Recreate ctr-std from latest nightly

1 files changed, 227 insertions, 54 deletions

diff --git a/ctr-std/src/io/buffered.rs b/ctr-std/src/io/buffered.rs
index 44dd4e9..4e7db5f 100644
--- a/ctr-std/src/io/buffered.rs
+++ b/ctr-std/src/io/buffered.rs
@@ -15,18 +15,18 @@ use io::prelude::*;
 use cmp;
 use error;
 use fmt;
-use io::{self, DEFAULT_BUF_SIZE, Error, ErrorKind, SeekFrom};
+use io::{self, Initializer, DEFAULT_BUF_SIZE, Error, ErrorKind, SeekFrom};
 use memchr;
 
 /// The `BufReader` struct adds buffering to any reader.
 ///
 /// It can be excessively inefficient to work directly with a [`Read`] instance.
-/// For example, every call to [`read`] on [`TcpStream`] results in a system call.
-/// A `BufReader` performs large, infrequent reads on the underlying [`Read`]
-/// and maintains an in-memory buffer of the results.
+/// For example, every call to [`read`][`TcpStream::read`] on [`TcpStream`]
+/// results in a system call. A `BufReader` performs large, infrequent reads on
+/// the underlying [`Read`] and maintains an in-memory buffer of the results.
 ///
 /// [`Read`]: ../../std/io/trait.Read.html
-/// [`read`]: ../../std/net/struct.TcpStream.html#method.read
+/// [`TcpStream::read`]: ../../std/net/struct.TcpStream.html#method.read
 /// [`TcpStream`]: ../../std/net/struct.TcpStream.html
 ///
 /// # Examples
@@ -37,11 +37,11 @@ use memchr;
 /// use std::fs::File;
 ///
 /// # fn foo() -> std::io::Result<()> {
-/// let mut f = try!(File::open("log.txt"));
+/// let f = File::open("log.txt")?;
 /// let mut reader = BufReader::new(f);
 ///
 /// let mut line = String::new();
-/// let len = try!(reader.read_line(&mut line));
+/// let len = reader.read_line(&mut line)?;
 /// println!("First line is {} bytes long", len);
 /// # Ok(())
 /// # }
@@ -64,8 +64,8 @@ impl<R: Read> BufReader<R> {
     /// use std::fs::File;
     ///
     /// # fn foo() -> std::io::Result<()> {
-    /// let mut f = try!(File::open("log.txt"));
-    /// let mut reader = BufReader::new(f);
+    /// let f = File::open("log.txt")?;
+    /// let reader = BufReader::new(f);
     /// # Ok(())
     /// # }
     /// ```
@@ -85,18 +85,23 @@ impl<R: Read> BufReader<R> {
     /// use std::fs::File;
     ///
     /// # fn foo() -> std::io::Result<()> {
-    /// let mut f = try!(File::open("log.txt"));
-    /// let mut reader = BufReader::with_capacity(10, f);
+    /// let f = File::open("log.txt")?;
+    /// let reader = BufReader::with_capacity(10, f);
     /// # Ok(())
     /// # }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn with_capacity(cap: usize, inner: R) -> BufReader<R> {
-        BufReader {
-            inner: inner,
-            buf: vec![0; cap].into_boxed_slice(),
-            pos: 0,
-            cap: 0,
+        unsafe {
+            let mut buffer = Vec::with_capacity(cap);
+            buffer.set_len(cap);
+            inner.initializer().initialize(&mut buffer);
+            BufReader {
+                inner,
+                buf: buffer.into_boxed_slice(),
+                pos: 0,
+                cap: 0,
+            }
         }
     }
 
