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// Copyright 2021 Colin Finck <colin@reactos.org>
// SPDX-License-Identifier: GPL-2.0-or-later
use crate::attribute_value::NtfsAttributeValue;
use crate::error::Result;
use crate::ntfs::Ntfs;
use crate::structured_values::NewNtfsStructuredValue;
use crate::traits::NtfsReadSeek;
use binread::io::{Read, Seek, SeekFrom};
use binread::{BinRead, BinReaderExt};
use bitflags::bitflags;
use core::iter::FusedIterator;
use core::marker::PhantomData;
use core::mem;
/// Size of all [`IndexEntryHeader`] fields plus some reserved bytes.
const INDEX_ENTRY_HEADER_SIZE: i64 = 16;
#[derive(BinRead, Clone, Debug)]
struct IndexEntryHeader {
file_ref: u64,
index_entry_length: u16,
key_length: u16,
flags: u8,
}
#[derive(Clone, Debug)]
pub struct NtfsIndexEntry<'n, K>
where
K: NewNtfsStructuredValue<'n>,
{
ntfs: &'n Ntfs,
header: IndexEntryHeader,
value: NtfsAttributeValue<'n>,
key_type: PhantomData<K>,
}
bitflags! {
pub struct NtfsIndexEntryFlags: u8 {
/// This index entry points to a sub-node.
const HAS_SUBNODE = 0x01;
/// This is the last index entry in the list.
const LAST_ENTRY = 0x02;
}
}
impl<'n, K> NtfsIndexEntry<'n, K>
where
K: NewNtfsStructuredValue<'n>,
{
pub(crate) fn new<T>(ntfs: &'n Ntfs, fs: &mut T, value: NtfsAttributeValue<'n>) -> Result<Self>
where
T: Read + Seek,
{
let mut value_attached = value.clone().attach(fs);
let header = value_attached.read_le::<IndexEntryHeader>()?;
let key_type = PhantomData;
let entry = Self {
ntfs,
header,
value,
key_type,
};
Ok(entry)
}
pub fn flags(&self) -> NtfsIndexEntryFlags {
NtfsIndexEntryFlags::from_bits_truncate(self.header.flags)
}
pub fn index_entry_length(&self) -> u16 {
self.header.index_entry_length
}
pub fn key_length(&self) -> u16 {
self.header.key_length
}
/// Returns the structured value of the key of this Index Entry,
/// or `None` if this Index Entry has no key.
/// The last Index Entry never has a key.
pub fn key_structured_value<T>(&self, fs: &mut T) -> Option<Result<K>>
where
T: Read + Seek,
{
if self.header.key_length == 0 || self.flags().contains(NtfsIndexEntryFlags::LAST_ENTRY) {
return None;
}
let mut value = self.value.clone();
iter_try!(value.seek(fs, SeekFrom::Current(INDEX_ENTRY_HEADER_SIZE)));
let length = self.header.key_length as u64;
let structured_value = iter_try!(K::new(self.ntfs, fs, value, length));
Some(Ok(structured_value))
}
/// Returns the Virtual Cluster Number (VCN) of the subnode of this Index Entry,
/// or `None` if this Index Entry has no subnode.
pub fn subnode_vcn<T>(&self, fs: &mut T) -> Option<Result<u64>>
where
T: Read + Seek,
{
if !self.flags().contains(NtfsIndexEntryFlags::HAS_SUBNODE) {
return None;
}
// Read the subnode VCN from the very end of the Index Entry.
let mut value_attached = self.value.clone().attach(fs);
iter_try!(value_attached.seek(SeekFrom::Current(
self.index_entry_length() as i64 - mem::size_of::<u64>() as i64
)));
let vcn = iter_try!(value_attached.read_le::<u64>());
Some(Ok(vcn))
}
}
#[derive(Clone, Debug)]
pub struct NtfsIndexEntries<'n, K>
where
K: NewNtfsStructuredValue<'n>,
{
ntfs: &'n Ntfs,
value: NtfsAttributeValue<'n>,
end: u64,
key_type: PhantomData<K>,
}
impl<'n, K> NtfsIndexEntries<'n, K>
where
K: NewNtfsStructuredValue<'n>,
{
pub(crate) fn new(ntfs: &'n Ntfs, value: NtfsAttributeValue<'n>, end: u64) -> Self {
debug_assert!(end <= value.len());
let key_type = PhantomData;
Self {
ntfs,
value,
end,
key_type,
}
}
pub fn attach<'a, T>(self, fs: &'a mut T) -> NtfsIndexEntriesAttached<'n, 'a, K, T>
where
T: Read + Seek,
{
NtfsIndexEntriesAttached::new(fs, self)
}
pub fn next<T>(&mut self, fs: &mut T) -> Option<Result<NtfsIndexEntry<'n, K>>>
where
T: Read + Seek,
{
if self.value.stream_position() >= self.end {
return None;
}
// Get the current entry.
let entry = iter_try!(NtfsIndexEntry::new(self.ntfs, fs, self.value.clone()));
if entry.flags().contains(NtfsIndexEntryFlags::LAST_ENTRY) {
// This is the last entry.
// Ensure that we don't read any other entries by seeking to the end.
iter_try!(self.value.seek(fs, SeekFrom::Start(self.end)));
} else {
// This is not the last entry.
// Advance our iterator to the next entry.
iter_try!(self
.value
.seek(fs, SeekFrom::Current(entry.index_entry_length() as i64)));
}
Some(Ok(entry))
}
}
pub struct NtfsIndexEntriesAttached<'n, 'a, K, T>
where
K: NewNtfsStructuredValue<'n>,
T: Read + Seek,
{
fs: &'a mut T,
index_entries: NtfsIndexEntries<'n, K>,
}
impl<'n, 'a, K, T> NtfsIndexEntriesAttached<'n, 'a, K, T>
where
K: NewNtfsStructuredValue<'n>,
T: Read + Seek,
{
fn new(fs: &'a mut T, index_entries: NtfsIndexEntries<'n, K>) -> Self {
Self { fs, index_entries }
}
pub fn detach(self) -> NtfsIndexEntries<'n, K> {
self.index_entries
}
}
impl<'n, 'a, K, T> Iterator for NtfsIndexEntriesAttached<'n, 'a, K, T>
where
K: NewNtfsStructuredValue<'n>,
T: Read + Seek,
{
type Item = Result<NtfsIndexEntry<'n, K>>;
fn next(&mut self) -> Option<Self::Item> {
self.index_entries.next(self.fs)
}
}
impl<'n, 'a, K, T> FusedIterator for NtfsIndexEntriesAttached<'n, 'a, K, T>
where
K: NewNtfsStructuredValue<'n>,
T: Read + Seek,
{
}
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