build: make lib no-std

Only when no runtime is used.

Author: soywod

Cargo.toml

@@ -1,13 +1,13 @@
 [package]
 name = "io-socket"
-description = "Set of I/O-free coroutines and runtimes to manage sockets"
+description = "I/O-free socket client library"
 version = "0.0.1"
 authors = ["Clément DOUIN <pimalaya.org@posteo.net>"]
 rust-version = "1.87"
 edition = "2024"
 license = "MIT OR Apache-2.0"
-categories = ["api-bindings"]
-keywords = ["io-free", "coroutine", "socket", "stream", "datagram"]
+categories = ["api-bindings", "no-std"]
+keywords = ["io-free", "no-std", "coroutine", "socket", "stream"]
 homepage = "https://pimalaya.org"
 documentation = "https://docs.rs/io-socket/latest/io_socket"
 repository = "https://github.com/pimalaya/io-socket"

README.md

@@ -1,6 +1,6 @@
 # I/O Socket [![Documentation](https://img.shields.io/docsrs/io-socket?style=flat&logo=docs.rs&logoColor=white)](https://docs.rs/io-socket/latest/io_socket) [![Matrix](https://img.shields.io/badge/chat-%23pimalaya-blue?style=flat&logo=matrix&logoColor=white)](https://matrix.to/#/#pimalaya:matrix.org) [![Mastodon](https://img.shields.io/badge/news-%40pimalaya-blue?style=flat&logo=mastodon&logoColor=white)](https://fosstodon.org/@pimalaya)
 
-Set of **I/O-free** Rust coroutines and runtimes to manage sockets.
+**I/O-free** socket client library written in Rust
 
 This library provides an I/O-agnostic abstraction over sockets — both stream sockets (TCP, Unix) and datagram sockets (UDP) — based on three concepts:
 
@@ -40,16 +40,16 @@ let mut read = ReadSocket::new();
 let (buf, n) = loop {
     match read.resume(arg.take()) {
         ReadSocketResult::Ok { buf, n } => break (buf, n),
+        ReadSocketResult::Io { input } => arg = Some(handle(&mut stream, input).unwrap()),
         ReadSocketResult::Eof => break (vec![], 0),
         ReadSocketResult::Err { err } => panic!("{err}"),
-        ReadSocketResult::Io { input } => arg = Some(handle(&mut stream, input).unwrap()),
     }
 };
 
 let bytes = &buf[..n];
 ```
 
-### Write to a TCP stream (async Tokio)
+### Write on a TCP stream (async)
 
 ```rust,ignore
 use tokio::net::TcpStream;
@@ -67,9 +67,9 @@ let mut write = WriteSocket::new(b"GET / HTTP/1.0\r\n\r\n".to_vec());
 loop {
     match write.resume(arg.take()) {
         WriteSocketResult::Ok { .. } => break,
+        WriteSocketResult::Io { input } => arg = Some(handle(&mut stream, input).await.unwrap()),
         WriteSocketResult::Eof => panic!("connection closed"),
         WriteSocketResult::Err { err } => panic!("{err}"),
-        WriteSocketResult::Io { input } => arg = Some(handle(&mut stream, input).await.unwrap()),
     }
 }
 ```
@@ -80,6 +80,7 @@ loop {
 
 Have a look at projects built on the top of this library:
 
+- [io-dns](https://github.com/pimalaya/io-dns): I/O-free DNS client library
 - [io-addressbook](https://github.com/pimalaya/io-addressbook): Set of I/O-free coroutines to manage contacts
 - [io-http](https://github.com/pimalaya/io-http): Set of I/O-free Rust coroutines to manage HTTP sockets
 - [io-oauth](https://github.com/pimalaya/io-oauth): Set of I/O-free Rust coroutines to manage OAuth flows

flake.nix

@@ -1,5 +1,5 @@
 {
-  description = "Set of I/O-free Rust coroutines and runtimes to manage sockets";
+  description = "I/O-free socket client library written in Rust";
 
   inputs = {
     nixpkgs = {

src/coroutines/read.rs

@@ -1,6 +1,7 @@
 //! I/O-free coroutine to read bytes into a buffer.
 
-use std::{fmt, mem};
+use alloc::{vec, vec::Vec};
+use core::{fmt, mem};
 
 use log::{debug, trace};
 use thiserror::Error;

src/coroutines/read_exact.rs

@@ -1,6 +1,7 @@
 //! I/O-free coroutine to read exactly N bytes from a socket.
 
-use std::mem;
+use alloc::vec::Vec;
+use core::mem;
 
 use log::{debug, trace};
 use thiserror::Error;

src/coroutines/read_to_end.rs

@@ -1,6 +1,7 @@
 //! I/O-free coroutine to read from a socket until EOF.
 
-use std::mem;
+use alloc::vec::Vec;
+use core::mem;
 
 use log::trace;
 use thiserror::Error;

src/coroutines/write.rs

@@ -1,6 +1,7 @@
 //! I/O-free coroutine to write bytes into a buffer.
 
-use std::{fmt, mem};
+use alloc::vec::Vec;
+use core::{fmt, mem};
 
 use log::{debug, trace};
 use thiserror::Error;

src/io.rs

@@ -1,6 +1,7 @@
 //! Socket input and output.
 
-use std::fmt;
+use alloc::vec::Vec;
+use core::fmt;
 
 /// Socket input emitted by [coroutines] and processed by [runtimes].
 ///

src/lib.rs

@@ -1,5 +1,14 @@
 #![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]
 #![doc = include_str!("../README.md")]
+#![no_std]
+extern crate alloc;
+// Runtime modules that wrap std or tokio bring std back explicitly.
+#[cfg(any(
+    feature = "std-stream",
+    feature = "std-udp-socket",
+    feature = "tokio-stream"
+))]
+extern crate std;
 
 pub mod coroutines;
 pub mod io;

src/runtimes/std_stream.rs

@@ -1,5 +1,6 @@
-//! Synchronous stream socket runtime backed by [`io`].
+//! Synchronous stream socket runtime backed by [`std::io`].
 
+use alloc::vec::Vec;
 use std::io::{Read, Result, Write};
 
 use log::trace;