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// SPDX-License-Identifier: GPL-2.0
//! IO vector iterators.
//!
//! C header: [`include/linux/uio.h`](../../../../include/linux/uio.h)
use crate::{
bindings,
error::code::*,
io_buffer::{IoBufferReader, IoBufferWriter},
Result,
};
/// Wraps the kernel's `struct iov_iter`.
///
/// # Invariants
///
/// The pointer `IovIter::ptr` is non-null and valid.
pub struct IovIter {
ptr: *mut bindings::iov_iter,
}
impl IovIter {
fn common_len(&self) -> usize {
// SAFETY: `IovIter::ptr` is guaranteed to be valid by the type invariants.
unsafe { (*self.ptr).count }
}
/// Constructs a new [`struct iov_iter`] wrapper.
///
/// # Safety
///
/// The pointer `ptr` must be non-null and valid for the lifetime of the object.
pub(crate) unsafe fn from_ptr(ptr: *mut bindings::iov_iter) -> Self {
// INVARIANTS: the safety contract ensures the type invariant will hold.
Self { ptr }
}
}
impl IoBufferWriter for IovIter {
fn len(&self) -> usize {
self.common_len()
}
fn clear(&mut self, mut len: usize) -> Result {
while len > 0 {
// SAFETY: `IovIter::ptr` is guaranteed to be valid by the type invariants.
let written = unsafe { bindings::iov_iter_zero(len, self.ptr) };
if written == 0 {
return Err(EFAULT);
}
len -= written;
}
Ok(())
}
unsafe fn write_raw(&mut self, data: *const u8, len: usize) -> Result {
let res = unsafe { bindings::copy_to_iter(data as _, len, self.ptr) };
if res != len {
Err(EFAULT)
} else {
Ok(())
}
}
}
impl IoBufferReader for IovIter {
fn len(&self) -> usize {
self.common_len()
}
unsafe fn read_raw(&mut self, out: *mut u8, len: usize) -> Result {
let res = unsafe { bindings::copy_from_iter(out as _, len, self.ptr) };
if res != len {
Err(EFAULT)
} else {
Ok(())
}
}
}
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