@@ -111,8 +116,8 @@ impl<R: Read> BufReader<R> {
     /// use std::fs::File;
     ///
     /// # fn foo() -> std::io::Result<()> {
-    /// let mut f1 = try!(File::open("log.txt"));
-    /// let mut reader = BufReader::new(f1);
+    /// let f1 = File::open("log.txt")?;
+    /// let reader = BufReader::new(f1);
     ///
     /// let f2 = reader.get_ref();
     /// # Ok(())
@@ -132,7 +137,7 @@ impl<R: Read> BufReader<R> {
     /// use std::fs::File;
     ///
     /// # fn foo() -> std::io::Result<()> {
-    /// let mut f1 = try!(File::open("log.txt"));
+    /// let f1 = File::open("log.txt")?;
     /// let mut reader = BufReader::new(f1);
     ///
     /// let f2 = reader.get_mut();
@@ -142,6 +147,31 @@ impl<R: Read> BufReader<R> {
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn get_mut(&mut self) -> &mut R { &mut self.inner }
 
+    /// Returns `true` if there are no bytes in the internal buffer.
+    ///
+    /// # Examples
+    /// ```
+    /// # #![feature(bufreader_is_empty)]
+    /// use std::io::BufReader;
+    /// use std::io::BufRead;
+    /// use std::fs::File;
+    ///
+    /// # fn foo() -> std::io::Result<()> {
+    /// let f1 = File::open("log.txt")?;
+    /// let mut reader = BufReader::new(f1);
+    /// assert!(reader.is_empty());
+    ///
+    /// if reader.fill_buf()?.len() > 0 {
+    ///     assert!(!reader.is_empty());
+    /// }
+    /// # Ok(())
+    /// # }
+    /// ```
+    #[unstable(feature = "bufreader_is_empty", issue = "45323", reason = "recently added")]
+    pub fn is_empty(&self) -> bool {
+        self.pos == self.cap
+    }
+
     /// Unwraps this `BufReader`, returning the underlying reader.
     ///
     /// Note that any leftover data in the internal buffer is lost.
@@ -153,8 +183,8 @@ impl<R: Read> BufReader<R> {
     /// use std::fs::File;
     ///
     /// # fn foo() -> std::io::Result<()> {
-    /// let mut f1 = try!(File::open("log.txt"));
-    /// let mut reader = BufReader::new(f1);
+    /// let f1 = File::open("log.txt")?;
+    /// let reader = BufReader::new(f1);
     ///
     /// let f2 = reader.into_inner();
     /// # Ok(())
@@ -164,6 +194,31 @@ impl<R: Read> BufReader<R> {
     pub fn into_inner(self) -> R { self.inner }
 }
 
