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//! Fractal heap managed-object access — mirrors libhdf5's `H5HFman.c`.
//! Decode the heap-ID for managed objects, descend through the doubling
//! table (direct or indirect / filtered or unfiltered), and return the
//! object bytes. Composes with the iblock/dblock decoders.
use std::io::{Read, Seek};
use crate::error::{Error, Result};
use crate::io::reader::HdfReader;
use super::iblock::{FilteredIndirectBlock, IndirectBlock};
use super::FractalHeapHeader;
impl FractalHeapHeader {
/// Read a managed (type 0) object.
pub(super) fn read_managed<R: Read + Seek>(
&self,
reader: &mut HdfReader<R>,
heap_id: &[u8],
) -> Result<Vec<u8>> {
// Managed object heap ID:
// byte 0: version(2 bits) + type(2 bits) + reserved(4 bits)
// then: offset (ceil(max_heap_size/8) bytes) + length (remaining bytes)
let offset_bytes = ((self.max_heap_size as usize) + 7) / 8;
if heap_id.len() < 1 + offset_bytes {
return Err(Error::InvalidFormat("heap ID too short for offset".into()));
}
let mut offset = 0u64;
for i in 0..offset_bytes {
offset |= (heap_id[1 + i] as u64) << (i * 8);
}
let len_start = 1 + offset_bytes;
let mut length = 0u64;
for i in 0..(heap_id.len() - len_start).min(8) {
length |= (heap_id[len_start + i] as u64) << (i * 8);
}
// Bound checks matching libhdf5's `H5HF__man_op_real`:
// - offset must be < 2^max_heap_size (the heap's address space)
// - object size must fit in the managed object size limit
if self.max_heap_size < 64 && offset >= (1u64 << self.max_heap_size) {
return Err(Error::InvalidFormat(format!(
"fractal heap object offset {offset} exceeds 2^{} address space",
self.max_heap_size
)));
}
if length > self.max_managed_obj_size as u64 {
return Err(Error::InvalidFormat(format!(
"fractal heap object size {length} exceeds max managed object size {}",
self.max_managed_obj_size
)));
}
if self.current_root_rows == 0 {
// Root is a direct block -- offset is relative to block start
self.read_from_direct_block(
reader,
self.root_block_addr,
self.start_block_size,
self.root_direct_filtered_size,
self.root_direct_filter_mask,
offset,
length,
)
} else {
// Root is an indirect block -- need to find which direct block contains the offset
self.read_from_indirect_block(reader, self.root_block_addr, offset, length)
}
}
pub(super) fn read_from_indirect_block<R: Read + Seek>(
&self,
reader: &mut HdfReader<R>,
block_addr: u64,
offset: u64,
length: u64,
) -> Result<Vec<u8>> {
if self.io_filter_len > 0 {
return self.read_from_filtered_indirect_block(reader, block_addr, offset, length);
}
self.read_from_indirect_block_rows(
reader,
block_addr,
self.current_root_rows as usize,
0,
offset,
length,
)
}
/// Walk a decoded indirect block to locate the heap object covering
/// `offset`. Mirrors libhdf5's `H5HF__man_op_real` traversal: walks
/// the row table, descending into nested indirect blocks once we leave
/// the direct-row range.
