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bh=2gkJQrcmtu07hJLZsxNO23mQmGAJYFCopm0+MuaUKqc=; b=Usu1/nPwyYbGuyytT90DVsmfscEHol8W22WbBHRUJFD1Z2JsXU1kWHoZqFdumcIzPPDku9 2Qv5sALQD/dnOxnvpDL0Rk+7ra+ewIoSgu2pusIRn1GqAhFtrS98KfckGq1qgbnBE8sfsA pIbzVoa38hAUF3vtHk0s6YVZ4xhEdOE= X-MC-Unique: MYBpZcgiMV2PJGRKG4T0cw-1 From: Eric Blake To: qemu-devel@nongnu.org Subject: [PULL 09/15] qcow2_format.py: separate generic functionality of structure classes Date: Tue, 9 Jun 2020 15:52:39 -0500 Message-Id: <20200609205245.3548257-10-eblake@redhat.com> In-Reply-To: <20200609205245.3548257-1-eblake@redhat.com> References: <20200609205245.3548257-1-eblake@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=205.139.110.120; envelope-from=eblake@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/09 02:44:16 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Andrey Shinkevich , Vladimir Sementsov-Ogievskiy , "open list:Block layer core" , Max Reitz Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" From: Vladimir Sementsov-Ogievskiy We are going to introduce more Qcow2 structure types, defined like QcowHeader. Move generic functionality into base class to be reused for further structure classes. Signed-off-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Andrey Shinkevich Message-Id: <20200606081806.23897-9-vsementsov@virtuozzo.com> Signed-off-by: Eric Blake --- tests/qemu-iotests/qcow2_format.py | 101 +++++++++++++++++++---------- 1 file changed, 66 insertions(+), 35 deletions(-) diff --git a/tests/qemu-iotests/qcow2_format.py b/tests/qemu-iotests/qcow2_= format.py index 28f2bfa63bc7..898d388b8adf 100644 --- a/tests/qemu-iotests/qcow2_format.py +++ b/tests/qemu-iotests/qcow2_format.py @@ -1,5 +1,7 @@ # Library for manipulations with qcow2 image # +# Copyright (c) 2020 Virtuozzo International GmbH. +# # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 2 of the License, or @@ -18,6 +20,68 @@ import struct import string +class Qcow2StructMeta(type): + + # Mapping from c types to python struct format + ctypes =3D { + 'u8': 'B', + 'u16': 'H', + 'u32': 'I', + 'u64': 'Q' + } + + def __init__(self, name, bases, attrs): + if 'fields' in attrs: + self.fmt =3D '>' + ''.join(self.ctypes[f[0]] for f in self.fie= lds) + + +class Qcow2Struct(metaclass=3DQcow2StructMeta): + + """Qcow2Struct: base class for qcow2 data structures + + Successors should define fields class variable, which is: list of tupl= es, + each of three elements: + - c-type (one of 'u8', 'u16', 'u32', 'u64') + - format (format_spec to use with .format() when dump or 'mask' to= dump + bitmasks) + - field name + """ + + def __init__(self, fd=3DNone, offset=3DNone, data=3DNone): + """ + Two variants: + 1. Specify data. fd and offset must be None. + 2. Specify fd and offset, data must be None. offset may be omi= tted + in this case, than current position of fd is used. + """ + if data is None: + assert fd is not None + buf_size =3D struct.calcsize(self.fmt) + if offset is not None: + fd.seek(offset) + data =3D fd.read(buf_size) + else: + assert fd is None and offset is None + + values =3D struct.unpack(self.fmt, data) + self.__dict__ =3D dict((field[2], values[i]) + for i, field in enumerate(self.fields)) + + def dump(self): + for f in self.fields: + value =3D self.__dict__[f[2]] + if f[1] =3D=3D 'mask': + bits =3D [] + for bit in range(64): + if value & (1 << bit): + bits.append(bit) + value_str =3D str(bits) + else: + value_str =3D f[1].format(value) + + print('{:<25} {}'.format(f[2], value_str)) + + class QcowHeaderExtension: def __init__(self, magic, length, data): @@ -34,16 +98,7 @@ class QcowHeaderExtension: return QcowHeaderExtension(magic, len(data), data) -# Mapping from c types to python struct format -ctypes =3D { - 'u8': 'B', - 'u16': 'H', - 'u32': 'I', - 'u64': 'Q' -} - - -class QcowHeader: +class QcowHeader(Qcow2Struct): fields =3D ( # Version 2 header fields @@ -69,18 +124,8 @@ class QcowHeader: ('u32', '{}', 'header_length'), ) - fmt =3D '>' + ''.join(ctypes[f[0]] for f in fields) - def __init__(self, fd): - - buf_size =3D struct.calcsize(QcowHeader.fmt) - - fd.seek(0) - buf =3D fd.read(buf_size) - - header =3D struct.unpack(QcowHeader.fmt, buf) - self.__dict__ =3D dict((field[2], header[i]) - for i, field in enumerate(QcowHeader.fields)) + super().__init__(fd=3Dfd, offset=3D0) self.set_defaults() self.cluster_size =3D 1 << self.cluster_bits @@ -148,20 +193,6 @@ class QcowHeader: buf =3D buf[0:header_bytes-1] fd.write(buf) - def dump(self): - for f in QcowHeader.fields: - value =3D self.__dict__[f[2]] - if f[1] =3D=3D 'mask': - bits =3D [] - for bit in range(64): - if value & (1 << bit): - bits.append(bit) - value_str =3D str(bits) - else: - value_str =3D f[1].format(value) - - print(f'{f[2]:<25} {value_str}') - def dump_extensions(self): for ex in self.extensions: --=20 2.27.0