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// Copyright 2021 Colin Finck <colin@reactos.org>
// SPDX-License-Identifier: MIT OR Apache-2.0
use crate::attribute_value::NtfsAttributeValue;
use crate::error::{NtfsError, Result};
use crate::index_entry::{IndexNodeEntryRanges, NtfsIndexNodeEntries};
use crate::indexes::NtfsIndexEntryType;
use crate::ntfs::Ntfs;
use crate::record::Record;
use crate::record::RecordHeader;
use crate::traits::NtfsReadSeek;
use crate::types::Vcn;
use binread::io::{Read, Seek};
use byteorder::{ByteOrder, LittleEndian};
use core::ops::Range;
use memoffset::offset_of;
/// Size of all [`IndexRecordHeader`] fields.
const INDEX_RECORD_HEADER_SIZE: u32 = 24;
#[repr(C, packed)]
struct IndexRecordHeader {
record_header: RecordHeader,
vcn: i64,
}
/// Size of all [`IndexNodeHeader`] fields plus some reserved bytes.
pub(crate) const INDEX_NODE_HEADER_SIZE: usize = 16;
#[repr(C, packed)]
pub(crate) struct IndexNodeHeader {
pub(crate) entries_offset: u32,
pub(crate) index_size: u32,
pub(crate) allocated_size: u32,
pub(crate) flags: u8,
}
/// A single NTFS Index Record.
///
/// These records are denoted via an `INDX` signature on the filesystem.
///
/// NTFS uses B-tree indexes to quickly look up files, Object IDs, Reparse Points, Security Descriptors, etc.
/// An Index Record is further comprised of Index Entries, which contain the actual key/data (see [`NtfsIndexEntry`],
/// iterated via [`NtfsIndexNodeEntries`]).
///
/// [`NtfsIndexEntry`]: crate::NtfsIndexEntry
///
/// Reference: <https://flatcap.github.io/linux-ntfs/ntfs/concepts/index_record.html>
#[derive(Debug)]
pub struct NtfsIndexRecord<'n> {
record: Record<'n>,
}
const HAS_SUBNODES_FLAG: u8 = 0x01;
impl<'n> NtfsIndexRecord<'n> {
pub(crate) fn new<T>(
ntfs: &'n Ntfs,
fs: &mut T,
mut value: NtfsAttributeValue<'n, '_>,
index_record_size: u32,
) -> Result<Self>
where
T: Read + Seek,
{
// The caller must have checked that value.stream_position() < value.len(),
// so that value.data_position() returns a value.
let data_position = value.data_position().unwrap();
let mut data = vec![0; index_record_size as usize];
value.read_exact(fs, &mut data)?;
let mut record = Record::new(ntfs, data, data_position);
Self::validate_signature(&record)?;
record.fixup()?;
let index_record = Self { record };
index_record.validate_sizes()?;
Ok(index_record)
}
/// Returns an iterator over all entries of this Index Record (cf. [`NtfsIndexEntry`]).
///
/// [`NtfsIndexEntry`]: crate::NtfsIndexEntry
pub fn entries<'r, E>(&'r self) -> Result<NtfsIndexNodeEntries<'r, E>>
where
E: NtfsIndexEntryType,
{
let (entries_range, position) = self.entries_range_and_position();
let data = &self.record.data()[entries_range];
Ok(NtfsIndexNodeEntries::new(data, position))
}
fn entries_range_and_position(&self) -> (Range<usize>, u64) {
let start = INDEX_RECORD_HEADER_SIZE as usize + self.index_entries_offset() as usize;
let end = INDEX_RECORD_HEADER_SIZE as usize + self.index_data_size() as usize;
let position = self.record.position() + start as u64;
(start..end, position)
}
/// Returns whether this index node has sub-nodes.
/// Otherwise, this index node is a leaf node.
pub fn has_subnodes(&self) -> bool {
let start = INDEX_RECORD_HEADER_SIZE as usize + offset_of!(IndexNodeHeader, flags);
let flags = self.record.data()[start];
(flags & HAS_SUBNODES_FLAG) != 0
}
/// Returns the allocated size of this NTFS Index Record, in bytes.
pub fn index_allocated_size(&self) -> u32 {
let start = INDEX_RECORD_HEADER_SIZE as usize + offset_of!(IndexNodeHeader, allocated_size);
LittleEndian::read_u32(&self.record.data()[start..])
}
/// Returns the size actually used by index data within this NTFS Index Record, in bytes.
pub fn index_data_size(&self) -> u32 {
let start = INDEX_RECORD_HEADER_SIZE as usize + offset_of!(IndexNodeHeader, index_size);
LittleEndian::read_u32(&self.record.data()[start..])
}
pub(crate) fn index_entries_offset(&self) -> u32 {
let start = INDEX_RECORD_HEADER_SIZE as usize + offset_of!(IndexNodeHeader, entries_offset);
LittleEndian::read_u32(&self.record.data()[start..])
}
pub(crate) fn into_entry_ranges<E>(self) -> IndexNodeEntryRanges<E>
where
E: NtfsIndexEntryType,
{
let (entries_range, position) = self.entries_range_and_position();
IndexNodeEntryRanges::new(self.record.into_data(), entries_range, position)
}
fn validate_signature(record: &Record) -> Result<()> {
let signature = &record.signature();
let expected = b"INDX";
if signature == expected {
Ok(())
} else {
Err(NtfsError::InvalidIndexSignature {
position: record.position(),
expected,
actual: *signature,
})
}
}
fn validate_sizes(&self) -> Result<()> {
let index_record_size = self.record.len() as u32;
// The total size allocated for this Index Record must not be larger than
// the size defined for all index records of this index.
let total_allocated_size = INDEX_RECORD_HEADER_SIZE + self.index_allocated_size();
if total_allocated_size > index_record_size {
return Err(NtfsError::InvalidIndexAllocatedSize {
position: self.record.position(),
expected: index_record_size,
actual: total_allocated_size,
});
}
// Furthermore, the total used size for this Index Record must not be
// larger than the total allocated size.
let total_data_size = INDEX_RECORD_HEADER_SIZE + self.index_data_size();
if total_data_size > total_allocated_size {
return Err(NtfsError::InvalidIndexUsedSize {
position: self.record.position(),
expected: total_allocated_size,
actual: total_data_size,
});
}
Ok(())
}
/// Returns the Virtual Cluster Number (VCN) of this Index Record, as reported by the header of this Index Record.
///
/// This can be used to double-check that an Index Record is the actually requested one.
/// [`NtfsIndexAllocation::record_from_vcn`] uses it for that purpose.
///
/// [`NtfsIndexAllocation::record_from_vcn`]: crate::structured_values::NtfsIndexAllocation::record_from_vcn
pub fn vcn(&self) -> Vcn {
let start = offset_of!(IndexRecordHeader, vcn);
Vcn::from(LittleEndian::read_i64(&self.record.data()[start..]))
}
}
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