+impl<R: Seek> BufReader<R> {
+    /// Seeks relative to the current position. If the new position lies within the buffer,
+    /// 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 {
+            if let Some(new_pos) = pos.checked_sub((-offset) as u64) {
+                self.pos = new_pos as usize;
+                return Ok(())
+            }
+        } else {
+            if let Some(new_pos) = pos.checked_add(offset as u64) {
+                if new_pos <= self.cap as u64 {
+                    self.pos = new_pos as usize;
+                    return Ok(())
+                }
+            }
+        }
+        self.seek(SeekFrom::Current(offset)).map(|_|())
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<R: Read> Read for BufReader<R> {
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
@@ -180,6 +235,11 @@ impl<R: Read> Read for BufReader<R> {
         self.consume(nread);
         Ok(nread)
     }
+
+    // we can't skip unconditionally because of the large buffer case in read.
+    unsafe fn initializer(&self) -> Initializer {
+        self.inner.initializer()
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -187,7 +247,10 @@ 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
         // some more data from the underlying reader.
-        if self.pos == self.cap {
+        // Branch using `>=` instead of the more correct `==`
+        // to tell the compiler that the pos..cap slice is always valid.
+        if self.pos >= self.cap {
+            debug_assert!(self.pos == self.cap);
             self.cap = self.inner.read(&mut self.buf)?;
             self.pos = 0;
         }
@@ -222,13 +285,17 @@ impl<R: Seek> Seek for BufReader<R> {
     /// `.into_inner()` immediately after a seek yields the underlying reader
     /// at the same position.
     ///
+    /// To seek without discarding the internal buffer, use [`seek_relative`].
+    ///
     /// See `std::io::Seek` for more details.
     ///
     /// Note: In the edge case where you're seeking with `SeekFrom::Current(n)`
-    /// where `n` minus the internal buffer length underflows an `i64`, two
+    /// where `n` minus the internal buffer length overflows an `i64`, two
     /// seeks will be performed instead of one. If the second seek returns
     /// `Err`, the underlying reader will be left at the same position it would
     /// have if you seeked to `SeekFrom::Current(0)`.
+    ///
+    /// [`seek_relative`]: #method.seek_relative
     fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
         let result: u64;
         if let SeekFrom::Current(n) = pos {
@@ -258,11 +325,15 @@ impl<R: Seek> Seek for BufReader<R> {
 /// Wraps a writer and buffers its output.
 ///
 /// It can be excessively inefficient to work directly with something that
-/// implements [`Write`]. For example, every call to [`write`] on [`TcpStream`]
-/// results in a system call. A `BufWriter` keeps an in-memory buffer of data
-/// and writes it to an underlying writer in large, infrequent batches.
+/// implements [`Write`]. For example, every call to
+/// [`write`][`Tcpstream::write`] on [`TcpStream`] results in a system call. A
+/// `BufWriter` keeps an in-memory buffer of data and writes it to an underlying
+/// writer in large, infrequent batches.
 ///
-/// The buffer will be written out when the writer is dropped.
+/// When the `BufWriter` is dropped, the contents of its buffer will be written
+/// out. However, any errors that happen in the process of flushing the buffer
+/// when the writer is dropped will be ignored. Code that wishes to handle such
+/// errors must manually call [`flush`] before the writer is dropped.
 ///
 /// # Examples
 ///
@@ -274,8 +345,8 @@ impl<R: Seek> Seek for BufReader<R> {
 ///
 /// let mut stream = TcpStream::connect("127.0.0.1:34254").unwrap();
 ///
-/// for i in 1..10 {
-///     stream.write(&[i]).unwrap();
+/// for i in 0..10 {
+///     stream.write(&[i+1]).unwrap();
 /// }
 /// ```
 ///
@@ -290,8 +361,8 @@ impl<R: Seek> Seek for BufReader<R> {
 ///
 /// let mut stream = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
 ///
-/// for i in 1..10 {
-///     stream.write(&[i]).unwrap();
+/// for i in 0..10 {
+///     stream.write(&[i+1]).unwrap();
 /// }
 /// ```
 ///
@@ -300,8 +371,9 @@ impl<R: Seek> Seek for BufReader<R> {
 /// the `stream` is dropped.
 ///
 /// [`Write`]: ../../std/io/trait.Write.html
-/// [`write`]: ../../std/net/struct.TcpStream.html#method.write
+/// [`Tcpstream::write`]: ../../std/net/struct.TcpStream.html#method.write
 /// [`TcpStream`]: ../../std/net/struct.TcpStream.html
+/// [`flush`]: #method.flush
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct BufWriter<W: Write> {
     inner: Option<W>,
@@ -443,6 +515,10 @@ impl<W: Write> BufWriter<W> {
     ///
     /// The buffer is written out before returning the writer.
     ///
+    /// # Errors
+    ///
+    /// An `Err` will be returned if an error occurs while flushing the buffer.
+    ///
     /// # Examples
     ///
     /// ```no_run
@@ -607,6 +683,9 @@ impl<W> fmt::Display for IntoInnerError<W> {
 /// completed, rather than the entire buffer at once. Enter `LineWriter`. It
 /// does exactly that.
 ///
+/// Like [`BufWriter`], a `LineWriter`’s buffer will also be flushed when the
+/// `LineWriter` goes out of scope or when its internal buffer is full.
+///
 /// [bufwriter]: struct.BufWriter.html
 ///
 /// If there's still a partial line in the buffer when the `LineWriter` is
@@ -629,7 +708,7 @@ impl<W> fmt::Display for IntoInnerError<W> {
 /// I took the one less traveled by,
 /// And that has made all the difference.";
 ///
-/// let file = try!(File::create("poem.txt"));
+/// let file = File::create("poem.txt")?;
 /// let mut file = LineWriter::new(file);
 ///
 /// for &byte in road_not_taken.iter() {
@@ -637,10 +716,10 @@ impl<W> fmt::Display for IntoInnerError<W> {
 /// }
 ///
 /// // let's check we did the right thing.
-/// let mut file = try!(File::open("poem.txt"));
+/// let mut file = File::open("poem.txt")?;
 /// let mut contents = String::new();
 ///
-/// try!(file.read_to_string(&mut contents));
+/// file.read_to_string(&mut contents)?;
 ///
 /// assert_eq!(contents.as_bytes(), &road_not_taken[..]);
 /// # Ok(())
@@ -649,6 +728,7 @@ impl<W> fmt::Display for IntoInnerError<W> {
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct LineWriter<W: Write> {
     inner: BufWriter<W>,
+    need_flush: bool,
 }
 
