Function decode

nodedb-codec/src/lz4.rs:77–120

Decompress LZ4 block-compressed bytes back to raw data.

(data: &[u8])

/// Decompress LZ4 block-compressed bytes back to raw data.
pub fn decode(data: &[u8]) -> Result<Vec<u8>, CodecError> {
    let header = read_header(data)?;

    if header.block_count == 0 {
        return Ok(Vec::new());
    }

    let mut result = Vec::with_capacity(header.uncompressed_size);
    let mut block_offset = header.data_offset;

    for i in 0..header.block_count {
        let compressed_len = header.block_lengths[i];
        let block_end = block_offset + compressed_len;

        if block_end > data.len() {
            return Err(CodecError::Truncated {
                expected: block_end,
                actual: data.len(),
            });
        }

        let block_data = &data[block_offset..block_end];
        let decompressed = lz4_flex::decompress_size_prepended(block_data).map_err(|e| {
            CodecError::DecompressFailed {
                detail: format!("LZ4 block {i}: {e}"),
            }
        })?;

        result.extend_from_slice(&decompressed);
        block_offset = block_end;
    }

    if result.len() != header.uncompressed_size {
        return Err(CodecError::Corrupt {
            detail: format!(
                "uncompressed size mismatch: header says {}, got {}",
                header.uncompressed_size,
                result.len()
            ),
        });
    }

    Ok(result)
}

/// Decompress a single block by index (for random access).
///