block: Add bdrv_make_absolute_filename()

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 <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-13-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
stable-4.0
Max Reitz 2019-02-01 20:29:16 +01:00
parent 6b6833c1b4
commit 9f4793d8f2
1 changed files with 21 additions and 8 deletions

29
block.c
View File

@ -338,16 +338,29 @@ char *bdrv_get_full_backing_filename_from_filename(const char *backed,
}
}
/*
* 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 *bs_filename;
bdrv_refresh_filename(relative_to);
bs_filename = relative_to->exact_filename[0]
? relative_to->exact_filename
: relative_to->filename;
return bdrv_get_full_backing_filename_from_filename(bs_filename,
filename ?: "", errp);
}
char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp)
{
char *backed;
bdrv_refresh_filename(bs);
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_make_absolute_filename(bs, bs->backing_file, errp);
}
void bdrv_register(BlockDriver *bdrv)