block: JSON filenames and relative backing files
When using a relative backing file name, qemu needs to know the
directory of the top image file. For JSON filenames, such a directory
cannot be easily determined (e.g. how do you determine the directory of
a qcow2 BDS directly on top of a quorum BDS?). Therefore, do not allow
relative filenames for the backing file of BDSs only having a JSON
filename.
Furthermore, BDS::exact_filename should be used whenever possible. If
BDS::filename is not equal to BDS::exact_filename, the former will
always be a JSON object.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/block.c b/block.c
index 86f2faa..cf0867c 100644
--- a/block.c
+++ b/block.c
@@ -305,19 +305,28 @@
void bdrv_get_full_backing_filename_from_filename(const char *backed,
const char *backing,
- char *dest, size_t sz)
+ char *dest, size_t sz,
+ Error **errp)
{
- if (backing[0] == '\0' || path_has_protocol(backing)) {
+ if (backing[0] == '\0' || path_has_protocol(backing) ||
+ path_is_absolute(backing))
+ {
pstrcpy(dest, sz, backing);
+ } else if (backed[0] == '\0' || strstart(backed, "json:", NULL)) {
+ error_setg(errp, "Cannot use relative backing file names for '%s'",
+ backed);
} else {
path_combine(dest, sz, backed, backing);
}
}
-void bdrv_get_full_backing_filename(BlockDriverState *bs, char *dest, size_t sz)
+void bdrv_get_full_backing_filename(BlockDriverState *bs, char *dest, size_t sz,
+ Error **errp)
{
- bdrv_get_full_backing_filename_from_filename(bs->filename, bs->backing_file,
- dest, sz);
+ char *backed = bs->exact_filename[0] ? bs->exact_filename : bs->filename;
+
+ bdrv_get_full_backing_filename_from_filename(backed, bs->backing_file,
+ dest, sz, errp);
}
void bdrv_register(BlockDriver *bdrv)
@@ -1225,7 +1234,14 @@
QDECREF(options);
goto free_exit;
} else {
- bdrv_get_full_backing_filename(bs, backing_filename, PATH_MAX);
+ bdrv_get_full_backing_filename(bs, backing_filename, PATH_MAX,
+ &local_err);
+ if (local_err) {
+ ret = -EINVAL;
+ error_propagate(errp, local_err);
+ QDECREF(options);
+ goto free_exit;
+ }
}
if (!bs->drv || !bs->drv->supports_backing) {
