This is a general function for making a filename that is relative to a
certain BDS absolute.
It calls bdrv_get_full_backing_filename_from_filename() for now, but
that will be changed in a follow-up patch.
Signed-off-by: Max Reitz <mre...@redhat.com>
Reviewed-by: Alberto Garcia <be...@igalia.com>
---
block.c | 27 ++++++++++++++++++++-------
1 file changed, 20 insertions(+), 7 deletions(-)
diff --git a/block.c b/block.c
index 369c8fa027..6606eeb7f4 100644
--- a/block.c
+++ b/block.c
@@ -319,16 +319,29 @@ char *bdrv_get_full_backing_filename_from_filename(const
char *backed,
}
}
-char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp)
+/*
+ * If @filename is empty or NULL, this function returns NULL without
+ * setting @errp. In all other cases, NULL will only be returned with
+ * @errp set.
+ */
+static char *bdrv_make_absolute_filename(BlockDriverState *relative_to,
+ const char *filename, Error **errp)
{
- char *backed;
+ char *bs_filename;
- bdrv_refresh_filename(bs);
+ bdrv_refresh_filename(relative_to);
+
+ bs_filename = relative_to->exact_filename[0]
+ ? relative_to->exact_filename
+ : relative_to->filename;
- backed = bs->exact_filename[0] ? bs->exact_filename : bs->filename;
- return bdrv_get_full_backing_filename_from_filename(backed,
- bs->backing_file,
- errp);
+ return bdrv_get_full_backing_filename_from_filename(bs_filename,
+ filename ?: "", errp);
+}
+
+char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp)
+{
+ return bdrv_make_absolute_filename(bs, bs->backing_file, errp);
}
void bdrv_register(BlockDriver *bdrv)
--
2.17.1
