Exceptions

ntcompress.exceptions

Exception hierarchy for :mod:ntcompress.

All errors derive from :class:CompressionLibError, so callers can catch the whole library with a single except. The hierarchy separates decode-time from encode-time failures and carries semantically meaningful leaf types: checksum mismatches, the SCRUB erase marker, incompressible input, and formats that are recognized but not implemented.

CompressionLibError

Bases: Exception

Base class for every error raised by :mod:ntcompress.

DecompressionError

Bases: CompressionLibError

Raised when a compressed buffer cannot be decoded.

CompressionError

Bases: CompressionLibError

Raised when input cannot be encoded by the requested format.

IntegrityError

Bases: DecompressionError

Raised when a stored checksum does not match the decoded data.

Applies to formats that carry checksums in their header, for example the XPRESS10 CRC-32C over the plaintext and CRC-64 over the payload.

ScrubDetectedError

Bases: DecompressionError

Raised when a record uses the SCRUB (0x4) format.

SCRUB is not a codec: it marks a long-value chunk that database maintenance or repair has overwritten with a known fill pattern, so there is no original plaintext to recover. Callers should handle this case explicitly.

IncompressibleError

Bases: CompressionError

Raised when a compressor cannot shrink the input below the ESE threshold.

ESE stores a compressed cell only when the compressed payload plus its header is strictly smaller than the original; otherwise the cell is stored uncompressed. Encoders surface that policy through this error.

FormatUnavailableError

Bases: CompressionLibError

Raised when a format is recognized but cannot be decoded.

Either no codec is registered for the format, or a registered codec does not support the requested operation (e.g. a decode-only format asked to compress).