 impl<W: Write> LineWriter<W> {
@@ -661,7 +741,7 @@ impl<W: Write> LineWriter<W> {
     /// use std::io::LineWriter;
     ///
     /// # fn foo() -> std::io::Result<()> {
-    /// let file = try!(File::create("poem.txt"));
+    /// let file = File::create("poem.txt")?;
     /// let file = LineWriter::new(file);
     /// # Ok(())
     /// # }
@@ -682,14 +762,17 @@ impl<W: Write> LineWriter<W> {
     /// use std::io::LineWriter;
     ///
     /// # fn foo() -> std::io::Result<()> {
-    /// let file = try!(File::create("poem.txt"));
+    /// let file = File::create("poem.txt")?;
     /// let file = LineWriter::with_capacity(100, file);
     /// # Ok(())
     /// # }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn with_capacity(cap: usize, inner: W) -> LineWriter<W> {
-        LineWriter { inner: BufWriter::with_capacity(cap, inner) }
+        LineWriter {
+            inner: BufWriter::with_capacity(cap, inner),
+            need_flush: false,
+        }
     }
 
     /// Gets a reference to the underlying writer.
@@ -701,7 +784,7 @@ impl<W: Write> LineWriter<W> {
     /// use std::io::LineWriter;
     ///
     /// # fn foo() -> std::io::Result<()> {
-    /// let file = try!(File::create("poem.txt"));
+    /// let file = File::create("poem.txt")?;
     /// let file = LineWriter::new(file);
     ///
     /// let reference = file.get_ref();
@@ -723,7 +806,7 @@ impl<W: Write> LineWriter<W> {
     /// use std::io::LineWriter;
     ///
     /// # fn foo() -> std::io::Result<()> {
-    /// let file = try!(File::create("poem.txt"));
+    /// let file = File::create("poem.txt")?;
     /// let mut file = LineWriter::new(file);
     ///
     /// // we can use reference just like file
@@ -738,6 +821,10 @@ impl<W: Write> LineWriter<W> {
     ///
     /// The internal buffer is written out before returning the writer.
     ///
+    // # Errors
+    ///
+    /// An `Err` will be returned if an error occurs while flushing the buffer.
+    ///
     /// # Examples
     ///
     /// ```
@@ -745,18 +832,21 @@ impl<W: Write> LineWriter<W> {
     /// use std::io::LineWriter;
     ///
     /// # fn foo() -> std::io::Result<()> {
-    /// let file = try!(File::create("poem.txt"));
+    /// let file = File::create("poem.txt")?;
     ///
     /// let writer: LineWriter<File> = LineWriter::new(file);
     ///
-    /// let file: File = try!(writer.into_inner());
+    /// let file: File = writer.into_inner()?;
     /// # 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)
+            IntoInnerError(LineWriter {
+                inner: buf,
+                need_flush: false,
+            }, e)
         })
     }
 }
@@ -764,20 +854,46 @@ impl<W: Write> LineWriter<W> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<W: Write> Write for LineWriter<W> {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        match memchr::memrchr(b'\n', buf) {
-            Some(i) => {
-                let n = self.inner.write(&buf[..i + 1])?;
-                if n != i + 1 || self.inner.flush().is_err() {
-                    // Do not return errors on partial writes.
-                    return Ok(n);
-                }
-                self.inner.write(&buf[i + 1..]).map(|i| n + i)
-            }
-            None => self.inner.write(buf),
+        if self.need_flush {
+            self.flush()?;
+        }
+
+        // Find the last newline character in the buffer provided. If found then
+        // we're going to write all the data up to that point and then flush,
+        // otherewise we just write the whole block to the underlying writer.
+        let i = match memchr::memrchr(b'\n', buf) {
+            Some(i) => i,
+            None => return self.inner.write(buf),
+        };
+
+
+        // Ok, we're going to write a partial amount of the data given first
+        // followed by flushing the newline. After we've successfully written
+        // some data then we *must* report that we wrote that data, so future
+        // errors are ignored. We set our internal `need_flush` flag, though, in
+        // case flushing fails and we need to try it first next time.
+        let n = self.inner.write(&buf[..i + 1])?;
+        self.need_flush = true;
+        if self.flush().is_err() || n != i + 1 {
+            return Ok(n)
+        }
+
+        // At this point we successfully wrote `i + 1` bytes and flushed it out,
+        // meaning that the entire line is now flushed out on the screen. While
+        // we can attempt to finish writing the rest of the data provided.
+        // Remember though that we ignore errors here as we've successfully
+        // written data, so we need to report that.
+        match self.inner.write(&buf[i + 1..]) {
+            Ok(i) => Ok(n + i),
+            Err(_) => Ok(n),
         }
     }
 
