block-export-add argument @name defaults to the value of argument
@node-name.
nbd_export_create() implements this by copying @node_name to @name.
It leaves @has_node_name false, violating the "has_node_name ==
!!node_name" invariant. Unclean. Falls apart when we elide
@has_node_name (next commit): then QAPI frees the same value twice,
once for @node_name and once @name. iotest 307 duly explodes.
Goes back to commit c62d24e906 "blockdev-nbd: Boxed argument type for
nbd-server-add" (v5.0.0). Got moved from qmp_nbd_server_add() to
nbd_export_create() (commit 56ee86261e), then copied back (commit
b6076afcab). Commit 8675cbd68b "nbd: Utilize QAPI_CLONE for type
conversion" (v5.2.0) cleaned up the copy in qmp_nbd_server_add()
noting
Second, our assignment to arg->name is fishy: the generated QAPI code
for qapi_free_NbdServerAddOptions does not visit arg->name if
arg->has_name is false, but if it DID visit it, we would have
introduced a double-free situation when arg is finally freed.
Exactly. However, the copy in nbd_export_create() remained dirty.
Clean it up. Since the value stored in member @name is not actually
used outside this function, use a local variable instead of modifying
the QAPI object.
Signed-off-by: Markus Armbruster<armbru@redhat.com>
Cc: Eric Blake<eblake@redhat.com>
Cc: Vladimir Sementsov-Ogievskiy<vsementsov@yandex-team.ru>
Cc:qemu-block@nongnu.org