Make all structured values ready for indexes and non-resident attributes

This introduces a `NewNtfsStructuredValue` trait for the `new` function of all structured values.
Indexes later need that to return the structured value specified by a type parameter.
We also have to pass an explicit length and can't just rely on the end of the passed `NtfsAttributeValue`/`NtfsAttributeValueAttached`.

For structured values of non-resident attributes, we have to store an `NtfsAttributeValue` instead of an absolute byte position, in order to let a structured value read additional data (e.g. the name of an `NtfsFileName`).
The `NtfsAttributeValue` properly moves between data runs while reading.

1 files changed, 9 insertions, 10 deletions

diff --git a/src/structured_values/index_root.rs b/src/structured_values/index_root.rs
index 14873e2..26c7115 100644
--- a/src/structured_values/index_root.rs
+++ b/src/structured_values/index_root.rs
@@ -2,8 +2,9 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 use crate::attribute::NtfsAttributeType;
-use crate::attribute_value::NtfsAttributeValueAttached;
+use crate::attribute_value::NtfsAttributeValue;
 use crate::error::{NtfsError, Result};
+use crate::structured_values::NewNtfsStructuredValue;
 use binread::io::{Read, Seek};
 use binread::{BinRead, BinReaderExt};
 
@@ -33,23 +34,21 @@ pub struct NtfsIndexRoot {
     header: IndexRootHeader,
 }
 
-impl NtfsIndexRoot {
-    pub(crate) fn new<T>(
-        attribute_position: u64,
-        mut value_attached: NtfsAttributeValueAttached<'_, '_, T>,
-    ) -> Result<Self>
+impl<'n> NewNtfsStructuredValue<'n> for NtfsIndexRoot<'n> {
+    fn new<T>(fs: &mut T, value: NtfsAttributeValue<'n>, _length: u64) -> Result<Self>
     where
         T: Read + Seek,
     {
-        if value_attached.len() < INDEX_ROOT_HEADER_SIZE {
-            return Err(NtfsError::InvalidAttributeSize {
-                position: attribute_position,
+        if value.len() < INDEX_ROOT_HEADER_SIZE {
+            return Err(NtfsError::InvalidStructuredValueSize {
+                position: value.data_position().unwrap(),
                 ty: NtfsAttributeType::IndexRoot,
                 expected: INDEX_ROOT_HEADER_SIZE,
-                actual: value_attached.len(),
+                actual: value.len(),
             });
         }
 
+        let mut value_attached = value.clone().attach(fs);
         let header = value_attached.read_le::<IndexRootHeader>()?;
 
         Ok(Self { header })