multiboot2: remove weird offset thingy

Author: phip1611

multiboot2/src/elf_sections.rs

@@ -41,7 +41,7 @@ impl ElfSectionsTag {
     }
 
     /// Get an iterator of loaded ELF sections.
-    pub(crate) fn sections(&self, offset: usize) -> ElfSectionIter {
+    pub(crate) fn sections(&self) -> ElfSectionIter {
         let string_section_offset = (self.shndx * self.entry_size) as isize;
         let string_section_ptr =
             unsafe { self.first_section().offset(string_section_offset) as *const _ };
@@ -50,7 +50,6 @@ impl ElfSectionsTag {
             remaining_sections: self.number_of_sections,
             entry_size: self.entry_size,
             string_section: string_section_ptr,
-            offset,
         }
     }
 
@@ -93,7 +92,6 @@ pub struct ElfSectionIter {
     remaining_sections: u32,
     entry_size: u32,
     string_section: *const u8,
-    offset: usize,
 }
 
 impl Iterator for ElfSectionIter {
@@ -105,7 +103,6 @@ impl Iterator for ElfSectionIter {
                 inner: self.current_section,
                 string_section: self.string_section,
                 entry_size: self.entry_size,
-                offset: self.offset,
             };
 
             self.current_section = unsafe { self.current_section.offset(self.entry_size as isize) };
@@ -136,7 +133,6 @@ impl Default for ElfSectionIter {
             remaining_sections: 0,
             entry_size: 0,
             string_section: core::ptr::null(),
-            offset: 0,
         }
     }
 }
@@ -147,7 +143,6 @@ pub struct ElfSection {
     inner: *const u8,
     string_section: *const u8,
     entry_size: u32,
-    offset: usize,
 }
 
 #[derive(Clone, Copy, Debug)]
@@ -282,7 +277,7 @@ impl ElfSection {
             64 => (*(self.string_section as *const ElfSectionInner64)).addr as usize,
             s => panic!("Unexpected entry size: {}", s),
         };
-        (addr + self.offset) as *const _
+        addr as *const _
     }
 }
 

multiboot2/src/lib.rs

@@ -144,6 +144,7 @@ pub unsafe fn load(address: usize) -> Result<BootInformation, MbiLoadError> {
 ///   memory is not (identity) mapped (UEFI does only identity mapping).
 /// * The memory at `address` must not be modified after calling `load` or the
 ///   program may observe unsynchronized mutation.
+#[deprecated("Please use load() instead.")]
 pub unsafe fn load_with_offset(
     address: usize,
     offset: usize,
@@ -193,16 +194,40 @@ pub enum MbiLoadError {
 impl core::error::Error for MbiLoadError {}
 
 /// A Multiboot 2 Boot Information struct.
-pub struct BootInformation {
-    inner: *const BootInformationInner,
-    offset: usize,
+#[derive(Debug)]
+#[repr(transparent)]
+pub struct BootInformation<'a>(&'a BootInformationInner<'a>);
+
+impl<'a> BootInformation {
+    /// Loads the [`BootInformation`] from a pointer..
+    pub unsafe fn load(ptr: *const ()) -> Result<Self, MbiLoadError> {
+        if ptr.is_null() {
+            return Err(MbiLoadError::IllegalAddress);
+        }
+
+        // not aligned
+        if ptr.align_offset(8) != 0 {
+            return Err(MbiLoadError::IllegalAddress);
+        }
+
+        let mbi = &*ptr.cast::<BootInformationInner>();
+
+        // Check if total size is a multiple of 8.
+        // See MbiLoadError::IllegalTotalSize for comments
+        if mbi.total_size & 0b111 != 0 {
+            return Err(MbiLoadError::IllegalTotalSize(multiboot.total_size));
+        }
+
+        Ok(Self(mbi))
+    }
 }
 
 #[derive(Clone, Copy)]
-#[repr(C)]
-struct BootInformationInner {
+#[repr(C), align(8)]
+struct BootInformationInner<'a> {
     total_size: u32,
     _reserved: u32,
+    // followed by multiboot2 tags ...
 }
 
 impl BootInformationInner {
@@ -565,7 +590,7 @@ pub trait TagTrait: Pointee {
 // All sized tags automatically have a Pointee implementation where
 // Pointee::Metadata is (). Hence, the TagTrait is implemented automatically for
 // all tags that are sized.
-impl<T: Pointee<Metadata = ()>> TagTrait for T {
+impl<T: Pointee<Metadata=()>> TagTrait for T {
     #[allow(clippy::unused_unit)]
     fn dst_size(_: &Tag) -> Self::Metadata {
         ()
@@ -737,16 +762,16 @@ mod tests {
             FramebufferType::RGB {
                 red: FramebufferField {
                     position: 16,
-                    size: 8
+                    size: 8,
                 },
                 green: FramebufferField {
                     position: 8,
-                    size: 8
+                    size: 8,
                 },
                 blue: FramebufferField {
                     position: 0,
-                    size: 8
-                }
+                    size: 8,
+                },
             }
         );
     }
@@ -798,22 +823,22 @@ mod tests {
                     FramebufferColor {
                         red: 255,
                         green: 0,
-                        blue: 0
+                        blue: 0,
                     },
                     FramebufferColor {
                         red: 0,
                         green: 255,
-                        blue: 0
+                        blue: 0,
                     },
                     FramebufferColor {
                         red: 0,
                         green: 0,
-                        blue: 255
+                        blue: 255,
                     },
                     FramebufferColor {
                         red: 0,
                         green: 0,
-                        blue: 0
+                        blue: 0,
                     }
                 ]
             ),
@@ -946,28 +971,28 @@ mod tests {
             vbe.mode_info.red_field,
             VBEField {
                 position: 16,
-                size: 8
+                size: 8,
             }
         );
         assert_eq!(
             vbe.mode_info.green_field,
             VBEField {
                 position: 8,
-                size: 8
+                size: 8,
             }
         );
         assert_eq!(
             vbe.mode_info.blue_field,
             VBEField {
                 position: 0,
-                size: 8
+                size: 8,
             }
         );
         assert_eq!(
             vbe.mode_info.reserved_field,
             VBEField {
                 position: 24,
-                size: 8
+                size: 8,
             }
         );
         assert_eq!(