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[Qemu-devel] [PATCH 15/16] block/parallels: support read-only parallels
From: |
Denis V. Lunev |
Subject: |
[Qemu-devel] [PATCH 15/16] block/parallels: support read-only parallels snapshots |
Date: |
Mon, 15 Dec 2014 11:28:00 +0300 |
This patch reads snapshot information from the XML descriptor file.
The lastest snapshot (read-write one) could be located using the
following rules:
GUID could be used as a source to locate leaf in the snapshot tree:
- TopGUID tag is specified in the XML file
- {704718E1-2314-44c8-9087-D78ED36B0F4E} snapshot is present. Used for
backups by Parallels
- {5FBAABE3-6958-40ff-92A7-860E329AAB41} snapshot
Without one of the snapshots above disk image is invalid.
Snapshots are read from top to bottom placing them into linear array,
which is already properly handled at the moment.
Signed-off-by: Denis V. Lunev <address@hidden>
CC: Jeff Cody <address@hidden>
CC: Kevin Wolf <address@hidden>
CC: Stefan Hajnoczi <address@hidden>
---
block/parallels.c | 102 +++++++++++++++++++++++++++++++++++++++++-------------
1 file changed, 77 insertions(+), 25 deletions(-)
diff --git a/block/parallels.c b/block/parallels.c
index d1b52f3..93a8498 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -42,6 +42,10 @@
#define HEADER_VERSION 2
#define HEADER_SIZE 64
+#define CURRENT_SNAP_ID "{5FBAABE3-6958-40ff-92A7-860E329AAB41}"
+#define BACKUP_SNAP_ID "{704718E1-2314-44c8-9087-D78ED36B0F4E}"
+
+
// always little-endian
struct parallels_header {
char magic[16]; // "WithoutFreeSpace"
@@ -239,13 +243,34 @@ static const char *xml_get_text(xmlNode *node, ...)
return NULL;
}
+static xmlNode *xml_find_snapshot(xmlNode *snaps, const char *guid)
+{
+ if (guid == NULL) {
+ return NULL;
+ }
+
+ for (snaps = snaps->children; snaps != NULL; snaps = snaps->next) {
+ const char *id;
+ if (snaps->type != XML_ELEMENT_NODE) {
+ continue;
+ }
+ id = xml_get_text(snaps, "GUID", NULL);
+
+ if (!xmlStrcasecmp((const xmlChar *)guid, (const xmlChar *)id)) {
+ return snaps;
+ }
+ }
+ return NULL;
+}
+
static int parallels_open_xml(BlockDriverState *bs, int flags, Error **errp)
{
- int size, ret;
+ int ret, size, i;
xmlDoc *doc = NULL;
- xmlNode *root, *image;
+ xmlNode *root, *storage, *snaps;
char *xml = NULL, *endptr;
const char *data;
+ const char *leaf_snap;
char image_path[PATH_MAX];
Error *local_err = NULL;
BDRVParallelsState *s = bs->opaque;
@@ -300,14 +325,47 @@ static int parallels_open_xml(BlockDriverState *bs, int
flags, Error **errp)
}
}
- image = xml_seek(root, "StorageData", "Storage", "Image", NULL);
- data = ""; /* make gcc happy */
- for (size = 0; image != NULL; image = image->next) {
- if (image->type != XML_ELEMENT_NODE) {
- continue;
+ snaps = xml_seek(root, "Snapshots", NULL);
+
+ leaf_snap = xml_get_text(snaps, "TopGUID", NULL);
+ if (leaf_snap != NULL && xml_find_snapshot(snaps, leaf_snap) == NULL) {
+ goto fail;
+ } else if (xml_find_snapshot(snaps, BACKUP_SNAP_ID) != NULL) {
+ leaf_snap = BACKUP_SNAP_ID;
+ } else if (xml_find_snapshot(snaps, CURRENT_SNAP_ID) != NULL) {
+ leaf_snap = CURRENT_SNAP_ID;
+ } else {
+ goto fail;
+ }
+
+ data = leaf_snap;
+ for (s->snaps_count = 0; data != NULL; s->snaps_count++) {
+ xmlNode *node = xml_find_snapshot(snaps, data);
+ if (node == NULL) {
