uefi: MemoryMap: simplify API

Author: phip1611

uefi/src/table/boot.rs

@@ -262,7 +262,9 @@ impl BootServices {
                 &mut entry_version,
             )
         }
-        .to_result_with_val(move || MemoryMap::from_raw(map_size, buffer, desc_size, map_key))
+        .to_result_with_val(move || {
+            MemoryMap::from_raw(&mut buffer[0..map_size], desc_size, map_key)
+        })
     }
 
     /// Allocates from a memory pool. The pointer will be 8-byte aligned.
@@ -1640,35 +1642,27 @@ pub struct MemoryMap<'buf> {
     /// Usually bound to the size of a [`MemoryDescriptor`] but can indicate if
     /// this field is ever extended by a new UEFI standard.
     desc_size: usize,
-    map_size: usize,
     num_entries: usize,
 }
 
 impl<'buf> MemoryMap<'buf> {
     /// Creates a [`MemoryMap`] from the given buffer, and the reported
-    /// memory map size, descriptor size, and [`MemoryMapKey`] from UEFI.
-    ///
-    /// This map technically owns the buffer (although not modeled yet by type
-    /// system).
-    pub fn from_raw(
-        map_size: usize,
-        buf: &'buf mut [u8],
-        desc_size: usize,
-        key: MemoryMapKey,
-    ) -> Self {
+    /// descriptor size, and [`MemoryMapKey`] from UEFI.
+    ///
+    /// The buffer length is expected to match `memory_map_size` reported by
+    /// UEFI.
+    pub fn from_raw(buf: &'buf mut [u8], desc_size: usize, key: MemoryMapKey) -> Self {
         assert!(!buf.is_empty());
-        assert!(map_size <= buf.len());
         assert_eq!(
             buf.len() % desc_size,
             0,
             "The buffer length must be a multiple of the desc_size"
         );
         assert!(desc_size >= mem::size_of::<MemoryDescriptor>());
-        let num_entries = map_size / desc_size;
+        let num_entries = buf.len() / desc_size;
         MemoryMap {
             key,
             buf,
-            map_size,
             desc_size,
             num_entries,
         }
@@ -1812,11 +1806,7 @@ impl<'buf> MemoryMap<'buf> {
         usize, /* desc_size */
         u32,   /* version */
     ) {
-        (
-            &self.buf[0..self.map_size],
-            self.desc_size,
-            MemoryDescriptor::VERSION,
-        )
+        (self.buf, self.desc_size, MemoryDescriptor::VERSION)
     }
 
     /// Mutable version of [`Self::raw`].
@@ -1832,11 +1822,7 @@ impl<'buf> MemoryMap<'buf> {
         usize, /* desc_size */
         u32,   /* version */
     ) {
-        (
-            &mut self.buf[0..self.map_size],
-            self.desc_size,
-            MemoryDescriptor::VERSION,
-        )
+        (self.buf, self.desc_size, MemoryDescriptor::VERSION)
     }
 }