<W: Write> BufWriter<W> {
     /// let stream = TcpStream::connect("127.0.0.1:34254").unwrap();
     /// let mut buffer = BufWriter::with_capacity(100, stream);
     /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn with_capacity(capacity: usize, inner: W) -> BufWriter<W> {
         BufWriter { inner: Some(inner), buf: Vec::with_capacity(capacity), panicked: false }
     }
@@ -632,6 +611,10 @@ impl<W: Write> BufWriter<W> {
         Ok(())
     }
 
+    pub fn purge_buf(&mut self) {
+        self.buf = vec![];
+    }
+
     /// Buffer some data without flushing it, regardless of the size of the
     /// data. Writes as much as possible without exceeding capacity. Returns
     /// the number of bytes written.
@@ -655,7 +638,6 @@ impl<W: Write> BufWriter<W> {
     /// // we can use reference just like buffer
     /// let reference = buffer.get_ref();
     /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn get_ref(&self) -> &W {
         self.inner.as_ref().unwrap()
     }
@@ -675,7 +657,6 @@ impl<W: Write> BufWriter<W> {
     /// // we can use reference just like buffer
     /// let reference = buffer.get_mut();
     /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn get_mut(&mut self) -> &mut W {
         self.inner.as_mut().unwrap()
     }
@@ -693,7 +674,6 @@ impl<W: Write> BufWriter<W> {
     /// // See how many bytes are currently buffered
     /// let bytes_buffered = buf_writer.buffer().len();
     /// ```
-    #[stable(feature = "bufreader_buffer", since = "1.37.0")]
     pub fn buffer(&self) -> &[u8] {
         &self.buf
     }
@@ -713,7 +693,6 @@ impl<W: Write> BufWriter<W> {
     /// // Calculate how many bytes can be written without flushing
     /// let without_flush = capacity - buf_writer.buffer().len();
     /// ```
-    #[stable(feature = "buffered_io_capacity", since = "1.46.0")]
     pub fn capacity(&self) -> usize {
         self.buf.capacity()
     }
@@ -737,7 +716,6 @@ impl<W: Write> BufWriter<W> {
     /// // unwrap the TcpStream and flush the buffer
     /// let stream = buffer.into_inner().unwrap();
     /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn into_inner(mut self) -> Result<W, IntoInnerError<BufWriter<W>>> {
         match self.flush_buf() {
             Err(e) => Err(IntoInnerError(self, e)),
@@ -746,7 +724,6 @@ impl<W: Write> BufWriter<W> {
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
 impl<W: Write> Write for BufWriter<W> {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         if self.buf.len() + buf.len() > self.buf.capacity() {
@@ -810,7 +787,6 @@ impl<W: Write> Write for BufWriter<W> {
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
 impl<W: Write> fmt::Debug for BufWriter<W>
 where
     W: fmt::Debug,
@@ -823,7 +799,6 @@ where
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
 impl<W: Write + Seek> Seek for BufWriter<W> {
     /// Seek to the offset, in bytes, in the underlying writer.
     ///
@@ -834,7 +809,6 @@ impl<W: Write + Seek> Seek for BufWriter<W> {
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
 impl<W: Write> Drop for BufWriter<W> {
     fn drop(&mut self) {
         if self.inner.is_some() && !self.panicked {
@@ -874,7 +848,6 @@ impl<W> IntoInnerError<W> {
     ///     }
     /// };
     /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn error(&self) -> &Error {
         &self.1
     }
@@ -909,28 +882,17 @@ impl<W> IntoInnerError<W> {
     ///     }
     /// };
     /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn into_inner(self) -> W {
         self.0
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
 impl<W> From<IntoInnerError<W>> for Error {
     fn from(iie: IntoInnerError<W>) -> Error {
         iie.1
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<W: Send + fmt::Debug> error::Error for IntoInnerError<W> {
-    #[allow(deprecated, deprecated_in_future)]
-    fn description(&self) -> &str {
-        error::Error::description(self.error())
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
 impl<W> fmt::Display for IntoInnerError<W> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         self.error().fmt(f)
@@ -1267,9 +1229,8 @@ impl<'a, W: Write> Write for LineWriterShim<'a, W> {
 ///     Ok(())
 /// }
 /// ```
-#[stable(feature = "rust1", since = "1.0.0")]
 pub struct LineWriter<W: Write> {
-    inner: BufWriter<W>,
+    pub inner: BufWriter<W>,
 }
 
 impl<W: Write> LineWriter<W> {
@@ -1287,7 +1248,6 @@ impl<W: Write> LineWriter<W> {
     ///     Ok(())
     /// }
     /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn new(inner: W) -> LineWriter<W> {
         // Lines typically aren't that long, don't use a giant buffer
         LineWriter::with_capacity(1024, inner)
@@ -1308,7 +1268,6 @@ impl<W: Write> LineWriter<W> {
     ///     Ok(())
     /// }
     /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn with_capacity(capacity: usize, inner: W) -> LineWriter<W> {
         LineWriter { inner: BufWriter::with_capacity(capacity, inner) }
     }
@@ -1329,7 +1288,6 @@ impl<W: Write> LineWriter<W> {
     ///     Ok(())
     /// }
     /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn get_ref(&self) -> &W {
         self.inner.get_ref()
     }
@@ -1354,7 +1312,6 @@ impl<W: Write> LineWriter<W> {
     ///     Ok(())
     /// }
     /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn get_mut(&mut self) -> &mut W {
         self.inner.get_mut()
     }
@@ -1382,15 +1339,17 @@ impl<W: Write> LineWriter<W> {
     ///     Ok(())
     /// }
     /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
     pub fn into_inner(self) -> Result<W, IntoInnerError<LineWriter<W>>> {
         self.inner
             .into_inner()
             .map_err(|IntoInnerError(buf, e)| IntoInnerError(LineWriter { inner: buf }, e))
     }
+
+    pub fn purge(&mut self) {
+        self.inner.purge_buf();
+    }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
 impl<W: Write> Write for LineWriter<W> {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         LineWriterShim::new(&mut self.inner).write(buf)
@@ -1421,7 +1380,6 @@ impl<W: Write> Write for LineWriter<W> {
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
 impl<W: Write> fmt::Debug for LineWriter<W>
 where
     W: fmt::Debug,