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wic: extend empty plugin with options to write zeros to partiton

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Adds features to explicitly write zeros to the start of the
partition. This is useful to overwrite old content like
filesystem signatures which may be re-recognized otherwise.

The new features can be enabled with
'--soucreparams="[fill|size=<N>[S|s|K|k|M|G]][,][bs=<N>[S|s|K|k|M|G]]"'
Conflicting or missing options throw errors.

The features are:
- fill
  Fill the entire partition with zeros. Requires '--fixed-size' option
  to be set.
- size=<N>[S|s|K|k|M|G]
  Set the first N bytes of the partition to zero. Default unit is 'K'.
- bs=<N>[S|s|K|k|M|G]
  Write at most N bytes at a time during source file creation.
  Defaults to '1M'. Default unit is 'K'.

(From OE-Core rev: d19d4529e7a2056caeb526fed980cc1df19a5f6e)

Signed-off-by: Malte Schmidt <malte.schmidt@weidmueller.com>
Signed-off-by: Lukas Funke <lukas.funke@weidmueller.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
This commit is contained in:
Malte Schmidt 2023-11-28 14:52:31 +01:00 committed by Richard Purdie
parent ef7ba05995
commit 29b2bda786
1 changed files with 56 additions and 1 deletions
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57
scripts/lib/wic/plugins/source/empty.py
View File

@ -9,9 +9,19 @@
# To use it you must pass "empty" as argument for the "--source" parameter in
# the wks file. For example:
# part foo --source empty --ondisk sda --size="1024" --align 1024
#
# The plugin supports writing zeros to the start of the
# partition. This is useful to overwrite old content like
# filesystem signatures which may be re-recognized otherwise.
# This feature can be enabled with
# '--soucreparams="[fill|size=<N>[S|s|K|k|M|G]][,][bs=<N>[S|s|K|k|M|G]]"'
# Conflicting or missing options throw errors.
import logging
import os
from wic import WicError
from wic.ksparser import sizetype
from wic.pluginbase import SourcePlugin
logger = logging.getLogger('wic')
@ -19,6 +29,16 @@ logger = logging.getLogger('wic')
class EmptyPartitionPlugin(SourcePlugin):
"""
Populate unformatted empty partition.
The following sourceparams are supported:
- fill
Fill the entire partition with zeros. Requires '--fixed-size' option
to be set.
- size=<N>[S|s|K|k|M|G]
Set the first N bytes of the partition to zero. Default unit is 'K'.
- bs=<N>[S|s|K|k|M|G]
Write at most N bytes at a time during source file creation.
Defaults to '1M'. Default unit is 'K'.
"""
name = 'empty'
@ -31,4 +51,39 @@ class EmptyPartitionPlugin(SourcePlugin):
Called to do the actual content population for a partition i.e. it
'prepares' the partition to be incorporated into the image.
"""
return
get_byte_count = sizetype('K', True)
size = 0
if 'fill' in source_params and 'size' in source_params:
raise WicError("Conflicting source parameters 'fill' and 'size' specified, exiting.")
# Set the size of the zeros to be written to the partition
if 'fill' in source_params:
if part.fixed_size == 0:
raise WicError("Source parameter 'fill' only works with the '--fixed-size' option, exiting.")
size = get_byte_count(part.fixed_size)
elif 'size' in source_params:
size = get_byte_count(source_params['size'])
if size == 0:
# Nothing to do, create empty partition
return
if 'bs' in source_params:
bs = get_byte_count(source_params['bs'])
else:
bs = get_byte_count('1M')
# Create a binary file of the requested size filled with zeros
source_file = os.path.join(cr_workdir, 'empty-plugin-zeros%s.bin' % part.lineno)
if not os.path.exists(os.path.dirname(source_file)):
os.makedirs(os.path.dirname(source_file))
quotient, remainder = divmod(size, bs)
with open(source_file, 'wb') as file:
for _ in range(quotient):
file.write(bytearray(bs))
file.write(bytearray(remainder))
part.size = (size + 1024 - 1) // 1024 # size in KB rounded up
part.source_file = source_file