The discriminator for anonymous unions is the data type. This allows to
have a union type that allows both of these:
{ 'file': 'my_existing_block_device_id' }
{ 'file': { 'filename': '/tmp/mydisk.qcow2', 'read-only': true } }
Unions like this are specified in the schema with an empty dict as
discriminator. For this example you could take:
{ 'union': 'BlockRef',
'discriminator': {},
'data': { 'definition': 'BlockOptions',
'reference': 'str' } }
{ 'type': 'ExampleObject',
'data: { 'file': 'BlockRef' } }
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Known bugs in to_json():
* A start byte for a three-byte sequence followed by less than two
continuation bytes is split into one-byte sequences.
* Start bytes for sequences longer than three bytes get misinterpreted
as start bytes for three-byte sequences. Continuation bytes beyond
byte three become one-byte sequences.
This means all characters outside the BMP are decoded incorrectly.
* One-byte sequences with the MSB are put into the JSON string
verbatim when char is unsigned, producing invalid UTF-8. When char
is signed, they're replaced by "\\uFFFF" instead.
This includes \xFE, \xFF, and stray continuation bytes.
* Overlong sequences are happily accepted, unless screwed up by the
bugs above.
* Likewise, sequences encoding surrogate code points or noncharacters.
* Unlike other control characters, ASCII DEL is not escaped. Except
in overlong encodings.
My rewrite fixes them as follows:
* Malformed UTF-8 sequences are replaced.
Except the overlong encoding \xC0\x80 of U+0000 is still accepted.
Permits embedding NUL characters in C strings. This trick is known
as "Modified UTF-8".
* Sequences encoding code points beyond Unicode range are replaced.
* Sequences encoding code points beyond the BMP produce a surrogate
pair.
* Sequences encoding surrogate code points are replaced.
* Sequences encoding noncharacters are replaced.
* ASCII DEL is now always escaped.
The replacement character is U+FFFD.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Kevin Wolf
Markus Armbruster
Paolo Bonzini