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// Copyright 2021 Colin Finck <colin@reactos.org>
// SPDX-License-Identifier: MIT OR Apache-2.0
use crate::attribute::NtfsAttributeType;
use crate::attribute_value::{NtfsAttributeValue, NtfsResidentAttributeValue};
use crate::error::{NtfsError, Result};
use crate::index_entry::{IndexNodeEntryRanges, NtfsIndexNodeEntries};
use crate::index_record::{IndexNodeHeader, INDEX_NODE_HEADER_SIZE};
use crate::indexes::NtfsIndexEntryType;
use crate::structured_values::{
NtfsStructuredValue, NtfsStructuredValueFromResidentAttributeValue,
};
use binread::io::{Read, Seek};
use byteorder::{ByteOrder, LittleEndian};
use core::ops::Range;
use memoffset::offset_of;
/// Size of all [`IndexRootHeader`] fields plus some reserved bytes.
const INDEX_ROOT_HEADER_SIZE: usize = 16;
#[repr(C, packed)]
struct IndexRootHeader {
ty: u32,
collation_rule: u32,
index_record_size: u32,
clusters_per_index_record: i8,
}
/// Structure of an $INDEX_ROOT attribute.
///
/// This attribute describes the top-level nodes of a B-tree.
/// The sub-nodes are managed via [`NtfsIndexAllocation`].
///
/// NTFS uses B-trees for describing directories (as indexes of [`NtfsFileName`]s), looking up Object IDs,
/// Reparse Points, and Security Descriptors, to just name a few.
///
/// An $INDEX_ROOT attribute is always resident.
///
/// Reference: <https://flatcap.github.io/linux-ntfs/ntfs/attributes/index_root.html>
///
/// [`NtfsFileName`]: crate::structured_values::NtfsFileName
/// [`NtfsIndexAllocation`]: crate::structured_values::NtfsIndexAllocation
#[derive(Clone, Debug)]
pub struct NtfsIndexRoot<'f> {
slice: &'f [u8],
position: u64,
}
const LARGE_INDEX_FLAG: u8 = 0x01;
impl<'f> NtfsIndexRoot<'f> {
fn new(slice: &'f [u8], position: u64) -> Result<Self> {
if slice.len() < INDEX_ROOT_HEADER_SIZE + INDEX_NODE_HEADER_SIZE {
return Err(NtfsError::InvalidStructuredValueSize {
position,
ty: NtfsAttributeType::IndexRoot,
expected: INDEX_ROOT_HEADER_SIZE as u64,
actual: slice.len() as u64,
});
}
let index_root = Self { slice, position };
index_root.validate_sizes()?;
Ok(index_root)
}
/// Returns an iterator over all top-level nodes of the B-tree.
pub fn entries<E>(&self) -> Result<NtfsIndexNodeEntries<'f, E>>
where
E: NtfsIndexEntryType,
{
let (entries_range, position) = self.entries_range_and_position();
let slice = &self.slice[entries_range];
Ok(NtfsIndexNodeEntries::new(slice, position))
}
fn entries_range_and_position(&self) -> (Range<usize>, u64) {
let start = INDEX_ROOT_HEADER_SIZE as usize + self.index_entries_offset() as usize;
let end = INDEX_ROOT_HEADER_SIZE as usize + self.index_data_size() as usize;
let position = self.position + start as u64;
(start..end, position)
}
pub(crate) fn entry_ranges<E>(&self) -> IndexNodeEntryRanges<E>
where
E: NtfsIndexEntryType,
{
let (entries_range, position) = self.entries_range_and_position();
let entries_data = self.slice[entries_range].to_vec();
let range = 0..entries_data.len();
IndexNodeEntryRanges::new(entries_data, range, position)
}
/// Returns the allocated size of this NTFS Index Root, in bytes.
pub fn index_allocated_size(&self) -> u32 {
let start = INDEX_ROOT_HEADER_SIZE + offset_of!(IndexNodeHeader, allocated_size);
LittleEndian::read_u32(&self.slice[start..])
}
/// Returns the size actually used by index data within this NTFS Index Root, in bytes.
pub fn index_data_size(&self) -> u32 {
let start = INDEX_ROOT_HEADER_SIZE + offset_of!(IndexNodeHeader, index_size);
LittleEndian::read_u32(&self.slice[start..])
}
fn index_entries_offset(&self) -> u32 {
let start = INDEX_ROOT_HEADER_SIZE + offset_of!(IndexNodeHeader, entries_offset);
LittleEndian::read_u32(&self.slice[start..])
}
/// Returns the size of a single Index Record, in bytes.
pub fn index_record_size(&self) -> u32 {
let start = offset_of!(IndexRootHeader, index_record_size);
LittleEndian::read_u32(&self.slice[start..])
}
/// Returns whether the index belonging to this Index Root is large enough
/// to need an extra Index Allocation attribute.
/// Otherwise, the entire index information is stored in this Index Root.
pub fn is_large_index(&self) -> bool {
let start = INDEX_ROOT_HEADER_SIZE + offset_of!(IndexNodeHeader, flags);
(self.slice[start] & LARGE_INDEX_FLAG) != 0
}
/// Returns the absolute position of this Index Root within the filesystem, in bytes.
pub fn position(&self) -> u64 {
self.position
}
fn validate_sizes(&self) -> Result<()> {
let (entries_range, _position) = self.entries_range_and_position();
if entries_range.start >= self.slice.len() {
return Err(NtfsError::InvalidIndexRootEntriesOffset {
position: self.position,
expected: entries_range.start,
actual: self.slice.len(),
});
}
if entries_range.end > self.slice.len() {
return Err(NtfsError::InvalidIndexRootUsedSize {
position: self.position,
expected: entries_range.end,
actual: self.slice.len(),
});
}
Ok(())
}
}
impl<'n, 'f> NtfsStructuredValue<'n, 'f> for NtfsIndexRoot<'f> {
const TY: NtfsAttributeType = NtfsAttributeType::IndexRoot;
fn from_attribute_value<T>(_fs: &mut T, value: NtfsAttributeValue<'n, 'f>) -> Result<Self>
where
T: Read + Seek,
{
let resident_value = match value {
NtfsAttributeValue::Resident(resident_value) => resident_value,
_ => {
let position = value.data_position().unwrap();
return Err(NtfsError::UnexpectedNonResidentAttribute { position });
}
};
let position = resident_value.data_position().unwrap();
Self::new(resident_value.data(), position)
}
}
impl<'n, 'f> NtfsStructuredValueFromResidentAttributeValue<'n, 'f> for NtfsIndexRoot<'f> {
fn from_resident_attribute_value(value: NtfsResidentAttributeValue<'f>) -> Result<Self> {
Self::new(value.data(), value.data_position().unwrap())
}
}
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