multiboot2: use TagIter from common package

Author: phip1611

multiboot2/src/boot_information.rs

@@ -410,7 +410,7 @@ impl<'a> BootInformation<'a> {
 
     /// Returns an iterator over all tags.
     fn tags(&self) -> TagIter {
-        TagIter::new(&self.0.payload())
+        TagIter::new(self.0.payload())
     }
 }
 

multiboot2/src/tag.rs

@@ -13,7 +13,7 @@ use crate::{TagTrait, TagType, TagTypeId};
 use core::fmt::{Debug, Formatter};
 use core::mem;
 use core::ptr;
-use multiboot2_common::increase_to_alignment;
+use multiboot2_common::iter::TagBytesIter;
 use multiboot2_common::{BytesRef, DynSizedStructure, Header};
 
 /// The common header that all tags have in common. This type is ABI compatible.
@@ -65,10 +65,8 @@ impl GenericTag {
     pub fn ref_from<'a>(bytes: &'a [u8]) -> &'a Self {
         let bytes = BytesRef::<TagHeader>::try_from(bytes).unwrap();
         let inner = DynSizedStructure::ref_from(bytes).unwrap();
-        let tag = unsafe { mem::transmute::<_, &'a Self>(inner) };
-        tag
+        unsafe { mem::transmute::<_, &'a Self>(inner) }
     }
-
     /// Returns the underlying [`TagHeader`].
     pub const fn header(&self) -> &TagHeader {
         self.0.header()
@@ -83,7 +81,7 @@ impl GenericTag {
     /// may be a ZST or DST typed tag.
     pub fn cast<T: TagTrait + ?Sized>(&self) -> &T {
         let base_ptr = ptr::addr_of!(*self);
-        let t_dst_size = T::dst_len(&self.0.header());
+        let t_dst_size = T::dst_len(self.0.header());
         let t_ptr = ptr_meta::from_raw_parts(base_ptr.cast(), t_dst_size);
         let t_ref = unsafe { &*t_ptr };
         assert_eq!(mem::size_of_val(self), mem::size_of_val(t_ref));
@@ -94,7 +92,7 @@ impl GenericTag {
 impl Debug for GenericTag {
     fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
         f.debug_struct("GenericTag")
-            .field("header", &self.0.header())
+            .field("header", self.0.header())
             .field("payload", &"<bytes>")
             .finish()
     }
@@ -109,65 +107,24 @@ impl TagTrait for GenericTag {
     }
 }
 
-/// Iterates the tags of the MBI from the first tag to the end tag. THe end tag
-/// included.
+/// Iterates the tags of the MBI from the first tag to the end tag. The end tag
+/// is included.
 #[derive(Clone, Debug)]
-pub struct TagIter<'a> {
-    /// Absolute offset to next tag and updated in each iteration.
-    next_tag_offset: usize,
-    exclusive_end: *const u8,
-    buffer: &'a [u8],
-}
+pub struct TagIter<'a>(TagBytesIter<'a, TagHeader>);
 
 impl<'a> TagIter<'a> {
-    /// Creates a new iterator
+    /// Creates a new iterator.
     pub fn new(mem: &'a [u8]) -> Self {
-        // Assert alignment.
-        assert_eq!(mem.as_ptr().align_offset(8), 0);
-
-        let exclusive_end = unsafe { mem.as_ptr().add(mem.len()) };
-
-        TagIter {
-            next_tag_offset: 0,
-            buffer: mem,
-            exclusive_end,
-        }
+        Self(TagBytesIter::new(mem))
     }
 }
 
 impl<'a> Iterator for TagIter<'a> {
     type Item = &'a GenericTag;
 
     fn next(&mut self) -> Option<Self::Item> {
-        let next_ptr = unsafe { self.buffer.as_ptr().add(self.next_tag_offset) };
-
-        if next_ptr == self.exclusive_end {
-            return None;
-        }
-        assert!(next_ptr < self.exclusive_end);
-
-        let next_tag_ptr = next_ptr.cast::<TagHeader>();
-
-        let tag_hdr = unsafe { &*next_tag_ptr };
-
-        // Get relevant byte portion for the next tag. This includes padding
-        // bytes to fulfill Rust memory guarantees. Otherwise, Miri complains.
-        // See <https://doc.rust-lang.org/reference/type-layout.html>.
-        let bytes = {
-            let from = self.next_tag_offset;
-            let to = from + tag_hdr.size as usize;
-            // The size of [the allocation for] a value is always a multiple of its
-            // alignment.
-            // https://doc.rust-lang.org/reference/type-layout.html
-            let to = increase_to_alignment(to);
-
-            // Update ptr for next iteration.
-            self.next_tag_offset += to - from;
-
-            &self.buffer[from..to]
-        };
-
-        Some(GenericTag::ref_from(bytes))
+        let bytes = self.0.next()?;
+        Some(GenericTag::ref_from(bytes.as_ref()))
     }
 }