Re: [PATCH v2 1/2] uaccess: rust: add strncpy_from_user

[John Hubbard <jhubbard@nvidia.com>]

On 4/29/25 10:30 AM, Boqun Feng wrote:
> On Tue, Apr 29, 2025 at 09:02:22AM +0000, Alice Ryhl wrote:
...
>> +#[inline]
>> +pub fn raw_strncpy_from_user(ptr: UserPtr, buf: &mut [MaybeUninit<u8>]) -> Result<usize> {
>> +    // CAST: Slice lengths are guaranteed to be `<= isize::MAX`.
>> +    let len = buf.len() as isize;
>> +
>> +    // SAFETY: `buf` is valid for writing `buf.len()` bytes.
>> +    let res = unsafe {
>> +        bindings::strncpy_from_user(buf.as_mut_ptr().cast::<c_char>(), ptr as *const c_char, len)
>> +    };
>> +
>> +    if res < 0 {
>> +        return Err(Error::from_errno(res as i32));
>> +    }
>> +
> 
> Nit: this can be a
> 
> 	let copy_len = kernel::error::to_result(res)?;
> 

Doesn't that discard the length, though, by returning Ok(()) ?


thanks,
-- 
John Hubbard