lib: add support for no_std builds

Introduce a new, default `std` feature to the library, and conditionally use structures and traits from `no_std` compatible libraries. Existing `std` users can continue using the library with no changes. `no_std` users can import the library using `default_features = false`.
sile · Feb 14, 2023 · b10f88a · b10f88a
1 parent 0c11c3e
commit b10f88a
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Showing 22 changed files with 389 additions and 89 deletions.
diff --git a/Cargo.toml b/Cargo.toml
@@ -17,7 +17,11 @@ coveralls = {repository = "sile/libflate"}
 [dependencies]
 adler32 = "1"
 crc32fast = "1.1.1"
-libflate_lz77 = { path = "libflate_lz77", version = "1.1" }
+libflate_lz77 = { path = "libflate_lz77", version = "1.1", default_features = false }
+core2 = { version = "0.4", default_features = false, features = ["alloc"], optional = true }
+
+[features]
+no_std = ["libflate_lz77/no_std", "core2"]
 
 [dev-dependencies]
 clap = "2"

diff --git a/examples/flate.rs b/examples/flate.rs
@@ -1,17 +1,31 @@
 extern crate clap;
 extern crate libflate;
 
+#[cfg(not(feature = "no_std"))]
 use clap::App;
+#[cfg(not(feature = "no_std"))]
 use clap::Arg;
+#[cfg(not(feature = "no_std"))]
 use clap::SubCommand;
+#[cfg(not(feature = "no_std"))]
 use libflate::gzip;
+#[cfg(not(feature = "no_std"))]
 use libflate::zlib;
+#[cfg(not(feature = "no_std"))]
 use std::fs;
+#[cfg(not(feature = "no_std"))]
 use std::io;
+#[cfg(not(feature = "no_std"))]
 use std::io::Read;
+#[cfg(not(feature = "no_std"))]
 use std::io::Write;
+#[cfg(not(feature = "no_std"))]
 use std::process;
 
+#[cfg(feature = "no_std")]
+fn main() {}
+
+#[cfg(not(feature = "no_std"))]
 fn main() {
     let matches = App::new("deflate")
         .arg(

diff --git a/libflate_lz77/Cargo.toml b/libflate_lz77/Cargo.toml
@@ -16,6 +16,11 @@ coveralls = {repository = "sile/libflate"}
 
 [dependencies]
 rle-decode-fast = "1.0.0"
+core2 = { version = "0.4", default-features = false, features = ["alloc"], optional = true }
+hashbrown = { version = "0.13", optional = true }
 
 [dev-dependencies]
 libflate = { path = "../", version = "1" }
+
+[features]
+no_std = ["core2", "hashbrown"]
diff --git a/libflate_lz77/src/default.rs b/libflate_lz77/src/default.rs
@@ -1,5 +1,11 @@
-use std::cmp;
-use std::collections::HashMap;
+#[cfg(feature = "no_std")]
+use alloc::vec::Vec;
+#[cfg(feature = "no_std")]
+use core::cmp;
+#[cfg(feature = "no_std")]
+use hashbrown::HashMap;
+#[cfg(not(feature = "no_std"))]
+use std::{cmp, collections::HashMap};
 
 use super::Code;
 use super::Lz77Encode;

diff --git a/libflate_lz77/src/lib.rs b/libflate_lz77/src/lib.rs
@@ -2,8 +2,19 @@
 //!
 //! LZ77 is a compression algorithm used in [DEFLATE](https://tools.ietf.org/html/rfc1951).
 #![warn(missing_docs)]
+#![cfg_attr(no_std, feature = "no_std")]
+
+#[cfg(feature = "no_std")]
+extern crate alloc;
+
 pub use self::default::{DefaultLz77Encoder, DefaultLz77EncoderBuilder};
+#[cfg(feature = "no_std")]
+use alloc::vec::Vec;
+#[cfg(feature = "no_std")]
+use core2::io;
 use rle_decode_fast::rle_decode;
+#[cfg(not(feature = "no_std"))]
+use std::io;
 
 mod default;
 
@@ -157,7 +168,7 @@ impl Lz77Decoder {
     ///
     /// The decoded bytes are appended to the buffer of [`Lz77Decoder`].
     #[inline]
-    pub fn decode(&mut self, code: Code) -> std::io::Result<()> {
+    pub fn decode(&mut self, code: Code) -> io::Result<()> {
         match code {
             Code::Literal(b) => {
                 self.buffer.push(b);
@@ -167,13 +178,16 @@ impl Lz77Decoder {
                 backward_distance,
             } => {
                 if self.buffer.len() < backward_distance as usize {
-                    return Err(std::io::Error::new(
-                        std::io::ErrorKind::InvalidData,
+                    return Err(io::Error::new(
+                        io::ErrorKind::InvalidData,
+                        #[cfg(not(feature = "no_std"))]
                         format!(
                             "Too long backword reference: buffer.len={}, distance={}",
                             self.buffer.len(),
                             backward_distance
                         ),
+                        #[cfg(feature = "no_std")]
+                        "Too long backword reference",
                     ));
                 }
                 rle_decode(
@@ -187,10 +201,7 @@ impl Lz77Decoder {
     }
 
     /// Appends the bytes read from `reader` to the buffer of [`Lz77Decoder`].
-    pub fn extend_from_reader<R: std::io::Read>(
-        &mut self,
-        mut reader: R,
-    ) -> std::io::Result<usize> {
+    pub fn extend_from_reader<R: io::Read>(&mut self, mut reader: R) -> io::Result<usize> {
         reader.read_to_end(&mut self.buffer)
     }
 
@@ -227,8 +238,8 @@ impl Lz77Decoder {
     }
 }
 
-impl std::io::Read for Lz77Decoder {
-    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
+impl io::Read for Lz77Decoder {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
         let copy_size = std::cmp::min(buf.len(), self.buffer.len() - self.offset);
         buf[..copy_size].copy_from_slice(&self.buffer[self.offset..][..copy_size]);
         self.offset += copy_size;
@@ -240,6 +251,11 @@ impl std::io::Read for Lz77Decoder {
 #[cfg(test)]
 mod tests {
     use super::*;
+    #[cfg(feature = "no_std")]
+    use alloc::vec::Vec;
+    #[cfg(feature = "no_std")]
+    use core2::io::Read as _;
+    #[cfg(not(feature = "no_std"))]
     use std::io::Read as _;
 
     #[test]

diff --git a/src/bit.rs b/src/bit.rs
@@ -1,3 +1,6 @@
+#[cfg(feature = "no_std")]
+use core2::io;
+#[cfg(not(feature = "no_std"))]
 use std::io;
 
 #[derive(Debug)]
@@ -176,6 +179,9 @@ pub(crate) struct BitReaderState {
 #[cfg(test)]
 mod tests {
     use super::*;
+    #[cfg(feature = "no_std")]
+    use core2::io;
+    #[cfg(not(feature = "no_std"))]
     use std::io;
 
     #[test]

diff --git a/src/checksum.rs b/src/checksum.rs
@@ -1,4 +1,7 @@
 use adler32::RollingAdler32;
+#[cfg(feature = "no_std")]
+use core::fmt;
+#[cfg(not(feature = "no_std"))]
 use std::fmt;
 
 pub struct Adler32(RollingAdler32);

diff --git a/src/deflate/decode.rs b/src/deflate/decode.rs
@@ -1,8 +1,10 @@
 use super::symbol;
 use crate::bit;
 use crate::lz77;
-use std::io;
-use std::io::Read;
+#[cfg(feature = "no_std")]
+use core2::io::{self, Read};
+#[cfg(not(feature = "no_std"))]
+use std::io::{self, Read};
 
 /// DEFLATE decoder.
 #[derive(Debug)]
@@ -21,6 +23,9 @@ where
     ///
     /// # Examples
     /// ```
+    /// #[cfg(feature = "no_std")]
+    /// use core2::io::{Cursor, Read};
+    /// #[cfg(not(feature = "no_std"))]
     /// use std::io::{Cursor, Read};
     /// use libflate::deflate::Decoder;
     ///
@@ -53,6 +58,9 @@ where
     ///
     /// # Examples
     /// ```
+    /// #[cfg(feature = "no_std")]
+    /// use core2::io::Cursor;
+    /// #[cfg(not(feature = "no_std"))]
     /// use std::io::Cursor;
     /// use libflate::deflate::Decoder;
     ///
@@ -90,7 +98,10 @@ where
                     if used != len.into() {
                         Err(io::Error::new(
                             io::ErrorKind::UnexpectedEof,
+                            #[cfg(not(feature = "no_std"))]
                             format!("The reader has incorrect length: expected {len}, read {used}"),
+                            #[cfg(feature = "no_std")]
+                            "The reader has incorrect length",
                         ))
                     } else {
                         Ok(())
@@ -155,8 +166,10 @@ where
 
 #[cfg(test)]
 mod tests {
+    #[cfg(not(feature = "no_std"))]
     use super::*;
     use crate::deflate::symbol::{DynamicHuffmanCodec, HuffmanCodec};
+    #[cfg(not(feature = "no_std"))]
     use std::io;
 
     #[test]
@@ -177,6 +190,7 @@ mod tests {
     }
 
     #[test]
+    #[cfg(not(feature = "no_std"))]
     fn it_works() {
         let input = [
             180, 253, 73, 143, 28, 201, 150, 46, 8, 254, 150, 184, 139, 75, 18, 69, 247, 32, 157,
@@ -198,6 +212,7 @@ mod tests {
     }
 
