on_write Event

Fires when the OS needs to write data to an open file.

Syntax

class FUSEWriteEventParams(object):
  @property
  def path() -> str: ...
  @property
  def file_context() -> int: ...
  @property
  def write_page() -> bool: ...
  @property
  def offset() -> int: ...
  @property
  def buffer() -> c_void_p: ...
  @property
  def size() -> int: ...
  @property
  def result() -> int: ...
  @result.setter
  def result(value) -> None: ...

# In class FUSE:
@property
def on_write() -> Callable[[FUSEWriteEventParams], None]: ...
@on_write.setter
def on_write(event_hook: Callable[[FUSEWriteEventParams], None]) -> None: ...

Remarks

This event fires when the OS needs to write data to the already-open file, identified by either Path or FileContext.

To handle this event properly, applications should write Size bytes of data from the memory region pointed to by Buffer to the specified file. Writing must begin at the specified Offset in the file and all of the provided data is expected to be written.

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

The WritePage parameter will be set to a non-zero value when writing is performed by the cache manager or another system component. If this is the case, FileContext may not match the value that would be passed in the case of a non-buffered write by a user-mode process.

When writing is complete, applications must set Result to the actual number of bytes written to the file.

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 negative error code value (e.g. -ENOENT to indicate that the file does not exist) to report an appropriate error. Please refer to the Error Reporting and Handling topic for more information.