Trait Read 

pub trait Read: IoBase {
    // Required method
    fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error>;

    // Provided method
    fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Self::Error> { ... }
}

The Read trait allows for reading bytes from a source.

It is based on the std::io::Read trait.

Required Methods

fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error>

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

This function does not provide any guarantees about whether it blocks waiting for data, but if an object needs to block for a read and cannot, it will typically signal this via an Err return value.

If the return value of this method is Ok(n), then it must be guaranteed that 0 <= n <= buf.len(). A nonzero n value indicates that the buffer buf has been filled in with n bytes of data from this source. If n is 0, then it can indicate one of two scenarios:

1. This reader has reached its “end of file” and will likely no longer be able to produce bytes. Note that this does not mean that the reader will always no longer be able to produce bytes.
2. The buffer specified was 0 bytes in length.

It is not an error if the returned value n is smaller than the buffer size, even when the reader is not at the end of the stream yet. This may happen for example because fewer bytes are actually available right now (e. g. being close to end-of-file) or because read() was interrupted by a signal.

Errors

If this function encounters any form of I/O or other error, an error will be returned. If an error is returned then it must be guaranteed that no bytes were read. An error for which IoError::is_interrupted returns true is non-fatal and the read operation should be retried if there is nothing else to do.

Provided Methods

fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Self::Error>

Read the exact number of bytes required to fill buf.

This function reads as many bytes as necessary to completely fill the specified buffer buf.

Errors

If this function encounters an error for which IoError::is_interrupted returns true then the error is ignored and the operation will continue.

If this function encounters an end of file before completely filling the buffer, it returns an error instantiated by a call to IoError::new_unexpected_eof_error. The contents of buf are unspecified in this case.

If this function returns an error, it is unspecified how many bytes it has read, but it will never read more than would be necessary to completely fill the buffer.

Implementors

impl<IO: ReadWriteSeek, TP: TimeProvider, OCC> Read for File<'_, IO, TP, OCC>

impl<T: Read> Read for StdIoWrapper<T>

Available on crate feature std only.