1 files changed, 81 insertions, 0 deletions
diff --git a/rust/kernel/iov_iter.rs b/rust/kernel/iov_iter.rs
new file mode 100644
index 000000000000..b9b8dc882bd0
--- /dev/null
+++ b/rust/kernel/iov_iter.rs
@@ -0,0 +1,81 @@
+// 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(())
+        }
+    }
+}