WasmVM: WASI sysroot wide character streams incomplete (open_wmemstream, swprintf)

[NathanFlurry]

Summary

Wide character stream functions open_wmemstream() and swprintf() do not work correctly in the WASI sysroot. These functions depend on wide character I/O support which may be incomplete in the musl-based WASI libc.

Affected os-test cases

• basic/wchar/open_wmemstream
• basic/wchar/swprintf

Expected behavior

Wide character stream operations should produce correct output matching POSIX semantics.

Context

Discovered via os-test POSIX conformance suite. Tracked in posix-exclusions.json as fail / patched-sysroot.

[NathanFlurry]

Fixed in 7d35dad0 — open_wmemstream reimplemented with fopencookie for correct wchar_t size tracking, swprintf wrapped to set errno=EOVERFLOW.