| // Licensed to the Apache Software Foundation (ASF) under one |
| // or more contributor license agreements. See the NOTICE file |
| // distributed with this work for additional information |
| // regarding copyright ownership. The ASF licenses this file |
| // to you under the Apache License, Version 2.0 (the |
| // "License"); you may not use this file except in compliance |
| // with the License. You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, |
| // software distributed under the License is distributed on an |
| // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| // KIND, either express or implied. See the License for the |
| // specific language governing permissions and limitations |
| // under the License.. |
| |
| #![allow(missing_copy_implementations)] |
| |
| use crate::io::{self, BufRead, ErrorKind, Initializer, IoSlice, IoSliceMut, Read, Write}; |
| use core::fmt; |
| use core::mem::MaybeUninit; |
| |
| /// Copies the entire contents of a reader into a writer. |
| /// |
| /// This function will continuously read data from `reader` and then |
| /// write it into `writer` in a streaming fashion until `reader` |
| /// returns EOF. |
| /// |
| /// On success, the total number of bytes that were copied from |
| /// `reader` to `writer` is returned. |
| /// |
| /// If you’re wanting to copy the contents of one file to another and you’re |
| /// working with filesystem paths, see the [`fs::copy`] function. |
| /// |
| /// [`fs::copy`]: ../fs/fn.copy.html |
| /// |
| /// # Errors |
| /// |
| /// This function will return an error immediately if any call to `read` or |
| /// `write` returns an error. All instances of `ErrorKind::Interrupted` are |
| /// handled by this function and the underlying operation is retried. |
| pub fn copy<R: ?Sized, W: ?Sized>(reader: &mut R, writer: &mut W) -> io::Result<u64> |
| where |
| R: Read, |
| W: Write, |
| { |
| let mut buf = MaybeUninit::<[u8; super::DEFAULT_BUF_SIZE]>::uninit(); |
| // FIXME(#53491): This is calling `get_mut` and `get_ref` on an uninitialized |
| // `MaybeUninit`. Revisit this once we decided whether that is valid or not. |
| // This is still technically undefined behavior due to creating a reference |
| // to uninitialized data, but within libstd we can rely on more guarantees |
| // than if this code were in an external lib. |
| unsafe { |
| reader.initializer().initialize(buf.get_mut()); |
| } |
| |
| let mut written = 0; |
| loop { |
| let len = match reader.read(unsafe { buf.get_mut() }) { |
| Ok(0) => return Ok(written), |
| Ok(len) => len, |
| Err(ref e) if e.kind() == ErrorKind::Interrupted => continue, |
| Err(e) => return Err(e), |
| }; |
| writer.write_all(unsafe { &buf.get_ref()[..len] })?; |
| written += len as u64; |
| } |
| } |
| |
| /// A reader which is always at EOF. |
| /// |
| /// This struct is generally created by calling [`empty`]. Please see |
| /// the documentation of [`empty()`][`empty`] for more details. |
| /// |
| /// [`empty`]: fn.empty.html |
| pub struct Empty { |
| _priv: (), |
| } |
| |
| /// Constructs a new handle to an empty reader. |
| /// |
| /// All reads from the returned reader will return [`Ok`]`(0)`. |
| /// |
| /// [`Ok`]: ../result/enum.Result.html#variant.Ok |
| /// |
| pub fn empty() -> Empty { Empty { _priv: () } } |
| |
| impl Read for Empty { |
| #[inline] |
| fn read(&mut self, _buf: &mut [u8]) -> io::Result<usize> { |
| Ok(0) |
| } |
| |
| #[inline] |
| unsafe fn initializer(&self) -> Initializer { |
| Initializer::nop() |
| } |
| } |
| |
| impl BufRead for Empty { |
| #[inline] |
| fn fill_buf(&mut self) -> io::Result<&[u8]> { |
| Ok(&[]) |
| } |
| #[inline] |
| fn consume(&mut self, _n: usize) {} |
| } |
| |
| impl fmt::Debug for Empty { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| f.pad("Empty { .. }") |
| } |
| } |
| |
| /// A reader which yields one byte over and over and over and over and over and... |
| /// |
| /// This struct is generally created by calling [`repeat`][repeat]. Please |
| /// see the documentation of `repeat()` for more details. |
| /// |
| /// [repeat]: fn.repeat.html |
| pub struct Repeat { |
| byte: u8, |
| } |
| |
| /// Creates an instance of a reader that infinitely repeats one byte. |
| /// |
| /// All reads from this reader will succeed by filling the specified buffer with |
| /// the given byte. |
| pub fn repeat(byte: u8) -> Repeat { |
| Repeat { byte } |
| } |
| |
| impl Read for Repeat { |
| #[inline] |
| fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> { |
| for slot in &mut *buf { |
| *slot = self.byte; |
| } |
| Ok(buf.len()) |
| } |
| |
| #[inline] |
| fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> { |
| let mut nwritten = 0; |
| for buf in bufs { |
| nwritten += self.read(buf)?; |
| } |
| Ok(nwritten) |
| } |
| |
| #[inline] |
| unsafe fn initializer(&self) -> Initializer { |
| Initializer::nop() |
| } |
| } |
| |
| impl fmt::Debug for Repeat { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| f.pad("Repeat { .. }") |
| } |
| } |
| |
| /// A writer which will move data into the void. |
| /// |
| /// This struct is generally created by calling [`sink`][sink]. Please |
| /// see the documentation of `sink()` for more details. |
| /// |
| /// [sink]: fn.sink.html |
| pub struct Sink { |
| _priv: (), |
| } |
| |
| /// Creates an instance of a writer which will successfully consume all data. |
| /// |
| /// All calls to `write` on the returned instance will return `Ok(buf.len())` |
| /// and the contents of the buffer will not be inspected. |
| pub fn sink() -> Sink { |
| Sink { _priv: () } |
| } |
| |
| impl Write for Sink { |
| #[inline] |
| fn write(&mut self, buf: &[u8]) -> io::Result<usize> { |
| Ok(buf.len()) |
| } |
| |
| #[inline] |
| fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> { |
| let total_len = bufs.iter().map(|b| b.len()).sum(); |
| Ok(total_len) |
| } |
| |
| #[inline] |
| fn flush(&mut self) -> io::Result<()> { |
| Ok(()) |
| } |
| } |
| |
| impl fmt::Debug for Sink { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| f.pad("Sink { .. }") |
| } |
| } |