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authorEric Blake <eblake@redhat.com>2016-04-28 15:45:16 -0600
committerMarkus Armbruster <armbru@redhat.com>2016-05-12 09:47:54 +0200
commited8415351941715f606749d6cdd64553b0de3f01 (patch)
treee677baf2d98a6e1a1e8b39a85c5cbaeaf1d5de91 /docs
parente5826a2fd727f0be54a81083f31fe02a275465cd (diff)
qapi-commands: Wrap argument visit in visit_start_struct
The qmp-input visitor was allowing callers to play rather fast and loose: when visiting a QDict, you could grab members of the root dictionary without first pushing into the dict; among the culprit callers was the generated marshal code on the 'arguments' dictionary of a QMP command. But we are about to tighten the input visitor, at which point the generated marshal code MUST follow the same paradigms as everyone else, of pushing into the struct before grabbing its keys. Generated code grows as follows: |@@ -515,7 +641,12 @@ void qmp_marshal_blockdev_backup(QDict * | BlockdevBackup arg = {0}; | | v = qmp_input_get_visitor(qiv); |+ visit_start_struct(v, NULL, NULL, 0, &err); |+ if (err) { |+ goto out; |+ } | visit_type_BlockdevBackup_members(v, &arg, &err); |+ visit_end_struct(v, err ? NULL : &err); | if (err) { | goto out; | } |@@ -527,7 +715,9 @@ out: | qmp_input_visitor_cleanup(qiv); | qdv = qapi_dealloc_visitor_new(); | v = qapi_dealloc_get_visitor(qdv); |+ visit_start_struct(v, NULL, NULL, 0, NULL); | visit_type_BlockdevBackup_members(v, &arg, NULL); |+ visit_end_struct(v, NULL); | qapi_dealloc_visitor_cleanup(qdv); | } The use of 'err ? NULL : &err' is temporary; a later patch will clean that up when it splits visit_end_struct(). Prior to this patch, the fact that there was no final visit_end_struct() meant that even though we are using a strict input visit, the marshalling code was not detecting excess input at the top level (only in nested levels). Fortunately, we have code in monitor.c:qmp_check_client_args() that also checks for no excess arguments at the top level. But as the generated code is more compact than the manual check, a later patch will clean up monitor.c to drop the redundancy added here. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1461879932-9020-9-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
Diffstat (limited to 'docs')
-rw-r--r--docs/qapi-code-gen.txt7
1 files changed, 7 insertions, 0 deletions
diff --git a/docs/qapi-code-gen.txt b/docs/qapi-code-gen.txt
index 4a917f9e25..b4ae1be3b4 100644
--- a/docs/qapi-code-gen.txt
+++ b/docs/qapi-code-gen.txt
@@ -1002,7 +1002,12 @@ Example:
UserDefOneList *arg1 = NULL;
v = qmp_input_get_visitor(qiv);
+ visit_start_struct(v, NULL, NULL, 0, &err);
+ if (err) {
+ goto out;
+ }
visit_type_UserDefOneList(v, "arg1", &arg1, &err);
+ visit_end_struct(v, err ? NULL : &err);
if (err) {
goto out;
}
@@ -1019,7 +1024,9 @@ Example:
qmp_input_visitor_cleanup(qiv);
qdv = qapi_dealloc_visitor_new();
v = qapi_dealloc_get_visitor(qdv);
+ visit_start_struct(v, NULL, NULL, 0, NULL);
visit_type_UserDefOneList(v, "arg1", &arg1, NULL);
+ visit_end_struct(v, NULL);
qapi_dealloc_visitor_cleanup(qdv);
}