Re: [Qemu-devel] [PATCH v5 05/18] qapi: add QMP input visitor

[Luiz Capitulino]

On Tue, 12 Jul 2011 08:46:13 -0500
Michael Roth <address@hidden> wrote:

> On 07/12/2011 08:16 AM, Luiz Capitulino wrote:
> > On Mon, 11 Jul 2011 19:05:58 -0500
> > Michael Roth<address@hidden>  wrote:
> >
> >> On 07/07/2011 09:32 AM, Luiz Capitulino wrote:
> >>> On Tue,  5 Jul 2011 08:02:32 -0500
> >>> Michael Roth<address@hidden>   wrote:
> >>>
> >>>> A type of Visiter class that is used to walk a qobject's
> >>>> structure and assign each entry to the corresponding native C type.
> >>>> Command marshaling function will use this to pull out QMP command
> >>>> parameters recieved over the wire and pass them as native arguments
> >>>> to the corresponding C functions.
> >>>>
> >>>> Signed-off-by: Michael Roth<address@hidden>
> >>>> ---
> >>>>    Makefile.objs            |    2 +-
> >>>>    qapi/qmp-input-visitor.c |  264 
> >>>> ++++++++++++++++++++++++++++++++++++++++++++++
> >>>>    qapi/qmp-input-visitor.h |   27 +++++
> >>>>    qerror.h                 |    3 +
> >>>>    4 files changed, 295 insertions(+), 1 deletions(-)
> >>>>    create mode 100644 qapi/qmp-input-visitor.c
> >>>>    create mode 100644 qapi/qmp-input-visitor.h
> >>>>
> >>>> diff --git a/Makefile.objs b/Makefile.objs
> >>>> index 0077014..997ecef 100644
> >>>> --- a/Makefile.objs
> >>>> +++ b/Makefile.objs
> >>>> @@ -375,7 +375,7 @@ libcacard-y = cac.o event.o vcard.o vreader.o 
> >>>> vcard_emul_nss.o vcard_emul_type.o
> >>>>    ######################################################################
> >>>>    # qapi
> >>>>
> >>>> -qapi-nested-y = qapi-visit-core.o
> >>>> +qapi-nested-y = qapi-visit-core.o qmp-input-visitor.o
> >>>>    qapi-obj-y = $(addprefix qapi/, $(qapi-nested-y))
> >>>>
> >>>>    vl.o: QEMU_CFLAGS+=$(GPROF_CFLAGS)
> >>>> diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
> >>>> new file mode 100644
> >>>> index 0000000..80912bb
> >>>> --- /dev/null
> >>>> +++ b/qapi/qmp-input-visitor.c
> >>>> @@ -0,0 +1,264 @@
> >>>> +/*
> >>>> + * Input Visitor
> >>>> + *
> >>>> + * Copyright IBM, Corp. 2011
> >>>> + *
> >>>> + * Authors:
> >>>> + *  Anthony Liguori<address@hidden>
> >>>> + *
> >>>> + * This work is licensed under the terms of the GNU LGPL, version 2.1 
> >>>> or later.
> >>>> + * See the COPYING.LIB file in the top-level directory.
> >>>> + *
> >>>> + */
> >>>> +
> >>>> +#include "qmp-input-visitor.h"
> >>>> +#include "qemu-queue.h"
> >>>> +#include "qemu-common.h"
> >>>> +#include "qemu-objects.h"
> >>>> +#include "qerror.h"
> >>>> +
> >>>> +#define QIV_STACK_SIZE 1024
> >>>> +
> >>>> +typedef struct StackObject
> >>>> +{
> >>>> +    const QObject *obj;
> >>>> +    const  QListEntry *entry;
> >>>> +} StackObject;
> >>>> +
> >>>> +struct QmpInputVisitor
> >>>> +{
> >>>> +    Visitor visitor;
> >>>> +    const QObject *obj;
> >>>> +    StackObject stack[QIV_STACK_SIZE];
> >>>> +    int nb_stack;
> >>>> +};
> >>>> +
> >>>> +static QmpInputVisitor *to_qiv(Visitor *v)
> >>>> +{
> >>>> +    return container_of(v, QmpInputVisitor, visitor);
> >>>> +}
> >>>> +
> >>>> +static const QObject *qmp_input_get_object(QmpInputVisitor *qiv, const 
> >>>> char *name)
> >>>> +{
> >>>> +    const QObject *qobj;
> >>>> +
> >>>> +    if (qiv->nb_stack == 0) {
> >>>> +        qobj = qiv->obj;
> >>>> +    } else {
> >>>> +        qobj = qiv->stack[qiv->nb_stack - 1].obj;
> >>>> +    }
> >>>> +
> >>>> +    if (name&&   qobject_type(qobj) == QTYPE_QDICT) {
> >>>> +        return qdict_get(qobject_to_qdict(qobj), name);
> >>>> +    } else if (qiv->nb_stack>   0&&   qobject_type(qobj) == 
> >>>> QTYPE_QLIST) {
> >>>> +        return qlist_entry_obj(qiv->stack[qiv->nb_stack - 1].entry);
> >>>> +    }
> >>>> +
> >>>> +    return qobj;
> >>>> +}
> >>>> +
> >>>> +static void qmp_input_push(QmpInputVisitor *qiv, const QObject *obj, 
> >>>> Error **errp)
> >>>> +{
> >>>> +    qiv->stack[qiv->nb_stack].obj = obj;
> >>>> +    if (qobject_type(obj) == QTYPE_QLIST) {
> >>>> +        qiv->stack[qiv->nb_stack].entry = 
> >>>> qlist_first(qobject_to_qlist(obj));
> >>>> +    }
> >>>> +    qiv->nb_stack++;
> >>>> +
> >>>> +    if (qiv->nb_stack>= QIV_STACK_SIZE) {
> >>>> +        error_set(errp, QERR_BUFFER_OVERRUN);
> >>>> +        return;
> >>>> +    }
> >>>> +}
> >>>> +
> >>>> +static void qmp_input_pop(QmpInputVisitor *qiv, Error **errp)
> >>>> +{
> >>>> +    qiv->nb_stack--;
> >>>> +    if (qiv->nb_stack<   0) {
> >>>> +        error_set(errp, QERR_BUFFER_OVERRUN);
> >>>> +        return;
> >>>> +    }
> >>>> +}
> >>>> +
> >>>> +static void qmp_input_start_struct(Visitor *v, void **obj, const char 
> >>>> *kind, const char *name, size_t size, Error **errp)
> >>>> +{
> >>>> +    QmpInputVisitor *qiv = to_qiv(v);
> >>>> +    const QObject *qobj = qmp_input_get_object(qiv, name);
> >>>> +
> >>>> +    if (!qobj || qobject_type(qobj) != QTYPE_QDICT) {
> >>>> +        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : 
> >>>> "null", "QDict");
> >>>> +        return;
> >>>> +    }
> >>>> +
> >>>> +    qmp_input_push(qiv, qobj, errp);
> >>>> +    if (error_is_set(errp)) {
> >>>> +        return;
> >>>> +    }
> >>>> +
> >>>> +    if (obj) {
> >>>> +        *obj = qemu_mallocz(size);
> >>>> +    }
> >>>> +}
> >>>> +
> >>>> +static void qmp_input_end_struct(Visitor *v, Error **errp)
> >>>> +{
> >>>> +    QmpInputVisitor *qiv = to_qiv(v);
> >>>> +
> >>>> +    qmp_input_pop(qiv, errp);
> >>>> +}
> >>>> +
> >>>> +static void qmp_input_start_list(Visitor *v, const char *name, Error 
> >>>> **errp)
> >>>> +{
> >>>> +    QmpInputVisitor *qiv = to_qiv(v);
> >>>> +    const QObject *qobj = qmp_input_get_object(qiv, name);
> >>>> +
> >>>> +    if (!qobj || qobject_type(qobj) != QTYPE_QLIST) {
> >>>> +        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : 
> >>>> "null", "list");
> >>>> +        return;
> >>>> +    }
> >>>> +
> >>>> +    qmp_input_push(qiv, qobj, errp);
> >>>> +}
> >>>> +
> >>>> +static GenericList *qmp_input_next_list(Visitor *v, GenericList **list, 
> >>>> Error **errp)
> >>>> +{
> >>>> +    QmpInputVisitor *qiv = to_qiv(v);
> >>>> +    GenericList *entry;
> >>>> +    StackObject *so =&qiv->stack[qiv->nb_stack - 1];
> >>>> +
> >>>> +    if (so->entry == NULL) {
> >>>> +        return NULL;
> >>>> +    }
> >>>> +
> >>>> +    entry = qemu_mallocz(sizeof(*entry));
> >>>> +    if (*list) {
> >>>> +        so->entry = qlist_next(so->entry);
> >>>> +        if (so->entry == NULL) {
> >>>> +            qemu_free(entry);
> >>>> +            return NULL;
> >>>> +        }
> >>>> +        (*list)->next = entry;
> >>>> +    }
> >>>> +    *list = entry;
> >>>> +
> >>>> +
> >>>> +    return entry;
> >>>> +}
> >>>> +
