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Use SMALL_ATOM_UTF8_EXT and ATOM_UTF8_EXT for safer atom encoding #16

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Merged
sile merged 4 commits into from
Sep 6, 2025
Merged

Use SMALL_ATOM_UTF8_EXT and ATOM_UTF8_EXT for safer atom encoding #16

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89b1443
feat: optimize atom encoding by using SMALL_ATOM_UTF8_EXT for short a…
sile Sep 6, 2025
231da4c
test: update expected bytes for SMALL_ATOM_UTF8_EXT encoding format
sile Sep 6, 2025
2df859d
docs: update example to use SMALL_ATOM_UTF8_EXT encoding format
sile Sep 6, 2025
0aa4781
refactor: improve atom encoding with better length validation and typ…
sile Sep 6, 2025
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16 changes: 7 additions & 9 deletions src/codec.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -624,17 +624,15 @@ impl<W: io::Write> Encoder<W> {
Ok(())
}
fn encode_atom(&mut self, x: &Atom) -> EncodeResult {
if x.name.len() > 0xFFFF {
return Err(EncodeError::TooLongAtomName(x.clone()));
}

let is_ascii = x.name.as_bytes().iter().all(|&c| c < 0x80);
if is_ascii {
self.writer.write_u8(ATOM_EXT)?;
} else {
if let Ok(len) = u8::try_from(x.name.len()) {
self.writer.write_u8(SMALL_ATOM_UTF8_EXT)?;
self.writer.write_u8(len)?;
} else if let Ok(len) = u16::try_from(x.name.len()) {
self.writer.write_u8(ATOM_UTF8_EXT)?;
self.writer.write_u16(len)?;
} else {
return Err(EncodeError::TooLongAtomName(x.clone()));
}
self.writer.write_u16(x.name.len() as u16)?;
self.writer.write_all(x.name.as_bytes())?;
Ok(())
}
Expand Down
4 changes: 2 additions & 2 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@
//! use std::io::Cursor;
//! use eetf::{Term, Atom};
//!
//! let bytes = vec![131, 100, 0, 3, 102, 111, 111];
//! let bytes = vec![131, 119, 3, 102, 111, 111];
//! let term = Term::decode(Cursor::new(&bytes)).unwrap();
//! assert_eq!(term, Term::from(Atom::from("foo")));
//! ```
Expand All @@ -21,7 +21,7 @@
//! let mut buf = Vec::new();
//! let term = Term::from(Atom::from("foo"));
//! term.encode(&mut buf).unwrap();
//! assert_eq!(vec![131, 100, 0, 3, 102, 111, 111], buf);
//! assert_eq!(vec![131, 119, 3, 102, 111, 111], buf);
//! ```
//!
//! # Reference
Expand Down
38 changes: 16 additions & 22 deletions tests/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@ fn atom_test() {

// Encode
assert_eq!(
vec![131, 100, 0, 3, 102, 111, 111],
vec![131, 119, 3, 102, 111, 111],
encode(Term::from(Atom::from("foo")))
);
}
Expand Down Expand Up @@ -170,8 +170,8 @@ fn pid_test() {
// Encode
assert_eq!(
vec![
131, 88, 100, 0, 13, 110, 111, 110, 111, 100, 101, 64, 110, 111, 104, 111, 115, 116, 0,
0, 0, 49, 0, 0, 0, 0, 0, 0, 0, 0
131, 88, 119, 13, 110, 111, 110, 111, 100, 101, 64, 110, 111, 104, 111, 115, 116, 0, 0,
0, 49, 0, 0, 0, 0, 0, 0, 0, 0
],
encode(Term::from(Pid::from(("nonode@nohost", 49, 0))))
);
Expand All @@ -198,8 +198,8 @@ fn port_test() {
// Encode
assert_eq!(
vec![
131, 89, 100, 0, 13, 110, 111, 110, 111, 100, 101, 64, 110, 111, 104, 111, 115, 116, 0,
0, 1, 110, 0, 0, 0, 0
131, 89, 119, 13, 110, 111, 110, 111, 100, 101, 64, 110, 111, 104, 111, 115, 116, 0, 0,
1, 110, 0, 0, 0, 0
],
encode(Term::from(Port::from(("nonode@nohost", 366))))
);
Expand Down Expand Up @@ -231,7 +231,7 @@ fn reference_test() {
// Encode
assert_eq!(
vec![
131, 90, 0, 1, 100, 0, 3, 102, 111, 111, 0, 0, 0, 0, 0, 0, 0, 123
131, 90, 0, 1, 119, 3, 102, 111, 111, 0, 0, 0, 0, 0, 0, 0, 123
],
encode(Term::from(Reference::from(("foo", 123))))
);
Expand All @@ -256,9 +256,7 @@ fn external_fun_test() {

