fix(runtime): replace unpaired surrogates with U+FFFD in UTF-16 TextD…#5304
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tkshsbcue wants to merge 1 commit intoboa-dev:mainfrom
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fix(runtime): replace unpaired surrogates with U+FFFD in UTF-16 TextD…#5304tkshsbcue wants to merge 1 commit intoboa-dev:mainfrom
tkshsbcue wants to merge 1 commit intoboa-dev:mainfrom
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…ecoder The UTF-16 TextDecoder (both LE and BE) was passing raw code units directly to JsString, preserving unpaired surrogates instead of replacing them with U+FFFD as required by the WHATWG Encoding Standard. Route both decoders through a shared `decode_utf16_units` helper that uses `std::char::decode_utf16` with replacement, and simplify the UTF-16 BE decoder to borrow instead of taking ownership. Closes boa-dev#4612
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Test262 conformance changes
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| const INVALID_UTF16_CASES: &[(&[u16], &[u16])] = &[ | ||
| // Lone high surrogate in the middle | ||
| ( | ||
| &[0x0061, 0x0062, 0xD800, 0x0077, 0x0078], | ||
| &[0x0061, 0x0062, 0xFFFD, 0x0077, 0x0078], | ||
| ), | ||
| // Lone high surrogate only | ||
| (&[0xD800], &[0xFFFD]), | ||
| // Two consecutive high surrogates | ||
| (&[0xD800, 0xD800], &[0xFFFD, 0xFFFD]), | ||
| // Lone low surrogate in the middle | ||
| ( | ||
| &[0x0061, 0x0062, 0xDFFF, 0x0077, 0x0078], | ||
| &[0x0061, 0x0062, 0xFFFD, 0x0077, 0x0078], | ||
| ), | ||
| // Low surrogate followed by high surrogate (wrong order) | ||
| (&[0xDFFF, 0xD800], &[0xFFFD, 0xFFFD]), | ||
| ]; | ||
|
|
||
| #[test] | ||
| fn decoder_utf16le_replaces_unpaired_surrogates() { | ||
| for (invalid, replaced) in INVALID_UTF16_CASES { | ||
| let mut input_bytes = Vec::with_capacity(invalid.len() * 2); | ||
| for &code_unit in *invalid { | ||
| input_bytes.extend_from_slice(&code_unit.to_le_bytes()); | ||
| } | ||
|
|
||
| let result = encodings::utf16le::decode(&input_bytes, false); | ||
| let expected = JsString::from(*replaced); | ||
| assert_eq!(result, expected, "utf16le failed for input {invalid:?}"); | ||
| } | ||
| } | ||
|
|
||
| #[test] | ||
| fn decoder_utf16be_replaces_unpaired_surrogates() { | ||
| for (invalid, replaced) in INVALID_UTF16_CASES { | ||
| let mut input_bytes = Vec::with_capacity(invalid.len() * 2); | ||
| for &code_unit in *invalid { | ||
| input_bytes.extend_from_slice(&code_unit.to_be_bytes()); | ||
| } | ||
|
|
||
| let result = encodings::utf16be::decode(&input_bytes, false); | ||
| let expected = JsString::from(*replaced); | ||
| assert_eq!(result, expected, "utf16be failed for input {invalid:?}"); | ||
| } | ||
| } | ||
|
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||
| #[test] | ||
| fn decoder_utf16le_dangling_byte_produces_replacement() { | ||
| // Odd-length input: the last byte is truncated and replaced with U+FFFD | ||
| let input: &[u8] = &[0x41, 0x00, 0x42]; // 'A' (LE) + dangling byte | ||
| let result = encodings::utf16le::decode(input, false); | ||
| let expected = JsString::from(&[0x0041u16, 0xFFFD][..]); | ||
| assert_eq!(result, expected); | ||
| } | ||
|
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||
| #[test] | ||
| fn decoder_utf16be_dangling_byte_produces_replacement() { | ||
| let input: &[u8] = &[0x00, 0x41, 0x42]; // 'A' (BE) + dangling byte | ||
| let result = encodings::utf16be::decode(input, false); | ||
| let expected = JsString::from(&[0x0041u16, 0xFFFD][..]); | ||
| assert_eq!(result, expected); | ||
| } |
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Do we need these tests? Might be better to enable the utf16 decoding tests from the wpt suite instead, since those basically compile to the same kind of tests
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fix(runtime): replace unpaired surrogates with U+FFFD in UTF-16 TextDecoder
Summary
Fixes #4612.
The UTF-16
TextDecoder(both LE and BE) passed raw code units directly toJsString, preserving unpaired surrogates (e.g.\ud800) instead of replacing them with U+FFFD as required by the WHATWG Encoding Standard.Changes
decode_utf16_units()helper usingstd::char::decode_utf16with.unwrap_or('\u{FFFD}')to produce well-formed outpututf16le::decodeandutf16be::decodethrough this helperutf16be::decodeto borrow (&[u8]) instead of taking ownership (Vec<u8>)Test plan
decoder_utf16le_replaces_unpaired_surrogates— lone high/low surrogates, consecutive, reversed pairsdecoder_utf16be_replaces_unpaired_surrogates— same for big-endiandecoder_utf16le_dangling_byte_produces_replacement— odd-length inputdecoder_utf16be_dangling_byte_produces_replacement— odd-length input (BE)cargo fmtandcargo clippyclean