From patchwork Sun May 18 09:01:02 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: lijun X-Patchwork-Id: 349984 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 990841400D2 for ; Sun, 18 May 2014 19:02:08 +1000 (EST) Received: from localhost ([::1]:42827 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wlwyr-0003O8-OL for incoming@patchwork.ozlabs.org; Sun, 18 May 2014 05:02:05 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60791) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WlwyU-00036c-Ls for qemu-devel@nongnu.org; Sun, 18 May 2014 05:01:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WlwyL-0002kw-JR for qemu-devel@nongnu.org; Sun, 18 May 2014 05:01:42 -0400 Received: from mail-pa0-x229.google.com ([2607:f8b0:400e:c03::229]:34861) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WlwyL-0002ks-BU for qemu-devel@nongnu.org; Sun, 18 May 2014 05:01:33 -0400 Received: by mail-pa0-f41.google.com with SMTP id lj1so4412676pab.14 for ; Sun, 18 May 2014 02:01:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id; bh=PtGwR60cXHwtnEA5zbJGO+xFdkOCjAMFGXYmX+i98Ho=; b=fVD/DS2fArfJeV8WAywBhWo3zlGAdmHmjDlAt2HjkOoQMYwh786t4lsZOw+TfDx6TM v11Yee0iZZe535n99QM+y4E9f478f0pHP8Z5HmYYUmPVe0MrZpiZWPHqiMcbT/Z0nGHL 0skE8FJ/p+bAfEf6GoWaok3kVjqypboZHKV+7/C5/1yNr7e7cWJ4qarUMfv92FTeMi09 Mz3i6TUOE7z78FPyDPAhsCJylF/v4VtHX6sLoWBoWpocnQ6c3/OMkgLCd9dnVVhXr7uW d/C2kYt18t5OKJn4mG9dDkx8vvmkp/pytruuMe5o3VC8jUrJfPYWiyQYtHrSvpJQlBzQ 9Mrg== X-Received: by 10.68.161.131 with SMTP id xs3mr34283669pbb.16.1400403691514; Sun, 18 May 2014 02:01:31 -0700 (PDT) Received: from localhost ([125.39.9.139]) by mx.google.com with ESMTPSA id tf10sm23765814pbc.70.2014.05.18.02.01.25 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 18 May 2014 02:01:30 -0700 (PDT) From: Jun Li To: kwolf@redhat.com, stefanha@redhat.com, famz@redhat.com, juli@redhat.com, junmuzi@gmail.com Date: Sun, 18 May 2014 17:01:02 +0800 Message-Id: <1400403662-12446-1-git-send-email-junmuzi@gmail.com> X-Mailer: git-send-email 1.9.0 X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2607:f8b0:400e:c03::229 Cc: qemu-devel@nongnu.org Subject: [Qemu-devel] [PATCH v4] snapshot: fixed bdrv_get_full_backing_filename can not get correct full_backing_filename X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org This patch fixed bdrv_get_full_backing_filename can not calculate the correct full path name for backing_file via path_combine. Such as: create a snapshot chain: $BASE_IMG<-sn1<-sn2 backing file is : /home/wookpecker/img.qcow2 sn1 : /home/woodpecker/tmp/sn1 sn2 : /home/woodpecker/tmp/sn2 when create sn2, path_combine can not got a correct path for $BASE_IMG. In this patch, will check the backing_filename is a symlink or not firstly, then return the full(absolute) path via realpath. Signed-off-by: Jun Li --- This is v4 of the patch. This version is the same with v3. Only difference is the commit description. What does this patch has fixed, please ref following bug(it gives the detailed description): https://bugzilla.redhat.com/show_bug.cgi?id=1084302 --- block.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/block.c b/block.c index c90c71a..d163a8c 100644 --- a/block.c +++ b/block.c @@ -304,10 +304,26 @@ void path_combine(char *dest, int dest_size, void bdrv_get_full_backing_filename(BlockDriverState *bs, char *dest, size_t sz) { + struct stat sb; + char *linkname; + if (bs->backing_file[0] == '\0' || path_has_protocol(bs->backing_file)) { pstrcpy(dest, sz, bs->backing_file); } else { - path_combine(dest, sz, bs->filename, bs->backing_file); + if (lstat(bs->backing_file, &sb) == -1) { + perror("lstat"); + exit(EXIT_FAILURE); + } + + /* Check linkname is a link or not */ + if (S_ISLNK(sb.st_mode)) { + linkname = malloc(sb.st_size + 1); + readlink(bs->backing_file, linkname, sb.st_size + 1); + linkname[sb.st_size] = '\0'; + realpath(linkname, dest); + } else { + realpath(bs->backing_file, dest); + } } }