// Encode
assert_eq!(
vec![
131, 113, 100, 0, 3, 102, 111, 111, 100, 0, 3, 98, 97, 114, 97, 3
],
vec![131, 113, 119, 3, 102, 111, 111, 119, 3, 98, 97, 114, 97, 3],
encode(Term::from(ExternalFun::from(("foo", "bar", 3))))
);
}
Expand All @@ -278,10 +276,10 @@ fn internal_fun_test() {
free_vars: vec![Term::from(FixInteger::from(10))],
};
let bytes = [
131, 112, 0, 0, 0, 71, 1, 115, 60, 203, 97, 151, 228, 98, 75, 71, 169, 49, 166, 34, 126,
65, 11, 0, 0, 0, 0, 0, 0, 0, 1, 100, 0, 1, 97, 97, 0, 98, 3, 153, 230, 91, 88, 100, 0, 13,
110, 111, 110, 111, 100, 101, 64, 110, 111, 104, 111, 115, 116, 0, 0, 0, 36, 0, 0, 0, 0, 0,
0, 0, 0, 97, 10,
131, 112, 0, 0, 0, 69, 1, 115, 60, 203, 97, 151, 228, 98, 75, 71, 169, 49, 166, 34, 126,
65, 11, 0, 0, 0, 0, 0, 0, 0, 1, 119, 1, 97, 97, 0, 98, 3, 153, 230, 91, 88, 119, 13, 110,
111, 110, 111, 100, 101, 64, 110, 111, 104, 111, 115, 116, 0, 0, 0, 36, 0, 0, 0, 0, 0, 0,
0, 0, 97, 10,
];
// Decode
assert_eq!(Ok(term.clone()), decode(&bytes).try_into());
Expand Down Expand Up @@ -381,7 +379,7 @@ fn list_test() {
// Encode
assert_eq!(vec![131, 106], encode(Term::from(List::nil())));
assert_eq!(
vec![131, 108, 0, 0, 0, 1, 100, 0, 1, 97, 106],
vec![131, 108, 0, 0, 0, 1, 119, 1, 97, 106],
encode(Term::from(List::from(vec![Term::from(Atom::from("a"))])))
);
}
Expand Down Expand Up @@ -409,7 +407,7 @@ fn improper_list_test() {

// Encode
assert_eq!(
vec![131, 108, 0, 0, 0, 1, 100, 0, 1, 97, 97, 1],
vec![131, 108, 0, 0, 0, 1, 119, 1, 97, 97, 1],
encode(Term::from(ImproperList::from((
vec![Term::from(Atom::from("a"))],
Term::from(FixInteger::from(1))
Expand Down Expand Up @@ -441,7 +439,7 @@ fn tuple_test() {

// Encode
assert_eq!(
vec![131, 104, 2, 100, 0, 1, 97, 97, 1],
vec![131, 104, 2, 119, 1, 97, 97, 1],
encode(Term::from(Tuple::from(vec![
Term::from(Atom::from("a")),
Term::from(FixInteger::from(1))
Expand Down Expand Up @@ -478,12 +476,8 @@ fn map_test() {
let buf = encode(Term::from(map.clone()));
// Hashmap Iter is not deterministic, so we need to check both possible outputs
assert!(
[
131, 116, 0, 0, 0, 2, 97, 1, 97, 2, 100, 0, 1, 97, 100, 0, 1, 98
] == buf.as_slice()
|| [
131, 116, 0, 0, 0, 2, 100, 0, 1, 97, 100, 0, 1, 98, 97, 1, 97, 2
] == buf.as_slice()
[131, 116, 0, 0, 0, 2, 97, 1, 97, 2, 119, 1, 97, 119, 1, 98] == buf.as_slice()
|| [131, 116, 0, 0, 0, 2, 119, 1, 97, 119, 1, 98, 97, 1, 97, 2] == buf.as_slice()
);

//Access
Expand Down