[PATCH v3 0/2] wic: extend empty plugin with options to write zeros to partiton

[PATCH v3 0/2] wic: extend empty plugin with options to write zeros to partiton

[Lukas Funke]

From: Lukas Funke <lukas.funke@weidmueller.com>

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'.

Changes in v3:
 - Add testcase 
 - Fix interpretation of --fixed-size parameter

Changed in v2:
 - Added SoB

---

Lukas Funke (1):
  selftest: wic: add test for zerorize option of empty plugin

Malte Schmidt (1):
  wic: extend empty plugin with options to write zeros to partiton

 meta/lib/oeqa/selftest/cases/wic.py     | 36 ++++++++++++++++
 scripts/lib/wic/plugins/source/empty.py | 57 ++++++++++++++++++++++++-
 2 files changed, 92 insertions(+), 1 deletion(-)

-- 
2.30.2

[PATCH v3 1/2] wic: extend empty plugin with options to write zeros to partiton

[Lukas Funke]

From: Malte Schmidt <malte.schmidt@weidmueller.com>

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'.

Signed-off-by: Malte Schmidt <malte.schmidt@weidmueller.com>
Signed-off-by: Lukas Funke <lukas.funke@weidmueller.com>
---
 scripts/lib/wic/plugins/source/empty.py | 57 ++++++++++++++++++++++++-
 1 file changed, 56 insertions(+), 1 deletion(-)

diff --git a/scripts/lib/wic/plugins/source/empty.py b/scripts/lib/wic/plugins/source/empty.py
index 9c492ca206..0a9f5fa27c 100644
--- a/scripts/lib/wic/plugins/source/empty.py
+++ b/scripts/lib/wic/plugins/source/empty.py
@@ -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
-- 
2.30.2

[PATCH v3 2/2] selftest: wic: add test for zerorize option of empty plugin

[Lukas Funke]

From: Lukas Funke <lukas.funke@weidmueller.com>

Add test for empty plugin which tests whether the plugin creates
partitions with actual data which is 'zero'.

Signed-off-by: Lukas Funke <lukas.funke@weidmueller.com>
---
 meta/lib/oeqa/selftest/cases/wic.py | 36 +++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/meta/lib/oeqa/selftest/cases/wic.py b/meta/lib/oeqa/selftest/cases/wic.py
index b4866bcb32..9672f3fae4 100644
--- a/meta/lib/oeqa/selftest/cases/wic.py
+++ b/meta/lib/oeqa/selftest/cases/wic.py
@@ -1391,6 +1391,42 @@ class Wic2(WicTestCase):
         result = runCmd("%s/usr/sbin/sfdisk --part-label %s 3" % (sysroot, image_path))
         self.assertEqual('ext-space', result.output)
 
+    def test_empty_zeroize_plugin(self):
+        img = 'core-image-minimal'
+        expected_size = [ 1024*1024,    # 1M
+                          512*1024,     # 512K
+                          2*1024*1024]  # 2M
+        # Check combination of sourceparams
+        with NamedTemporaryFile("w", suffix=".wks") as wks:
+            wks.writelines(
+                ['part empty --source empty --sourceparams="fill" --ondisk sda --fixed-size 1M\n',
+                 'part empty --source empty --sourceparams="size=512K" --ondisk sda --size 1M --align 1024\n',
+                 'part empty --source empty --sourceparams="size=2048k,bs=512K" --ondisk sda --size 4M --align 1024\n'
+                 ])
+            wks.flush()
+            cmd = "wic create %s -e %s -o %s" % (wks.name, img, self.resultdir)
+            runCmd(cmd)
+            wksname = os.path.splitext(os.path.basename(wks.name))[0]
+            wicout = glob(os.path.join(self.resultdir, "%s-*direct" % wksname))
+            # Skip the complete image and just look at the single partitions
+            for idx, value in enumerate(wicout[1:]):
+                self.logger.info(wicout[idx])
+                # Check if partitions are actually zeroized
+                with open(wicout[idx], mode="rb") as fd:
+                    ba = bytearray(fd.read())
+                    for b in ba:
+                        self.assertEqual(b, 0)
+                self.assertEqual(expected_size[idx], os.path.getsize(wicout[idx]))
+
+        # Check inconsistancy check between "fill" and "--size" parameter
+        with NamedTemporaryFile("w", suffix=".wks") as wks:
+            wks.writelines(['part empty --source empty --sourceparams="fill" --ondisk sda --size 1M\n'])
+            wks.flush()
+            cmd = "wic create %s -e %s -o %s" % (wks.name, img, self.resultdir)
+            result = runCmd(cmd, ignore_status=True)
+            self.assertIn("Source parameter 'fill' only works with the '--fixed-size' option, exiting.", result.output)
+            self.assertNotEqual(0, result.status)
+
 class ModifyTests(WicTestCase):
     def test_wic_ls(self):
         """Test listing image content using 'wic ls'"""
-- 
2.30.2