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Diffstat (limited to 'src/libstd/io/buffered.rs')
| -rw-r--r-- | src/libstd/io/buffered.rs | 1703 |
1 files changed, 0 insertions, 1703 deletions
diff --git a/src/libstd/io/buffered.rs b/src/libstd/io/buffered.rs deleted file mode 100644 index b4c91cced43..00000000000 --- a/src/libstd/io/buffered.rs +++ /dev/null @@ -1,1703 +0,0 @@ -//! Buffering wrappers for I/O traits - -use crate::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; - -/// The `BufReader<R>` struct adds buffering to any reader. -/// -/// It can be excessively inefficient to work directly with a [`Read`] instance. -/// For example, every call to [`read`][`TcpStream::read`] on [`TcpStream`] -/// results in a system call. A `BufReader<R>` performs large, infrequent reads on -/// the underlying [`Read`] and maintains an in-memory buffer of the results. -/// -/// `BufReader<R>` can improve the speed of programs that make *small* and -/// *repeated* read calls to the same file or network socket. It does not -/// help when reading very large amounts at once, or reading just one or a few -/// times. It also provides no advantage when reading from a source that is -/// already in memory, like a `Vec<u8>`. -/// -/// When the `BufReader<R>` is dropped, the contents of its buffer will be -/// discarded. Creating multiple instances of a `BufReader<R>` on the same -/// stream can cause data loss. Reading from the underlying reader after -/// unwrapping the `BufReader<R>` with `BufReader::into_inner` can also cause -/// data loss. -/// -/// [`Read`]: ../../std/io/trait.Read.html -/// [`TcpStream::read`]: ../../std/net/struct.TcpStream.html#method.read -/// [`TcpStream`]: ../../std/net/struct.TcpStream.html -/// -/// # Examples -/// -/// ```no_run -/// use std::io::prelude::*; -/// use std::io::BufReader; -/// use std::fs::File; -/// -/// fn main() -> std::io::Result<()> { -/// let f = File::open("log.txt")?; -/// let mut reader = BufReader::new(f); -/// -/// let mut line = String::new(); -/// let len = reader.read_line(&mut line)?; -/// println!("First line is {} bytes long", len); -/// Ok(()) -/// } -/// ``` -#[stable(feature = "rust1", since = "1.0.0")] -pub struct BufReader<R> { - inner: R, - buf: Box<[u8]>, - pos: usize, - cap: usize, -} - -impl<R: Read> BufReader<R> { - /// Creates a new `BufReader<R>` with a default buffer capacity. The default is currently 8 KB, - /// but may change in the future. - /// - /// # Examples - /// - /// ```no_run - /// use std::io::BufReader; - /// use std::fs::File; - /// - /// fn main() -> std::io::Result<()> { - /// let f = File::open("log.txt")?; - /// let reader = BufReader::new(f); - /// Ok(()) - /// } - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - pub fn new(inner: R) -> BufReader<R> { - BufReader::with_capacity(DEFAULT_BUF_SIZE, inner) - } - - /// Creates a new `BufReader<R>` with the specified buffer capacity. - /// - /// # Examples - /// - /// Creating a buffer with ten bytes of capacity: - /// - /// ```no_run - /// use std::io::BufReader; - /// use std::fs::File; - /// - /// fn main() -> std::io::Result<()> { - /// 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(capacity: usize, inner: R) -> BufReader<R> { - unsafe { - let mut buffer = Vec::with_capacity(capacity); - buffer.set_len(capacity); - inner.initializer().initialize(&mut buffer); - BufReader { inner, buf: buffer.into_boxed_slice(), pos: 0, cap: 0 } - } - } -} - -impl<R> BufReader<R> { - /// Gets a reference to the underlying reader. - /// - /// It is inadvisable to directly read from the underlying reader. - /// - /// # Examples - /// - /// ```no_run - /// use std::io::BufReader; - /// use std::fs::File; - /// - /// fn main() -> std::io::Result<()> { - /// let f1 = File::open("log.txt")?; - /// let reader = BufReader::new(f1); - /// - /// let f2 = reader.get_ref(); - /// Ok(()) - /// } - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - pub fn get_ref(&self) -> &R { - &self.inner - } - - /// Gets a mutable reference to the underlying reader. - /// - /// It is inadvisable to directly read from the underlying reader. - /// - /// # Examples - /// - /// ```no_run - /// use std::io::BufReader; - /// use std::fs::File; - /// - /// fn main() -> std::io::Result<()> { - /// let f1 = File::open("log.txt")?; - /// let mut reader = BufReader::new(f1); - /// - /// let f2 = reader.get_mut(); - /// Ok(()) - /// } - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - pub fn get_mut(&mut self) -> &mut R { - &mut self.inner - } - - /// Returns a reference to the internally buffered data. - /// - /// Unlike `fill_buf`, this will not attempt to fill the buffer if it is empty. - /// - /// # Examples - /// - /// ```no_run - /// use std::io::{BufReader, BufRead}; - /// use std::fs::File; - /// - /// fn main() -> std::io::Result<()> { - /// let f = File::open("log.txt")?; - /// let mut reader = BufReader::new(f); - /// assert!(reader.buffer().is_empty()); - /// - /// if reader.fill_buf()?.len() > 0 { - /// assert!