Trait positioned_io::WriteAt
source · pub trait WriteAt {
// Required methods
fn write_at(&mut self, pos: u64, buf: &[u8]) -> Result<usize>;
fn flush(&mut self) -> Result<()>;
// Provided method
fn write_all_at(&mut self, pos: u64, buf: &[u8]) -> Result<()> { ... }
}Expand description
Trait for writing bytes at an offset.
Implementations should be able to write bytes at an offset, without changing any sort of write position. Self should not change at all.
When writing beyond the end of the underlying object it is extended and intermediate bytes are filled with the value 0.
Examples
use std::fs::OpenOptions;
use positioned_io::WriteAt;
let mut file = OpenOptions::new().write(true).open("tests/pi.txt")?;
// write some bytes
let bytes_written = file.write_at(2, b"1415926535897932384626433")?;Required Methods§
sourcefn write_at(&mut self, pos: u64, buf: &[u8]) -> Result<usize>
fn write_at(&mut self, pos: u64, buf: &[u8]) -> Result<usize>
Writes bytes from a buffer to an offset, returning the number of bytes written.
This function may write fewer bytes than the size of buf, for example
if it is interrupted.
See Write::write()
for details.
sourcefn flush(&mut self) -> Result<()>
fn flush(&mut self) -> Result<()>
Flush this writer, ensuring that any intermediately buffered data reaches its destination.
This should rarely do anything, since buffering is not very useful for positioned writes.
This should be equivalent to
Write::flush(),
so it does not actually sync changes to disk when writing a File.
Use
File::sync_data()
instead.
Provided Methods§
sourcefn write_all_at(&mut self, pos: u64, buf: &[u8]) -> Result<()>
fn write_all_at(&mut self, pos: u64, buf: &[u8]) -> Result<()>
Writes a complete buffer at an offset.
Errors if it could not write the entire buffer.
See Write::write_all()
for details.