pub(super) fn lookup_in_indirect_block<R: Read + Seek>(
&self,
reader: &mut HdfReader<R>,
iblock: &IndirectBlock,
block_start: u64,
offset: u64,
length: u64,
) -> Result<Vec<u8>> {
let width = self.table_width as usize;
let max_direct_rows = self.max_direct_rows();
let mut current_heap_offset = block_start;
let mut entry_index = 0usize;
for row in 0..iblock.nrows {
if row < max_direct_rows {
let block_span = self.row_block_size(row);
for _ in 0..width {
let child_addr = iblock.child_addrs[entry_index];
entry_index += 1;
if crate::io::reader::is_undef_addr(child_addr) {
current_heap_offset += block_span;
continue;
}
if offset >= current_heap_offset && offset < current_heap_offset + block_span {
let local_offset = offset - current_heap_offset;
return self.read_from_direct_block(
reader,
child_addr,
block_span,
None,
0,
local_offset,
length,
);
}
current_heap_offset += block_span;
}
} else {
let child_rows = self.child_indirect_rows(row);
let child_span = self.indirect_data_span(reader, child_rows)?;
for _ in 0..width {
let child_addr = iblock.child_addrs[entry_index];
entry_index += 1;
if offset >= current_heap_offset && offset < current_heap_offset + child_span {
if crate::io::reader::is_undef_addr(child_addr) {
break;
}
return self.read_from_indirect_block_rows(
reader,
child_addr,
child_rows,
current_heap_offset,
offset,
length,
);
}
current_heap_offset += child_span;
}
}
}
Err(Error::InvalidFormat(format!(
"fractal heap offset {offset} not found in indirect block"
)))
}
/// Drive `decode_indirect_block` + `lookup_in_indirect_block` — the
/// C-side composition is `H5HF__man_iblock_protect` (which loads &
/// deserializes the iblock) followed by the lookup loop in
/// `H5HF__man_op_real`.
pub(super) fn read_from_indirect_block_rows<R: Read + Seek>(
&self,
reader: &mut HdfReader<R>,
block_addr: u64,
nrows: usize,
block_start: u64,
offset: u64,
length: u64,
) -> Result<Vec<u8>> {
let iblock = self.decode_indirect_block(reader, block_addr, nrows)?;
self.lookup_in_indirect_block(reader, &iblock, block_start, offset, length)
}
/// Walk a decoded filtered indirect block to locate the heap object
/// covering `offset`. Mirrors the filtered traversal in
/// `H5HF__man_op_real`.
pub(super) fn lookup_in_filtered_indirect_block<R: Read + Seek>(
&self,
reader: &mut HdfReader<R>,
iblock: &FilteredIndirectBlock,
offset: u64,
length: u64,
) -> Result<Vec<u8>> {
let width = self.table_width as usize;
let dblock_header_size = 5
+ self.sizeof_addr as u64
+ iblock.block_offset_bytes as u64
+ if self.has_checksum { 4 } else { 0 };
let mut current_heap_offset = 0u64;
let mut entry_index = 0usize;
for row in 0..iblock.nrows {
let block_size = if row < 2 {
self.start_block_size
} else {
self.start_block_size * (1u64 << (row - 1))
};
if block_size > self.max_direct_block_size {
entry_index += width; // indirect-row entries carry no payload to consume here
continue;
}
let data_capacity = block_size - dblock_header_size;
for _ in 0..width {
let entry = &iblock.entries[entry_index];
entry_index += 1;
if crate::io::reader::is_undef_addr(entry.addr) {
current_heap_offset += data_capacity;
continue;
}
if offset >= current_heap_offset && offset < current_heap_offset + data_capacity {
return self.read_from_direct_block(
reader,
entry.addr,
block_size,
Some(entry.filtered_size),
entry.filter_mask,
offset - current_heap_offset,
length,
);
}
current_heap_offset += data_capacity;
}
}
Err(Error::InvalidFormat(format!(
"filtered fractal heap offset {offset} not found in indirect block"
)))
}
/// Drive `decode_filtered_indirect_block` + `lookup_in_filtered_…` —
/// C-side composition is `H5HF__man_iblock_protect` + the filtered
/// branch of `H5HF__man_op_real`.
pub(super) fn read_from_filtered_indirect_block<R: Read + Seek>(
&self,
reader: &mut HdfReader<R>,
block_addr: u64,
offset: u64,
length: u64,
) -> Result<Vec<u8>> {
let iblock = self.decode_filtered_indirect_block(reader, block_addr)?;
self.lookup_in_filtered_indirect_block(reader, &iblock, offset, length)
}
}