(!reader.buffer().is_empty()); - /// } - /// Ok(()) - /// } - /// ``` - #[stable(feature = "bufreader_buffer", since = "1.37.0")] - pub fn buffer(&self) -> &[u8] { - &self.buf[self.pos..self.cap] - } - - /// Returns the number of bytes the internal buffer can hold at once. - /// - /// # Examples - /// - /// ```no_run - /// use std::io::{BufReader, BufRead}; - /// use std::fs::File; - /// - /// fn main() -> std::io::Result<()> { - /// let f = File::open("log.txt")?; - /// let mut reader = BufReader::new(f); - /// - /// let capacity = reader.capacity(); - /// let buffer = reader.fill_buf()?; - /// assert!(buffer.len() <= capacity); - /// Ok(()) - /// } - /// ``` - #[stable(feature = "buffered_io_capacity", since = "1.46.0")] - pub fn capacity(&self) -> usize { - self.buf.len() - } - - /// Unwraps this `BufReader<R>`, returning the underlying reader. - /// - /// Note that any leftover data in the internal buffer is lost. Therefore, - /// a following read from the underlying reader may lead to data loss. - /// - /// # Examples - /// - /// ```no_run - /// use std::io::BufReader; - /// use std::fs::File; - /// - /// fn main() -> std::io::Result<()> { - /// let f1 = File::open("log.txt")?; - /// let reader = BufReader::new(f1); - /// - /// let f2 = reader.into_inner(); - /// Ok(()) - /// } - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - pub fn into_inner(self) -> R { - self.inner - } - - /// Invalidates all data in the internal buffer. - #[inline] - fn discard_buffer(&mut self) { - self.pos = 0; - self.cap = 0; - } -} - -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(drop) - } -} - -#[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 - // (larger than our internal buffer), bypass our internal buffer - // entirely. - if self.pos == self.cap && buf.len() >= self.buf.len() { - self.discard_buffer(); - return self.inner.read(buf); - } - let nread = { - let mut rem = self.fill_buf()?; - rem.read(buf)? - }; - self.consume(nread); - Ok(nread) - } - - fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> { - let total_len = bufs.iter().map(|b| b.len()).sum::<usize>(); - if self.pos == self.cap && total_len >= self.buf.len() { - self.discard_buffer(); - return self.inner.read_vectored(bufs); - } - let nread = { - let mut rem = self.fill_buf()?; - rem.read_vectored(bufs)? - }; - self.consume(nread); - Ok(nread) - } - - fn is_read_vectored(&self) -> bool { - self.inner.is_read_vectored() - } - - // 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")] -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. - // 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; - } - Ok(&self.buf[self.pos..self.cap]) - } - - fn consume(&mut self, amt: usize) { - self.pos = cmp::min(self.pos + amt, self.cap); - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<R> fmt::Debug for BufReader<R> -where - R: fmt::Debug, -{ - fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt.debug_struct("BufReader") - .field("reader", &self.inner) - .field("buffer", &format_args!("{}/{}", self.cap - self.pos, self.buf.len())) - .finish() - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<R: Seek> Seek for BufReader<R> { - /// Seek to an offset, in bytes, in the underlying reader. - /// - /// The position used for seeking with `SeekFrom::Current(_)` is the - /// position the underlying reader would be at if the `BufReader<R>` had no - /// internal buffer. - /// - /// Seeking always discards the internal buffer, even if the seek position - /// would otherwise fall within it. This guarantees that calling - /// `.into_inner()` immediately after a seek yields the underlying reader - /// at the same position. - /// - /// To seek without discarding the internal buffer, use [`BufReader::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 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 called `seek` with `SeekFrom::Current(0)`. - /// - /// [`BufReader::seek_relative`]: struct.BufReader.html#method.seek_relative - /// [`std::io::Seek`]: trait.Seek.html - fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { - let result: u64; - if let SeekFrom::Current(n) = pos { - let remainder = (self.cap - self.pos) as i64; - // it should be safe to assume that remainder fits within an i64 as the alternative - // means we managed to allocate 8 exbibytes and that's absurd. - // But it's not out of the realm of possibility for some weird underlying reader to - // support seeking by i64::MIN so we need to handle underflow when subtracting - // remainder. - if let Some(offset) = n.checked_sub(remainder) { - result = self.inner.seek(SeekFrom::Current(offset))?; - } else { - // seek backwards by our remainder, and then by the offset - self.inner.seek(SeekFrom::Current(-remainder))?; - self.discard_buffer(); - result = self.inner.seek(SeekFrom::Current(n))?; - } - } else { - // Seeking with Start/End doesn't care about our buffer length. - result = self.inner.seek(pos)?; - } - self.discard_buffer(); - Ok(result) - } -} - -/// 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`][`TcpStream::write`] on [`TcpStream`] results in a system call. A -/// `BufWriter<W>` keeps an in-memory buffer of data and writes it to an underlying -/// writer in large, infrequent batches. -/// -/// `BufWriter<W>` can improve the speed of programs that make *small* and -/// *repeated* write calls to the same file or network socket. It does not -/// help when writing very large amounts at once, or writing just one or a few -/// times. It also provides no advantage when writing to a destination that is -/// in memory, like a `Vec<u8>`. -/// -/// It is critical to call [`flush`] before `BufWriter<W>` is dropped. Though -/// dropping will attempt to flush the contents of the buffer, any errors -/// that happen in the process of dropping will be ignored. Calling [`flush`] -/// ensures that the buffer is empty and thus dropping will not even attempt -/// file operations. -/// -/// # Examples -/// -/// Let's write the numbers one through ten to a [`TcpStream`]: -/// -/// ```no_run -/// use std::io::prelude::*; -/// use std::net::TcpStream; -/// -/// let mut stream = TcpStream::connect("127.0.0.1:34254").unwrap(); -/// -/// for i in 0..10 { -/// stream.write(&[i+1]).unwrap(); -/// } -/// ``` -/// -/// Because we're not buffering, we write each one in turn, incurring the -/// overhead of a system call per byte written. We can fix this with a -/// `BufWriter<W>`: -/// -/// ```no_run -/// use std::io::prelude::*; -/// use std::io::BufWriter; -/// use std::net::TcpStream; -/// -/// let mut stream = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap()); -/// -/// for i in 0..10 { -/// stream.write(&[i+1]).unwrap(); -/// } -/// stream.flush().unwrap(); -/// ``` -/// -/// By wrapping the stream with a `BufWriter<W>`, these ten writes are all grouped -/// together by the buffer and will all be written out in one system call when -/// the `stream` is flushed. -/// -/// [`Write`]: ../../std/io/trait.Write.html -/// [`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>, - 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. - panicked: bool, -} - -/// An error returned by `into_inner` which combines an error that -/// happened while writing out the buffer, and the buffered writer object -/// which may be used to recover from the condition. -/// -/// # Examples -/// -/// ```no_run -/// use std::io::BufWriter; -/// use std::net::TcpStream; -/// -/// let mut stream = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap()); -/// -/// // do stuff with the stream -/// -/// // we want to get our `TcpStream` back, so let's try: -/// -/// let stream = match stream.into_inner() { -/// Ok(s) => s, -/// Err(e) => { -/// // Here, e is an IntoInnerError -/// panic!("An error occurred"); -/// } -/// }; -/// ``` -#[derive(Debug)] -#[stable(feature = "rust1", since = "1.0.0")] -pub struct IntoInnerError<W>(W, Error); - -impl<W: Write> BufWriter<W> { - /// Creates a new `BufWriter<W>` with a default buffer capacity. The default is currently 8 KB, - /// but may change in the future. - /// - /// # Examples - /// - /// ```no_run - /// use std::io::BufWriter; - /// use std::net::TcpStream; - /// - /// 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) - } - - /// Creates a new `BufWriter<W>` with the specified buffer capacity. - /// - /// # Examples - /// - /// Creating a buffer with a buffer of a hundred bytes. - /// - /// ```no_run - /// use std::io::BufWriter; - /// use std::net::TcpStream; - /// - /// 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 } - } - - fn flush_buf(&mut self) -> io::Result<()> { - let mut written = 0; - let len = self.buf.len(); - let mut ret = Ok(()); - while written < len { - self.panicked = true; - let r = self.inner.as_mut().unwrap().write(&self.buf[written..]); - self.panicked = false; - - match r { - Ok(0) => { - ret = - Err(Error::new(ErrorKind::WriteZero, "failed to write the buffered data")); - break; - } - Ok(n) => written += n, - Err(ref e) if e.kind() == io::ErrorKind::Interrupted => {} - Err(e) => { - ret = Err(e); - break; - } - } - } - if written > 0 { - self.buf.drain(..written); - } - ret - } - - /// Gets a reference to the underlying writer. - /// - /// # Examples - /// - /// ```no_run - /// use std::io::BufWriter; - /// use std::net::TcpStream; - /// - /// let mut buffer = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap()); - /// - /// // 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() - } - - /// Gets a mutable reference to the underlying writer. - /// - /// It is inadvisable to directly write to the underlying writer. - /// - /// # Examples - /// - /// ```no_run - /// use std::io::BufWriter; - /// use std::net::TcpStream; - /// - /// let mut buffer = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap()); - /// - /// // 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() - } - - /// Returns a reference to the internally buffered data. - /// - /// # Examples - /// - /// ```no_run - /// use std::io::BufWriter; - /// use std::net::TcpStream; - /// - /// let buf_writer = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap()); - /// - /// // 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 - } - - /// Returns the number of bytes the internal buffer can hold without flushing. - /// - /// # Examples - /// - /// ```no_run - /// use std::io::BufWriter; - /// use std::net::TcpStream; - /// - /// let buf_writer = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap()); - /// - /// // Check the capacity of the inner buffer - /// let capacity = buf_writer.capacity(); - /// // 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() - } - - /// Unwraps this `BufWriter<W>`, returning the underlying writer. - /// - /// 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 - /// use std::io::BufWriter; - /// use std::net::TcpStream; - /// - /// let mut buffer = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap()); - /// - /// // 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)), - Ok(()) => Ok(self.inner.take().unwrap()), - } - } -} - -#[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() { - self.flush_buf()?; - } - if buf.len() >= self.buf.capacity() { - self.panicked = true; - let r = self.get_mut().write(buf); - self.panicked = false; - r - } else { - self.buf.write(buf) - } - } - - fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> { - let total_len = bufs.iter().map(|b| b.len()).sum::<usize>(); - if self.buf.len() + total_len > self.buf.capacity() { - self.flush_buf()?; - } - if total_len >= self.buf.capacity() { - self.panicked = true; - let r = self.get_mut().write_vectored(bufs); - self.panicked = false; - r - } else { - self.buf.write_vectored(bufs) - } - } - - fn is_write_vectored(&self) -> bool { - self.get_ref().is_write_vectored() - } - - fn flush(&mut self) -> io::Result<()> { - self.flush_buf().and_then(|()| self.get_mut().flush()) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<W: Write> fmt::Debug for BufWriter<W> -where - W: fmt::Debug, -{ - fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt.debug_struct("BufWriter") - .field("writer", &self.inner.as_ref().unwrap()) - .field("buffer", &format_args!("{}/{}", self.buf.len(), self.buf.capacity())) - .finish() - } -} - -#[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. - /// - /// Seeking always writes out the internal buffer before seeking. - fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { - self.flush_buf().and_then(|_| self.get_mut().seek(pos)) - } -} - -#[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 { - // dtors should not panic, so we ignore a failed flush - let _r = self.flush_buf(); - } - } -} - -impl<W> IntoInnerError<W> { - /// Returns the error which caused the call to `into_inner()` to fail. - /// - /// This error was returned when attempting to write the internal buffer. - /// - /// # Examples - /// - /// ```no_run - /// use std::io::BufWriter; - /// use std::net::TcpStream; - /// - /// let mut stream = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap()); - /// - /// // do stuff with the stream - /// - /// // we want to get our `TcpStream` back, so let's try: - /// - /// let stream = match stream.into_inner() { - /// Ok(s) => s, - /// Err(e) => { - /// // Here, e is an IntoInnerError, let's log the inner error. - /// // - /// // We'll just 'log' to stdout for this example. - /// println!("{}", e.error()); - /// - /// panic!("An unexpected error occurred."); - /// } - /// }; - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - pub fn error(&self) -> &Error { - &self.1 - } - - /// Returns the buffered writer instance which generated the error. - /// - /// The returned object can be used for error recovery, such as - /// re-inspecting the buffer. - /// - /// # Examples - /// - /// ```no_run - /// use std::io::BufWriter; - /// use std::net::TcpStream; - /// - /// let mut stream = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap()); - /// - /// // do stuff with the stream - /// - /// // we want to get our `TcpStream` back, so let's try: - /// - /// let stream = match stream.into_inner() { - /// Ok(s) => s, - /// Err(e) => { - /// // Here, e is an IntoInnerError, let's re-examine the buffer: - /// let buffer = e.into_inner(); - /// - /// // do stuff to try to recover - /// - /// // afterwards, let's just return the stream - /// buffer.into_inner().unwrap() - /// } - /// }; - /// ``` - #[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) - } -} - -/// Wraps a writer and buffers output to it, flushing whenever a newline -/// (`0x0a`, `'\n'`) is detected. -/// -/// The [`BufWriter`][bufwriter] struct wraps a writer and buffers its output. -/// But it only does this batched write when it goes out of scope, or when the -/// internal buffer is full. Sometimes, you'd prefer to write each line as it's -/// completed, rather than the entire buffer at once. Enter `LineWriter`. It -/// does exactly that. -/// -/// Like [`BufWriter`][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 -/// dropped, it will flush those contents. -/// -/// # Examples -/// -/// We can use `LineWriter` to write one line at a time, significantly -/// reducing the number of actual writes to the file. -/// -/// ```no_run -/// use std::fs::{self, File}; -/// use std::io::prelude::*; -/// use std::io::LineWriter; -/// -/// fn main() -> std::io::Result<()> { -/// let road_not_taken = b"I shall be telling this with a sigh -/// Somewhere ages and ages hence: -/// Two roads diverged in a wood, and I - -/// I took the one less traveled by, -/// And that has made all the difference."; -/// -/// let file = File::create("poem.txt")?; -/// let mut file = LineWriter::new(file); -/// -/// file.write_all(b"I shall be telling this with a sigh")?; -/// -/// // No bytes are written until a newline is encountered (or -/// // the internal buffer is filled). -/// assert_eq!