fix(driver, IOCP): cap buf, sys_slice length to u32

[KR-bluejay]

Closes #610

Summary

1. Cap sys_slice length at u32::MAX

   • Avoids IOCP truncation issues.

2. Cap Write/WriteAt buffer lengths to u32::MAX

   • These are the only IOCP paths that touch the user buffer directly.
   • Other ops go through sys_slice and don’t need a separate clamp.

3. Adjust read_len_over_u32 test

   • Updated to run on Windows in addition to existing platforms (io_uring).

[Berrysoft]

Would you also fix for Read & ReadAt?

[KR-bluejay]

Hi @Berrysoft ,
Is there a specific reason to do so, given that sys_slice_mut already handles it?

Regarding Read and ReadAt operations: they already invoke the sys_slice_mut function. Since the length is already capped to u32::MAX within the sys_slice implementation, I think additional clamping in these specific operations is unnecessary.

compio/compio-driver/src/sys/iocp/op.rs

Lines 169 to 193 in 4c2bb42

	impl<T: IoBufMut, S: AsFd> OpCode for ReadAt<T, S> {
	unsafe fn operate(self: Pin<&mut Self>, optr: *mut OVERLAPPED) -> Poll<io::Result<usize>> {
	if let Some(overlapped) = unsafe { optr.as_mut() } {
	overlapped.Anonymous.Anonymous.Offset = (self.offset & 0xFFFFFFFF) as _;
	overlapped.Anonymous.Anonymous.OffsetHigh = (self.offset >> 32) as _;
	}
	let fd = self.fd.as_fd().as_raw_fd();
	let slice = self.project().buffer.sys_slice_mut();
	let mut transferred = 0;
	let res = unsafe {
	ReadFile(
	fd,
	slice.ptr() as _,
	slice.len() as _,
	&mut transferred,
	optr,
	)
	};
	win32_result(res, transferred)
	}
	fn cancel(self: Pin<&mut Self>, optr: *mut OVERLAPPED) -> io::Result<()> {
	cancel(self.fd.as_fd().as_raw_fd(), optr)
	}
	}

compio/compio-driver/src/sys/iocp/op.rs

Lines 230 to 250 in 4c2bb42

	impl<T: IoBufMut, S: AsFd> OpCode for Read<T, S> {
	unsafe fn operate(self: Pin<&mut Self>, optr: *mut OVERLAPPED) -> Poll<io::Result<usize>> {
	let fd = self.fd.as_fd().as_raw_fd();
	let slice = self.project().buffer.sys_slice_mut();
	let mut transferred = 0;
	let res = unsafe {
	ReadFile(
	fd,
	slice.ptr() as _,
	slice.len() as _,
	&mut transferred,
	optr,
	)
	};
	win32_result(res, transferred)
	}
	fn cancel(self: Pin<&mut Self>, optr: *mut OVERLAPPED) -> io::Result<()> {
	cancel(self.fd.as_fd().as_raw_fd(), optr)
	}
	}

[Berrysoft]

Fair enough. LGTM.