CBFS Storage 2020 Python Edition

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on_data_decompress Event

Fires to decompress a block of data using a custom compression algorithm.

Syntax

class CBVaultDataDecompressEventParams(object):
  @property
  def in_data() -> c_void_p: ...
  @property
  def in_size() -> int: ...
  @property
  def out_data() -> c_void_p: ...
  @property
  def out_size() -> int: ...
  @out_size.setter
  def out_size(value) -> None: ...
  @property
  def result_code() -> int: ...
  @result_code.setter
  def result_code(value) -> None: ...

# In class CBVault:
@property
def on_data_decompress() -> Callable[[CBVaultDataDecompressEventParams], None]: ...
@on_data_decompress.setter
def on_data_decompress(event_hook: Callable[[CBVaultDataDecompressEventParams], None]) -> None: ...

Remarks

This event fires when the class needs to decompress a block of data using an application-defined compression algorithm. Please refer to the Compression topic for more information.

This event only needs to be handled by applications that use the CBFSSTORAGE_CM_CUSTOM compression mode. To handle this event properly, applications must decompress all InSize bytes of data in the InData buffer, write the decompressed data to the OutData buffer, and set OutSize to reflect the total number of bytes written to OutData.

Note that OutSize is initially set to the capacity of the OutData buffer, which (under normal circumstances) should be large enough to accommodate all of the decompressed data. Only if the vault is corrupted should the OutData buffer ever be too small to hold the decompressed data; so if this occurs, do not write any data to OutData. Instead, set ResultCode to CBFSSTORAGE_ERR_VAULT_CORRUPTED.

Please refer to the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource isn't available, security checks failed, etc.), set it to a non-zero value to report an appropriate error. Please refer to the Error Reporting and Handling topic for more information.

Note: An application should not attempt to call class's methods from handlers of this event. Doing this is guaranteed to cause a deadlock.

Note: when a storage is opened concurrently in read-only mode by several applications using CBDrive or CBMemDrive class, the event will fire only in the first application. To prevent such a situation, always open a vault in read-write mode.

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CBFS Storage 2020 Python Edition - Version 20.0 [Build 8031]