From patchwork Tue Jun 9 20:52:42 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Blake X-Patchwork-Id: 1306288 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=NrfPwt5B; 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 49hMsQ3GHBz9sRh for ; Wed, 10 Jun 2020 06:58:18 +1000 (AEST) Received: from localhost ([::1]:52402 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jilK4-0001UO-1w for incoming@patchwork.ozlabs.org; Tue, 09 Jun 2020 16:58:16 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36390) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jilEy-0001nN-Oj for qemu-devel@nongnu.org; Tue, 09 Jun 2020 16:53:00 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:44726 helo=us-smtp-delivery-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 1jilEx-0005cu-FW for qemu-devel@nongnu.org; Tue, 09 Jun 2020 16:53:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1591735978; 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=xT7Dl2Np4lOx6956wQcDiocA0YR43F2Wm7BjuOHNaGo=; b=NrfPwt5BkCmfKj5dTmk2+Got1gQtRDEHzZV7xZ7WiZLZ0iPiG4v0S4EzJt6+3P64hTjKx2 Z/QQmSaJ29mJ03H96MoaT/oRV/bnjm1mlxUQkpNwTQleN53CUDxZQhgPovxZaVtvhsFuqP OdV7Di0bqPwpHUEjvd5KjURMXJWD/dI= 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-307-hK0iZE50NXuPlW9nJy6RyA-1; Tue, 09 Jun 2020 16:52:56 -0400 X-MC-Unique: hK0iZE50NXuPlW9nJy6RyA-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 554AA8015CE; Tue, 9 Jun 2020 20:52:55 +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 CD94F60C80; Tue, 9 Jun 2020 20:52:54 +0000 (UTC) From: Eric Blake To: qemu-devel@nongnu.org Subject: [PULL 12/15] qcow2_format: refactor QcowHeaderExtension as a subclass of Qcow2Struct Date: Tue, 9 Jun 2020 15:52:42 -0500 Message-Id: <20200609205245.3548257-13-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=207.211.31.81; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/09 16:46:48 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 Only two fields we can parse by generic code, but that is better than nothing. Keep further refactoring of variable-length fields for another day. Signed-off-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Andrey Shinkevich Message-Id: <20200606081806.23897-12-vsementsov@virtuozzo.com> Signed-off-by: Eric Blake --- tests/qemu-iotests/qcow2_format.py | 53 +++++++++++++++++++++--------- 1 file changed, 37 insertions(+), 16 deletions(-) diff --git a/tests/qemu-iotests/qcow2_format.py b/tests/qemu-iotests/qcow2_format.py index d4ad5431b296..32371e42da4e 100644 --- a/tests/qemu-iotests/qcow2_format.py +++ b/tests/qemu-iotests/qcow2_format.py @@ -97,16 +97,41 @@ class Qcow2Struct(metaclass=Qcow2StructMeta): print('{:<25} {}'.format(f[2], value_str)) -class QcowHeaderExtension: +class QcowHeaderExtension(Qcow2Struct): - def __init__(self, magic, length, data): - if length % 8 != 0: - padding = 8 - (length % 8) - data += b'\0' * padding + fields = ( + ('u32', '{:#x}', 'magic'), + ('u32', '{}', 'length') + # length bytes of data follows + # then padding to next multiply of 8 + ) - self.magic = magic - self.length = length - self.data = data + def __init__(self, magic=None, length=None, data=None, fd=None): + """ + Support both loading from fd and creation from user data. + For fd-based creation current position in a file will be used to read + the data. + + This should be somehow refactored and functionality should be moved to + superclass (to allow creation of any qcow2 struct), but then, fields + of variable length (data here) should be supported in base class + somehow. So, it's a TODO. We'll see how to properly refactor this when + we have more qcow2 structures. + """ + if fd is None: + assert all(v is not None for v in (magic, length, data)) + self.magic = magic + self.length = length + if length % 8 != 0: + padding = 8 - (length % 8) + data += b'\0' * padding + self.data = data + 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 def dump(self): data = self.data[:self.length] @@ -115,8 +140,7 @@ class QcowHeaderExtension: else: data = '' - print(f'{"magic":<25} {self.magic:#x}') - print(f'{"length":<25} {self.length}') + super().dump() print(f'{"data":<25} {data}') @classmethod @@ -182,14 +206,11 @@ class QcowHeader(Qcow2Struct): end = self.cluster_size while fd.tell() < end: - (magic, length) = struct.unpack('>II', fd.read(8)) - if magic == 0: + ext = QcowHeaderExtension(fd=fd) + if ext.magic == 0: break else: - padded = (length + 7) & ~7 - data = fd.read(padded) - self.extensions.append(QcowHeaderExtension(magic, length, - data)) + self.extensions.append(ext) def update_extensions(self, fd):