diff --git a/rust/kernel/uaccess.rs b/rust/kernel/uaccess.rs index 1409cb907015..dde8a0abb46d 100644 --- a/rust/kernel/uaccess.rs +++ b/rust/kernel/uaccess.rs @@ -9,6 +9,7 @@ use crate::{ bindings, error::Result, ffi::{c_char, c_void}, + fs::file, prelude::*, transmute::{AsBytes, FromBytes}, }; @@ -304,6 +305,31 @@ impl UserSliceReader { Ok(dst.len()) } + /// Reads raw data from the user slice into a kernel buffer partially. + /// + /// This is the same as [`Self::read_slice_partial`] but updates the given [`file::Offset`] by + /// the number of bytes read. + /// + /// This is equivalent to C's `simple_write_to_buffer()`. + /// + /// On success, returns the number of bytes read. + pub fn read_slice_file(&mut self, out: &mut [u8], offset: &mut file::Offset) -> Result { + if offset.is_negative() { + return Err(EINVAL); + } + + let Ok(offset_index) = (*offset).try_into() else { + return Ok(0); + }; + + let read = self.read_slice_partial(out, offset_index)?; + + // OVERFLOW: `offset + read <= data.len() <= isize::MAX <= Offset::MAX` + *offset += read as i64; + + Ok(read) + } + /// Reads a value of the specified type. /// /// Fails with [`EFAULT`] if the read happens on a bad address, or if the read goes out of