(fs::read_to_string("poem.txt")?, ""); -/// file.write_all(b"\n")?; -/// assert_eq!( -/// fs::read_to_string("poem.txt")?, -/// "I shall be telling this with a sigh\n", -/// ); -/// -/// // Write the rest of the poem. -/// file.write_all(b"Somewhere ages and ages hence: -/// Two roads diverged in a wood, and I - -/// I took the one less traveled by, -/// And that has made all the difference.")?; -/// -/// // The last line of the poem doesn't end in a newline, so -/// // we have to flush or drop the `LineWriter` to finish -/// // writing. -/// file.flush()?; -/// -/// // Confirm the whole poem was written. -/// assert_eq!(fs::read("poem.txt")?, &road_not_taken[..]); -/// Ok(()) -/// } -/// ``` -#[stable(feature = "rust1", since = "1.0.0")] -pub struct LineWriter<W: Write> { - inner: BufWriter<W>, - need_flush: bool, -} - -impl<W: Write> LineWriter<W> { - /// Creates a new `LineWriter`. - /// - /// # Examples - /// - /// ```no_run - /// use std::fs::File; - /// use std::io::LineWriter; - /// - /// fn main() -> std::io::Result<()> { - /// let file = File::create("poem.txt")?; - /// let file = LineWriter::new(file); - /// 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) - } - - /// Creates a new `LineWriter` with a specified capacity for the internal - /// buffer. - /// - /// # Examples - /// - /// ```no_run - /// use std::fs::File; - /// use std::io::LineWriter; - /// - /// fn main() -> std::io::Result<()> { - /// 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(capacity: usize, inner: W) -> LineWriter<W> { - LineWriter { inner: BufWriter::with_capacity(capacity, inner), need_flush: false } - } - - /// Gets a reference to the underlying writer. - /// - /// # Examples - /// - /// ```no_run - /// use std::fs::File; - /// use std::io::LineWriter; - /// - /// fn main() -> std::io::Result<()> { - /// let file = File::create("poem.txt")?; - /// let file = LineWriter::new(file); - /// - /// let reference = file.get_ref(); - /// Ok(()) - /// } - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - pub fn get_ref(&self) -> &W { - self.inner.get_ref() - } - - /// Gets a mutable reference to the underlying writer. - /// - /// Caution must be taken when calling methods on the mutable reference - /// returned as extra writes could corrupt the output stream. - /// - /// # Examples - /// - /// ```no_run - /// use std::fs::File; - /// use std::io::LineWriter; - /// - /// fn main() -> std::io::Result<()> { - /// let file = File::create("poem.txt")?; - /// let mut file = LineWriter::new(file); - /// - /// // we can use reference just like file - /// let reference = file.get_mut(); - /// Ok(()) - /// } - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - pub fn get_mut(&mut self) -> &mut W { - self.inner.get_mut() - } - - /// Unwraps this `LineWriter`, returning the underlying writer. - /// - /// 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 - /// - /// ```no_run - /// use std::fs::File; - /// use std::io::LineWriter; - /// - /// fn main() -> std::io::Result<()> { - /// let file = File::create("poem.txt")?; - /// - /// let writer: LineWriter<File> = LineWriter::new(file); - /// - /// 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, need_flush: false }, e) - }) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<W: Write> Write for LineWriter<W> { - fn write(&mut self, buf: &[u8]) -> io::Result<usize> { - 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, - // otherwise 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])?; - 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), - } - } - - // Vectored writes are very similar to the writes above, but adjusted for - // the list of buffers that we have to write. - fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> { - if self.need_flush { - self.flush()?; - } - - // Find the last newline, and failing that write the whole buffer - let last_newline = bufs.iter().enumerate().rev().find_map(|(i, buf)| { - let pos = memchr::memrchr(b'\n', buf)?; - Some((i, pos)) - }); - let (i, j) = match last_newline { - Some(pair) => pair, - None => return self.inner.write_vectored(bufs), - }; - let (prefix, suffix) = bufs.split_at(i); - let (buf, suffix) = suffix.split_at(1); - let buf = &buf[0]; - - // Write everything up to the last newline, flushing afterwards. Note - // that only if we finished our entire `write_vectored` do we try the - // subsequent - // `write` - let mut n = 0; - let prefix_amt = prefix.iter().map(|i| i.len()).sum(); - if prefix_amt > 0 { - n += self.inner.write_vectored(prefix)?; - self.need_flush = true; - } - if n == prefix_amt { - match self.inner.write(&buf[..=j]) { - Ok(m) => n += m, - Err(e) if n == 0 => return Err(e), - Err(_) => return Ok(n), - } - self.need_flush = true; - } - if self.flush().is_err() || n != j + 1 + prefix_amt { - return Ok(n); - } - - // ... and now write out everything remaining - match self.inner.write(&buf[j + 1..]) { - Ok(i) => n += i, - Err(_) => return Ok(n), - } - - if suffix.iter().map(|s| s.len()).sum::<usize>() == 0 { - return Ok(n); - } - match self.inner.write_vectored(suffix) { - Ok(i) => Ok(n + i), - Err(_) => Ok(n), - } - } - - fn flush(&mut self) -> io::Result<()> { - self.inner.flush()?; - self.need_flush = false; - Ok(()) - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<W: Write> fmt::Debug for LineWriter<W> -where - W: fmt::Debug, -{ - fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt.debug_struct("LineWriter") - .field("writer", &self.inner.inner) - .field( - "buffer", - &format_args!("{}/{}", self.inner.buf.len(), self.inner.buf.capacity()), - ) - .finish() - } -} - -#[cfg(test)] -mod tests { - use crate::io::prelude::*; - use crate::io::{self, BufReader, BufWriter, IoSlice, LineWriter, SeekFrom}; - use crate::sync::atomic::{AtomicUsize, Ordering}; - use crate::thread; - - /// A dummy reader intended at testing short-reads propagation. - pub struct ShortReader { - lengths: Vec<usize>, - } - - impl Read for ShortReader { - fn read(&mut self, _: &mut [u8]) -> io::Result<usize> { - if self.lengths.is_empty() { Ok(0) } else { Ok(self.lengths.remove(0)) } - } - } - - #[test] - fn test_buffered_reader() { - let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4]; - let mut reader = BufReader::with_capacity(2, inner); - - let mut buf = [0, 0, 0]; - let nread = reader.read(&mut buf); - assert_eq!(nread.unwrap(), 3); - assert_eq!(buf, [5, 6, 7]); - assert_eq!(reader.buffer(), []); - - let mut buf = [0, 0]; - let nread = reader.read(&mut buf); - assert_eq!(nread.unwrap(), 2); - assert_eq!(buf, [0, 1]); - assert_eq!(reader.buffer(), []); - - let mut buf = [0]; - let nread = reader.read(&mut buf); - assert_eq!(nread.unwrap(), 1); - assert_eq!(buf, [2]); - assert_eq!(reader.buffer(), [3]); - - let mut buf = [0, 0, 0]; - let nread = reader.read(&mut buf); - assert_eq!(nread.unwrap(), 1); - assert_eq!(buf, [3, 0, 0]); - assert_eq!(reader.buffer(), []); - - let nread = reader.read(&mut buf); - assert_eq!(nread.unwrap(), 1); - assert_eq!(buf, [4, 0, 0]); - assert_eq!(reader.buffer(), []); - - assert_eq!(reader.read(&mut buf).unwrap(), 0); - } - - #[test] - fn test_buffered_reader_seek() { - let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4]; - let mut reader = BufReader::with_capacity(2, io::Cursor::new(inner)); - - assert_eq!(reader.seek(SeekFrom::Start(3)).ok(), Some(3)); - assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..])); - assert_eq!(reader.seek(SeekFrom::Current(0)).ok(), Some(3)); - assert_eq!(reader.fill_buf().ok(), Some(&[0, 1][..])); - assert_eq!(reader.seek(SeekFrom::Current(1)).ok(), Some(4)); - assert_eq!(reader.fill_buf().ok(), Some(&[1, 2][..])); - reader.consume(1); - assert_eq!(reader.seek(SeekFrom::Current(-2)).ok(), Some(3)); - } - - #[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_invalidated_after_read() { - let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4]; - let mut reader = BufReader::with_capacity(3, io::Cursor::new(inner)); - - assert_eq!(reader.fill_buf().ok(), Some(&[5, 6, 7][..])); - reader.consume(3); - - let mut buffer = [0, 0, 0, 0, 0]; - assert_eq!(reader.read(&mut buffer).ok(), Some(5)); - assert_eq!(buffer, [0, 1, 2, 3, 4]); - - assert!(reader.seek_relative(-2).is_ok()); - let mut buffer = [0, 0]; - assert_eq!(reader.read(&mut buffer).ok(), Some(2)); - assert_eq!(buffer, [3, 4]); - } - - #[test] - fn test_buffered_reader_invalidated_after_seek() { - let inner: &[u8] = &[5, 6, 7, 0, 1, 2, 3, 4]; - let mut reader = BufReader::with_capacity(3, io::Cursor::new(inner)); - - assert_eq!(reader.fill_buf().ok(), Some(&[5, 6, 7][..])); - reader.consume(3); - - assert!(reader.seek(SeekFrom::Current(5)).is_ok()); - - assert!(reader.seek_relative(-2).is_ok()); - let mut buffer = [0, 0]; - assert_eq!(reader.read(&mut buffer).ok(), Some(2)); - assert_eq!(buffer, [3, 4]); - } - - #[test] - fn test_buffered_reader_seek_underflow() { - // gimmick reader that yields its position modulo 256 for each byte - struct PositionReader { - pos: u64, - } - impl Read for PositionReader { - fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> { - let len = buf.len(); - for x in buf { - *x = self.pos as u8; - self.pos = self.pos.wrapping_add(1); - } - Ok(len) - } - } - impl Seek for PositionReader { - fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> { - match pos { - SeekFrom::Start(n) => { - self.pos = n; - } - SeekFrom::Current(n) => { - self.pos = self.pos.wrapping_add(n as u64); - } - SeekFrom::End(n) => { - self.pos = u64::MAX.wrapping_add(n as u64); - } - } - Ok(self.pos) - } - } - - let mut reader = BufReader::with_capacity(5, PositionReader { pos: 0 }); - assert_eq!(reader.fill_buf().ok(), Some(&[0, 1, 2, 3, 4][..])); - assert_eq!(reader.seek(SeekFrom::End(-5)).ok(), Some(u64::MAX - 5)); - assert_eq!(reader.fill_buf().ok().map(|s| s.len()), Some(5)); - // the following seek will require two underlying seeks - let expected = 9223372036854775802; - assert_eq!(reader.seek(SeekFrom::Current(i64::MIN)).ok(), Some(expected)); - assert_eq!(reader.fill_buf().ok().map(|s| s.len()), Some(5)); - // seeking to 0 should empty the buffer. - assert_eq!(reader.seek(SeekFrom::Current(0)).ok(), Some(expected)); - assert_eq!