sparsefile

This module implements sparse file "hole punching" on GNU+Linux, Microsoft Windows, and probably Mac OS X (untested). This allows you to quickly create sparse file gaps such that the gaps appear to be filled with null (b"\0") bytes but they don't occupy any actual disk space.

This is a pure-Python module which uses ctypes/pywin32/fcntl to do its dirty work.

Dependencies

pywin32 on Windows. None otherwise.

Examples

First import the library and choose an appropriate victim.

>>> from pathlib import Path
>>> import sparsefile
>>> path = Path("my_file.bin")

Then sparsification comes in three different flavours:

• sparsefile.ensure_sparse(path, offset=1000, length=3000)

  Make the byte range 1000-3999 (inclusive) sparse. If the OS or filesystem do not support the operation, raise a SparsifyError.

• sparsefile.ensure_zeros_maybe_sparse(path, offset=1000, length=3000)

  Fill the byte range 1000-3999 (inclusive) with zeros. The byte range will also be sparse if the OS and filesystem support it. The function returns a boolean that indicates whether the byte range was successfully made sparse.

• sparsefile.maybe_sparse(path, offset=1000, length=3000)

  Try to make the byte range 1000-3999 (inclusive) sparse. Do nothing if the OS or filesystem do not support it. If the file is currently shorter than 4000 bytes, then it will remain so.

Issues

• The test suite is severely lacking.
• Hasn't been tested on OS X (sorry).