multiboot2: simplify BoxedDst::new

Author: phip1611

multiboot2/Changelog.md

@@ -5,6 +5,8 @@
   constant. This is only breaking to users that used `BootInformation::get_tag`
   or that implement custom tags. `BootInformation::get_tag` doesn't need the
   `typ` parameter anymore, as it can be deduced from the provided type.
+- **BREAKING** `BoxedDst::new` doesn't have the `typ` parameter anymore. This
+  only effects you when you wrote a custom DST tag.
 
 ## 0.17.0 (2023-07-12)
 - **BREAKING** Make functions of `InformationBuilder` chainable. They now consume the builder.

multiboot2/src/boot_loader_name.rs

@@ -25,7 +25,7 @@ impl BootLoaderNameTag {
             // terminating null-byte
             bytes.push(0);
         }
-        BoxedDst::new(TagType::BootLoaderName, &bytes)
+        BoxedDst::new(&bytes)
     }
 
     /// Reads the name of the bootloader that is booting the kernel as Rust

multiboot2/src/builder/mod.rs

@@ -35,11 +35,10 @@ impl<T: TagTrait<Metadata = usize> + ?Sized> BoxedDst<T> {
     /// Create a boxed tag with the given content.
     ///
     /// # Parameters
-    /// - `typ` - The given [`TagTypeId`]
     /// - `content` - All payload bytes of the DST tag without the tag type or
     ///               the size. The memory is only read and can be discarded
     ///               afterwards.
-    pub(crate) fn new(typ: impl Into<TagTypeId>, content: &[u8]) -> Self {
+    pub(crate) fn new(content: &[u8]) -> Self {
         // Currently, I do not find a nice way of making this dynamic so that
         // also miri is guaranteed to be happy. But it seems that 4 is fine
         // here. I do have control over allocation and deallocation.
@@ -63,7 +62,7 @@ impl<T: TagTrait<Metadata = usize> + ?Sized> BoxedDst<T> {
         unsafe {
             // write tag type
             let ptrx = ptr.cast::<TagTypeId>();
-            ptrx.write(typ.into());
+            ptrx.write(T::ID.into());
 
             // write tag size
             let ptrx = ptrx.add(1).cast::<u32>();
@@ -139,11 +138,10 @@ mod tests {
 
     #[test]
     fn test_boxed_dst_tag() {
-        let tag_type_id = 1337_u32;
         let content = "hallo";
 
-        let tag = BoxedDst::<CustomTag>::new(tag_type_id, content.as_bytes());
-        assert_eq!(tag.typ, tag_type_id);
+        let tag = BoxedDst::<CustomTag>::new(content.as_bytes());
+        assert_eq!(tag.typ, CustomTag::ID);
         assert_eq!(tag.size as usize, METADATA_SIZE + content.len());
         assert_eq!(tag.string(), Ok(content));
     }

multiboot2/src/command_line.rs

@@ -33,7 +33,7 @@ impl CommandLineTag {
             // terminating null-byte
             bytes.push(0);
         }
-        BoxedDst::new(TagType::Cmdline, &bytes)
+        BoxedDst::new(&bytes)
     }
 
