1cdf2be0ac
Make use of the new immutable-flag ioctl helpers. While at it, move the `chmod` to `fchmod` and re-use the open file-descriptor. Document the behavior and move the `fchmod` into its own try-block for the same reasons as the `ioctl` call: We rely on the following unlink() to catch any errors. Errors in the fixperms() step are non-consequential.
98 lines
2.9 KiB
Python
98 lines
2.9 KiB
Python
"""Recursive File System Removal
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This module implements `rm -rf` as a python function. Its core is the
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`rmtree()` function, which takes a file-system path and then recursively
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deletes everything it finds on that path, until eventually the path entry
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itself is dropped. This is modeled around `shutil.rmtree()`.
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This function tries to be as thorough as possible. That is, it tries its best
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to modify permission bits and other flags to make sure directory entries can be
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removed.
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"""
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import os
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import shutil
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import osbuild.util.linux as linux
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__all__ = [
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"rmtree",
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]
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def rmtree(path: str):
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"""Recursively Remove from File System
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This removes the object at the given path from the file-system. It
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recursively iterates through its content and removes them, before removing
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the object itself.
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This function is modeled around `shutil.rmtree()`, but extends its
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functionality with a more aggressive approach. It tries much harder to
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unlink file system objects. This includes immutable markers and more.
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Note that this function can still fail. In particular, missing permissions
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can always prevent this function from succeeding. However, a caller should
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never assume that they can intentionally prevent this function from
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succeeding. In other words, this function might be extended in any way in
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the future, to be more powerful and successful in removing file system
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objects.
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Parameters
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---------
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path
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A file system path pointing to the object to remove.
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Raises
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------
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Exception
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This raises the same exceptions as `shutil.rmtree()` (since that
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function is used internally). Consult its documentation for details.
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"""
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def fixperms(p):
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fd = None
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try:
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fd = os.open(p, os.O_RDONLY)
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# The root-only immutable flag prevents files from being unlinked
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# or modified. Clear it, so we can unlink the file-system tree.
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try:
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linux.ioctl_toggle_immutable(fd, False)
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except OSError:
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pass
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# If we do not have sufficient permissions on a directory, we
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# cannot traverse it, nor unlink its content. Make sure to set
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# sufficient permissions up front.
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try:
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os.fchmod(fd, 0o777)
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except OSError:
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pass
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finally:
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if fd is not None:
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os.close(fd)
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def unlink(p):
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try:
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os.unlink(p)
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except IsADirectoryError:
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rmtree(p)
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except FileNotFoundError:
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pass
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def on_error(_fn, p, exc_info):
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e = exc_info[0]
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if issubclass(e, FileNotFoundError):
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pass
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elif issubclass(e, PermissionError):
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if p != path:
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fixperms(os.path.dirname(p))
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fixperms(p)
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unlink(p)
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else:
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raise e
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shutil.rmtree(path, onerror=on_error)
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