(reader.get_ref().pos, expected); - } - - #[test] - fn test_buffered_reader_seek_underflow_discard_buffer_between_seeks() { - // gimmick reader that returns Err after first seek - struct ErrAfterFirstSeekReader { - first_seek: bool, - } - impl Read for ErrAfterFirstSeekReader { - fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> { - for x in &mut *buf { - *x = 0; - } - Ok(buf.len()) - } - } - impl Seek for ErrAfterFirstSeekReader { - fn seek(&mut self, _: SeekFrom) -> io::Result<u64> { - if self.first_seek { - self.first_seek = false; - Ok(0) - } else { - Err(io::Error::new(io::ErrorKind::Other, "oh no!")) - } - } - } - - let mut reader = BufReader::with_capacity(5, ErrAfterFirstSeekReader { first_seek: true }); - assert_eq!(reader.fill_buf().ok(), Some(&[0, 0, 0, 0, 0][..])); - - // The following seek will require two underlying seeks. The first will - // succeed but the second will fail. This should still invalidate the - // buffer. - assert!(reader.seek(SeekFrom::Current(i64::MIN)).is_err()); - assert_eq!(reader.buffer().len(), 0); - } - - #[test] - fn test_buffered_writer() { - let inner = Vec::new(); - let mut writer = BufWriter::with_capacity(2, inner); - - writer.write(&[0, 1]).unwrap(); - assert_eq!(writer.buffer(), []); - assert_eq!(*writer.get_ref(), [0, 1]); - - writer.write(&[2]).unwrap(); - assert_eq!(writer.buffer(), [2]); - assert_eq!(*writer.get_ref(), [0, 1]); - - writer.write(&[3]).unwrap(); - assert_eq!(writer.buffer(), [2, 3]); - assert_eq!(*writer.get_ref(), [0, 1]); - - writer.flush().unwrap(); - assert_eq!(writer.buffer(), []); - assert_eq!(*writer.get_ref(), [0, 1, 2, 3]); - - writer.write(&[4]).unwrap(); - writer.write(&[5]).unwrap(); - assert_eq!(writer.buffer(), [4, 5]); - assert_eq!(*writer.get_ref(), [0, 1, 2, 3]); - - writer.write(&[6]).unwrap(); - assert_eq!(writer.buffer(), [6]); - assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5]); - - writer.write(&[7, 8]).unwrap(); - assert_eq!(writer.buffer(), []); - assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8]); - - writer.write(&[9, 10, 11]).unwrap(); - assert_eq!(writer.buffer(), []); - assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]); - - writer.flush().unwrap(); - assert_eq!(writer.buffer(), []); - assert_eq!(*writer.get_ref(), [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]); - } - - #[test] - fn test_buffered_writer_inner_flushes() { - let mut w = BufWriter::with_capacity(3, Vec::new()); - w.write(&[0, 1]).unwrap(); - assert_eq!(*w.get_ref(), []); - let w = w.into_inner().unwrap(); - assert_eq!(w, [0, 1]); - } - - #[test] - fn test_buffered_writer_seek() { - let mut w = BufWriter::with_capacity(3, io::Cursor::new(Vec::new())); - w.write_all(&[0, 1, 2, 3, 4, 5]).unwrap(); - w.write_all(&[6, 7]).unwrap(); - assert_eq!(w.seek(SeekFrom::Current(0)).ok(), Some(8)); - assert_eq!(&w.get_ref().get_ref()[..], &[0, 1, 2, 3, 4, 5, 6, 7][..]); - assert_eq!(w.seek(SeekFrom::Start(2)).ok(), Some(2)); - w.write_all(&[8, 9]).unwrap(); - assert_eq!(&w.into_inner().unwrap().into_inner()[..], &[0, 1, 8, 9, 4, 5, 6, 7]); - } - - #[test] - fn test_read_until() { - let inner: &[u8] = &[0, 1, 2, 1, 0]; - let mut reader = BufReader::with_capacity(2, inner); - let mut v = Vec::new(); - reader.read_until(0, &mut v).unwrap(); - assert_eq!(v, [0]); - v.truncate(0); - reader.read_until(2, &mut v).unwrap(); - assert_eq!(v, [1, 2]); - v.truncate(0); - reader.read_until(1, &mut v).unwrap(); - assert_eq!(v, [1]); - v.truncate(0); - reader.read_until(8, &mut v).unwrap(); - assert_eq!(v, [0]); - v.truncate(0); - reader.read_until(9, &mut v).unwrap(); - assert_eq!(v, []); - } - - #[test] - fn test_line_buffer_fail_flush() { - // Issue #32085 - struct FailFlushWriter<'a>(&'a mut Vec<u8>); - - impl Write for FailFlushWriter<'_> { - fn write(&mut self, buf: &[u8]) -> io::Result<usize> { - self.0.extend_from_slice(buf); - Ok(buf.len()) - } - fn flush(&mut self) -> io::Result<()> { - Err(io::Error::new(io::ErrorKind::Other, "flush failed")) - } - } - - let mut buf = Vec::new(); - { - let mut writer = LineWriter::new(FailFlushWriter(&mut buf)); - let to_write = b"abc\ndef"; - if let Ok(written) = writer.write(to_write) { - assert!(written < to_write.len(), "didn't flush on new line"); - // PASS - return; - } - } - assert!(buf.is_empty(), "write returned an error but wrote data"); - } - - #[test] - fn test_line_buffer() { - let mut writer = LineWriter::new(Vec::new()); - writer.write(&[0]).unwrap(); - assert_eq!(*writer.get_ref(), []); - writer.write(&[1]).unwrap(); - assert_eq!(*writer.get_ref(), []); - writer.flush().unwrap(); - assert_eq!(*writer.get_ref(), [0, 1]); - writer.write(&[0, b'\n', 1, b'\n', 2]).unwrap(); - assert_eq!(*writer.get_ref(), [0, 1, 0, b'\n', 1, b'\n']); - writer.flush().unwrap(); - assert_eq!(*writer.get_ref(), [0, 1, 0, b'\n', 1, b'\n', 2]); - writer.write(&[3, b'\n']).unwrap(); - assert_eq!(*writer.get_ref(), [0, 1, 0, b'\n', 1, b'\n', 2, 3, b'\n']); - } - - #[test] - fn test_read_line() { - let in_buf: &[u8] = b"a\nb\nc"; - let mut reader = BufReader::with_capacity(2, in_buf); - let mut s = String::new(); - reader.read_line(&mut s).unwrap(); - assert_eq!(s, "a\n"); - s.truncate(0); - reader.read_line(&mut s).unwrap(); - assert_eq!