Commit Graph

1 Commits

Author SHA1 Message Date
robobun
7110dc10a4 Fix UTF-16 encoding crash with odd-length byte arrays (#21966)
## Summary
- Fixes a panic: "exact division produced remainder" that occurs when
reading files with odd number of bytes using utf16le/ucs2 encoding
- The crash happened in `encoding.zig:136` when
`std.mem.bytesAsSlice(u16, input)` was called on a byte slice with odd
length
- Fixed by properly checking for odd-length input and truncating to the
nearest even length

## Test plan
- Added regression tests in
`test/regression/issue/utf16-encoding-crash.test.ts`
- Tests verify that reading files with odd byte counts doesn't crash
- Tests verify correct truncation behavior matches Node.js expectations
- Verified edge cases (0, 1 byte inputs) return empty strings

## Root Cause
The original code checked `if (input.len / 2 == 0)` which only caught 0
and 1-byte inputs, but `std.mem.bytesAsSlice(u16, input)` panics on any
odd-length input (3, 5, 7, etc. bytes).

## Fix Details
- Changed condition to check `input.len % 2 != 0` for any odd length
- Truncate odd-length inputs to the nearest even length for valid UTF-16
processing
- Handle edge cases by returning empty string for 0 or 1-byte inputs

🤖 Generated with [Claude Code](https://claude.ai/code)

---------

Co-authored-by: Claude Bot <claude-bot@bun.sh>
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Jarred Sumner <jarred@jarredsumner.com>
Co-authored-by: Dylan Conway <dylan.conway567@gmail.com>
2025-08-20 00:02:14 -07:00