Function read_header

nodedb-codec/src/lz4.rs:171–202

(data: &[u8])

}

fn read_header(data: &[u8]) -> Result<Lz4Header, CodecError> {
    if data.len() < 12 {
        return Err(CodecError::Truncated {
            expected: 12,
            actual: data.len(),
        });
    }

    let uncompressed_size = u32::from_le_bytes([data[0], data[1], data[2], data[3]]) as usize;
    let _block_size = u32::from_le_bytes([data[4], data[5], data[6], data[7]]) as usize;
    let block_count = u32::from_le_bytes([data[8], data[9], data[10], data[11]]) as usize;

    let lengths_end = 12 + block_count * 4;
    if data.len() < lengths_end {
        return Err(CodecError::Truncated {
            expected: lengths_end,
            actual: data.len(),
        });
    }

    let block_lengths: Vec<usize> = data[12..lengths_end]
        .chunks_exact(4)
        .map(|c| u32::from_le_bytes([c[0], c[1], c[2], c[3]]) as usize)
        .collect();

    Ok(Lz4Header {
        uncompressed_size,
        block_count,
        block_lengths,
        data_offset: lengths_end,
    })
}

// ---------------------------------------------------------------------------
// Streaming encoder / decoder types