From mboxrd@z Thu Jan 1 00:00:00 1970 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) From: Jun Li Date: Sun, 18 May 2014 17:01:02 +0800 Message-Id: <1400403662-12446-1-git-send-email-junmuzi@gmail.com> Subject: [Qemu-devel] [PATCH v4] snapshot: fixed bdrv_get_full_backing_filename can not get correct full_backing_filename List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: kwolf@redhat.com, stefanha@redhat.com, famz@redhat.com, juli@redhat.com, junmuzi@gmail.com Cc: qemu-devel@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); + } } } -- 1.9.0