     #[test]
+    #[cfg(not(feature = "no_std"))]
     fn test_issue_64() {
         let input = b"\x04\x04\x04\x05:\x1az*\xfc\x06\x01\x90\x01\x06\x01";
         let mut decoder = Decoder::new(&input[..]);

diff --git a/src/deflate/encode.rs b/src/deflate/encode.rs
@@ -3,8 +3,12 @@ use super::BlockType;
 use crate::bit;
 use crate::finish::{Complete, Finish};
 use crate::lz77;
-use std::cmp;
-use std::io;
+#[cfg(feature = "no_std")]
+use core::cmp;
+#[cfg(feature = "no_std")]
+use core2::io;
+#[cfg(not(feature = "no_std"))]
+use std::{cmp, io};
 
 /// The default size of a DEFLATE block.
 pub const DEFAULT_BLOCK_SIZE: usize = 1024 * 1024;
@@ -142,11 +146,14 @@ where
     ///
     /// # Examples
     /// ```
+    /// #[cfg(feature = "no_std")]
+    /// use core2::io::Write;
+    /// #[cfg(not(feature = "no_std"))]
     /// use std::io::Write;
     /// use libflate::deflate::Encoder;
     ///
     /// let mut encoder = Encoder::new(Vec::new());
-    /// encoder.write_all(b"Hello World!").unwrap();
+    /// encoder.write_all(b"Hello World!".as_ref()).unwrap();
     ///
     /// assert_eq!(encoder.finish().into_result().unwrap(),
     ///            [5, 192, 49, 13, 0, 0, 8, 3, 65, 43, 224, 6, 7, 24, 128, 237,
@@ -167,12 +174,15 @@ where
     ///
     /// # Examples
     /// ```
+    /// #[cfg(feature = "no_std")]
+    /// use core2::io::Write;
+    /// #[cfg(not(feature = "no_std"))]
     /// use std::io::Write;
     /// use libflate::deflate::{Encoder, EncodeOptions};
     ///
     /// let options = EncodeOptions::new().no_compression();
     /// let mut encoder = Encoder::with_options(Vec::new(), options);
-    /// encoder.write_all(b"Hello World!").unwrap();
+    /// encoder.write_all(b"Hello World!".as_ref()).unwrap();
     ///
     /// assert_eq!(encoder.finish().into_result().unwrap(),
     ///            [1, 12, 0, 243, 255, 72, 101, 108, 108, 111, 32, 87, 111,
@@ -189,11 +199,14 @@ where
     ///
     /// # Examples
     /// ```
+    /// #[cfg(feature = "no_std")]
+    /// use core2::io::Write;
+    /// #[cfg(not(feature = "no_std"))]
     /// use std::io::Write;
     /// use libflate::deflate::Encoder;
     ///
     /// let mut encoder = Encoder::new(Vec::new());
-    /// encoder.write_all(b"Hello World!").unwrap();
+    /// encoder.write_all(b"Hello World!".as_ref()).unwrap();
     ///
     /// assert_eq!(encoder.finish().into_result().unwrap(),
     ///            [5, 192, 49, 13, 0, 0, 8, 3, 65, 43, 224, 6, 7, 24, 128, 237,
@@ -428,6 +441,9 @@ where
 mod tests {
     use super::super::Decoder;
     use super::*;
+    #[cfg(feature = "no_std")]
+    use core2::io::{Read as _, Write as _};
+    #[cfg(not(feature = "no_std"))]
     use std::io::{Read as _, Write as _};
 
     #[test]

diff --git a/src/deflate/mod.rs b/src/deflate/mod.rs
@@ -4,12 +4,15 @@
 //!
 //! # Examples
 //! ```
-//! use std::io::{self, Read};
+//! #[cfg(feature = "no_std")]
+//! use core2::io::{Read, Write};
+//! #[cfg(not(feature = "no_std"))]
+//! use std::io::{Read, Write};
 //! use libflate::deflate::{Encoder, Decoder};
 //!
 //! // Encoding
 //! let mut encoder = Encoder::new(Vec::new());
-//! io::copy(&mut &b"Hello World!"[..], &mut encoder).unwrap();
+//! encoder.write_all(b"Hello World!".as_ref()).unwrap();
 //! let encoded_data = encoder.finish().into_result().unwrap();
 //!
 //! // Decoding
@@ -42,6 +45,9 @@ enum BlockType {
 mod tests {
     use super::*;
     use crate::lz77;
+    #[cfg(feature = "no_std")]
+    use core2::io::{Read, Write};
+    #[cfg(not(feature = "no_std"))]
     use std::io::{Read, Write};
 
     #[test]