fixed-buffer

This is a Rust library with fixed-size buffers, useful for network protocol parsers and file parsers.

Features

• No unsafe
• Depends only on std
• Write bytes to the buffer and read them back
• Lives on the stack
• Does not allocate memory
• Use it to read a stream, search for a delimiter, and save leftover bytes for the next read.
• Easy to learn & use. Easy to maintain code that uses it.
• Works with Rust latest, beta, and nightly
• No macros
• Good test coverage (99%)
• fixedbuffertokio adds async functions

Limitations

• Not a circular buffer. You can call shift() periodically to move unread bytes to the front of the buffer.

Documentation

https://docs.rs/fixed-buffer

Examples

Read and handle requests from a remote client: ```rust use fixedbuffer::{ deframeline, FixedBuf, ReadWriteChain}; use std::io::{Error, Read, Write}; use std::net::TcpStream;

fn handlerequest( readerwriter: &mut RW, request: Request, ) -> Result<(), Error> { // ... Ok(()) }

fn handleconn(mut tcpstream: TcpStream ) -> Result<(), Error> { let mut buf: FixedBuf<4096> = FixedBuf::new(); loop { // Read a line // and leave leftover bytes in buf. let linebytes = match buf.readframe( &mut tcpstream, deframeline)? { Some(linebytes) => linebytes, None => return Ok(()), }; let request = Request::parse(linebytes)?; // Read any request payload // from buf + TcpStream. let mut readerwriter = ReadWriteChain::new( &mut buf, &mut tcpstream); handlerequest(&mut reader_writer, request)?; } } `` For a complete example, see [tests/server.rs`](https://gitlab.com/leonhard-llc/fixed-buffer-rs/-/blob/main/fixed-buffer/tests/server.rs).

Read and process records: ```rust use fixed_buffer::FixedBuf; use std::io::{Error, ErrorKind, Read}; use std::net::TcpStream;

fn tryprocessrecord(b: &[u8]) -> Result { if b.len() < 2 { return Ok(0); } if b.startswith("ab".asbytes()) { println!("found record"); Ok(2) } else { Err(Error::new(ErrorKind::InvalidData, "bad record")) } }

fn readandprocess(mut input: R) -> Result<(), Error> { let mut buf: FixedBuf<1024> = FixedBuf::new(); loop { // Read a chunk into the buffer. if buf.copyoncefrom(&mut input)? == 0 { return if buf.len() == 0 { // EOF at record boundary Ok(()) } else { // EOF in the middle of a record Err(Error::from( ErrorKind::UnexpectedEof)) }; } // Process records in the buffer. loop { let bytesread = tryprocessrecord(buf.readable())?; if bytesread == 0 { break; } buf.readbytes(bytesread); } // Shift data in the buffer to free up // space at the end for writing. buf.shift(); } } # ```

The filled constructor is useful in tests.

Alternatives

• bytes
• buf_redux, circular buffer support
• std::io::BufReader
• std::io::BufWriter
• static-buffer, updated in 2016
• block-buffer, for processing fixed-length blocks of data
• arrayvec, vector with fixed capacity.

Changelog

• v0.3.0 - Breaking API changes:
  • Change type parameter to const buffer size. Example: FixedBuf<1024>.
  • Remove new arg.
  • Remove capacity.
  • Remove Copy impl.
  • Change writable return type to &mut [u8].
• v0.2.3
  • Add read_byte, try_read_byte, try_read_bytes, try_read_exact, try_parse.
  • Implement UnwindSafe
• v0.2.2 - Add badges to readme
• v0.2.1 - Add deframe and mem, needed by AsyncFixedBuf::read_frame.
• v0.2.0
  • Move tokio support to fixedbuffertokio.
  • Add copy_once_from, read_block, ReadWriteChain, and ReadWriteTake.
• v0.1.7 - Add FixedBuf::escape_ascii.
• v0.1.6 - Add filled constructor.
• v0.1.5 - Change read_delimited to return Option<&[u8]>, for clean EOF handling.
• v0.1.4 - Add clear().
• v0.1.3
  • Thanks to freax13 for these changes:
  • Support any buffer size. Now you can make FixedBuf<[u8; 42]>.
  • Support any AsRef<[u8]> + AsMut<[u8]> value for internal memory:
    • [u8; N]
    • Box<[u8; N]>
    • &mut [u8]
    • Vec<u8>
  • Renamed new_with_mem to new. Use FixedBuf::default() to construct any FixedBuf<T: Default>, which includes arrays of sizes up to 32.
• v0.1.2 - Updated documentation.
• v0.1.1 - First published version

TO DO

• Change deframer function type to allow consuming bytes without returning a block.
• Implement async-std read & write traits
• Add an frame_copy_iter function. Because of borrowing rules, this function must return non-borrowed (allocated and copied) data.
• Set up CI on:
  • DONE - Linux x86 64-bit
  • macOS
  • Windows
  • https://crate-ci.github.io/pr/testing.html#travisci
  • Linux ARM 64-bit (Raspberry Pi 3 and newer)
  • Linux ARM 32-bit (Raspberry Pi 2)
  • RISCV & ESP32 firmware?
• DONE - Switch to const generics once they are stable:
  • https://github.com/rust-lang/rust/issues/44580
  • https://stackoverflow.com/a/56543462
• DONE - Try to make this crate comply with the Rust API Guidelines.
• DONE - Find out how to include Readme.md info in the crate's docs.
• DONE - Make the repo public
• DONE - Set up continuous integration tests and banner.
  • https://github.com/actions-rs/example
  • https://alican.codes/rust-github-actions/
• DONE - Add some documentation tests
  • https://doc.rust-lang.org/rustdoc/documentation-tests.html
  • https://doc.rust-lang.org/stable/rust-by-example/testing/doc_testing.html
• DONE - Set up public repository on Gitlab.com
  • https://gitlab.com/mattdark/firebase-example/blob/master/.gitlab-ci.yml
  • https://medium.com/astraol/optimizing-ci-cd-pipeline-for-rust-projects-gitlab-docker-98df64ae3bc4
  • https://hub.docker.com/_/rust
• DONE - Publish to creates.io
• DONE - Read through https://crate-ci.github.io/index.html
• DONE - Get a code review from an experienced rustacean
• DONE - Add and update a changelog
  • Update it manually
  • https://crate-ci.github.io/release/changelog.html

Release Process

1. Edit Cargo.toml and bump version number.
2. Run ../release.sh

License: Apache-2.0