WIP/oliver/no_std

.travis.yml

@@ -3,7 +3,7 @@ language: rust
 rust:
 - beta
 - stable
-- 1.42.0
+- 1.60.0
 before_script:
 - |
   pip install 'travis-cargo<0.2' --user &&
@@ -12,6 +12,8 @@ script:
 - |
   travis-cargo build &&
   travis-cargo test &&
+  travis-cargo check -- --no-default-features &&
+  travis-cargo test -- --no-default-features &&
   travis-cargo bench &&
   travis-cargo --only stable doc
 addons:

Cargo.toml

@@ -9,12 +9,32 @@ readme = "README.md"
 repository = "https://github.com/jcreekmore/pem-rs.git"
 version = "1.1.2-alpha.0"
 categories = [ "cryptography" ]
-edition = "2018"
-rust-version = "1.34.2"
+keywords = [
+    "pem",
+    "no_std",
+]
+edition = "2021"
+rust-version = "1.60.0" # 1.60.0 required for the "serde?/std" dependency feature
 
-[dependencies]
-base64 = "0.13.0"
-serde = { version = "1", optional = true, features = ["serde_derive"] }
+[features]
+default = ["std"]
+std = [
+    "base64/std",
+    # enable serde's std feature iff the serde and std features are both activated
+    "serde?/std",
+]
+serde = ["dep:serde"]
+
+[dependencies.base64]
+version = "0.13.0"
+default-features = false
+features = ["alloc"]
+
+[dependencies.serde]
+version = "1"
+optional = true
+default-features = false
+features = ["serde_derive"]
 
 [dev-dependencies]
 criterion = "0.3.0"

src/errors.rs

@@ -3,8 +3,9 @@
 // Licensed under the MIT license <LICENSE.md or
 // http://opensource.org/licenses/MIT>. This file may not be
 // copied, modified, or distributed except according to those terms.
+use core::fmt;
+#[cfg(any(feature = "std", test))]
 use std::error::Error;
-use std::fmt;
 
 /// The `pem` error type.
 #[derive(Debug, Eq, PartialEq)]
@@ -16,7 +17,7 @@ pub enum PemError {
     MissingEndTag,
     MissingData,
     InvalidData(::base64::DecodeError),
-    NotUtf8(::std::str::Utf8Error),
+    NotUtf8(::core::str::Utf8Error),
 }
 
 impl fmt::Display for PemError {
@@ -35,6 +36,7 @@ impl fmt::Display for PemError {
     }
 }
 
+#[cfg(feature = "std")]
 impl Error for PemError {
     fn source(&self) -> Option<&(dyn Error + 'static)> {
         match self {
@@ -47,5 +49,24 @@ impl Error for PemError {
     }
 }
 
+// FIXME(oliveruv): this could be better. Wanted to just do
+// #[cfg(any(feature = "std", test))]
+// but then it seems base64::DecodeError doesn't get the Error impl even
+// though it's got the same cfg attribute. Guess the test attribute is
+// only valid for the current crate?
+#[cfg(not(feature = "std"))]
+impl PemError {
+    #[allow(missing_docs)]
+    pub fn source(&self) -> Option<&(dyn core::fmt::Display + 'static)> {
+        match self {
+            // Errors originating from other libraries.
+            PemError::InvalidData(e) => Some(e),
+            PemError::NotUtf8(e) => Some(e),
+            // Errors directly originating from `pem-rs`.
+            _ => None,
+        }
+    }
+}
+
 /// The `pem` result type.
-pub type Result<T> = ::std::result::Result<T, PemError>;
+pub type Result<T> = ::core::result::Result<T, PemError>;

src/lib.rs

@@ -92,6 +92,18 @@
 //!  assert_eq!(pems[0].tag, "INTERMEDIATE CERT");
 //!  assert_eq!(pems[1].tag, "CERTIFICATE");
 //! ```
+//!
+//! # Features
+//!
+//! This crate supports two features: `std` and `serde`.
+//!
+//! The `std` feature is enabled by default. If you specify
+//! `default-features = false` to disable `std`, be aware that
+//! this crate still needs an allocator, so `alloc` is still
+//! required.
+//!
+//! The `serde` feature implements `serde::{Deserialize, Serialize}`
+//! for this crate's `Pem` struct.
 
 #![recursion_limit = "1024"]
 #![deny(
@@ -106,12 +118,17 @@
     unused_qualifications
 )]
 
+#[cfg(not(any(feature = "std", test)))]
+extern crate alloc;
+#[cfg(not(any(feature = "std", test)))]
+use alloc::vec::Vec;
+
 mod errors;
 mod parser;
 use parser::{parse_captures, parse_captures_iter, Captures};
 
 pub use crate::errors::{PemError, Result};
-use std::str;
+use core::str;
 
 /// The line length for PEM encoding
 const LINE_WRAP: usize = 64;