From nobody Thu Oct 30 15:31:14 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 152588140211723.783257510594353; Wed, 9 May 2018 08:56:42 -0700 (PDT) Received: from localhost ([::1]:57244 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fGRSL-0000kK-BT for importer@patchew.org; Wed, 09 May 2018 11:56:41 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42139) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fGRLp-0002pZ-On for qemu-devel@nongnu.org; Wed, 09 May 2018 11:49:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fGRLo-0000Gl-LK for qemu-devel@nongnu.org; Wed, 09 May 2018 11:49:57 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:40272 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fGRLl-0000Bq-K8; Wed, 09 May 2018 11:49:53 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id ED099EFDE1; Wed, 9 May 2018 15:49:52 +0000 (UTC) Received: from localhost (unknown [10.40.205.23]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 934352166BAD; Wed, 9 May 2018 15:49:52 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Date: Wed, 9 May 2018 17:49:48 +0200 Message-Id: <20180509154949.8206-2-mreitz@redhat.com> In-Reply-To: <20180509154949.8206-1-mreitz@redhat.com> References: <20180509154949.8206-1-mreitz@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Wed, 09 May 2018 15:49:52 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Wed, 09 May 2018 15:49:52 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'mreitz@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PATCH 1/2] qemu-img: Resolve relative backing paths in rebase X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , qemu-stable@nongnu.org, qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Currently, rebase interprets a relative path for the new backing image as follows: (1) Open the new backing image with the given relative path (thus relative = to qemu-img's working directory). (2) Write it directly into the overlay's backing path field (thus relative to the overlay). If the overlay is not in qemu-img's working directory, both will be different interpretations, which may either lead to an error somewhere (either rebase fails because it cannot open the new backing image, or your overlay becomes unusable because its backing path does not point to a file), or, even worse, it may result in your rebase being performed for a different backing file than what your overlay will point to after the rebase. Fix this by interpreting the target backing path as relative to the overlay, like qemu-img does everywhere else. Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=3D1569835 Cc: qemu-stable@nongnu.org Signed-off-by: Max Reitz --- qemu-img.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) diff --git a/qemu-img.c b/qemu-img.c index ea62d2d61e..50540519e3 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -3191,6 +3191,9 @@ static int img_rebase(int argc, char **argv) } =20 if (out_baseimg[0]) { + const char *overlay_filename; + char *out_real_path; + options =3D qdict_new(); if (out_basefmt) { qdict_put_str(options, "driver", out_basefmt); @@ -3199,8 +3202,25 @@ static int img_rebase(int argc, char **argv) qdict_put_bool(options, BDRV_OPT_FORCE_SHARE, true); } =20 - blk_new_backing =3D blk_new_open(out_baseimg, NULL, + overlay_filename =3D bs->exact_filename[0] ? bs->exact_filename + : bs->filename; + out_real_path =3D g_malloc(PATH_MAX); + + bdrv_get_full_backing_filename_from_filename(overlay_filename, + out_baseimg, + out_real_path, + PATH_MAX, + &local_err); + if (local_err) { + error_reportf_err(local_err, + "Could not resolve backing filename: "); + ret =3D -1; + goto out; + } + + blk_new_backing =3D blk_new_open(out_real_path, NULL, options, src_flags, &local_err); + g_free(out_real_path); if (!blk_new_backing) { error_reportf_err(local_err, "Could not open new backing file '%s': ", --=20 2.14.3