@@ -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