-    fn flush(&mut self) -> io::Result<()> { self.inner.flush() }
+    fn flush(&mut self) -> io::Result<()> {
+        self.inner.flush()?;
+        self.need_flush = false;
+        Ok(())
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -867,6 +983,23 @@ mod tests {
     }
 
     #[test]
+    fn test_buffered_reader_seek_relative() {
+        let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4];
+        let mut reader = BufReader::with_capacity(2, io::Cursor::new(inner));
+
+        assert!(reader.seek_relative(3).is_ok());
+        assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..]));
+        assert!(reader.seek_relative(0).is_ok());
+        assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..]));
+        assert!(reader.seek_relative(1).is_ok());
+        assert_eq!(reader.fill_buf().ok(), Some(&[1][..]));
+        assert!(reader.seek_relative(-1).is_ok());
+        assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..]));
+        assert!(reader.seek_relative(2).is_ok());
+        assert_eq!(reader.fill_buf().ok(), Some(&[2, 3][..]));
+    }
+
+    #[test]
     fn test_buffered_reader_seek_underflow() {
         // gimmick reader that yields its position modulo 256 for each byte
         struct PositionReader {
@@ -1150,4 +1283,44 @@ mod tests {
             BufWriter::new(io::sink())
         });
     }
+
+    struct AcceptOneThenFail {
+        written: bool,
+        flushed: bool,
+    }
+
+    impl Write for AcceptOneThenFail {
+        fn write(&mut self, data: &[u8]) -> io::Result<usize> {
+            if !self.written {
+                assert_eq!(data, b"a\nb\n");
+                self.written = true;
+                Ok(data.len())
+            } else {
+                Err(io::Error::new(io::ErrorKind::NotFound, "test"))
+            }
+        }
+
+        fn flush(&mut self) -> io::Result<()> {
+            assert!(self.written);
+            assert!(!self.flushed);
+            self.flushed = true;
+            Err(io::Error::new(io::ErrorKind::Other, "test"))
+        }
+    }
+
+    #[test]
+    fn erroneous_flush_retried() {
+        let a = AcceptOneThenFail {
+            written: false,
+            flushed: false,
+        };
+
+        let mut l = LineWriter::new(a);
+        assert_eq!(l.write(b"a\nb\na").unwrap(), 4);
+        assert!(l.get_ref().written);
+        assert!(l.get_ref().flushed);
+        l.get_mut().flushed = false;
+
+        assert_eq!(l.write(b"a").unwrap_err().kind(), io::ErrorKind::Other)
+    }
 }