> >>>> +static void qmp_input_end_list(Visitor *v, Error **errp)
> >>>> +{
> >>>> +    QmpInputVisitor *qiv = to_qiv(v);
> >>>> +
> >>>> +    qmp_input_pop(qiv, errp);
> >>>> +}
> >>>> +
> >>>> +static void qmp_input_type_int(Visitor *v, int64_t *obj, const char 
> >>>> *name, Error **errp)
> >>>> +{
> >>>> +    QmpInputVisitor *qiv = to_qiv(v);
> >>>> +    const QObject *qobj = qmp_input_get_object(qiv, name);
> >>>> +
> >>>> +    if (!qobj || qobject_type(qobj) != QTYPE_QINT) {
> >>>> +        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : 
> >>>> "null", "integer");
> >>>> +        return;
> >>>> +    }
> >>>> +
> >>>> +    *obj = qint_get_int(qobject_to_qint(qobj));
> >>>> +}
> >>>> +
> >>>> +static void qmp_input_type_bool(Visitor *v, bool *obj, const char 
> >>>> *name, Error **errp)
> >>>> +{
> >>>> +    QmpInputVisitor *qiv = to_qiv(v);
> >>>> +    const QObject *qobj = qmp_input_get_object(qiv, name);
> >>>> +
> >>>> +    if (!qobj || qobject_type(qobj) != QTYPE_QBOOL) {
> >>>> +        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : 
> >>>> "null", "boolean");
> >>>> +        return;
> >>>> +    }
> >>>> +
> >>>> +    *obj = qbool_get_int(qobject_to_qbool(qobj));
> >>>> +}
> >>>> +
> >>>> +static void qmp_input_type_str(Visitor *v, char **obj, const char 
> >>>> *name, Error **errp)
> >>>> +{
> >>>> +    QmpInputVisitor *qiv = to_qiv(v);
> >>>> +    const QObject *qobj = qmp_input_get_object(qiv, name);
> >>>> +
> >>>> +    if (!qobj || qobject_type(qobj) != QTYPE_QSTRING) {
> >>>> +        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : 
> >>>> "null", "string");
> >>>> +        return;
> >>>> +    }
> >>>> +
> >>>> +    *obj = qemu_strdup(qstring_get_str(qobject_to_qstring(qobj)));
> >>>> +}
> >>>> +
> >>>> +static void qmp_input_type_number(Visitor *v, double *obj, const char 
> >>>> *name, Error **errp)
> >>>> +{
> >>>> +    QmpInputVisitor *qiv = to_qiv(v);
> >>>> +    const QObject *qobj = qmp_input_get_object(qiv, name);
> >>>> +
> >>>> +    if (!qobj || qobject_type(qobj) != QTYPE_QFLOAT) {
> >>>> +        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : 
> >>>> "null", "double");
> >>>> +        return;
> >>>> +    }
> >>>> +
> >>>> +    *obj = qfloat_get_double(qobject_to_qfloat(qobj));
> >>>> +}
> >>>> +
> >>>> +static void qmp_input_type_enum(Visitor *v, int *obj, const char *kind, 
> >>>> const char *name, Error **errp)
> >>>> +{
> >>>> +    int64_t value;
> >>>> +    qmp_input_type_int(v,&value, name, errp);
> >>>> +    *obj = value;
> >>>> +}
> >>>> +
> >>>> +static void qmp_input_start_optional(Visitor *v, bool *present,
> >>>> +                                     const char *name, Error **errp)
> >>>> +{
> >>>> +    QmpInputVisitor *qiv = to_qiv(v);
> >>>> +    const QObject *qobj = qmp_input_get_object(qiv, name);
> >>>> +
> >>>> +    if (!qobj) {
> >>>> +        *present = false;
> >>>> +        return;
> >>>> +    }
> >>>> +
> >>>> +    *present = true;
> >>>> +}
> >>>> +
> >>>> +static void qmp_input_end_optional(Visitor *v, Error **errp)
> >>>> +{
> >>>> +}
> >>>> +
> >>>> +Visitor *qmp_input_get_visitor(QmpInputVisitor *v)
> >>>> +{
> >>>> +    return&v->visitor;
> >>>> +}
> >>>> +
> >>>> +void qmp_input_visitor_cleanup(QmpInputVisitor *v)
> >>>> +{
> >>>
> >>> We talked about doing a qobject_incref(v->obj) in qmp_input_visitor_new() 
> >>> and
> >>> decrefing here.