+ break;
+ }
+ data = xml_get_text(node, "ParentGUID", NULL);
+ }
+ if (s->snaps_count == 0) {
+ goto fail;
+ }
+ s->snaps = g_malloc0(sizeof(ParallelsSnapshot) * s->snaps_count);
+
+ storage = xml_seek(root, "StorageData", "Storage", NULL);
+ if (storage == NULL) {
+ goto fail;
+ }
+
+ data = leaf_snap;
+ for (i = 0; i < s->snaps_count; i++) {
+ int64_t total_sectors;
+ xmlNode *image = xml_find_snapshot(storage, data);
+ xmlNode *snap = xml_find_snapshot(snaps, data);
+
+ if (image == NULL || snap == NULL) {
+ goto fail;
}
- size++;
data = xml_get_text(image, "Type", NULL);
if (data != NULL && strcmp(data, "Compressed")) {
error_setg(errp, "Only compressed Parallels images are supported");
@@ -318,32 +376,26 @@ static int parallels_open_xml(BlockDriverState *bs, int
flags, Error **errp)
if (data == NULL) {
goto fail;
}
- }
- /* Images with more than 1 snapshots are not supported at the moment */
- if (size != 1) {
- error_setg(errp, "Parallels images with snapshots are not supported");
- goto done;
- }
- s->snaps_count = size;
- s->snaps = g_malloc0(sizeof(ParallelsSnapshot) * s->snaps_count);
+ path_combine(image_path, sizeof(image_path), bs->file->filename, data);
- path_combine(image_path, sizeof(image_path), bs->file->filename, data);
+ ret = bdrv_open(&s->snaps[i].file, image_path, NULL, NULL,
+ flags | BDRV_O_PROTOCOL, NULL, &local_err);
+ if (ret < 0) {
+ error_setg_errno(errp, -ret, "Could not open '%s': %s",
+ image_path, error_get_pretty(local_err));
+ error_free(local_err);
+ goto done;
+ }
- ret = bdrv_open(&s->snaps[0].file, image_path, NULL, NULL,
- flags | BDRV_O_PROTOCOL, NULL, &local_err);
- if (ret < 0) {
- error_setg_errno(errp, -ret, "Could not open '%s': %s",
- image_path, error_get_pretty(local_err));
- error_free(local_err);
- } else {
- int64_t total_sectors;
ret = parallels_open_image(s->snaps, &total_sectors, errp);
if (bs->total_sectors != total_sectors) {
error_setg(errp, "Invalid image: wrong total sectors");
ret = -EINVAL;
goto done;
}
+
+ data = xml_get_text(snap, "ParentGUID", NULL);
}
done:
--
1.9.1
- Re: [Qemu-devel] [PATCH 04/16] iotests: simple parallels XML disk descriptor file test added, (continued)
- [Qemu-devel] [PATCH 05/16] block/parallels: support padded Parallels images, Denis V. Lunev, 2014/12/15
- [Qemu-devel] [PATCH 06/16] iotests: padded parallels image test, Denis V. Lunev, 2014/12/15
- [Qemu-devel] [PATCH 03/16] iotests, parallels: quote TEST_IMG in 076 test to be path-safe, Denis V. Lunev, 2014/12/15
- [Qemu-devel] [PATCH 16/16] iotests: testcase parallels image with snapshots, Denis V. Lunev, 2014/12/15
- [Qemu-devel] [PATCH 02/16] block/parallels: allow to specify DiskDescriptor.xml instead of image file, Denis V. Lunev, 2014/12/15
- [Qemu-devel] [PATCH 15/16] block/parallels: support read-only parallels snapshots,
Denis V. Lunev <=
- [Qemu-devel] [PATCH 13/16] block/parallels: read disk size from XML if DiskDescriptor.xml is passed, Denis V. Lunev, 2014/12/15
- [Qemu-devel] [PATCH 14/16] block/parallels: introduce ParallelsSnapshot data structure, Denis V. Lunev, 2014/12/15
- [Qemu-devel] [PATCH 11/16] block/parallels: add support for backing files, Denis V. Lunev, 2014/12/15
- [Qemu-devel] [PATCH 10/16] block/parallels: add get_block_status, Denis V. Lunev, 2014/12/15