[PATCH RFC v2 4/6] rust/scatterlist: add SGEntry::init_one

[Manos Pitsidianakis <manos@pitsidianak.is>]

Add a method to allow creation of an SGEntry with borrowed data.
Analogous of `sg_init_one` in C.

Signed-off-by: Manos Pitsidianakis <manos@pitsidianak.is>
---
 rust/kernel/scatterlist.rs | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/rust/kernel/scatterlist.rs b/rust/kernel/scatterlist.rs
index 146e738cbd4351b41c11dd39a45e20f404c5cd64..b065762af1a734fcdd5d3acde89199f1a626fd89 100644
--- a/rust/kernel/scatterlist.rs
+++ b/rust/kernel/scatterlist.rs
@@ -95,6 +95,24 @@ pub fn dma_len(&self) -> ResourceSize {
         // SAFETY: `self.as_raw()` is a valid pointer to a `struct scatterlist`.
         unsafe { bindings::sg_dma_len(self.as_raw()) }.into()
     }
+
+    /// Initialize a new entry with borrowed data.
+    ///
+    /// # Safety
+    ///
+    /// Callers must ensure that:
+    /// - `buf` is a valid pointer
+    /// - `buf_len` describes a valid allocation size for this pointer
+    pub unsafe fn init_one(
+        val: &'_ mut core::mem::MaybeUninit<bindings::scatterlist>,
+        buf: NonNull<u8>,
+        buf_len: u32,
+    ) -> &'_ Self {
+        // SAFETY: `val` points to a correctly sized `struct scatterlist`.
+        unsafe { bindings::sg_init_one(val.as_mut_ptr(), buf.as_ptr().cast(), buf_len) };
+        // SAFETY: `val` points to an initialized `struct scatterlist`.
+        unsafe { Self::from_raw(val.as_mut_ptr()) }
+    }
 }
 
 /// The borrowed generic type of an [`SGTable`], representing a borrowed or externally managed

-- 
2.47.3