> >>>
> >>
> >> I think it was either that, or just making the QObject arg to
> >> qmp_input_visitor_new() const, to make it clear it was caller-freed.
> >
> > No, because (at least theoretically) a client could free it before walking
> > the struct with the visitor functions. The rule is: if you store it, you
> > have to increment its reference or get its ownership.
> >
> >
> 
> Makes sense. Sucks to have to remove the const for that though...would a 
> temporary cast to non-const be acceptable in a case like this?

Well, if we have to change it, it's not const anymore :)

> 
> >>
> >>>> +    qemu_free(v);
> >>>> +}
> >>>> +
> >>>> +QmpInputVisitor *qmp_input_visitor_new(const QObject *obj)
> >>>> +{
> >>>> +    QmpInputVisitor *v;
> >>>> +
> >>>> +    v = qemu_mallocz(sizeof(*v));
> >>>> +
> >>>> +    v->visitor.start_struct = qmp_input_start_struct;
> >>>> +    v->visitor.end_struct = qmp_input_end_struct;
> >>>> +    v->visitor.start_list = qmp_input_start_list;
> >>>> +    v->visitor.next_list = qmp_input_next_list;
> >>>> +    v->visitor.end_list = qmp_input_end_list;
> >>>> +    v->visitor.type_enum = qmp_input_type_enum;
> >>>> +    v->visitor.type_int = qmp_input_type_int;
> >>>> +    v->visitor.type_bool = qmp_input_type_bool;
> >>>> +    v->visitor.type_str = qmp_input_type_str;
> >>>> +    v->visitor.type_number = qmp_input_type_number;
> >>>> +    v->visitor.start_optional = qmp_input_start_optional;
> >>>> +    v->visitor.end_optional = qmp_input_end_optional;
> >>>> +
> >>>> +    v->obj = obj;
> >>>> +
> >>>> +    return v;
> >>>> +}
> >>>> diff --git a/qapi/qmp-input-visitor.h b/qapi/qmp-input-visitor.h
> >>>> new file mode 100644
> >>>> index 0000000..0f77916
> >>>> --- /dev/null
> >>>> +++ b/qapi/qmp-input-visitor.h
> >>>> @@ -0,0 +1,27 @@
> >>>> +/*
> >>>> + * Input Visitor
> >>>> + *
> >>>> + * Copyright IBM, Corp. 2011
> >>>> + *
> >>>> + * Authors:
> >>>> + *  Anthony Liguori<address@hidden>
> >>>> + *
> >>>> + * This work is licensed under the terms of the GNU LGPL, version 2.1 
> >>>> or later.
> >>>> + * See the COPYING.LIB file in the top-level directory.
> >>>> + *
> >>>> + */
> >>>> +
> >>>> +#ifndef QMP_INPUT_VISITOR_H
> >>>> +#define QMP_INPUT_VISITOR_H
> >>>> +
> >>>> +#include "qapi-visit-core.h"
> >>>> +#include "qobject.h"
> >>>> +
> >>>> +typedef struct QmpInputVisitor QmpInputVisitor;
> >>>> +
> >>>> +QmpInputVisitor *qmp_input_visitor_new(const QObject *obj);
> >>>> +void qmp_input_visitor_cleanup(QmpInputVisitor *v);
> >>>> +
> >>>> +Visitor *qmp_input_get_visitor(QmpInputVisitor *v);
> >>>> +
> >>>> +#endif
> >>>> diff --git a/qerror.h b/qerror.h
> >>>> index 16c830d..9a9fa5b 100644
> >>>> --- a/qerror.h
> >>>> +++ b/qerror.h
> >>>> @@ -124,6 +124,9 @@ QError *qobject_to_qerror(const QObject *obj);
> >>>>    #define QERR_JSON_PARSE_ERROR \
> >>>>        "{ 'class': 'JSONParseError', 'data': { 'message': %s } }"
> >>>>
> >>>> +#define QERR_BUFFER_OVERRUN \
> >>>> +    "{ 'class': 'BufferOverrun', 'data': {} }"
> >>>> +
> >>>
> >>> You also have to add an entry in qerror.c. I slightly prefer 
> >>> NotEnoughMemory,
> >>> but BufferOverrrun is probably fine.
> >>>
> >>>>    #define QERR_KVM_MISSING_CAP \
> >>>>        "{ 'class': 'KVMMissingCap', 'data': { 'capability': %s, 
> >>>> 'feature': %s } }"
> >>>>
> >>>
> >>
> >
>