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host_env: Don't truncate two byte wchar_t #8296

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Merged
youknowone merged 1 commit into from
Jul 17, 2026
Merged

host_env: Don't truncate two byte wchar_t #8296

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32 changes: 16 additions & 16 deletions crates/host_env/src/ctypes.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -440,7 +440,7 @@ pub fn read_pointer_from_buffer(buffer: &[u8]) -> usize {
pub const WCHAR_SIZE: usize = core::mem::size_of::<WChar>();

#[inline]
pub fn wchar_from_bytes(bytes: &[u8]) -> Option<u32> {
pub const fn wchar_from_bytes(bytes: &[u8]) -> Option<u32> {
if bytes.len() < WCHAR_SIZE {
return None;
}
Expand Down Expand Up @@ -524,20 +524,17 @@ pub fn encode_wtf8_to_wchar_padded(s: &Wtf8, size: usize) -> Vec<u8> {
}

pub fn wchar_null_terminated_bytes(s: &Wtf8) -> Vec<u8> {
let wchars: Vec<WChar> = s
.code_points()
.map(|cp| cp.to_u32() as WChar)
.chain(core::iter::once(0))
.collect();
vec_into_bytes(wchars)
}

pub fn vec_into_bytes<T>(vec: Vec<T>) -> Vec<u8> {
let len = vec.len() * core::mem::size_of::<T>();
let cap = vec.capacity() * core::mem::size_of::<T>();
let ptr = vec.as_ptr() as *mut u8;
core::mem::forget(vec);
unsafe { Vec::from_raw_parts(ptr, len, cap) }
if size_of::<WChar>() == 2 {
// We can't cast u32 to WChar because it would truncate the value on platforms where WChar
// is two bytes. Wtf8::encode_wide does all of the hard work for us, so all we have to do
// is split the bytes.
utf16z_bytes(s)
} else {
s.code_points()
.flat_map(|cp| (cp.to_u32() as WChar).to_ne_bytes())
.chain((0 as WChar).to_ne_bytes())
.collect()
}
}

pub enum IntegerValue {
Expand Down Expand Up @@ -1108,7 +1105,10 @@ pub fn simple_storage_value_to_bytes_endian(
}

pub fn utf16z_bytes(s: &Wtf8) -> Vec<u8> {
vec_into_bytes::<u16>(s.encode_wide().chain(core::iter::once(0)).collect())
s.encode_wide()
.flat_map(|cp| cp.to_ne_bytes())
.chain(0u16.to_ne_bytes())
.collect()
}

pub fn null_terminated_bytes(bytes: &[u8]) -> Vec<u8> {
Expand Down
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