Trait esp_idf_svc::hal::io::Read
source · pub trait Read: ErrorType {
// Required method
fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error>;
// Provided method
fn read_exact(
&mut self,
buf: &mut [u8],
) -> Result<(), ReadExactError<Self::Error>> { ... }
}Expand description
Blocking reader.
This trait is the embedded-io equivalent of [std::io::Read].
Required Methods§
sourcefn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error>
fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error>
Read some bytes from this source into the specified buffer, returning how many bytes were read.
If no bytes are currently available to read, this function blocks until at least one byte is available.
If bytes are available, a non-zero amount of bytes is read to the beginning of buf, and the amount
is returned. It is not guaranteed that all available bytes are returned, it is possible for the
implementation to read an amount of bytes less than buf.len() while there are more bytes immediately
available.
If the reader is at end-of-file (EOF), Ok(0) is returned. There is no guarantee that a reader at EOF
will always be so in the future, for example a reader can stop being at EOF if another process appends
more bytes to the underlying file.
If buf.len() == 0, read returns without blocking, with either Ok(0) or an error.
The Ok(0) doesn’t indicate EOF, unlike when called with a non-empty buffer.
Provided Methods§
sourcefn read_exact(
&mut self,
buf: &mut [u8],
) -> Result<(), ReadExactError<Self::Error>>
fn read_exact( &mut self, buf: &mut [u8], ) -> Result<(), ReadExactError<Self::Error>>
Read the exact number of bytes required to fill buf.
This function calls read() in a loop until exactly buf.len() bytes have
been read, blocking if needed.
If you are using ReadReady to avoid blocking, you should not use this function.
ReadReady::read_ready() returning true only guarantees the first call to read() will
not block, so this function may still block in subsequent calls.
Implementations on Foreign Types§
source§impl Read for &[u8]
impl Read for &[u8]
Read is implemented for &[u8] by copying from the slice.
Note that reading updates the slice to point to the yet unread part. The slice will be empty when EOF is reached.