| #![allow(missing_copy_implementations)] |
| |
| use crate::fmt; |
| use crate::io::{self, Read, Initializer, Write, ErrorKind, BufRead, IoSlice, IoSliceMut}; |
| use crate::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. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::io; |
| /// |
| /// fn main() -> io::Result<()> { |
| /// let mut reader: &[u8] = b"hello"; |
| /// let mut writer: Vec<u8> = vec![]; |
| /// |
| /// io::copy(&mut reader, &mut writer)?; |
| /// |
| /// assert_eq!(&b"hello"[..], &writer[..]); |
| /// Ok(()) |
| /// } |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| 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 |
| #[stable(feature = "rust1", since = "1.0.0")] |
| 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 |
| /// |
| /// # Examples |
| /// |
| /// A slightly sad example of not reading anything into a buffer: |
| /// |
| /// ``` |
| /// use std::io::{self, Read}; |
| /// |
| /// let mut buffer = String::new(); |
| /// io::empty().read_to_string(&mut buffer).unwrap(); |
| /// assert!(buffer.is_empty()); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn empty() -> Empty { Empty { _priv: () } } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| 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() |
| } |
| } |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl BufRead for Empty { |
| #[inline] |
| fn fill_buf(&mut self) -> io::Result<&[u8]> { Ok(&[]) } |
| #[inline] |
| fn consume(&mut self, _n: usize) {} |
| } |
| |
| #[stable(feature = "std_debug", since = "1.16.0")] |
| 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 |
| #[stable(feature = "rust1", since = "1.0.0")] |
| 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. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::io::{self, Read}; |
| /// |
| /// let mut buffer = [0; 3]; |
| /// io::repeat(0b101).read_exact(&mut buffer).unwrap(); |
| /// assert_eq!(buffer, [0b101, 0b101, 0b101]); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn repeat(byte: u8) -> Repeat { Repeat { byte } } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| 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() |
| } |
| } |
| |
| #[stable(feature = "std_debug", since = "1.16.0")] |
| 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 |
| #[stable(feature = "rust1", since = "1.0.0")] |
| 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. |
| /// |
| /// # Examples |
| /// |
| /// ```rust |
| /// use std::io::{self, Write}; |
| /// |
| /// let buffer = vec![1, 2, 3, 5, 8]; |
| /// let num_bytes = io::sink().write(&buffer).unwrap(); |
| /// assert_eq!(num_bytes, 5); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn sink() -> Sink { Sink { _priv: () } } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| 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(()) } |
| } |
| |
| #[stable(feature = "std_debug", since = "1.16.0")] |
| impl fmt::Debug for Sink { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| f.pad("Sink { .. }") |
| } |
| } |
| |
| #[cfg(test)] |
| mod tests { |
| use crate::io::prelude::*; |
| use crate::io::{copy, sink, empty, repeat}; |
| |
| #[test] |
| fn copy_copies() { |
| let mut r = repeat(0).take(4); |
| let mut w = sink(); |
| assert_eq!(copy(&mut r, &mut w).unwrap(), 4); |
| |
| let mut r = repeat(0).take(1 << 17); |
| assert_eq!(copy(&mut r as &mut dyn Read, &mut w as &mut dyn Write).unwrap(), 1 << 17); |
| } |
| |
| #[test] |
| fn sink_sinks() { |
| let mut s = sink(); |
| assert_eq!(s.write(&[]).unwrap(), 0); |
| assert_eq!(s.write(&[0]).unwrap(), 1); |
| assert_eq!(s.write(&[0; 1024]).unwrap(), 1024); |
| assert_eq!(s.by_ref().write(&[0; 1024]).unwrap(), 1024); |
| } |
| |
| #[test] |
| fn empty_reads() { |
| let mut e = empty(); |
| assert_eq!(e.read(&mut []).unwrap(), 0); |
| assert_eq!(e.read(&mut [0]).unwrap(), 0); |
| assert_eq!(e.read(&mut [0; 1024]).unwrap(), 0); |
| assert_eq!(e.by_ref().read(&mut [0; 1024]).unwrap(), 0); |
| } |
| |
| #[test] |
| fn repeat_repeats() { |
| let mut r = repeat(4); |
| let mut b = [0; 1024]; |
| assert_eq!(r.read(&mut b).unwrap(), 1024); |
| assert!(b.iter().all(|b| *b == 4)); |
| } |
| |
| #[test] |
| fn take_some_bytes() { |
| assert_eq!(repeat(4).take(100).bytes().count(), 100); |
| assert_eq!(repeat(4).take(100).bytes().next().unwrap().unwrap(), 4); |
| assert_eq!(repeat(1).take(10).chain(repeat(2).take(10)).bytes().count(), 20); |
| } |
| } |