     /// Reads the command line of the kernel as Rust string slice without

multiboot2/src/efi.rs

@@ -18,7 +18,7 @@ impl EFISdt32Tag {
     /// Create a new tag to pass the EFI32 System Table pointer.
     pub fn new(pointer: u32) -> Self {
         Self {
-            typ: TagType::Efi32.into(),
+            typ: Self::ID.into(),
             size: size_of::<Self>().try_into().unwrap(),
             pointer,
         }
@@ -49,7 +49,7 @@ impl EFISdt64Tag {
     /// Create a new tag to pass the EFI64 System Table pointer.
     pub fn new(pointer: u64) -> Self {
         Self {
-            typ: TagType::Efi64.into(),
+            typ: Self::ID.into(),
             size: size_of::<Self>().try_into().unwrap(),
             pointer,
         }
@@ -81,7 +81,7 @@ impl EFIImageHandle32Tag {
     #[cfg(feature = "builder")]
     pub fn new(pointer: u32) -> Self {
         Self {
-            typ: TagType::Efi32Ih.into(),
+            typ: Self::ID.into(),
             size: size_of::<Self>().try_into().unwrap(),
             pointer,
         }
@@ -113,7 +113,7 @@ impl EFIImageHandle64Tag {
     #[cfg(feature = "builder")]
     pub fn new(pointer: u64) -> Self {
         Self {
-            typ: TagType::Efi64Ih.into(),
+            typ: Self::ID.into(),
             size: size_of::<Self>().try_into().unwrap(),
             pointer,
         }

multiboot2/src/elf_sections.rs

@@ -37,7 +37,7 @@ impl ElfSectionsTag {
         ]
         .concat();
         bytes.extend_from_slice(sections);
-        BoxedDst::new(TagType::ElfSections, &bytes)
+        BoxedDst::new(&bytes)
     }
 
     /// Get an iterator of loaded ELF sections.

multiboot2/src/framebuffer.rs

@@ -97,7 +97,7 @@ impl FramebufferTag {
         bytes.extend(height.to_le_bytes());
         bytes.extend(bpp.to_le_bytes());
         bytes.extend(buffer_type.to_bytes());
-        BoxedDst::new(TagType::Framebuffer, &bytes)
+        BoxedDst::new(&bytes)
     }
 
     /// Contains framebuffer physical address.

multiboot2/src/image_load_addr.rs

@@ -17,7 +17,7 @@ impl ImageLoadPhysAddrTag {
     #[cfg(feature = "builder")]
     pub fn new(load_base_addr: u32) -> Self {
         Self {
-            typ: TagType::ImageLoadPhysAddr.into(),
+            typ: Self::ID.into(),
             size: size_of::<Self>().try_into().unwrap(),
             load_base_addr,
         }
@@ -30,7 +30,7 @@ impl ImageLoadPhysAddrTag {
 }
 
 impl TagTrait for ImageLoadPhysAddrTag {
-    const ID: TagType = TagType::ImageLoadPhysAddr;
+    const ID: TagType = TagType::LoadBaseAddr;
 
     fn dst_size(_base_tag: &Tag) {}
 }

multiboot2/src/lib.rs

@@ -526,7 +526,7 @@ impl fmt::Debug for BootInformation<'_> {
 ///
 /// # Trivia
 /// This crate uses the [`Pointee`]-abstraction of the [`ptr_meta`] crate to
-/// create fat pointers.
+/// create fat pointers for tags that are DST.
 pub trait TagTrait: Pointee {
     /// The numeric ID of this tag.
     const ID: TagType;

multiboot2/src/memory_map.rs

@@ -40,7 +40,7 @@ impl MemoryMapTag {
         for area in areas {
             bytes.extend(area.as_bytes());
         }
-        BoxedDst::new(TagType::Mmap, bytes.as_slice())
+        BoxedDst::new(bytes.as_slice())
     }
 
     /// Returns the entry size.
@@ -239,7 +239,7 @@ pub struct BasicMemoryInfoTag {
 impl BasicMemoryInfoTag {
     pub fn new(memory_lower: u32, memory_upper: u32) -> Self {
         Self {
-            typ: TagType::BasicMeminfo.into(),
+            typ: Self::ID.into(),
             size: mem::size_of::<BasicMemoryInfoTag>().try_into().unwrap(),
             memory_lower,
             memory_upper,
@@ -293,7 +293,7 @@ impl EFIMemoryMapTag {
         for desc in descs {
             bytes.extend(desc.as_bytes());
         }
-        BoxedDst::new(TagType::EfiMmap, bytes.as_slice())
+        BoxedDst::new(bytes.as_slice())
     }
 
     /// Return an iterator over ALL marked memory areas.