[Qemu-devel] [PATCH v2 2/3] qom: Avoid unvisited 'id'/'qom-type' in user_creatable_add_opts

[Eric Blake]

A regression in commit 15c2f669e caused us to silently ignore
excess input to the QemuOpts visitor.  Later, commit ea4641
accidentally abused that situation, by removing "qom-type" and
"id" from the corresponding QDict but leaving them defined in
the QemuOpts, when using the pair of containers to create a
user-defined object. Note that since we are already traversing
two separate items (a QDict and a QemuOpts), we are already
able to flag bogus arguments, as in:

$ ./x86_64-softmmu/qemu-system-x86_64 -nodefaults -nographic -qmp stdio -object 
memory-backend-ram,id=mem1,size=4k,bogus=huh
qemu-system-x86_64: -object memory-backend-ram,id=mem1,size=4k,bogus=huh: 
Property '.bogus' not found

So the only real concern is that when we re-enable strict checking
in the QemuOpts visitor, we do not want to start flagging the two
leftover keys as unvisited.  Rearrange the code to clean out the
QemuOpts listing in advance, rather than removing items from the
QDict.  Since "qom-type" is usually an automatic implicit default,
we don't have to restore it; but "id" has to be put back (requiring
us to cast away a const).

CC: address@hidden
Signed-off-by: Eric Blake <address@hidden>

---
v2: new patch
---
 qom/object_interfaces.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/qom/object_interfaces.c b/qom/object_interfaces.c
index 03a95c3..cc9a694 100644
--- a/qom/object_interfaces.c
+++ b/qom/object_interfaces.c
@@ -114,7 +114,7 @@ Object *user_creatable_add_opts(QemuOpts *opts, Error 
**errp)
     QDict *pdict;
     Object *obj;
     const char *id = qemu_opts_id(opts);
-    const char *type = qemu_opt_get(opts, "qom-type");
+    char *type = qemu_opt_get_del(opts, "qom-type");

     if (!type) {
         error_setg(errp, QERR_MISSING_PARAMETER, "qom-type");
@@ -125,14 +125,15 @@ Object *user_creatable_add_opts(QemuOpts *opts, Error 
**errp)
         return NULL;
     }

+    qemu_opts_set_id(opts, NULL);
     pdict = qemu_opts_to_qdict(opts, NULL);
-    qdict_del(pdict, "qom-type");
-    qdict_del(pdict, "id");

     v = opts_visitor_new(opts);
     obj = user_creatable_add_type(type, id, pdict, v, errp);
     visit_free(v);

+    qemu_opts_set_id(opts, (char *) id);
+    g_free(type);
     QDECREF(pdict);
     return obj;
 }
-- 
2.9.3