From patchwork Tue Jun 9 20:52:39 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Blake X-Patchwork-Id: 1306278 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=Usu1/nPw; dkim-atps=neutral Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 49hMmK71mmz9sRh for ; Wed, 10 Jun 2020 06:53:53 +1000 (AEST) Received: from localhost ([::1]:34904 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jilFn-0002ee-Mf for incoming@patchwork.ozlabs.org; Tue, 09 Jun 2020 16:53:51 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36366) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jilEw-0001iC-Gn for qemu-devel@nongnu.org; Tue, 09 Jun 2020 16:52:58 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:35399 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jilEv-0005c0-AO for qemu-devel@nongnu.org; Tue, 09 Jun 2020 16:52:58 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1591735976; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=2gkJQrcmtu07hJLZsxNO23mQmGAJYFCopm0+MuaUKqc=; b=Usu1/nPwyYbGuyytT90DVsmfscEHol8W22WbBHRUJFD1Z2JsXU1kWHoZqFdumcIzPPDku9 2Qv5sALQD/dnOxnvpDL0Rk+7ra+ewIoSgu2pusIRn1GqAhFtrS98KfckGq1qgbnBE8sfsA pIbzVoa38hAUF3vtHk0s6YVZ4xhEdOE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-474-MYBpZcgiMV2PJGRKG4T0cw-1; Tue, 09 Jun 2020 16:52:54 -0400 X-MC-Unique: MYBpZcgiMV2PJGRKG4T0cw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 53185835B44; Tue, 9 Jun 2020 20:52:53 +0000 (UTC) Received: from blue.redhat.com (ovpn-113-22.phx2.redhat.com [10.3.113.22]) by smtp.corp.redhat.com (Postfix) with ESMTP id C959C6116D; Tue, 9 Jun 2020 20:52:52 +0000 (UTC) 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 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+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" 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 = { + 'u8': 'B', + 'u16': 'H', + 'u32': 'I', + 'u64': 'Q' + } + + def __init__(self, name, bases, attrs): + if 'fields' in attrs: + self.fmt = '>' + ''.join(self.ctypes[f[0]] for f in self.fields) + + +class Qcow2Struct(metaclass=Qcow2StructMeta): + + """Qcow2Struct: base class for qcow2 data structures + + Successors should define fields class variable, which is: list of tuples, + 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=None, offset=None, data=None): + """ + Two variants: + 1. Specify data. fd and offset must be None. + 2. Specify fd and offset, data must be None. offset may be omitted + in this case, than current position of fd is used. + """ + if data is None: + assert fd is not None + buf_size = struct.calcsize(self.fmt) + if offset is not None: + fd.seek(offset) + data = fd.read(buf_size) + else: + assert fd is None and offset is None + + values = struct.unpack(self.fmt, data) + self.__dict__ = dict((field[2], values[i]) + for i, field in enumerate(self.fields)) + + def dump(self): + for f in self.fields: + value = self.__dict__[f[2]] + if f[1] == 'mask': + bits = [] + for bit in range(64): + if value & (1 << bit): + bits.append(bit) + value_str = str(bits) + else: + value_str = 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 = { - 'u8': 'B', - 'u16': 'H', - 'u32': 'I', - 'u64': 'Q' -} - - -class QcowHeader: +class QcowHeader(Qcow2Struct): fields = ( # Version 2 header fields @@ -69,18 +124,8 @@ class QcowHeader: ('u32', '{}', 'header_length'), ) - fmt = '>' + ''.join(ctypes[f[0]] for f in fields) - def __init__(self, fd): - - buf_size = struct.calcsize(QcowHeader.fmt) - - fd.seek(0) - buf = fd.read(buf_size) - - header = struct.unpack(QcowHeader.fmt, buf) - self.__dict__ = dict((field[2], header[i]) - for i, field in enumerate(QcowHeader.fields)) + super().__init__(fd=fd, offset=0) self.set_defaults() self.cluster_size = 1 << self.cluster_bits @@ -148,20 +193,6 @@ class QcowHeader: buf = buf[0:header_bytes-1] fd.write(buf) - def dump(self): - for f in QcowHeader.fields: - value = self.__dict__[f[2]] - if f[1] == 'mask': - bits = [] - for bit in range(64): - if value & (1 << bit): - bits.append(bit) - value_str = str(bits) - else: - value_str = f[1].format(value) - - print(f'{f[2]:<25} {value_str}') - def dump_extensions(self): for ex in self.extensions: