| Message ID | 1594676203-436999-4-git-send-email-andrey.shinkevich@virtuozzo.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | iotests: Dump QCOW2 dirty bitmaps metadata | expand |
14.07.2020 00:36, Andrey Shinkevich wrote: > There are two ways to initialize a class derived from Qcow2Struct: > 1. Pass a block of binary data to the constructor. > 2. Pass the file descriptor to allow reading the file from constructor. > Let's change the Qcow2BitmapExt initialization method from 1 to 2 to > support a scattered reading in the initialization chain. > The implementation comes with the patch that follows. > > Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> > Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com> > --- > tests/qemu-iotests/qcow2_format.py | 33 +++++++++++++++++++-------------- > 1 file changed, 19 insertions(+), 14 deletions(-) > > diff --git a/tests/qemu-iotests/qcow2_format.py b/tests/qemu-iotests/qcow2_format.py > index 2f3681b..cbaffc4 100644 > --- a/tests/qemu-iotests/qcow2_format.py > +++ b/tests/qemu-iotests/qcow2_format.py > @@ -113,6 +113,11 @@ class Qcow2BitmapExt(Qcow2Struct): > ('u64', '{:#x}', 'bitmap_directory_offset') > ) > > + def __init__(self, fd): > + super().__init__(fd=fd) > + pad = (struct.calcsize(self.fmt) + 7) & ~7 It's a size of structure rounded up to 8-bytes boundary. But after super init, we should alread be at the end of the structure and need to add only padding, not the whole structure rounded up. I think, correct code should be: tail = struct.calcsize(self.fmt) % 8 if tail: fd.seek(8 - tail, 1) > + if pad: > + fd.seek(pad, 1) > > QCOW2_EXT_MAGIC_BITMAPS = 0x23852875 > > @@ -161,21 +166,21 @@ class QcowHeaderExtension(Qcow2Struct): > else: Hmm, you parse data now only for this "else:" branch. Prior to this patch, it was parsed for "if fd is None:" branch as well, after the whole "if" statement. This is wrong. > assert all(v is None for v in (magic, length, data)) > super().__init__(fd=fd) > - padded = (self.length + 7) & ~7 > - self.data = fd.read(padded) > - assert self.data is not None > - > - data_str = self.data[:self.length] > - if all(c in string.printable.encode('ascii') for c in data_str): > - data_str = f"'{ data_str.decode('ascii') }'" > - else: > - data_str = '<binary>' > - self.data_str = data_str > + if self.magic == QCOW2_EXT_MAGIC_BITMAPS: > + self.obj = Qcow2BitmapExt(fd=fd) > + else: > + padded = (self.length + 7) & ~7 > + self.data = fd.read(padded) > + assert self.data is not None > + self.obj = None > + data_str = self.data[:self.length] > + if all(c in string.printable.encode( > + 'ascii') for c in data_str): > + data_str = f"'{ data_str.decode('ascii') }'" > + else: > + data_str = '<binary>' > + self.data_str = data_str > > - if self.magic == QCOW2_EXT_MAGIC_BITMAPS: > - self.obj = Qcow2BitmapExt(data=self.data) > - else: > - self.obj = None > > def dump(self): > super().dump() >
diff --git a/tests/qemu-iotests/qcow2_format.py b/tests/qemu-iotests/qcow2_format.py index 2f3681b..cbaffc4 100644 --- a/tests/qemu-iotests/qcow2_format.py +++ b/tests/qemu-iotests/qcow2_format.py @@ -113,6 +113,11 @@ class Qcow2BitmapExt(Qcow2Struct): ('u64', '{:#x}', 'bitmap_directory_offset') ) + def __init__(self, fd): + super().__init__(fd=fd) + pad = (struct.calcsize(self.fmt) + 7) & ~7 + if pad: + fd.seek(pad, 1) QCOW2_EXT_MAGIC_BITMAPS = 0x23852875 @@ -161,21 +166,21 @@ class QcowHeaderExtension(Qcow2Struct): else: assert all(v is None for v in (magic, length, data)) super().__init__(fd=fd) - padded = (self.length + 7) & ~7 - self.data = fd.read(padded) - assert self.data is not None - - data_str = self.data[:self.length] - if all(c in string.printable.encode('ascii') for c in data_str): - data_str = f"'{ data_str.decode('ascii') }'" - else: - data_str = '<binary>' - self.data_str = data_str + if self.magic == QCOW2_EXT_MAGIC_BITMAPS: + self.obj = Qcow2BitmapExt(fd=fd) + else: + padded = (self.length + 7) & ~7 + self.data = fd.read(padded) + assert self.data is not None + self.obj = None + data_str = self.data[:self.length] + if all(c in string.printable.encode( + 'ascii') for c in data_str): + data_str = f"'{ data_str.decode('ascii') }'" + else: + data_str = '<binary>' + self.data_str = data_str - if self.magic == QCOW2_EXT_MAGIC_BITMAPS: - self.obj = Qcow2BitmapExt(data=self.data) - else: - self.obj = None def dump(self): super().dump()
There are two ways to initialize a class derived from Qcow2Struct: 1. Pass a block of binary data to the constructor. 2. Pass the file descriptor to allow reading the file from constructor. Let's change the Qcow2BitmapExt initialization method from 1 to 2 to support a scattered reading in the initialization chain. The implementation comes with the patch that follows. Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com> --- tests/qemu-iotests/qcow2_format.py | 33 +++++++++++++++++++-------------- 1 file changed, 19 insertions(+), 14 deletions(-)