Struct ChunkReader 

pub struct ChunkReader<R: Read + Seek> { /* private fields */ }

Reader for chunked Data.db files (NB format)

This reader handles NB format Data.db files where:

• No magic number or header exists (file starts with compressed data)
• Each compressed chunk is followed by a 4-byte CRC32 checksum
• CRC32 uses Java’s java.util.zip.CRC32 algorithm (IEEE polynomial 0x04C11DB7)
• Checksums are stored in big-endian format

Implementations

impl<R: Read + Seek> ChunkReader<R>

pub fn new( reader: R, compression_info: CompressionInfo, total_file_size: u64, ) -> Self

Create new chunk reader

Arguments

• reader - The underlying reader for Data.db file
• compression_info - Parsed CompressionInfo containing chunk metadata
• total_file_size - Total size of the Data.db file in bytes

Returns

A new ChunkReader instance ready to read chunks

pub fn read_chunk(&mut self, chunk_index: usize) -> Result<Vec<u8>>

Read and validate a specific chunk by index

This method:

1. Seeks to the chunk offset in Data.db
2. Reads the compressed chunk bytes
3. Reads the trailing 4-byte CRC32 checksum
4. Validates the CRC32 (fail-fast on mismatch)

Arguments

• chunk_index - Zero-based index of the chunk to read

Returns

Compressed chunk bytes ready for decompression

Errors

Returns an error if:

• Chunk index is invalid
• I/O error occurs during reading
• CRC32 validation fails

pub fn read_all_chunks(&mut self) -> Result<Vec<Vec<u8>>>

Read all chunks and validate CRC32 for each

This is a convenience method that reads all chunks in sequential order.

Returns

A vector of compressed chunk byte arrays, one per chunk

Errors

Returns an error on the first chunk that fails to read or validate

pub fn chunk_count(&self) -> usize

Get the number of chunks in this file

pub fn compression_algorithm(&self) -> &str

Get the compression algorithm name

pub fn chunk_length(&self) -> u32

Get the uncompressed chunk size