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qapi: dealloc visitor, implement visit_start_union

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If the .data field of a QAPI Union is NULL, we don't need to free
any of the union fields.

Make use of the new visit_start_union interface to access this
information and instruct the generated code to not visit these
fields when this occurs.

Cc: qemu-stable@nongnu.org
Reported-by: Fam Zheng <famz@redhat.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
This commit is contained in:
Michael Roth 2014-09-18 15:36:41 -05:00 committed by Luiz Capitulino
parent cee2dedb85
commit 146db9f919
1 changed files with 26 additions and 0 deletions
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26
qapi/qapi-dealloc-visitor.c
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@ -162,6 +162,31 @@ static void qapi_dealloc_type_enum(Visitor *v, int *obj, const char *strings[],
{
}
/* If there's no data present, the dealloc visitor has nothing to free.
* Thus, indicate to visitor code that the subsequent union fields can
* be skipped. This is not an error condition, since the cleanup of the
* rest of an object can continue unhindered, so leave errp unset in
* these cases.
*
* NOTE: In cases where we're attempting to deallocate an object that
* may have missing fields, the field indicating the union type may
* be missing. In such a case, it's possible we don't have enough
* information to differentiate data_present == false from a case where
* data *is* present but happens to be a scalar with a value of 0.
* This is okay, since in the case of the dealloc visitor there's no
* work that needs to done in either situation.
*
* The current inability in QAPI code to more thoroughly verify a union
* type in such cases will likely need to be addressed if we wish to
* implement this interface for other types of visitors in the future,
* however.
*/
static bool qapi_dealloc_start_union(Visitor *v, bool data_present,
Error **errp)
{
return data_present;
}
Visitor *qapi_dealloc_get_visitor(QapiDeallocVisitor *v)
{
return &v->visitor;
@ -191,6 +216,7 @@ QapiDeallocVisitor *qapi_dealloc_visitor_new(void)
v->visitor.type_str = qapi_dealloc_type_str;
v->visitor.type_number = qapi_dealloc_type_number;
v->visitor.type_size = qapi_dealloc_type_size;
v->visitor.start_union = qapi_dealloc_start_union;
QTAILQ_INIT(&v->stack);