(s, "b\n"); - s.truncate(0); - reader.read_line(&mut s).unwrap(); - assert_eq!(s, "c"); - s.truncate(0); - reader.read_line(&mut s).unwrap(); - assert_eq!(s, ""); - } - - #[test] - fn test_lines() { - let in_buf: &[u8] = b"a\nb\nc"; - let reader = BufReader::with_capacity(2, in_buf); - let mut it = reader.lines(); - assert_eq!(it.next().unwrap().unwrap(), "a".to_string()); - assert_eq!(it.next().unwrap().unwrap(), "b".to_string()); - assert_eq!(it.next().unwrap().unwrap(), "c".to_string()); - assert!(it.next().is_none()); - } - - #[test] - fn test_short_reads() { - let inner = ShortReader { lengths: vec![0, 1, 2, 0, 1, 0] }; - let mut reader = BufReader::new(inner); - let mut buf = [0, 0]; - assert_eq!(reader.read(&mut buf).unwrap(), 0); - assert_eq!(reader.read(&mut buf).unwrap(), 1); - assert_eq!(reader.read(&mut buf).unwrap(), 2); - assert_eq!(reader.read(&mut buf).unwrap(), 0); - assert_eq!(reader.read(&mut buf).unwrap(), 1); - assert_eq!(reader.read(&mut buf).unwrap(), 0); - assert_eq!(reader.read(&mut buf).unwrap(), 0); - } - - #[test] - #[should_panic] - fn dont_panic_in_drop_on_panicked_flush() { - struct FailFlushWriter; - - impl Write for FailFlushWriter { - fn write(&mut self, buf: &[u8]) -> io::Result<usize> { - Ok(buf.len()) - } - fn flush(&mut self) -> io::Result<()> { - Err(io::Error::last_os_error()) - } - } - - let writer = FailFlushWriter; - let _writer = BufWriter::new(writer); - - // If writer panics *again* due to the flush error then the process will - // abort. - panic!(); - } - - #[test] - #[cfg_attr(target_os = "emscripten", ignore)] - fn panic_in_write_doesnt_flush_in_drop() { - static WRITES: AtomicUsize = AtomicUsize::new(0); - - struct PanicWriter; - - impl Write for PanicWriter { - fn write(&mut self, _: &[u8]) -> io::Result<usize> { - WRITES.fetch_add(1, Ordering::SeqCst); - panic!(); - } - fn flush(&mut self) -> io::Result<()> { - Ok(()) - } - } - - thread::spawn(|| { - let mut writer = BufWriter::new(PanicWriter); - let _ = writer.write(b"hello world"); - let _ = writer.flush(); - }) - .join() - .unwrap_err(); - - assert_eq!(WRITES.load(Ordering::SeqCst), 1); - } - - #[bench] - fn bench_buffered_reader(b: &mut test::Bencher) { - b.iter(|| BufReader::new(io::empty())); - } - - #[bench] - fn bench_buffered_writer(b: &mut test::Bencher) { - b.iter(|| 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) - } - - #[test] - fn line_vectored() { - let mut a = LineWriter::new(Vec::new()); - assert_eq!( - a.write_vectored(&[ - IoSlice::new(&[]), - IoSlice::new(b"\n"), - IoSlice::new(&[]), - IoSlice::new(b"a"), - ]) - .unwrap(), - 2, - ); - assert_eq!(a.get_ref(), b"\n"); - - assert_eq!( - a.write_vectored(&[ - IoSlice::new(&[]), - IoSlice::new(b"b"), - IoSlice::new(&[]), - IoSlice::new(b"a"), - IoSlice::new(&[]), - IoSlice::new(b"c"), - ]) - .unwrap(), - 3, - ); - assert_eq!(a.get_ref(), b"\n"); - a.flush().unwrap(); - assert_eq!(a.get_ref(), b"\nabac"); - assert_eq!(a.write_vectored(&[]).unwrap(), 0); - assert_eq!( - a.write_vectored(&[ - IoSlice::new(&[]), - IoSlice::new(&[]), - IoSlice::new(&[]), - IoSlice::new(&[]), - ]) - .unwrap(), - 0, - ); - assert_eq!(a.write_vectored(&[IoSlice::new(b"a\nb"),]).unwrap(), 3); - assert_eq!(a.get_ref(), b"\nabaca\n"); - } - - #[test] - fn line_vectored_partial_and_errors() { - enum Call { - Write { inputs: Vec<&'static [u8]>, output: io::Result<usize> }, - Flush { output: io::Result<()> }, - } - struct Writer { - calls: Vec<Call>, - } - - impl Write for Writer { - fn write(&mut self, buf: &[u8]) -> io::Result<usize> { - self.write_vectored(&[IoSlice::new(buf)]) - } - - fn write_vectored(&mut self, buf: &[IoSlice<'_>]) -> io::Result<usize> { - match self.calls.pop().unwrap() { - Call::Write { inputs, output } => { - assert_eq!(inputs, buf.iter().map(|b| &**b).collect::<Vec<_>>()); - output - } - _ => panic!("unexpected call to write"), - } - } - - fn flush(&mut self) -> io::Result<()> { - match self.calls.pop().unwrap() { - Call::Flush { output } => output, - _ => panic!("unexpected call to flush"), - } - } - } - - impl Drop for Writer { - fn drop(&mut self) { - if !thread::panicking() { - assert_eq!(self.calls.len(), 0); - } - } - } - - // partial writes keep going - let mut a = LineWriter::new(Writer { calls: Vec::new() }); - a.write_vectored(&[IoSlice::new(&[]), IoSlice::new(b"abc")]).unwrap(); - a.get_mut().calls.push(Call::Flush { output: Ok(()) }); - a.get_mut().calls.push(Call::Write { inputs: vec![b"bcx\n"], output: Ok(4) }); - a.get_mut().calls.push(Call::Write { inputs: vec![b"abcx\n"], output: Ok(1) }); - a.write_vectored(&[IoSlice::new(b"x"), IoSlice::new(b"\n")]).unwrap(); - a.get_mut().calls.push(Call::Flush { output: Ok(()) }); - a.flush().unwrap(); - - // erroneous writes stop and don't write more - a.get_mut().calls.push(Call::Write { inputs: vec![b"x\n"], output: Err(err()) }); - assert_eq!(a.write_vectored(&[IoSlice::new(b"x"), IoSlice::new(b"\na")]).unwrap(), 2); - a.get_mut().calls.push(Call::Flush { output: Ok(()) }); - a.get_mut().calls.push(Call::Write { inputs: vec![b"x\n"], output: Ok(2) }); - a.flush().unwrap(); - - fn err() -> io::Error { - io::Error::new(io::ErrorKind::Other, "x") - } - } -} |