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util/rmrf: use immutable helpers

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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.
This commit is contained in:
David Rheinsberg 2020-04-20 12:34:47 +02:00 • committed by Tom Gundersen
parent e5ff287f5a
commit 1cdf2be0ac
1 changed files with 23 additions and 22 deletions
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45
osbuild/util/rmrf.py
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@ -11,11 +11,11 @@ removed.
"""
import array
import fcntl
import os
import shutil
import osbuild.util.linux as linux
__all__ = [
"rmtree",
@ -52,27 +52,28 @@ def rmtree(path: str):
function is used internally). Consult its documentation for details.
"""
def clear_mutable_flag(path):
FS_IOC_GETFLAGS = 0x80086601
FS_IOC_SETFLAGS = 0x40086602
FS_IMMUTABLE_FL = 0x010
fd = -1
try:
fd = os.open(path, os.O_RDONLY)
flags = array.array('L', [0])
fcntl.ioctl(fd, FS_IOC_GETFLAGS, flags, True)
flags[0] &= ~FS_IMMUTABLE_FL
fcntl.ioctl(fd, FS_IOC_SETFLAGS, flags, False)
except OSError:
pass # clearing flags is best effort
finally:
if fd > -1:
os.close(fd)
def fixperms(p):
clear_mutable_flag(p)
os.chmod(p, 0o777)
fd = None
try:
fd = os.open(p, os.O_RDONLY)
# The root-only immutable flag prevents files from being unlinked
# or modified. Clear it, so we can unlink the file-system tree.
try:
linux.ioctl_toggle_immutable(fd, False)
except OSError:
pass
# If we do not have sufficient permissions on a directory, we
# cannot traverse it, nor unlink its content. Make sure to set
# sufficient permissions up front.
try:
os.fchmod(fd, 0o777)
except OSError:
pass
finally:
if fd is not None:
os.close(fd)
def unlink(p):
try: